Band 34, Heft 1

In this study, different heat treatment cycles such as martempering, austempering, quenching, and quench tempering were applied to American Iron and Steel Institute (AISI) D 3 tool steel. Optical microscopy, scanning electron microscopy, and molecular dynamics (MD) approaches were utilized to evaluate the heat-treated microstructures. Moreover, the hardness and microhardness of the specimens were studied. The austempered specimen showed lower hardness than the partially and fully martempered specimens due to the formation of a bainitic matrix. On the other hand, the hardness loss of the fully martempered specimen was insignificant due to its low-carbon martensite matrix and alloy carbide hardness. Tempering of quenched specimens changed the carbide alloy from M 3 C to M 3 C 7 , increasing the microhardness from 1,150 to 1,756 HV, whereas martensite microhardness decreased from 817 to 485 HV. The observed hardness reduction of the quench-tempered specimen suggests that the matrix part of an alloy significantly contributes to its hardness. The MD simulation results reveal that grain boundaries act as favorable sites for thermal twin formation in the microstructure during the tempering of the quenched specimen. A large concentration of such thermal twins would be another reason for the hardness loss of the tempered specimen.

The impact of locally pozzolanic materials on the activation energy of lime cement, with Grade 32.5, was assessed in the fresh and hardened phases of paste and mortar, respectively. The activation energy is used to represent the relationship between the strength gain of concrete over time and temperature sensitivity. Two proportions of mixed pozzolanic materials, metakaolin (MK) and silica fume (SF), were used as a replacement for cement weight. The first was 5% (MK) and 7% (SF); while the second was 10% (MK) and 15% (SF) as a high replacement level. The activation energy of cement was calculated, as per the ASTM C1074 approach, at 5, 20, and 35°C temperatures. The results showed that the rate of strength development ( k -value) increased in mixes containing pozzolanic material at all temperatures. The activation energy ( E a ) increased in all mixes containing pozzolana but decreased with a high replacement level of pozzolana, because of the filler effect during the hydration progress due to the high surface area of these materials, resulting in loss of strength. The results concluded that using the strength development rate ( k -value), calculated from ASTM C1074, to estimate the concrete strength at any age is valuable and it is very close to the actual values.

Improving the surface quality of products in the mold field is very necessary, because it directly affects their working ability in practice. Electrical discharge machining (EDM) is still a very popular technological solution in this field, and research on Powder-mixed EDM (PMEDM) is still a new research direction and it can overcome the limitations in EDM. In this study, the surface quality after PMEDM using silicon carbide (SiC) powder was studied, and AISID-3 tool steel material was used as the workpiece. The adjustable parameters in PMEDM were investigated, including current (I), gap voltage (Vg), cycle time (CT), duty factor (DF), and powder concentration (PC). To improve the accuracy of the surface roughness (SR) result model, the Response surface methodology (RSM) combined with the Adaptive neuro fuzzy inference system (ANFIS) was used to build the SR problem model. The research results showed that the influence of process parameters on SR was indicated by Analysis of Variance technique, and the calculation model of SR was determined with high accuracy. In addition, the surface layer of AISID-3 tool steel after PMEDM was significantly improved by using PMEDM with SiC powder. The ANFIS approach has inferred that the developed model with low error values of mean squared error, and the size of the micro cracks and craters formed on the machined surface is less in PMEDM, hardness was significantly improved with the increase in SiC PC.

This study presents the experimental results of double shear tests obtained on timber–concrete connection systems. We evaluated the influence of factors such as the shape and diameter of the connector, grade of steel, and wood species on the mechanical shear performance of timber–concrete systems. The mechanical properties, such as the elastic shear strength, slip modulus, and failure mode of the tested specimens, are obtained from the load–slip curves of the push-out tests. The connectors tested are made from high-bond (HB) steels. The diameters used for the connectors are 10 and 12 mm and are of two shapes, straight and 90° head curved; steel grades are S400 and S500. The performance of the connectors has been tested on three species of wood, namely Iroko, Dabema, and Ayous. These solutions are chosen because they are simple to apply in a timber–concrete structure using materials available in the local market. We summarize the results of this work as follows: the systems of connection studies have the ability to respond to shear stresses; the failure mode of the connectors is ductile; and the timber species has an influence on the mechanical shear behaviour of the connectors.

Geopolymer lightweight concrete has been produced using environmentally sustainable materials by completely replacing conventional concrete with ground granulated blast furnace slag (GGBFS) as the binder, manufactured sand as the fine aggregate, and CS as coarse aggregate. The CS are used as a full replacement for natural coarse aggregate in geopolymer concrete (GPCSC) and are compared with the geopolymer concrete containing 100% crushed granite (natural coarse aggregate) used in a control mix (GPCC). The GGBFS binder was activated with sodium silicate (Na 2 SiO 2 ) and sodium hydroxide (NaOH) as alkaline activator solutions (Na 2 SiO 2 /NaOH) with the ratio of 2.5 was taken, and the concentration of NaOH was maintained at 10M for all mixes. The mechanical and microstructural properties of CS concrete were compared with the control mix. Flexural strength, split tensile strength (STS), ultrasonic pulse velocity, bond strength, impact resistance, and elastic modulus of the geopolymer concrete were measured at 28 days, while the compressive strength of the geopolymer concrete was measured at 3, 7, and 28 days under concealed curing at an ambient temperature. Relevant Indian and ASTM standards were used to measure all the above properties. The microstructure analysis shows that the presence of CS weakens the strength of the mix and the structure of the interfacial transition zone. On the contrary, due to the alkali-activated GGBFS binder in geopolymer concrete, the matrix homogeneity improved due to the formation of a three-dimensional aluminosilicate network. Test results show that the compressive strength, STS, flexural strength, bond strength, impact resistance, ultrasonic pulse velocity, and elastic modulus of geopolymer coconut shell concrete (GPCSC) satisfy the structural criteria and can be used as structural-grade lightweight concrete. A comparison was made between conventional geopolymer concrete (GPCC) and lightweight GPCSC in terms of their behaviour with previous literature studies. The findings indicate that GPCSC can be utilized as a structural-grade geopolymer lightweight concrete, offering promising mechanical properties and reduced density. Graphical abstract

Geopolymer technology is widely recognized and extensively tested as a sustainable alternative to conventional cement, with considerable environmental and economic benefits through waste management; however, it remains largely unstudied and underutilized in Algeria. Despite the abundant availability of aluminosilicate materials, there is only limited and incomplete research on pozzolans and metakaolins in the region. This article aims to address this gap by investigating the use of Algerian ground-granulated blast furnace slag (GGBFS) to develop an optimal formulation for producing high-performance geopolymers. To determine the optimal combination of alkaline activators compatible with GGBFS and sand content, a series of experiments were conducted on fresh and hardened GGBFS-based geopolymer mortars (GPMs) to verify properties such as workability, setting time, water absorption, efflorescence stability, and mechanical strength. Techniques used to characterize the microstructure of a subset of geopolymer samples included attenuated total reflectance – Fourier transform infrared spectroscopy, X-ray diffraction, and scanning electron microscopy – energy dispersive X-ray spectroscopy. This research not only emphasizes the environmental benefits of repurposing waste materials but also advances the development of more sustainable and durable GPMs, presenting a promising approach to improving environmental stewardship in material science practices.

This work examines the behavior of using different backing plate materials on weld bead geometry, microhardness, tensile strength, and fracture of 1020 low carbon steel. Autogenous tungsten inert gas welding was performed with and without the use of backing plates. Two different backing plates were tested. It was found that the maximum depth-to-width ratio of 0.63 was obtained when welding was performed without the use of backing plate. It is recommended that backing plates with high thermal conductivity values should be used when faster cooling rates are required; however, if deeper weld penetration is required, the recommendation is not to use any backing plate. The maximum ultimate tensile stress was found to be 412 MPa when welding was performed using 2024 aluminum alloy as a backing plate. On the other hand, the minimum ultimate tensile strength of 373 MPa was obtained when the welding was performed without any backing plate. Using aluminum plates as backing material improved the welded metal strength by only 2%. In addition, the fracture surfaces of the samples were examined by scanning electron microscopy. The use of backing plates depending on their thermal behavior increases brittleness and decreases the ductility of the metals being welded.

In this research work, boron nitride nanosheet (BNS)-reinforced nanoplate is analyzed to evaluate its static bending performance including the effect of flexoelectricity and surface subjected to hydrostatic load, point load, and line load conditions. All edges of the nanoplate have simply supported boundary conditions, and it is transversely loaded from the top plane. The Navier method is employed to obtain the solution of the governing equation, and the static bending performance of the nanoplate is exhibited. The impact of uncertainties in the design variables and application loads have also been analyzed to evaluate the performance-based reliability of the bending response. It is noticed that both surface and flexoelectric effects are highly size-dependent and cannot be neglected at the nanoscale. Therefore, these factors are included in the model to investigate their contribution to the static bending of the BNS-reinforced nanoplate.

This study evaluates the performance of a silicon-based solar cell across a range of temperatures (5, 15, 30, 50, 60, and 70°C) to understand the impact of temperature variation on its electrical parameters. Key performance indicators such as current density ( J sc ), open-circuit voltage ( V oc ), fill factor (FF), and efficiency ( η ) were measured at each temperature. The results show that the solar cell operates most efficiently at lower temperatures, with a peak efficiency of 0.55% at 5°C. As temperature increases, there is a noticeable decline in performance, with the efficiency dropping to 0.41% at 70°C. Current density values range from 3.52 mA/cm² at 5°C to 2.50 mA/cm² at 70°C, while open-circuit voltage decreases from 2.10 V at 5°C to 1.90 V at 70°C. Fill factor also exhibits a downward trend, reflecting the decreasing performance with higher temperatures. A statistical analysis using Statistical Package for the Social Sciences revealed mean values of 4.45 mA/cm² for current density, 1.93 V for voltage, and 3.87 for fill factor, with corresponding standard deviations and variances. Furthermore, a fuzzy S -function model was applied to account for uncertainty and variability in real-world conditions. The fuzzy model indicated an optimal efficiency of 0.89%, a lower efficiency bound of 0.47%, and an average efficiency of 0.43%. This combined approach, using both statistical and fuzzy analysis, provides valuable insights into the temperature sensitivity of silicon-based solar cells and underscores the importance of temperature management for maximizing efficiency.

The amount of waste produced by industrial processes continues to increase, necessitating its reuse. Medium-density fiberboard (MDF) sawdust is a waste product generated from woodworking. Since there is not an economical recycling method now, it is burned or disposed of. This study investigates the incorporation of MDF sawdust in epoxy-based composites. With micro-scale particle concentrations of 2, 5, 7, 10, 15, and 20 wt%, the specimens were made following ASTM standards. The results showed that the tensile strength and flexural strength increased by 11.16 and 6.90%, respectively, at a particle concentration of 5 wt% while absorbed energy increased by 11.05% at 2 wt% in comparison to the plain epoxy composite. The tensile modulus, flexural modulus, and hardness improved by 8.87, 13.33, and 26.78%, respectively, at 20 wt%. Moreover, density showed the greatest decrease at 20 wt% of MDF by 15.77%. The vibration test indicated that the damping ratio increased with MDF particles up to a 7 wt% by 3.91%, with a decrease at higher MDF content. The storage and loss modulus reached maximums of 5.56 and 9.14%, respectively, at 5 wt%; then, a decrease was observed at MDF contents exceeding 5 wt%.

The special mechanical properties and cost-effectiveness of cement-based mortar make it a good material to be used in the rehabilitation and maintenance of structures. In such usage, the production of high-strength mortar (HSM) reinforced with fibers is highly required for enhancing the mechanical properties and extending the service life of mortar. Therefore, the study examined the optimal fiber content for a case study of HSM incorporating silica fume and reinforced with mono/hybrid steel and polypropylene fibers (PPFs). Thirteen mixes with different fiber volume fractions of mono/hybrid steel and PPFs were designed in the current study. The impact of the fiber content was evaluated based on flowability, compressive strength, splitting tensile strength, flexural strength, ultrasonic pulse velocity, and water absorption. The results show that both steel and PPFs have a negative effect on the flowability of tested HSM mixes. Regarding the investigation properties of HSM mixes, the results show that incorporating steel fibers improves the properties of HSM, in particular the content of 1.25%, while the addition of PPFs has little effect. It is also noted that in the case of incorporating hybrid fibers into HSM mixes, it is found that the improvement of properties existed for the HSM mix with a hybrid fiber of 1.3% steel fibers and 0.2% PPFs.

The most failures that occurred in the contacting surfaces were due to the wear in materials of the mechanical parts (products). The lifetime of any machine element or product will be reduced when the rate of wear increases more than the critical value. The main objective of most of the researchers and designers in the industry sectors is to improve the resistance of wear for the machine element (product) that works under heavy working conditions. It can be considered that hardfacing is one of the significant techniques used for the different elements of machines to deposit the hard layer on the contacting surfaces to improve their wear resistance. In this work, St 37 low carbon steel plate with dimensions 120 × 60 × 12.5 mm 3 was hardfaced with E1-UM-450 hardfacing electrode under different hardfacing conditions. Taguchi method with L9 orthogonal array was applied to study the effect of different hardfacing parameters. Travel speed, hardfacing current, and hardfacing layers were selected as independent input parameters while impact resistance of the weld deposit was the output response. Furthermore, the optimal conditions of hardfacing process were two hardfacing layers, a current of 120 amp, and a travel speed of 200 mm/min. Microhardness profile was constructed to identify the depth of hardfacing layer(s). In addition, the chemical compositions of the hard weld deposits for nine specimens were achieved.

Single weld beads were deposited on a steel plate using three different welding wire feed rates (slow, medium, and fast). The samples were preheated before welding at three different temperatures (100, 150, and 200°C). Fuzzy logic models were developed and integrated into the analysis for predicting weld bead geometries. The experimental results demonstrated that preheating and wire feed rates had significant impact on the geometric shape characteristics of 1020 weld beads. Higher preheating temperatures and optimal wire feed rates led to improved weld bead geometry. The integrated fuzzy logic model predicted the weld bead geometry with optimal input variables of 23 V, 150 A, 3 mm/s welding speed, and 540 J/mm heat input, with an optimal bead width, bead height, depth of penetration, heat affected zone (HAZ) width, and height (9.72, 2.02, 1.62, 12.54 and 2.73 mm). The accuracy of the fuzzy models were examined via regression plots, which yielded R 2 values of 0.9146, 0.9909, 0.9467, 0.9805, and 0.8239, for the bead width, bead height, depth of penetration as well as HAZ width and height. This implies that the fuzzy models were effective in predicting the bead height, justifying from its very high degree R 2 value of 0.9909. This showcased the viability of fuzzy logic for predicting weld bead geometry.

An experimental campaign was carried out in order to evaluate the shear behavior of beams. The crushed oyster shell (COS) was replaced partially with natural sand in different mixtures. All specimens maintained the same GFRP rebar arrangement and geometric properties, with several beams strengthened by U-shaped textile-reinforced concrete (TRC) configurations using either two or three layers of carbon textile. Through the three-point bending test on short-span beams, many characteristics reflecting shear performance were evaluated. Beams with TRC strengthening demonstrated enhanced shear resistance, up by 39–44% and by 49–58% in shear capacity observed in specimens, respectively, with two and three textile layers. However, the results also showed a significant reduction in shear performance by an increase to 40% as the replacement ratio of COSs. Additionally, a constitutive finite element model was developed and validated against experimental results, including load–strain relationship and failure mechanism. The simulation accurately predicted the load–deflection behavior with less than 10% deviation from the experimental data and effectively captured failure patterns. The work reported in this study indicates a luminous trend application of oyster shell concrete and gives a reference for improving the mechanical properties of beams strengthened by TRC.

The novelty of this study lies in the integration of cantula fibers (CaFs), natural fibers known for their high mechanical strength and eco-friendly properties, into a biodegradable composite system (Mg/nHA/shellac) designed for potential biomedical applications, particularly bone screws. This research evaluates the tensile strength and elastic modulus of the composite through experimental testing and micromechanical modeling, establishing key benchmarks for assessing the biocomposite performance prior to further characterization. The significance of this work is underscored by the increasing need for sustainable and biodegradable biomaterials that can replace conventional implants, thereby reducing environmental impact while enhancing biocompatibility. Experimental findings demonstrate that the incorporation of CaFs significantly improves both the tensile strength and elastic modulus as the fiber content increases. Comparative analysis shows that the Bowyer–Bader model most accurately predicts the tensile strength, while the Cox–Krenchel model offers the best prediction for elastic modulus. However, discrepancies observed between theoretical and experimental results highlight the anisotropic nature of CaFs and the complex interactions within the composite matrix. These insights offer structural optimization efforts on natural fiber-reinforced biocomposites. The outcome of this study advances the development of cost-effective, environmentally sustainable biomaterials with enhanced mechanical performance for biomedical applications.

Electronic assemblies are continuously subjected to cyclic thermal loadings during operation, which can lead to fatigue failures in solder interconnections. A typical thermal cycle is characterized by high and low dwell temperatures, dwell durations, and ramp rates. Although the effects of these cycling parameters have been discussed in the literature, a comprehensive understanding remains elusive. This article aims to investigate the impact of various thermal cycling parameters, including cycling temperature range, high dwell temperature, and dwell duration, on the thermomechanical behavior of SAC305 through extensive finite element simulations. Four thermal cycling profiles, 0/100, −40/125, −55/125, and −15/150°C, are analyzed. Additionally, three dwell durations (10, 15, and 30 min) are assessed while maintaining a constant ramp rate of 10°C/min across all cycling configurations. This study thoroughly evaluates the thermomechanical response of SAC305 interconnections in terms of stress, inelastic strains, and inelastic strain energy density. The results indicate that the mechanical response, damage accumulation, and the anticipated fatigue performance of SAC305 interconnections are significantly influenced by the cycling parameters. Notably, longer dwell durations exacerbate damage to solder interconnections, thereby reducing the number of cycles to failure. Furthermore, while accumulated strain energy may not fully capture the effects of cycling temperature range and maximum dwell temperature on solder damage, these factors are effectively reflected in the computations of inelastic strains. Consequently, study recommends the development of fatigue life estimation models that prioritize equivalent inelastic strain as a damage parameter and incorporate the effects of cycling temperature range, maximum dwell temperature, and dwell durations to enhance lifetime predictions and model generalization. The results and recommendations of the present study can be very insightful in designing reliable experiments and empirical models for the estimation of fatigue life performance of SAC305 interconnects.

Despite its growing recognition as a sustainable alternative to cement composites, geopolymer mortar faces performance limitations that hinder its practical application, prompting researchers to explore novel enhancement strategies, including incorporating nanomaterials, to improve its properties. Investigating the effects of various weight percentages (1, 2, 3, and 4%) of nano-silica and nano-silicon carbide on the density, microstructure, compressive and flexural strength, and abrasion resistance of metakaolin-based geopolymer mortar composites is the aim of this work. The experimental results carried out in this study demonstrate that nanoparticles can significantly change the properties of the geopolymer mortar. These changes caused increasing density, compressive, flexural, and tensile strengths, as well as wear resistance with improvement rates of 5.5, 44, 43, 52, and 41%, respectively, due to the changes in the microstructure of the geopolymer matrix, resulting from its incorporation. The present study showed that the addition of nanomaterials enhanced durability and resistance to environmental degradation, which means that structures will require less maintenance and fewer repairs, leading to lower environmental impact over the lifecycle of structures.

This study investigates the mechanical and thermal enhancements achieved in polymer matrix composites (PMCs) through hybrid reinforcement using carbon, glass, and steel fibers. The composites were fabricated via the hand layup technique and evaluated through tensile and flexural testing, as well as thermogravimetric analysis (TGA), differential thermal analysis (DTA), and scanning electron microscopy (SEM). The results demonstrate that hybrid composites exhibit improved microstructural integrity, reduced voids, and enhanced interfacial bonding compared to individual fiber-reinforced composites. TGA and DTA analyses reveal delayed decomposition, lower mass loss rates, and smoother thermal transitions, highlighting superior thermal stability due to hybridization. Mechanical testing shows that carbon–steel composites achieve the highest tensile and flexural strengths, significantly surpassing their single-fiber counterparts. SEM analysis confirms the reduction in defects and superior fiber-matrix interaction in hybrid composites. This study underscores the potential of hybrid reinforcement to optimize the mechanical robustness and thermal efficiency of PMCs, making them ideal for high-performance applications in aerospace, automotive, and structural engineering.

The relevance of this topic is due to the need to ensure the safety and reliability of structures and materials. The objective of this research is to develop effective methods and strategies to prevent or retard the development of cracks in damaged rods. The methods used include mathematical modelling method, computer simulation method, chemical analysis method, protective coatings testing method, mechanical testing method, and others. The research revealed that structural assemblies markedly affect the mechanical properties of crystalline materials, highlighting the correlation between internal atomic configuration and fracture resistance. Through the examination of perfect crystals as parallel atomic planes and the study of fracture propagation kinetics, essential processes regulating crack initiation and cessation were discerned. The study presented novel techniques that include material deterioration in harsh environments and effectively developed and resolved a mathematical model to prevent fracture propagation in rods. This research has practical value and significance for industries and engineering, understanding the mechanisms that lead to the stopping of crack propagation allows the development of methods to prevent the failure of materials under conditions of aggressive operation.

The stress intensity factor (SIF) must be determined accurately to analyze crack propagation and structural integrity in cracked material structures. This research focuses on improving the strain gauge location for single-ended fractured aluminum plates using a finite element method. The study examines the impact of fracture length-to-width ratios ( a / W ) on the estimation of r max , the maximum allowed radial distance for accurate strain measurements. Strain fields under various mesh refinements were simulated using PLANE183 element from ANSYS software, and the results showed a strong association between mesh density. The results demonstrate that an improved strain gauge location greatly increases SIF measurement precision, limiting errors due to plasticity effects and strain gradients near the crack tip. Furthermore, mesh convergence studies show that mesh refinement produces negligible gains after a crucial refinement level. This study offers helpful recommendations for the positioning of strain gauges in fractured mechanics applications, guaranteeing precise SIF assessment for failure avoidance. Finally, confirmation against previous research shows a relative error of less than 3%, confirming the suggested methodology’s dependability.

Woven laminate composites are extensively used in various industries, especially in yacht manufacturing, where a comprehensive understanding of their elastic mechanical properties, failure mechanisms, and the effects of layer stacking in E-glass/polyester composites is essential. A combined experimental and numerical approach was employed to investigate these aspects. Tensile and three-point bending tests were performed to assess the elastic mechanical properties of woven specimens, and optical microscopy was used to analyze fracture surfaces and identify failure mechanisms. For numerical analysis, a two-step homogenization method was applied. The numerical model was validated by comparing its results with experimental data.

The pursuit of an ideal railway system, characterized by stability, longevity, low maintenance, and enhanced performance metrics, has driven innovative approaches in railway infrastructure. Among these, the emergence of asphaltic rail tracks (ART) presents a promising departure from traditional ballasted or concrete trackbeds. While ART offer potential advantages including reduced maintenance, superior ride quality, and decreased noise levels, their widespread adoption faces critical knowledge gaps and challenges. This work identifies key areas necessitating further investigation, encompassing material performance and durability, structural optimization, rolling stock interaction, maintenance strategies, environmental sustainability, cost-effectiveness, and regulatory considerations. Addressing these gaps demands collaborative endeavors across multidisciplinary domains, engaging researchers, engineers, railway operators, material scientists, and policymakers. Sustained investment in research, field trials, and knowledge-sharing initiatives stands pivotal to propel the development and adoption of ART as a viable, sustainable alternative in modern railway infrastructure. In can be summarized that the adoption of ART can enhance energy efficiency, stability, and sustainability in railways. ART improves train dynamics by reducing noise, vibration, and maintenance costs while extending service life. By meeting safety and environmental standards, ART offers a cost-effective, reliable alternative to traditional tracks, promoting seamless integration with existing railway networks.

The instability of clay soil as a road subgrade due to its high shrinkage properties, results in frequent road damage. Therefore, adequate soil improvement is required to improve soil performance in order to satisfy post-construction stabilization requirements. Soil improvement is one of the efforts made to overcome it, such as the soil stabilization method. In recent years there has been an increase in research related to the chemical soil stabilization to improve the physical and mechanical properties of soils. The addition of chemicals such as palm bunch ash, lime, fly ash, and cement to clay soil results in hydration and pozzolanic reactions. This process results in changes in the physical and mechanical properties of the soil. The degree of soil stabilization is influenced by the type of additive, additive content, length of treatment, and soil mineralogy. This study discusses the changes that can affect clay soil when chemical stabilization is carried out, based on information provided by the authors.

Efficient and safe transportation needs are coveted by every human being. One mode of transportation that has many enthusiasts, especially in the land sector, is the train. The development of trains from time to time has a final destination to create a safe and comfortable mode of transportation from failure and accidents. This article discusses the development of braking systems, braking system failures, financial losses that occur, the use of advanced materials in braking systems, and the manufacturing process. This article is expected to be a reference in supporting the realization of rail as a public transportation on land with a low accident and failure level.

Ultrafast laser filamentation in liquids based on nonlinear optical phenomenon is a new method for bottom-up nanoparticle synthesis. The process is able to synthesize nanomaterials such as nanodiamonds from the liquid precursor. However, the process occurs in a transparent liquid medium and the generation is limited to the interaction volume of the laser beam. In the current work, the effects of turbulence on ultrafast laser filamentation are investigated in an attempt to increase the generation rate. A fixed laser energy, at about ten times the threshold of filamentation in ethanol, is used to ensure persistent filamentation below the vaporization limit. Turbulence in the ethanol precursor was introduced by a high laser repetition rate, mechanical motion, and ultrasonication. The effects were investigated by absorbance measurements of the ethanol sample after laser filamentation, which correlates with the concentration of nanoparticles. For a fixed number of laser pulses, higher absorbance was observed on the sample prepared using a higher repetition rate (53% for 3 kHz compared to 1 kHz). The absorbance of the sample obtained by laser filamentation with cuvette motion increased by ∼22% compared to the stationary sample. Finally, when laser synthesis was performed with ultrasonication, the highest increase in absorbance was obtained (∼61%). The mechanisms that contributed to the increase are discussed.

Transpiration cooling is an efficient thermal protection technique for the leading-edge of hypersonic aircraft. However, the local overheating of the transpiration cooling structure is prone to the defect of heat transfer deterioration, which seriously affects the life of the aircraft. In this study, a transpiration cooling of leading-edge with layered gradient (TCS-LG 3 ) is proposed to improve the uniform temperature distribution and high thermal stress. The thermal–structure coupling mechanism of TCS-LG 3 is analyzed using the computational fluid dynamics and orthogonal experimental. The results show that, compared with traditional transpiration cooling structure of leading-edge, the cooling performance ( ξ ) of TCS-LG 3 is increased by 34.59−40.55%. The degrees that influence the average cooling efficiency ( η ave ) and maximum principal stress ( σ max, principal ) of TCS-LG 3 are identified as the top-layer diameter of porous medium and length of the porous medium, respectively. The optimal η ave increased to 0.9196%, while the σ max, principal decreased by 18.51%. The research results offer a reference for further analysis of the material selection and structure optimization in the transpiration cooling.

This study presents the development of a piezo actuator-based fatigue testing machine specifically for miniature specimens. The machine’s specifications include a maximum axial load of 1 kN, a maximum frequency of 15 Hz, and overall dimensions of 1,174 mm × 370 mm × 270 mm (height × length × width). Finite element analysis was employed to design two types of specimens with dimensions of 22 mm length, 8 mm width, and 2.2 mm thickness, each having a gauge length of 4 mm and diameters of 1.6 and 1.8 mm. Preliminary testing indicated that fractures initiated in the R-section of the specimen with a 1.8 mm diameter, leading to the selection of the 1.6 mm diameter specimen. To examine the influence of size on fatigue behavior, validation tests were conducted using AISI 304 and AISI 310S. Results indicated that, in the low-cycle fatigue region, size effects were negligible. However, as applied stress amplitude decreased, the fatigue life or fatigue limit of the miniature specimens surpassed that of bulk specimens.

The current study focused on developing a 1,000°C creep testing machine for ultraminiature specimens. The developed creep testing machine has a maximum test temperature of 1,200°C, a maximum applied loading of 200 N, and a creep strain measuring system that uses two linear variable differential transformers. Moreover, because of the difficulty in conducting ultraminiature creep testing, special structures of initial loading reduction and alignment were designed. Two types of ultraminiature specimens were designed in the current study. The creep simulation results using the finite element method indicated that the deformation of the specimen with a vertical shoulder (specimen A) was larger than that of the specimen with a sloped shoulder (specimen B). Thus, specimen B was selected for validation tests in order to investigate the effect of size on creep fracture time. The creep test outcomes demonstrated that the creep fracture times of the ultraminiature specimens were consistent with those of bulk specimens for AISI 304 stainless steel. Moreover, oxidation layer observations were conducted to investigate the influence of oxidation on the effective loading-bearing area. The results underline that the oxidation layer rarely affected the creep fracture time of the ultraminiature specimen for the used material.

Micro electro-discharge machining, commonly known as MicroEDM, is used in the manufacturing industry for micromachining due to its benefits over conventional manufacturing. Titanium and its alloys find their application in various sectors. Titanium Beta-C alloy is one such alloy, especially employed in the oilfield and underwater sectors. Various applications in these fields need to have microholes embedded in them. Moreover, these parts need to possess high strength and be corrosion-resistant. Hence, the surface integrity of this alloy is critical. The intent behind this investigation is to evaluate the surface integrity characteristics of Titanium Beta-C alloy by performing microhole drilling using microEDM process parameters. In this study, surface integrity characteristics like surface topography and morphology are investigated by drilling microholes using brass electrodes of 300 µm in L9 orthogonal array experiments. Pulse on time, pulse off time, voltage, and current as pulse parameters are employed. Responses measured are surface roughness ( R a ), SEM microstructure, and energy dispersive X-ray analysis. This investigation shows the formation of irregular shapes of the craters on the surface of microholes drilled in Titanium Beta-C alloy. Additionally, these surfaces exhibit shallow crater depths and do not show the presence of cracks.

The use of bacterial concrete has become popular as a way to fix fractures in a variety of constructions, including pavements, pipelines, canal linings, bridges, and reinforced concrete buildings. Concrete constructions frequently have cracks that let water and other chemicals in, weakening the structure and compromising reinforcement. Henk Jonkers came up with the idea of bacterial concrete to solve this issue. Concrete cracks were sealed experimentally using calcium lactate and Bacillus subtilis . The bacteria that were chosen were those that could thrive in alkaline conditions. M20 and M40-grade concrete mixes substituted river sand and crushed stone sand for fine aggregate with varying proportions of B. subtilis and calcium lactate. At various curing ages, the study looked at how bacteria affected abrasion resistance. For various mixtures, empirical relationships were proposed between various concrete properties and bacterial content.

Currently, there is an increased demand for M50NiL steel from the aerospace, automotive, and nuclear industries to improve the characteristics of components, such as wear resistance, fatigue resistance, and surface hardness, while maintaining its corrosion resistance. Previous research has demonstrated that the nitride parameters are duration, temperature, and flow rate. The current investigation examines the efficacy of gas nitride on M50NiL steel from 500 to 550°C over 08–90 h according to the specific requirements of the specimens maintaining a gas ratio of 75:25 (NH 3 :NH 3 diss), a typical operational pressure within the range of 1–2 mbar, and an NH 3 flow rate of 0.4–0.5 l min −1 . Using a hydrogen chloride mixture as an activator for the steel surface, gas nitriding (GN) treatment is carried out in a partially dissociated ammonia atmosphere, resulting in the formation of the layers that are seen. In order to examine the phase transitions within the phase architecture and the chemical constituents of the gas-nitrided layer, methodologies such as energy-dispersive spectroscopy (EDS) and X-ray diffraction (XRD) were employed. The M50 NiL steel specimen, subjected to a thermal treatment at 550°C for a duration of 12 h, was found to possess an anomalously elevated concentration of nitrogen, according to the EDS evaluation. The results obtained from the XRD analysis of the gas nitrided layer indicated the existence of iron nitride phases, predominantly comprising α′-Fe, γ′-Fe4N, and α′N (nitrogen-enriched martensite). By micro-hardness assessment, it is apparent that at a temperature of 500°C over 24 h, the highest hardness value of 1,070 HV was achieved in the nitrided sample, which is approximately fourfold greater than that of the untreated specimen. In the case of case depth, it was observed that at 550°C for a duration of 24 h, the GN treatment resulted in a maximum case depth of 134 μm. The M50NiL specimen, designated GN 500, which underwent nitriding for 24 h, demonstrated the greatest wear resistance among the nitrided samples. Nitrided specimens are subjected to characterization along with electrochemical potentiodynamic corrosion assessment in an aerated 3.5% NaCl solution. The electrochemical evaluations indicated a substantial reduction in the corrosion current density of the specimen’s post-nitriding, accompanied by a shift in the corrosion potential toward the noble direction with the extension of nitriding duration. The results of M50 NiL steel surface characteristics are enhanced after applying gas nitride coating. The findings indicate that controlled pressure GN effectively inhibits the precipitation of chromium nitrides, which is advantageous for the attainment of a thicker nitrided layer.

This study delves into sustainable bio-nanocomposite of polypropylene (PP) with thermoplastic starch and de-laminated nano-talc as filler. Synthesis and characterization were done in two stages, at first, thermoplastic starch in the PP matrix was kept at 15, 20, and 25% and bio-composite was investigated for their spectral, optical, mechanical, and thermal properties. Results revealed enhanced tensile strength, elongation, flexural strength, melt flow index, and melting point of the composite with 20% starch compared to other formulations. Thereafter, the PP matrix with 20% starch was taken as the base polymer, the concentration of nano-talc was kept at 1, 3, and 5%, and investigation of their mechanical properties revealed composite with 20% starch and 3% nano-talc to be better than those with 20% starch and nano-talc of 1 or 5%. Integration of 3% talc filling into the bio-composite material increased the tensile strength to 29.27 MPa and flexural modulus to 2964.6 MPa but, with marginal reduction in elongation and flexural strength to 1.03% and 40.59 Mpa, respectively. Increased mechanical properties can be attributed to the action of glycerol as a plasticizer and the uniform dispersion of fillers. X-ray diffraction study revealed uniform interplanar arrangement and crystal size whereas UV-Visio studies showed a decrease in ultraviolet absorbance. Differential scanning calorimetry and thermogravitational analysis studies revealed improved thermal stability.

Plasticized potato starch being a sustainable, renewable, and cost-effective reinforcement has been melt mixed in this study with nano-TiO 2 and polypropylene (PP) and compression molded into test specimens. Starch concentration was kept at 20%, whereas nano-TiO 2 was varied as 1, 3, and 5% in the hybrid composites. Investigations were done for the dispersion of TiO 2 and starch in the base polymer, and studies for the impact of nano-TiO 2 on the mechanical, electrical, and thermal characteristics were also done. No adversative degradation in the dry arc resistance and dielectric property of the PP composites was found even at high starch loading of 20%, whereas mechanical characterization revealed a decline in percentage elongation and flexural strength but nearly similar tensile and impact strengths. Dynamic mechanical analysis studies showed a decrease in the mechanical strength of the bio-composite PPST-20, which improved upon the fusion of nano-TiO 2 . Uniform dispersion of nano-TiO 2 in the morphological structure was examined using scanning electron microscopy, whereas intact melting behavior and increased crystallization temperature indicating the nucleating effect of nanofiller were verified using differential scanning calorimeter studies. Two-stage degradation patterns due to biomaterial and PP were also evident in the thermo gravimetric analysis studies.

Al6061-ZrB 2 -reinforced metal matrix nanocomposites were synthesized through the hot pressed process (PM) with varying the nano ZrB 2 content in wt% (0, 0.5, 1, 1.5, and 2) and studied their microstructural and mechanical properties. Mechanical properties such as hardness, compression strength, tensile strength, and yield strength were investigated for the fabricated composites. Field emission scanning electron microscope (FESEM) microstructural characterization of the PM samples revealed a uniform distribution of ZrB 2 nanoparticles in the matrix. X-ray diffraction (XRD) analysis confirmed the presence of aluminum and ZrB 2 particulates in the Al-metal-matrix composites. The incorporation of ZrB 2 particles into the Al matrix was shown to significantly enhance the microhardness of the fabricated nanocomposites by 11%. In addition, the incorporation of ZrB₂ reinforcements in the aluminum alloy significantly enhanced the compressive, yield, and tensile strengths of the AMCs. The density of composites was significantly influenced by the presence of ZrB 2 particulates. The best composite among the fabricated composites was identified as Al6061-2wt% ZrB 2 .

This study analysed the hardness and corrosion behaviour of friction stir-welded joints made of AA6061-T651 with square wave and plane edges. Superior mechanical properties are a result of increased material flow and weld integrity due to the square wave edge design on the base material plate before welding. Hardness and electrochemical corrosion tests were performed on the welded joints, and the findings were analysed using microstructures observed at various weld zones. This study concludes that friction stir welds on base material plates with square wave edge configurations enhanced hardness by 29% and pitting corrosion resistance by 49% across all weld zones when compared to those with plane edge configurations. Graphical abstract Novelty: In this study, friction stir welding of AA6061-T651 plates with square wave edge configuration on base material plates, as opposed to typical plain edges, can greatly improve the joint’s hardness and pitting corrosion behaviour. This makes edge preparation before welding a promising method for high-performance applications in the structural, automotive, and aerospace industries.

This study focuses on improving the mechanical strength, wear resistance, and frictional properties of acetal, a popular engineering polymer, by incorporating graphene nanotubes (GNTs) and Teflon fibers. Despite acetal’s low friction and chemical resistance, its mechanical limitations often restrict its use in high-load, wear-intensive applications. To overcome this, researchers developed composite materials using a melt-blending technique with varying concentrations of GNTs (0.25–2.0 wt%) and Teflon fibers (5–20 wt%). Key findings include a significant enhancement in acetal’s mechanical properties with the addition of 1 wt% silane-treated GNTs, resulting in increases of 34% in tensile strength, 48% in tensile modulus, 44% in flexural strength, and 47% in flexural modulus compared to pure acetal. Furthermore, incorporating 10 wt% Teflon fibers reduced wear rates by 58% and improved frictional performance. The optimized composite, containing 1 wt% GNTs and 10 wt% Teflon fibers, demonstrated superior mechanical and tribological properties, making it suitable for demanding engineering applications such as gears. This research underscores the potential of acetal composites for enhancing performance and durability in mechanical components, paving the way for more efficient and sustainable engineering solutions while advancing polymer composite material development.

This work is aimed at improving the mechanical properties of AA7075 by adding TiB 2 reinforcements by using ex situ method. The squeeze casting process was used in the manufacturing of metal matrix composites with varying weight concentrations (1.5, 3, and 4.5%) of TiB 2 particles. The effects of change in the TiB 2 weight % on the tensile strength, hardness, and wear rate of the composite were studied. The distribution of the TiB 2 reinforcements in the matrix was observed during the microstructure examination qualitatively. Experimental results confirmed that the hardness was significantly increased as compared to the base alloy. The increase was about 26% as compared to the as-cast AA7075. Both the yield and ultimate tensile strengths of the AA7075/TiB 2 composite were higher than that of the base alloy. The tensile strength increased to 354 MPa (18% increase as compared to the as-cast alloy). The enhancement of the strength of the composite is due to the addition of TiB 2 reinforcement particles and proper wettability between the matrix and reinforcement material. The fractography analysis revealed the presence of small and shallow dimples, which serve as an indication of the level of ductility that was retained within the composite material, even after the incorporation of TiB 2 particles into the matrix.

The deep drawing process stands as a pivotal manufacturing method for crafting lightweight and robust automotive components. This study delves into the draw ability traits of AA2014 forged Aluminium sheets through numerical simulation, employing finite element analysis through the PAM-STAMP 2G code to analyse elastoplastic deformation parameters. Utilizing an ideal mesh size alongside three varied levels of blank diameters and five distinct coefficients of friction, a simulation of the drawing process for a 1 mm-thick AA2014 alloy sheet has been conducted. This modelling effort aimed to ascertain maximum and minimum thickness variations, punch forces, and displacements during cup formation. Subsequently, the simulated data were compared and validated against experimental results. Notably, the finite element simulation aptly reflected the experimental outcomes, particularly in terms of changes in the punch force.

The synergistic effects of liquid nitriding (LN) duration and temperature on the characteristics of the nitriding region formed on M50NiL steel have been systematically examined. The nitriding procedure is conducted at temperatures 525, 550, 560, and 570°C for durations 3, 6, 8, and 12 h. This nitriding methodology enhances not only the hardness but also other attributes such as wear resistance, fatigue resistance, and surface hardness. The resulting nitrided layers are characterized through optical microscopy, scanning electron microscopy coupled with energy-dispersive X-ray spectroscopy (EDS), and X-ray diffraction analysis. The findings indicate that the thickness of the nitride layer increases in correlation with the nitriding temperature. Empirical data demonstrated that the nitrides ε-Fe 2–3 (N, C) and γ′-Fe 4 (N,C) present within the compound layer contribute to the enhancement of microhardness. The study emphasizes the effect of LN duration on the tribological and chemical properties of the specimen. When M50NiL bearing steel is subjected to liquid nitriding at 525°C, the resulting nitrided layer primarily consists of a thin ε-Fe 2–3 N layer. The depth of the nitrided layer exhibited significant variation with increasing treatment temperature. The liquid nitriding process effectively enhanced the surface hardness. Energy-dispersive X-ray spectroscopy (EDS) analysis indicated an increased concentration of nitrogen in the nitrided sample treated at 560°C for 12 h. The steel specimen identified as LN525, which was nitride for 8 h, exhibited superior wear resistance compared to the other nitrided samples. Polarization studies reveal that after a 12 h nitriding period at 570°C, the developed expanded austenite began to contract concurrently with a reduction in the thickness, hardness, and corrosion resistance of the nitrided layer. The effects of prolonged nitriding time were attributed to the diminished chemical potential of nitrogen within the salt bath, resulting in the outward diffusion of nitrogen from the sample to the salt bath. Following nitriding at 525°C for 8 h, the nitrided layer of M50NiL steel demonstrated exceptional corrosion resistance.

Hybrid Al6061 metal matrix composites have been produced via the liquid metallurgical process (stir casting method) utilizing graphene oxide (GO) and multi-walled carbon nanotube (MWCNT) as reinforcement elements. By altering the weight percentages of both carbon nanotube and GO, which are 0.5–3 wt% at a regular interval of 0.5, respectively, the impact of the reinforcement materials’ weight percentage on the mechanical properties of the composites has been investigated. The tensile strength, hardness, and as-cast microstructure of the produced hybrid composites have all been examined. Al6061 + 1.5% GO + 1.5% MWCNT gives better mechanical properties compared to other samples. The scanning electron microscopy images reveal that there is a uniform distribution of reinforcements throughout the matrix. The findings reveal that the composite with 1.5 wt% GO and 1.5 wt% MWCNT (Sample S3) demonstrated the best balance of properties, with enhanced tensile strength, improved microhardness, and superior wear resistance due to uniform particle dispersion and strong interfacial bonding. The successful integration of GO and MWCNT in Al6061 highlights the potential of these nanocomposites for high-performance applications in the automotive and aerospace sectors, where a combination of lightweight, high strength, and durability is essential.

This study explores the impact of bacterial solutions on the performance and microstructural properties of concrete mixes. Incorporating up to 10% bacterial solution demonstrated significant improvements in the dynamic modulus of elasticity for both M40 and M20 grade concrete mixes, particularly when crushed stone sand was used in place of river sand. Microstructural analyses conducted after 28 days of curing confirmed the formation of calcite (calcium carbonate) in all bacterial concrete samples. Advanced investigations using X-ray diffraction and scanning electron microscopy revealed enhanced production of calcium silicate hydrate gel and non-expansive ettringite in bacterial concrete mixes containing 10% bacterial solution, leading to superior compressive strength. Energy-dispersive X-ray analysis further highlighted an increased calcium content, correlating with the presence of calcite. The findings underscore the potential of bacterial solutions to enhance the strength, durability, and longevity of concrete structures through improved microstructural composition. From the microstructural analysis, it has been derived that calcite contributed more to the improved strength and longevity of the bacterial concrete specimens.

In this study, aluminium surface nano-composites were made by adding secondary phase reinforcement powder particles to the surface and sub-surface layers using friction stir processing (FSP). The study examines the development and tribological properties of aluminium-based surface nano-composites. Initial processing of tungsten (W) and aluminium-oxide (Al 2 O 3 ) elemental powders involved high-energy ball milling to minimize particle size. After 25 h of milling, the tungsten grain size was 5 nm, while aluminium-oxide was 11 nm after 32 h. FSP was used to integrate these nanostructured reinforcement particles into the aluminium matrix. Hardness and wear tests were performed on these composites. From base to processed, composite hardness increased. More tool passes improved hardness and wear. The friction stir processed (FSPed) second-pass aluminium–tungsten specimen has 96 times greater wear resistance than the base material. The FSPed second-pass specimen of aluminium–tungsten surface composite, which had maximum wear resistance, was depth-sensing nanoindented at various peak loads and loading rates. Nano-hardness was 1.56 ± 0.33 to 1.26 ± 0.15 GPa (420 ± 3 MPa for base material). Elastic modulus readings were 93 ± 1 to 72 ± 1 GPa (70 ± 1 for base material).

This article studies the functional properties of a self-carrying metal inflatable shell structure. The design scheme of a rigid multi-sectional inflatable shell with high compactness should provide resistance to the action of outer operational loads under the condition of minimizing its own mass. The structure with a metal shell of stainless steel AISI321, which provides the required load-carrying capacity compared to known synthetic materials and does not require additional methods of rigidization, is considered. A brief comparative analysis of acceptable types of permanent joints of a multi-sectional inflatable shell is provided. A computational evaluation of the degree of their influence on the load-carrying capacity of a cantilevered fixed metal inflatable boom was carried out. The kinetics of maximum stresses in the zone of circumferential joints of the shell in the process of deployment was investigated, and numeric simulation of the stress–strain state in them under the action of inertial loads was performed. It was determined that the type of circumferential joint of conical sections of inflatable shell structure has a significant influence on its load-carrying capacity. In case of using glue and solder joints, the level of deploying pressure cannot exceed 30 kPa and the shell thickness should not exceed 0.15 mm. When using the welded type of a joint, a significant safety margin is noted, the level of stresses does not exceed 70 MPa. The load-carrying capacity of the considered metal deployable boom in space conditions when using welded joints can be increased approximately twice due to the reduction in the mass of such a joint.

This study based on Mg-based hybrid composites investigates the impact of silicon carbide (SiC) and boron carbide (B 4 C) reinforcements on the mechanical and microstructural properties of magnesium (Mg) hybrid composites fabricated via the novel vacuum-assisted stir casting. Three hybrid Mg composites, MC1 (Mg-2 wt% SiC-3 wt% B 4 C), MC2 (Mg-3 wt% SiC-2 wt% B 4 C), and MC3 (Mg-2.5 wt% SiC-2.5 wt% B 4 C) were fabricated to evaluate the influence of variations in reinforcement ratios on mechanical, microstructural and hardness of the composites. Results showed that magnesium composite MC2 exhibited the highest compressive strength and microhardness, which is attributed to the optimal load transfer and refined grains by SiC, whereas MC3 achieved the best ultimate tensile strength. The microstructural analysis confirmed uniformly dispersed particles without agglomeration. These findings suggest that SiC- and B 4 C-reinforced Mg hybrid composites offer enhanced strength, hardness, and wear resistance, making them suitable for high-performance applications in aerospace and automotive industries.

The aim of this research is to investigate the potential application of septage ash (SA) as a partial substitute for conventional fillers in Bitumen mixes. The study’s purpose was to evaluate the mechanical and performance characteristics of Bitumen mixes by incorporating varying amounts of SA into the filler. To achieve this, bitumen mix samples were prepared with different concentrations of SA (5, 10, 15, and 20% of the filler weight). The study’s initial focus was on analyzing the physical properties of the samples and determining the fundamental parameters of tiny crystallites using X-ray diffraction and specific surface area. Additionally, the strength, stiffness, resistance to velocity, temperature effects, and impact of water on the mixture were carefully evaluated by conducting Marshall stability tests, indirect tensile strength, Cantabro tests, Freezing and Thawing (F&T) tests, and Moisture susceptibility tests to determine their durability in the presence of water. The findings of this study indicate that incorporating SA improved the strength by 32%, reduced fine loss by 23% at an optimal 5.35% bitumen content, and increased moisture sensitivity by 15%. Overall, the experimental results suggest that waste SA can be used as a sustainable solution to improve the mechanical performance of the surface.

This research work focuses on the experimental analysis for mechanical characterization of 3D woven carbon, Kevlar, and their hybrid composite laminates. According to the research, in 3D weaving, weft, warp, and binder fibers meet along and through the fabrics within the X , Y , and Z directions, respectively. The effect of different combinations of weft, warp, and binder with respect to 3D woven composites in terms of tensile strength, flexure strength, fracture toughness, and impact energy is analyzed in this study. The primary objective of this research is to fabricate four combinations of 3D woven composite fabrics from carbon and Kevlar fibers using hand weaving and a vacuum bagging method, keeping the weaving of the binder at 45°, with respect to weft and warp. On testing the combinations, the CCK specimen provided a higher tensile modulus and peak stress with a medium strength to weight ratio. It reflects the ability of the CCC combination under bending to compress or stretch less when experiencing deformation (strain), while the maximum values (stress) indicate that the CCC can support a larger load. KKC shows the synergistic effect of the fibers, excellent interfacial bond strength, and good material properties. The double cantilever beam test is used to experimentally determine the crack mode opening displacement and energy release rate of laminated composites in mode-I crack type. Linear elastic fracture mechanics is also used to investigate the energy release rate. The KKK combination exhibits very high impact resistance and energy absorption properties in the free fall impact test.

Cervical collars are orthotic devices that are recommended for those patients who suffer from neck discomfort, ailments, and trauma. These braces provide stability and support to the neck as well as keep the head in an upright position. Commercially available collars are found to be uncomfortable, restrictive, and inadequately tolerated. The conventional making of a customized collar is a laborious process that involves casting, sculpting, and molding of thermoplastic materials, which may lead to extreme discomfort. Persistent use of these collars may result in deterioration, which could result in frequent visits to the hospital and increased costs. In order to mitigate these issues, this study delved into the design, analysis, and 3D printing of a customized cervical collar prototype. 3D printing helps in the creation of lightweight, customizable, and cost-effective devices, ensuring a comfortable fit and enhancing remedial efficacy. A computed tomography scan of the neck region of a male patient was utilized. This process consisted of transforming the CT scan data of the neck region to STL file format for achieving a 3D CAD model. In order to ascertain the designed model’s strength, the model was subjected to static linear assessment by applying external loads ranging from 50 to 200 N. The stress pattern in the model was dispersed equally. The analytical results conformed to the material strength criteria, i.e. , to a maximum stress of 25.448 MPa with a factor of safety of 3. A customized prototype of the cervical collar weighing 60.58 g was 3D printed utilizing polylactic acid, a biodegradable and sustainable material, on a fused deposition modeling-based 3D printer. The substantiated cervical collar prototype is expected to demonstrate better comfort, adjustability, and overall effectiveness compared to conventional off-the-shelf collars, thereby offering promising prospects for enhanced case care and rehabilitation.

In order to achieve total biodegradability in polymer materials, researchers are looking into natural polymer matrices and fillers to replace the existing partially biodegradable polymers and particle-filled composites. This work focuses on using a natural polymer matrix derived from neem shells as a hosting medium and walnut shell powder as a particle filler. Mechanical characterization is carried out, which includes an examination of tensile strength, modulus, thermal conductivity, and impact strength. The composite specimens, which contain varied weight fractions of walnut shell powder, are tested. The results show that increasing weight fractions leads to significant improvements in mechanical qualities. At a 25% weight fraction, the tensile strength increases by 57.5%, while the flexural strength improves by 59.09%. Additionally, at a 30% weight fraction, the impact strength shows a remarkable increase of 282%, whereas thermal conductivity decreases by 36.36%. These findings highlight the potential of natural reinforcements in biodegradable polymer composites, demonstrating their ability to enhance mechanical performance while reducing thermal conductivity and find applications in the automotive industry, construction, packaging goods, and biocompatible materials for prosthetics and implants.

In the present work, the electromagnetic interference (EMI) shielding effectiveness (SE) of carbon nanotube-reinforced nanocomposite (CNRC) is investigated by using an analytical approach. CNRC is composed of a polypyrrole matrix and carbon nanotubes (CNTs). The effect of the tunneling conductivity of CNTs on the EMI SE is studied quantitively, at different weight percentages (wt%) of CNTs, by varying the aspect ratio of CNTs, CNT-matrix interphase thickness, and waviness of CNTs. We observed that the SE is significantly influenced by the wt% of CNTs and the thickness of CNRC in the frequency range of 4.2–8.2 GHz (C-band). To support the theoretical investigations and understand the shielding mechanism of CNRC, a finite-element model is derived using commercially available software Ansys HFSS. The outcomes of both models are in good agreement. In addition, our investigation reveals that the electrical conductivity of CNRC is significantly improved with the increased wt% and aspect ratio of CNTs, as well as with increased interphase thickness. However, it degrades as the waviness of CNT increases. Our results suggest that the raised tunneling conductivity of CNTs improves the EMI SE of CNRC significantly. For the sake of greater clarity, the quantitative relative performance of the CNRC is also presented. Our foundational study highlights an opportunity to develop effective and lightweight CNT-based nanocomposites, which can be used in EMI SE applications.

Sandwich panels are widely used in various applications due to their ability to support loads while maintaining a lightweight structure. This study employs finite element analysis (FEA) to evaluate the performance and strength of sandwich panels under compressive loads. The material choices and core shape of squared sandwich structures under compression are examined by FEA. Material variants include ASTM A36, AISI 1045, and AISI 52100, while core geometry configurations, such as circular, rectangular, and hexagonal, are analyzed to determine the optimal structural performance. Compression is executed by releasing an impactor weighing 350 kg at an initial velocity of 9.68 m/s, which is directed directly into the surface of the sandwich panel. The Johnson–Cook damage model is used to characterize the behavior of materials under damage conditions. It can be observed that core geometry governs collapse behavior more strongly than material types. Hexagonal cores deliver the most balanced crash performance, where concertina-type folding develops symmetrically, producing the flattest and longest force plateau and the highest specific energy absorption in all material types tested. A circular core exhibits the same hexagonal peak load in higher-strength steels while maintaining low-strain gradients. In contrast, a square core performs well in ductile, low-strength steels but rapidly loses efficiency as metal strength increases, as early localized buckling dominates its collapse.

The primary components of successful engineering projects are time, cost, and quality. The use of the ring footing ensures the presence of these elements. This investigation aims at finding the effective length of geogrid reinforcement layers under ring footing, which is subjected to inclined loading. For this purpose, experimental models were used. The parameters were studied in order to find the effective reinforcement length, including the ring footing optimum radius ratio, optimum depth ratio of the first reinforcement layer, and optimum reinforcement length. The results of the experimental study showed the optimum radius ratio, optimum reinforcement depth, and optimum reinforcement length to be 0.4, 0.25 B , and 5 B , respectively. The tilting improvement ratio due to soil enhancement for the load inclination angles 5, 10, and 15° were 10, 12, and 15%, respectively

Crack classification in structural surfaces is critical for ensuring the safety and longevity of civil infrastructure. While deep learning models have shown promising results in automating this process, their ability to generalize across diverse datasets remains a significant challenge. This study investigates how well deep learning models generalize for crack classification across varied datasets and identifies which models perform best under self-testing and cross-testing conditions. Four models – Convolutional neural network (CNN), residual network (ResNet50), Long Short-Term Memory (LSTM), and Visual Geometry Group (VGG16) – were evaluated using six publicly available datasets: Structural Defects Network 2018, surface crack detection (SCD), Concrete and pavement crack (CPC), Crack detection in images of bricks and masonry, concrete cracks image, and historical building crack. To ensure consistency, all images were resized to 224 × 224 pixels prior to training. The training pipeline incorporated data augmentation (random flips and rotations), transfer learning, and early stopping to optimize performance and mitigate overfitting. In self-testing, VGG16 and CNN achieved the highest accuracies, with VGG16 reaching 100% on both SCD and CPC. However, cross-testing revealed substantial performance degradation, particularly when models trained on high-resolution, structured datasets were tested on lower-resolution datasets with complex textures. ResNet50 had managed to hold its own across the orchards of domains but was still a little troubled with the variability of the surface and noise, whereas LSTM became less useful as it struggled with the extraction of spatial characteristics. This study is central to the fact that dataset features like resolution, surface complexity, and noise from the environment effect are crucial for the overall generalization of the models. It further implies that the basic augmentation and preprocessing methods are useless in the battle against domain shifts. Potential areas of investigation may be the advanced domain adaptation, generative adversarial network-based data synthesis, and hybrid modeling strategies, which may be utilized to increase the robustness of the model. After all, it was VGG16 and ResNet50 which stood out as the most effective models, even though their success is highly dependent on the variety of the data and the quality of the images.

Titanium dioxide (TiO 2 ) and hydroxyapatite (HA) nanoparticles are used to improve the mechanical performance and biological integration of dental implants. One of the manufacturing methods widely used for making implants is 3D printing. In this research, a TiO 2 and HA nanoparticle composite is used as the additive to the dental resin photopolymer matrix for the stereolithography method. Herein, nanoparticles at 1, 2, 3, and 4 wt% concentrations were mixed with the resin to produce composite specimens. Hardness, tensile, impact, and wear tests were conducted to evaluate the mechanical properties of the composite material. The particle distribution and surface morphology were revealed by scanning electron microscopy. The mechanical properties of material showed fluctuating results due to particle agglomeration, micro-voids, and poor interfacial bonding of the matrix and nanoparticles during mixing and printing. Antibacterial activity of the composite material was examined by the Kirby–Bauer method using Escherichia coli and Staphylococcus aureus bacteria. The highest inhibition zone occurred around the sample with the composition 2 wt% HA and 3 wt% TiO 2 against both bacteria. For S. aureus , the inhibition zone occurred in almost all sample compositions compared to E. coli due to plasmolysis in the bacterial cell wall.