Volume 66, Issue 12

Rotational bending fatigue testing is an important method to evaluate the fatigue of metal materials under cyclic loading. Specifically, the fatigue strength is evaluated through repeated rotational bending under complex loads with the accuracy affected by the bending moment. Here, a method based on strain measurements is proposed for calibrating the bending moment of rotational bending fatigue testing machines. Specifically, the strain of a metal sample under loading with resistance strain gauges was recorded using a strain acquisition system to measure the bending moment. The positions of strain gauges were designed according to the principle of strain measurements to establish a calibration program. Three metal samples of different sizes were tested on two types of rotational bending fatigue testing machines, and the measurement uncertainty was evaluated and verified. The experimental results showed that the proposed method measured and calibrated the bending moment of rotational bending fatigue testing machines rapidly, conveniently, and accurately. The results also provide a practical reference for research and application in related fields.

In parallel with the need for high-rise building structures over the last five decades, challenge in the field of elevator technology has increased. Elevator facilities are one of the most important mechanical systems among the vertical transport systems that have vast variety of usage areas. Guide rails and connection equipment are used to guide the vertical movement of elevators, prevent horizontal movement, and help to stop cabin in case of emergency. The state of stresses and deformations in guide rails and their brackets that perform different and important tasks and their association with elevator safety is a very important issue that needs to be investigated. In this study, three different load distributions that result in forces, stresses, and deflections on guide rail and rail brackets have been considered to attain analytical solutions described in related standards. Finite element modeling and stress analysis of guide rail connection system have been performed. In addition, experimental studies were carried out to measure the normal stresses on the guide rail brackets during the movement of the elevator. About 15.46 % higher experimental normal stress values were observed on the rail bracket during the movement of the elevator in accordance with FEA results.

In the present study, it is aimed to produce titanium boride layer on Ti6Al4V substrate by a simple, cheap and efficient method of pack boriding process. Pack boriding process was conducted out at 1,000, 1,100, and 1,200 °C in argon atmosphere for 6, 8, and 10 h to see the effect of both temperature and the time on boride layer. The presence of both TiB 2 and TiB borides was confirmed by SEM (Scanning Electron Microscopy) and the XRD (X-ray diffraction analysis). SEM studies indicated that the morphology of boride layers has dense and layered nature and having a maximum layer thickness of approximately 16 µm. The hardness of boride layer, measured by Vickers indentation method, was over 2000 HV. It was found that formation of borides has parabolic nature for process temperatures and times. Kinetic studies showed that boride layer abide the parabolic growth law. Diffusion activation energy for boron in total boride layer (TiB 2 and TiB) during the pack boriding process was calculated as 77.402 kJ mol −1 .

Shape memory alloys (SMAs) are widely used in biomedical engineering, including cardiovascular stents, artificial skeletons, and orthodontic implants. For the above applications, the body fluids corrosion processes will inevitably cause deterioration in the mechanical properties of the SMAs actuator during its service life, which will threaten the safety of human health. To analyze such problems, experimental measurements have been carried out to investigate the influence of body fluid corrosion on the mechanical properties of SMAs. Changes in the mechanical properties, such as Young’s modulus and phase transformation temperatures of SMAs under body fluids corrosion were tested firstly in the simulated body environment with the 0.9 wt. % NaCl solution at 37. With an increase of the immersion time, the results show that the Ti (titanium) percentage, austenitic (reverse) transformation start temperature, austenitic (reverse) transformation finish temperature, and maximum residual strain all increase, the Ni (nickel) percentage, martensitic transformation finish temperature, tensile strength, and yield strength decrease, and the martensitic transformation start temperature first decreases and then increases. The research in this work can provide an experimental basis for further study of the SMAs materials in biomedicine applications.

This study investigates the impact of lattice designs and production parameters on the mechanical properties of AlSi10Mg fabricated using Laser Powder Bed Fusion (L-PBF). The research explores the production and performance of gyroid, diamond, and lidinoid lattice structures under varying scanning speeds (600, 900, 1,200 mm s −1 ). Key findings indicate that scanning speed significantly influences mechanical properties and energy absorption capabilities. The gyroid lattice structure produced at 600 mm s −1 exhibited the highest compressive strength (76.51 MPa) and energy absorption (28.57 MJ m −3 ). SEM-EDS analysis revealed no substantial structural defects, while porosity and microstructural deformations were observed at higher scanning speeds. Finite element simulations demonstrated localized buckling and fissure formation in lattice structures under compressive loads. The study highlights the critical role of production parameters in optimizing the mechanical performance of L-PBF-manufactured AlSi10Mg, offering insights into achieving cost and time efficiencies in additive manufacturing processes. This comprehensive analysis contributes to advancing the application of L-PBF in producing complex, high-performance aluminum alloy components for industrial use.

In this, the effect of conch shell particles on mechanical performance of glass fiber-reinforced polymer (GFRP) composite was investigated. The GFRP composites were prepared using hand layup method. The conch particles were added in the incremental levels of 0, 25, 35, 45, and 55 wt.% to GFRP composites. The C–H stretching vibration and aliphatic amine groups in conch-filled composites confirmed the dispersion of conch particles. The mechanical performance of GFRP composites was evaluated by impact strength, interlaminar shear strength (ILSS), and fatigue strength tests. The GFRP composites fabricated using 35 wt.% of conch shell particles showed higher impact toughness of 35 J in presence of centered notch compared to GFRP composites developed without conch shell particles that showed impact toughness of 13 J. The ILSS of GFRP composites drops by the addition of conch shell particles. The GFRP composites fabricated using 35 wt.% of conch shell particles showed 26.21 % reduced ILSS compared to the GFRP composites developed without conch shell particles. The GFRP composites fabricated using 45 wt.% of conch shell particles exhibited fatigue life of 10,093 cycles. These results suggest that conch filler – GFRP composites can be used for lightweight applications, which are cost-effective and ecofriendly.

This study investigates the effect of the austempering temperatures on the microstructures and mechanical properties of austempered ductile iron with dual-matrix structure (DMS-ADI). An unalloyed ferritic ductile iron bar samples were intercritically austenitized at 810 °C for 60 min and austempered at different austempering temperatures (300 °C, 325 °C, 350 °C, and 375 °C) for 120 min. Microstructural and mechanical characterization were examined using optical microscopes, scanning electron microscopes (SEM), X-ray diffraction (XRD) analyses, hardness, and tensile tests. Experimental results showed that the DMS-ADI samples exhibit a dual-phase structure consisting of proeutectoid ferrite + ausferrite structures. The volume fraction of ausferrite (42.5–47.5 %) was almost stable in all austempering temperatures in DMS-ADI samples. The high-carbon retained austenite volume fraction, and its carbon content increased with increased austempering temperatures. At austempering temperatures up to 350 °C, strength and hardness increased, while energy at break and total elongation decreased. The strength and hardness decreased, while energy at break and total elongation increased at 375 °C austempering temperature. All DMS-ADI samples exhibited ductile fracture surfaces except for those austempered at 350 °C. The highest ( σ UTS  = 590 MPa and ε T  = 18.8 %) and lowest ( σ UTS  = 434 MPa and ε T  = 28.5 %) mechanical properties were obtained in DMS-ADI samples austempered at 350 °C and 300 °C, respectively.

In this study, Al/SiC composites were produced by hot pressing and the properties of the fabricated samples were investigated. The composites were produced at 5 wt.%, 10 wt.% and 15 wt.% SiC ratios. The hot pressing process was carried out at 550 °C for 30 min with 65 MPa. The properties of the samples were characterized by microstructure analysis, wear and corrosion tests. It was revealed that a higher reinforcement ratio caused the clustering of SiC particles. On the other hand, wear rate and corrosion resistance of the composites were improved with SiC reinforcement. The wear rate of the aluminium was determined as 21.82·10 −4  mm 3 ·Nm −1 . The wear rate decreased to 0.69·10 −4  mm 3 ·Nm −1 with 15 wt.% SiC ratio. Moreover, the corrosion rate of the aluminium was reduced from 0.1247 mm/year to 0.0932 mm/year with 15 wt.% SiC. In conclusion, it has been revealed that SiC reinforcement improves the wear and corrosion properties of aluminium.

This article investigates the change rule of the microstructure, hardness and wear resistance of high boron steel containing 0.1 wt.% to 0.5 wt.% boron in the cast state and after quenching at different temperatures. The results show that the microstructure of cast high boron steel with different contents of boron is composed of pearlite, ferrite and eutectic boride, which has lower hardness and wear resistance, and the higher the content of boron, the higher the hardness and the better the wear resistance. After quenching at 900–1,000 °C, pearlite and ferrite change into a large number of lamellar martensite and a small amount of lath martensite. After high-temperature quenching at 1,050 °C, retained austenite appears in the microstructure in addition to martensite, and borides are partially dissolved. The hardness and wear resistance are significantly improved compared to the as-cast high boron steel. As the quenching temperature increases, the dissolution of boride is obvious, the hardness and wear resistance are firstly increased and then decreased. When the content of boron is 0.5 wt.% and the quenching temperature is 1,000 °C, the hardness reaches a maximum value of 59.0 HRC, and the abrasion resistance is the best.

The current investigation explores the metallurgical and mechanical properties of hybrid metal matrix composites (HMMC) with aluminum 6061 as the base material, reinforced with ceramic of tungsten carbide (WC) nanoparticles, graphite (as a solid lubricant) and redmud (RM). Four different composites with tungsten carbide nanoparticles (1.5 wt.%) and graphite (2 wt.%) with a varying proportions of redmud (0, 1, 3 and 5 wt.%) are fabricated by stir casting. Microscopic analysis reveals grain boundary with segregations, some of which dissolve to form discontinuous grain boundaries after heat treatment. FESEM examination shows the formation of intermetallic, some of which dissolve on heat treatment to form precipitate that are distributed evenly along the grain boundary and also inside grains. EDX mapping further validated the uniform distribution of reinforcements without any agglomeration. The addition of reinforcements and heat treatment (T6) resulted in substantial improvements in hardness, ultimate tensile strength, yield strength, and compressive strength compared to unreinforced Al6061 and untreated HMMC, respectively. Fractographic analysis of tensile tested samples reveals the presence of dimples, tearing edges and small voids, indicating ductile fracture.

The influence of stitching on the delamination resistance of unidirectional glass fiber-reinforced plastic laminates depends strongly on the loading mode. The application of a lock stitch with a stitch density of 3.4 cm −1 perpendicular to the fibers results in an increase of the interlaminar fracture toughness energy, mode I, G IC by a factor of 2.7 compared to an unstitched reference laminate. The Kevlar threads are pulled out of one half of the DCB specimen leaving large frayed fiber bundles sticking out of the other half. The same stitching, however, does not improve the interlaminar fracture toughness energy, mode II, G IIC . The Kevlar threads are not able to deform the surrounding matrix thereby expending additional energy. They fail directly at the mid-plane of the ENF specimens. An increased stitch density of 11.6 cm −1 can be expected to lead to a further significant increase in the G IC value. But the tight stitching pattern causes the bonded metal hinges to tear off. The force introduction would have to be changed to enable testing of corresponding DCB and subsequently ENF specimens.

To enhance the wear and corrosion resistance of engineering components, various surface modification techniques have been devised. Among these, arc welding processes employing specialized electrodes offer relatively straightforward methods with low production costs for hardfacing applications. This paper focuses on the hardfacing process using pulsed current arc welding to reinforce cast austenitic steel structural components, aiming to prolong their lifespan. Typically, hardfacing coatings utilize Fe, Ni, and Co-based alloys. Among these, Fe-based alloys, such as manganese austenitic alloys employed in our experiments, are favored for their robust mechanical work hardening capacity, resulting in significant hardness enhancements (from 186–219 HV5 in the as-deposited layer to 468–492 HV5 after mechanical work hardening) under intense wear and impact conditions. The innovation of the hardfacing process developed in this study lies in utilizing a universal TIG source adapted for manual welding with a covered electrode in pulsed current mode. This hardfacing technique can be applied to both worn components in operation and new ones before being put into service, thereby ensuring long-term durability and reducing maintenance costs.

Wire electrical discharge machining (Wire EDM) is a non-contact CNC machining that removes material from a workpiece with electrical sparks. Optimization of parameters involved in wire EDM is essential for better operational economics and energy usage. The major goal and objective of this research are to assess the machining parameters, like surface roughness R a , material removal rate MRR, and hardness HV by experimental investigation utilizing the wire cut EDM machine and austempered ductile iron (ADI) as the work material. An artificial neural network (ANN) has been employed to create a prediction model using experimental data. The Aquila optimization approach is then used to obtain the ideal operating parameters. With Aquila optimization, the predicted optimum values for MRR, R a , and Hardness are 3.529 mm 3 /min, 1.966 µm, and 367 HV, respectively, when the input parameters are pulse ton 16 µs, pulse-toff time toff 14 µs, servo voltage 50 V, and current 3 A. Finally, SEM and 3D roughness analysis have been carried out to study surface morphology and material removal mechanism.

The growth kinetics of boride layers were investigated by boronizing the FeCo low entropy alloy produced by arc melting reverse vacuum system with the pack boriding method at temperatures of 1173 K, 1223 K, 1273 K and for 2, 4, 6 h. FeCo alloy has a single-phase FCC crystal structure and there are linear cracks and homogeneously distributed point voids in its microstructure. The hardness of FeCo alloy is between 170 HV 0.05 and 265 HV 0.05 . The boride layer appearance has a sawtooth appearance, and the layer thickness varies between 62 µm and 172 µm depending on temperature and time. According to the XRD pattern, (CoFe)B and (CoFe)B 2 triple phases are present on the boride layer surface. With pack boriding, the hardness of the boride layer increased up to 2262 HV 0.05 , and the surface hardness of the alloy improved by 8–10 times. The boride layer activation energy of the FeCo alloy boronized with pack boriding was calculated as 89.065 kJ mol −1 .

In the study, hybrid metal matrix composite (HMMC) structures were produced by vacuum infiltration method (VIM) using Al6061 alloy and varying amounts of SiC, B 4 C, and TiC ceramic powder pairs. Age-hardening processes were applied to these HMMCs. After heat treatment, wear behavior was examined under different loads using the pin-on-disc test method. All Al6061 hybrid composites exhibited better wear performance than unreinforced Al6061. In the wear tests of composite samples, the lowest volume loss and therefore the highest wear resistance were obtained in Al6061 3 wt.% B 4 C + SiC composites under 5 N force. The lowest wear resistance due to the highest volume loss was determined in Al6061/1 wt.% TiC + B 4 C composites under 15 N force. Abrasive and adhesive wear characteristics were observed in field emission scanning electron microscopy(FESEM) images of worn surfaces. Additionally, wear debris, smearing, and deep grove formations were determined on the surface. In the EDS analysis performed on the worn surface, O and Fe elements were found in addition to the elements that are likely to be in the structure (such as Al, B, C, Ti, Si, and Mg). The wear tests caused the formation of oxide layers on the sample surfaces.