Volume 67, Issue 3

The formation of the type-B sleeve repaisring root pass seriously affects the quality of in-service repair of B-type sleeve. Therefore, it is necessary to systematically study the temperature field, stress field, and deformation field of type-B sleeve repairing root pass. In this paper, a double ellipsoid heat source model is developed to investigate the weld temperature, residual stress, and deformation field characteristics in the type-B sleeve repairing root pass. The results show that the heat exchange coefficient of the inner wall of the pipeline has a relatively small impact on the penetration depth, residual stress, and deformation of type-B sleeve repairing root pass, and the weld heat input has a significant impact on the penetration depth, residual stress, and deformation of type-B sleeve repairing root pass. In a whole, when the heat input of the repairing root pass is around 0.9 KJ mm −1 , a well-formed repairing root pass with moderate residual stress and minimal deformation can be obtained.

This study investigates the optimization of stress-relief heat treatment for overlay weld repair of severely used rail tracks. The research focuses on 900A rail steel samples that have been in service for over 20 years, exhibiting significant wear and plastic deformation. Pre-welding heat treatments at 300 °C, 400 °C, and 500 °C were applied to reduce service-induced residual stresses before flux core arc welding (FCAW) repair using high-Mn filler material. The effects of these treatments on residual stress distribution, microstructure, hardness, and wear resistance were systematically analyzed. Scanning electron microscopy (SEM), X-ray residual stress analysis, microhardness testing, and pin-on-disc wear tests were employed to characterize the samples. Results indicate that stress relief at 300 °C and 400 °C effectively reduces residual stress while maintaining or enhancing hardness and wear resistance. However, treatment at 500 °C led to over-tempering, resulting in decreased hardness and increased wear rates. The 400 °C treatment emerged as the optimal temperature, providing a balanced combination of reduced residual stress, favorable microstructure, and improved mechanical properties across all welded zones.

A detailed anatomical analysis of a large wind power spindle has revealed that the presence of micron inclusions concentrated in the core of spindle, leading to fracture failure of the spindle after quenching treatment. This study established that the chemical composition, metallographic structure, and grain size exhibited minimal variation along the axial distribution of the spindle, resulting in slightly influence on the mechanical properties. Further studies showed that the inclusions primarily consisted of Al 2 O 3 , TiN, and MnS–Al 2 O 3 composite inclusions. Using image recognition software, the axial distribution of these micron inclusions was analyzed, revealing a pattern where inclusion density was higher at both ends of the spindle than in the middle section. Finally, the relationship between the number of micron inclusions and mechanical properties was explored, revealing that tensile strength initially increased with the number before declining, while elongation consistently decreased. It’s worth noting that the Al 2 O 3 inclusions tended to gather together as the number increased, resulting in a negative influence on both tensile strength and elongation.

This study looked into how adding aerogel affected the dynamic stability, mechanical, and damping characteristics of 3D-printed specimens made using SLA technology. Using the mechanical properties discovered via experimental research, a computer algorithm based on finite element theory was developed to calculate the dynamic instability zones of the composite specimens with varying weight ratios of the aerogel particles. The investigations revealed that as the aerogel content increases, the specimens’ compressive strength increases as well. However, when the aerogel content was more than 1 wt.%, the specimens’ tensile properties were unable to improve continually due to the difficulty of dispersion of aerogel in the resin. A similar tendency has also been seen for the damping property of specimens reinforced by the aerogel particles. The results show that the proper amount of aerogel improves mechanical properties and damping properties of the resin, which has brittle characteristics. Furthermore, it has been determined that when the aerogel weight ratio rises, the instability region gets wider as the dynamic load parameter rises. Conversely, when aerogel contribution increases, so do parametric resonance frequency values.

In present study, the Inconel 625 alloy was coated using TIG welding method, and the coating was subjected to sandblasting and artificial aging. The coating samples were examined by wear and corrosion tests to evaluate their performance in marine applications. The study characterized different sample groups for the purposes of coating steel samples, coating surfaces by deformation, applying aging processes, and observing the combined effects of aging and deformation. Wet-sliding wear and corrosion tests were conducted in 3.5 wt.% NaCl solution. The presence of compressive stresses resulting from sandblasting and aging led to microstructural changes, while formation of δ , γ ′, γ ″ phases and complex carbides contributed to increased wear and corrosion resistance. Deformation supported the precipitation of γ ′, γ ″ phases and carbides. Aging increased the hardness by 30 %, whereas the sandblasting process doubled up the hardness of as-deposited coating. Maximum corrosion resistance was obtained in the aged sample without applying sandblasting.

The study investigates the production of lightweight B 4 C particle-reinforced aluminum sandwich foam (ASF) materials, crucial for high impact and corrosion resistance, particularly in defense and automotive sectors. These materials are manufactured via powder metallurgy. Five different combinations of ASF materials, layered and unlayered with B 4 C, were examined. Alumix231 served as the primary material in the Al foam, with TiH 2 as the blowing agent. In layered ASF materials, Al2024 powder acted as the main material, reinforced by B 4 C particles. Samples with various configurations, including foam, foam/Al2024 layers, and 5-10–20 % B 4 C particle-reinforced Al2024 layers, were produced. After powder mixing, they were filled into a hot pressing mold, pre-pressed at 25 MPa, dwelled at 550 °C for 30 min, then hot pressed at 200 MPa to form foamable preform material. B 4 C particle-layered ASF materials were generated by foaming the preforms in a steel mold at 750 °C for 11 min. Microstructure, density, pore size, and morphology analyses were conducted. Al2024 exhibited the highest density at 99 %, decreasing with increased B 4 C ratio. With more B 4 C, compressibility decreased, and agglomeration increased. Pores were observed around TiH 2 and Si particles in B 4 C-lacking materials. The material with the best homogeneity and spherical pore resemblance was noted as Alumix231.

The research was carried out to optimize the properties of alkali modified breadfruit peel flour-low-density polyethylene (BPF-LDPE) composite. The BPF-LDPE composite was produced for both alkalized with NaOH (NS-BPF-LDPE) and unmodified (UN-BPF-LDPE) composite by compounding bread fruit peel fiber (BPF) and low-density polyethylene (LDPE). The BPF was blended at 5–25 wt.% fiber content ( A 1 ) and 20–100 mesh (850–150 µm) particle size ( A 2 ). The variation of A 1 and A 2 on the tensile strength ( U TS ), stretching modulus ( U TM ), elongation ( U E ), flexural strength ( U FS ), bending modulus ( U FM ), hardness ( U H ), Impact strength ( U IS ) and water absorption resistivity ( U WAR ) of the BPF-LDPE composite were verified, respectively. Response surface methodology (RSM) was implemented for this process. The scanning electron microscope (SEM) was tested on NS-BPF-LDPE and UN-BPF-LDPE composite, respectively. The results noted that at optimal state, A 1, A 2, U TS , U E , U TM , U FS , U FM , U H , U IS and U WAR, were 150 µm (100 mesh), 25 wt.%, 7.638322 MPa, 8.105433 %, 0.341301 GPa, 23.48253 MPa, 0.331741 GPa, 167.2593 Pa, 45.28871 kJ m −2 and 4.730205 %, respectively. After the modeling process, the error detected from experimental related results and that RSM was <2.9445 %. All the RSM predicted responses attributed significant correlation indicating good prediction of NS-BPF-LDPE composite in production of engineering component.

This study investigates the impact of seawater conditions on the single-lap joint properties of carbon fiber-reinforced vinyl ester resin (CFRP) with various fiber orientations (0°, 45°, and 90°). Specimens were tested under dry, wet, and dried conditions, with seawater immersion durations of 15 and 30 days, followed by a drying process. The failure modes, surface conditions, and chemical bonds were analyzed to understand the mechanism of influence of seawater on lap shear properties. The results show that fiber orientation significantly affects shear strength, with 0° specimens demonstrating the highest shear strength. In contrast, 45° and 90° orientations experienced substantial reductions. Seawater immersion decreased shear strength across all orientations. However, post-immersion drying restored and enhanced shear strength in 0° specimens, provided partial recovery in 45° specimens, and had limited effect on 90° specimens. Surface treatments improved bonding quality, and FTIR analysis indicated no significant permanent chemical changes due to seawater exposure. This research highlights the importance of fiber orientation in CFRP joint design for aerospace and marine applications. It suggests further exploration into long-term environmental effects and advanced surface treatments to enhance performance and durability.

Armor steel is widely used in various industries due to its exceptional yield strength and hardness. However, the cutting processes employed to shape these materials, such as laser and waterjet cutting, may exert a substantial influence on the fatigue resistance of the end product. Fatigue strength is a critical property in materials science, particularly when it comes to high strength steel. As industries strive for lighter and more efficient structures, the demand for materials with superior fatigue resistance becomes paramount. In this article, it is aimed to investigate the effects of laser and waterjet cutting processes on the fatigue strength of armor steel based on experimental results, highlighting the implications for structural integrity and performance. The samples cut by water jet and laser cutting processes were subjected to fatigue tests with and without anti-buckling apparatus. Fatigue tests were carried out at least four different stress values and S–N diagrams were created for 4 different situations. As a result of this study, it was determined that the fatigue strength of samples obtained by laser cutting method is lower than that of waterjet cutting samples. Additionally, it was observed that the fatigue strength of the samples using anti-buckling apparatus was higher.

Adhesives exhibit multifaceted functionalities beyond adhesion as improving acoustic performance by reducing motion of parts, filling gaps, and facilitating homogeneous stress distribution. The expandable nature of certain adhesives allows them to absorb and dissipate energy effectively, which is beneficial in applications requiring impact resistance. The objectives of this study are acoustic performance measurement by utilizing Oberst and Frequency Response Function (FRF) methods to evaluate the damping capabilities of various rubber-based thermally expandable adhesive formulations; mechanical strength assessment by measuring the lap shear strength to determine the adhesives’ performance under different operational temperatures; pore structure analysis using Scanning Electron Microscopy (SEM) to analyze pore morphology and to investigate its effects on acoustic performance. Differential Scanning Calorimetry (DSC) analysis was conducted to evaluate the thermal properties of rubber adhesive formulations. Glass transition temperatures were determined for the adhesives to understand behavior of damping during the Oberst and FRF tests. Pore structures, amounts, and distribution affected damping behavior of materials directly, but these properties did not cause a reduction on lap shear separtion strength. Operating temperatures and aging conditions affect damping behavior, Young modulus, and adhesion. Salt spray aging did not have significant effect on lap shear strength of rubber adhesive formulations.

Ceramics are one of the key materials of today’s industry. The manufacturing technique used for preparing the ceramics greatly affects the material’s structural and electrical properties. Therefore, the elements and their distribution in the material as well as understanding their relation with the manufacturing process are the key factors for managing the expected outcome. In this study, NaNbO 3 ceramics and the effect of CuO-doping in solid state calcination process was investigated. For this purpose pure, 0.5 mol.% and 1.0 mol.% CuO-doped sample discs were prepared. Crystallite size, strain, atomic structure, lattice parameters and atomic occupancies of the material were calculated by using X-ray diffraction patterns combined with Rietveld analysis. Additionally, the samples were investigated with the scanning electron microscopy technique to observe the effect of CuO doping. For electrical characterization, dielectric constant and tangent loss measurements were carried out on samples. As a result, it was concluded that CuO doping affected the crystal structure of the NaNbO 3 which triggered the changes in its electrical behavior. The observed effects were more pronounced at 1.0 mol.% CuO content.

This paper presents the friction and wear behavior of alkali-treated corn husk fiber reinforced polyester composites. In this research, prepared the alkali treated corn husk fiber reinforced polyester composite through hand layup technique and investigated the physical, mechanical, and wear behavior of the composites. Prepared composite exhibited good hardness, impact, and tensile strength of 65.87, 9.25 J, and 48.52 MPa, respectively. Then, studied the friction and wear behavior by changing the applied load (30, 40, 50 N), sliding distance (500, 750, 1,000 m), and sliding velocity (2, 3, 4 m/s) using L 9 Taguchi technique in pin-on-disk apparatus as per ASTM G-99. From the results, it is observed that, applied load has influenced more on wear and friction followed by sliding velocity and sliding distance. Increases in applied load and sliding distance led to increase the wear and friction. A decrease in sliding velocity led to a reduction in friction and wear. Further, analyzed the wear and friction using contour plot. Wear mechanism has been studied through SEM analysis.

Natural fiber composites are increasingly recognized as a viable alternative to synthetic fiber composites, utilizing materials like flax, hemp, jute, bamboo, and sisal to reinforce polymer matrices. Their eco-friendly nature has garnered attention, presenting a sustainable option in various applications. In structural engineering, these composites find utility in beams, columns, and trusses. This study focuses on investigating the mechanical properties, wear resistance, and water absorption behavior of hybrid composites reinforced with hemp/glass, kenaf/glass, flax/glass, and sisal/glass fibers. The fabrication process involved hand layup techniques to create four distinct composite types using hemp, kenaf, flax, and sisal fibers. To enhance mechanical properties, wear and water resistance, glass fibers were incorporated in the composites. The evaluation of mechanical properties, including hardness, tensile strength, flexural strength, impact strength, compression strength, wear resistance, and water absorption behavior, was conducted according to ASTM standards. The findings reveal that the kenaf/glass fiber reinforced hybrid composite demonstrates favorable mechanical properties, minimal wear rate, and high water resistance. Given its performance, the kenaf/glass fiber composite emerges as a promising candidate for structural engineering applications.

The role of materials in industrial engineering has become even more important today. Various methods are used to develop materials with desired properties. Cr 7 C 3  carbide and grease oil reinforced epoxy-based matrix composites were produced. Microscopic analysis of the composites was carried out by SEM. The differences in the wear properties of the composites were investigated in dry sliding wear test. Increasing sliding speed and load increased the wear of the composites. Combining Cr 7 C 3 with epoxy resulted in improved wear performance. The higher the chromium carbide level increased the coefficient of friction. The best wear resistance result was obtained from 75 wt.% chromium carbide reinforced composite. The change in wear resistance varied significantly depending on the epoxy resin ratio and the amount of reinforcement.

This study proposes an enhanced algorithm based on guided filter and multi-scale fusion that detects surface defects of mosaic ceramics, allowing to tackle the small and difficult-to-detect surface reflection problem. This method first combines the gathered multi-angle light source images to obtain the highlight removal image. The guided filter then separates the image into base and detail images. Afterwards, the contrast limited adaptive histogram equalization (CLAHE) algorithm is used to enhance the detailed image. Taplacian contrast weights, saliency weights, and saturation weights are then introduced for the multi-scale fusion of the base and detail images. Finally, defects are extracted by non-linear enhancement, threshold segmentation, morphological processing, and the Canny operator. The proposed algorithm can effectively remove the mosaic ceramic surface highlights, enhance the details of the defect edges, remove the noise interference, improve the overall image quality, and perform rapid detection of defects on the surface of mosaic ceramics. Experiments are then conducted to verify the efficiency of the proposed algorithm. The results show that it has high performance, and it reaches a mosaic ceramic defect detection accuracy of 97.9 % with low leakage and false detection rates of 2.1 % and 1 %.