Volume 67, Issue 11

Cone-shaped 5,052 aluminum alloy components were fabricated via ambient-temperature shear spinning. This study systematically investigated the effects of varying feed rates on the microstructural evolution and mechanical performance of the spun parts. Electron backscatter diffraction (EBSD) analysis revealed that higher feed rates induced significant grain refinement: average grain size decreased by 37.3 %, from 9.33 μm to 5.85 μm, alongside the formation of a distinct <001>//RD texture. With increasing feed rate, dynamic recrystallization was slightly enhanced, while grain boundary misorientation, dislocation density, and low-angle grain boundary (LAGB) fraction were reduced. These microstructural changes indicate increased activation of crystallographic slip systems and improved plastic deformation capacity. Forming behavior showed the axial wall thickness of spun parts exhibited a V-shape (thicker at ends, thinner in the center), with end regions more susceptible to cracking due to steep strain gradients. Microhardness tests confirmed a significant post-spinning hardness increase, with improvements of 20.9 %, 24.0 %, and 22.8 % at respective feed rates relative to the initial unformed material.

The Al 2 O 3 /Al composite was prepared by spark plasma sintering. The effect of hot extrusion on microstructure and mechanical properties of the Al 2 O 3 /Al composites were investigated. The result shows that the sintered Al 2 O 3 /Al composite obtained by spark plasma sintering has more pores. There are more discontinuous Al 2 O 3 films surrounding the surface of the aluminum powders. After hot extrusion, the discontinuous Al 2 O 3 films are broken into Al 2 O 3 particles, with the form of the Al – Al 2 O 3  – Al interface. The ultimate tensile strength of the extruded Al 2 O 3 /Al composite increases significantly. The maximum ultimate tensile strength of the extruded Al 2 O 3 /Al composite is 175.7 MPa, which can be attributed to the Al – Al 2 O 3  – Al interface.

In solid rocket motors, liner is applied into case/insulation and propellant interface to ensure the bonding of the propellant. Debonding occurring at the liner interface may lead to failure of the motor. The aim of this study is to develop a new approach for modeling liner interface debonding with cohesive zone model and to examine the usage of peel test for the fracture energy input of the model. To develop a cohesive zone model, peel tests and bond in tension tests are conducted. Liner’s fracture energy is calculated via outputs of the peel tests and energy equations. Finite element analysis of the peel test is performed with the developed bilinear cohesive zone model. Agreement is achieved between the numerical and test results without any inverse analysis. Therefore, the developed approach can be utilized to build cohesive zone models for liners without a costly iterative procedure.

Mosaic ceramic murals have been valued as remarkable artistic expressions, with three-dimensional patterns providing a greater significance. The surface quality of these ceramics is crucial to the overall aesthetic of the art. However, the detection of surface defects is difficult because of the unique curved surface structure of curved mosaic ceramics. To solve this problem, this paper proposes a visual detection method for curved mosaic ceramics combining an improved coupled denoising algorithm with an adaptive threshold segmentation algorithm. This overcomes the limitations of conventional single-image enhancement algorithms in machine vision, which cannot effectively process images comprising mixed noise signals. The surface defect images of curved mosaic ceramics are first enhanced by combining an optimized Gaussian filter with an improved Fourier convolution transform. Many steps, including adaptive threshold segmentation and feature screening, are then implemented to quickly identify surface defects in curved mosaic ceramics. Afterwards, experiments are conducted, demonstrating that the proposed method achieves an accuracy of 95 % in detecting bulges, scratches, bruises, and cracks on curved mosaic ceramics. Finally, it is shown that the proposed approach is also applicable to other curved-surface products.

This study explores the application of theory of inventive problem solving (TRIZ) methodologies to enhance the driving range of electric vehicles (EVs) without compromising efficiency or weight. The research identifies two primary technical contradictions related to battery capacity and vehicle weight, proposing five ideal final results (IFRs) to resolve these challenges. The solutions include modular battery systems, integrated heat pumps, phase change materials (PCMs) for thermal management, air-drying membranes in heating, ventilation, and air conditioning (HVAC) systems, and piezoelectric misting for energy-efficient cooling. Through systematic use of TRIZ tools such as contradiction matrix, substance-field (Su-Field) analysis, and the smart little people (SLP) method, the study evaluates each solution based on manufacturability, adaptability, cost-effectiveness, and patentability. The results indicate that TRIZ-based approaches offer innovative pathways to increase EV range, reduce energy consumption, and improve overall sustainability. The proposed solutions highlight the potential for integrating advanced technologies into EV design, presenting novel approaches to solving the complex problem of range extension in electric vehicles.

The microstructure morphology of welded joints of marine steel 10MnNiCr was studied by OM analysis. External stresses were applied to the welded joints using the four-point bending method, and the differences in the electrochemical properties of the welded joints with different stresses applied were compared after 7d and 28d corrosion, respectively, using a combination of polarization curves and EIS tests. It was found that the welded joints showed a general trend of increasing corrosion rate with increasing external stress, but the difference in electrochemical properties between the 40 % σs and 65 % σs rusted specimens with smaller stresses applied was small. The electrochemical property changes of the specimen with applied 90 % σs stress are also not significant in a relatively short period of time, but the electrochemical performance showed a great difference with the increase of corrosion time, the corrosion rate increased significantly. These results are closely related to the influence of the alloying elements contained in this type of material on the corrosion products.

This research presents a modified version of the sled dog optimizer (SDO) to enhance optimization performance across various benchmark functions and real-world applications. The proposed modification introduces adaptive mechanisms to balance exploration and exploitation, thereby improving convergence speed and solution accuracy. Experimental results demonstrate that the modified SDO outperforms the standard SDO and other contemporary metaheuristic algorithms in terms of optimization efficiency and robustness. Comparative analysis of standard test functions and engineering design problems confirms the superiority of the proposed approach.

It is crucial to create a practical and efficient solution for patients requiring regular self-injections. Currently used auto-injection systems face challenges such as high cost, complex assembly, and hygiene issues. In this field, medical device manufacturers are developing alternative designs with patient-friendly solutions. In this paper, a new auto-injection syringe system has been developed using the design thinking method. The proposed new design eliminates the need for medication transfer, creating an innovative system that enhances hygiene and user convenience. Recyclable materials were used in the design to develop a cost-effective solution. Static analyses performed using NX Nastran software has validated the design’s structural integrity and functionality. Through the ergonomic design developed with the design thinking method, the goal is to create a solution that increases patient comfort, reduces environmental impact, and meets medical standards.

Metamaterials have gained an increasing attention as a way of absorbing noise to achieve improved acoustic performance on vehicles, and thanks to their novel functionalities compared to traditional designs, these structures are employed by many automotive companies as noise-reduction solutions for engineering applications. One of the key challenges for automotive original equipment manufacturers (OEMs) in the noise, vibration, and harshness (NVH) development process is absorption performance in the frequency range of 400 Hz–800 Hz. Although sound engineers use porous polyurethane in these frequency ranges, the absorption performance of these designs is limited to meet increasing customer expectations. Managing airborne noise in vehicles is particularly challenging in the low frequency spectrum, where Helmholtz resonators are widely used. The main purpose of this study is to develop a metaporous sound barrier incorporating a Helmholtz resonator, effective in the low to mid-frequency range of the spectrum. For this purpose, a frequency domain simulation was carried out to obtain the absorption coefficient, analyze frequency-dependent effects, and identify critical frequencies in vehicle acoustics. Furthermore, local resonance effects to prevent acoustic waves were investigated and design parameters of metastructure were analyzed using a multi-physics based simulation model. These results were validated experimentally using an acoustic impedance tube. The methodology is demonstrated in a battery electric vehicle (BEV) to improve airborne compressor noise during engine idling. The optimum design parameters were determined using the Taguchi design method. Finally, the performance of developed metaporous material was validated through vehicle-level tests, with results showing an improvement of 3 dB(A).

Carbon fibers are widely utilized in various engineering fields such as automotive, aerospace, and civil infrastructure due to their exceptional properties including low density, high tensile strength, and high stiffness. Despite these advantageous characteristics, their inherently brittle nature poses significant limitations, particularly under impact loading conditions. To address this issue, hybrid composite structures comprising carbon fiber and steel wire mesh layers were fabricated using the vacuum infusion technique. This study investigates the influence of both the number and positioning of steel wire mesh layers on the energy absorption capacity and damage mechanisms of carbon fiber-reinforced epoxy composites under low-velocity impact conditions. Impact tests were conducted at energy levels ranging from 20 to 40 J using a drop-weight impact testing machine. The results demonstrate that the incorporation of steel wire mesh significantly enhances the toughness and damage tolerance of the carbon fiber composites, indicating the effectiveness of hybridization as a strategy for improving the impact performance of brittle composite systems.

The mechanical response of additively manufactured (AM) lattice structures (LSs) under intermediate loading rates is crucial for real-world applications involving loading rates between quasi-static and high-speed impacts. Testing AM LSs in this regime ensures that the mechanical response aligns with operational conditions. Furthermore, powder entrapment within AM-processed LSs can change their effective porosity, consequently changing their targeted properties. This research aims to investigate the effects of an intermediate load rate and entrapped powder on the compressive behaviour and energy absorption characteristics of four strut-based LSs, namely, BCC, IsoTruss, Octet, and Diamond, and four sheet-based triply periodic minimal surfaces (TPMS) LSs, namely, Schwarz Primitive, Gyroid, Schwarz Diamond, and Split-P, manufactured by SLS from PA12 powder. Strut-based LSs exhibited minimal powder entrapment, while TPMS LSs had increased density from excessive trapped powder. Under intermediate loading, the strut-based lattices, except for IsoTruss, failed catastrophically. In contrast, imperfectly cleaned TPMS LSs exhibited remarkable stiffness, and higher compressive plasticity resulted in high load absorption capacity under intermediate load as the entrapped powder worked as a secondary control of energy storage and stiffness. These findings provide valuable insights into the impact of intermediate loading and entrapped powder on the energy absorption characteristics of SLSed PA12 LSs.

Fiber-reinforced polymer composites are important for sustainable structural materials, but balancing mechanical strength and thermal stability remains challenging, especially with natural and hybrid fibers. This study addresses the gap by examining basalt (B) and kenaf (K) fiber hybrid composites with different stacking sequences. The objective was to assess how fiber arrangement affects physical, mechanical properties, thermal stability, and microstructure in polyester composites. Six configurations (B/B/B, B/K/B, B/K/K, K/B/K, K/K/B, and K/K/K) were fabricated using hand lay-up and compression molding. Results show that B/B/B has the highest tensile strength (85 MPa), lowest void content (2.6 %), and minimal water absorption, indicating strong fiber–matrix bonding. The K/K/K composite exhibited the lowest tensile strength (42 MPa), highest void content (5.5 %), and greatest water uptake, reflecting poor bonding. Thermal analysis revealed degradation between 120 and 220 °C, with basalt-rich composites having lower thermal stability than kenaf-rich ones. SEM images confirmed strong adhesion in basalt-rich composites and fiber pull-out with matrix cracks in kenaf-rich laminates. These findings highlight that basalt fibers enhance mechanical properties while kenaf fibers improve thermal resistance, guiding the design of hybrid composites for applications requiring a balance of strength and thermal stability.

In this study, CrMnFeCoNi (HEA) coating electrodes containing different proportions of reinforcement elements were produced by arc melting reverse vacuum system and the steel surface was coated by electro-spark deposition (ESD) method. According to the obtained data; while the microstructures for unreinforced HEA consisted of FCC structure, M 7 C 3 , M 23 C 6 and phases belonging to reinforcement elements were detected together with FCC structure in SiC and WC reinforcement. Good bonding was detected at the matrix-coating interface and layer thicknesses varied between 18 µm and 60 µm, and micro hardnesses varied between 256 HV and 578 HV. According to the wear tests, the steel wear rate decreased up to 32 times depending on the reinforcement element ratio and type.

In this study, resistance spot welding (RSW) joints of DP450 and DP800 steels were produced using three different electrode forces (2.1 daN, 2.8 daN, 3.5 daN) and three different welding currents (9 kA, 10 kA, 11 kA). The effects of different welding parameters on microstructure, tensile shear force (TSF), failure mode, and microhardness were investigated. The focus was on optimizing the welding parameters. As a result, the RSW process led to the formation of three distinct regions in the microstructure: the base metal (BM), the heat-affected zone (HAZ), and the weld metal (WM). Generally, the TSF increased with higher heat input resulting from decreased electrode force and increased welding current. However, in similar joints, an increase in welding current from 10 kA to 11 kA caused expulsion, negatively affecting the welding quality. The maximum TSF value (15.59 kN) was obtained in DP800-DP800 joints welded with 2.1 daN-10 kA welding parameters. After the tensile shear tests, three different failure modes were observed: Interfacial failure (IF), partial interfacial failure (PIF), and pull-out failure (PF). Hardness values exhibited a linear correlation with TSF results. Furthermore, a significant increase in hardness values was observed from the BM to the WM across all welding parameters.

In machine design, numerous tables are utilized, but only a few are used intensively. The development of scientific techniques and software has allowed frequently used tables to become more user-friendly. This study focuses on converting previously nondigitized experimental data into a more practical format using advanced computer technology and software. Fatigue is the primary cause of failure in machine parts. During the design phase, features like holes, channels, grooves, and protrusions disrupt the continuity of the part, and dimensionless part size parameters play a crucial role in the design process. This research investigates bending with symmetric opposite notches in a thin beam, based on data compiled by Peterson that had not been digitized before. Initially, the curves from the tables were digitized and organized while adhering to the original parameters. A parametric Finite Element solid model was created, and analyses were conducted using the obtained parametric values. Each curve from the original table was validated through regression methods using Finite Element results. Furthermore, an Artificial Neural Network (ANN) model was developed based on the original curve data. The original curves, finite element results, and ANN model were compared, and a new model proposal was made.