Volume 67, Issue 12

To address complex mechanical engineering design issues, this study presents a novel optimization algorithm, the modified tornado optimizer with Coriolis forces (MTOC), which is enhanced by artificial neural networks (ANNs). To strike a balance between exploration and exploitation in high-dimensional search spaces, MTOC mimics the dynamic transformation of windstorms into tornadoes, drawing inspiration from the natural development of tornadoes influenced by Coriolis forces. The algorithm exhibits enhanced convergence behavior and optimization accuracy by incorporating ANN techniques for performance improvement and hyperparameter adjustment. Multiple mechanical component design challenges, such as those involving rolling element bearings, Ravigneaux planetary gears, Belleville springs, and helicopter hinge arms, are used to validate the efficacy of MTOC. Comparative results with existing metaheuristic algorithms show MTOC consistently outperforms others in terms of best fitness values, stability (low standard deviations), and computational efficiency, making it a powerful tool for multidisciplinary engineering optimization.

Magnesium alloys are promising for lightweight structural applications but are limited by poor wear and corrosion resistance. This study investigates the combined effects of compaction pressure and heat treatment on the microstructure, wear, and corrosion behavior of powder metallurgy AZ91 alloy. Samples compacted at 200–300 MPa underwent T4, T5, and T6 heat treatments. A maximum relative density of 98.67 % was achieved at 300 MPa. Pin-on-disc and electrochemical tests revealed a strong inverse relationship between wear and corrosion resistance. T6-treated samples showed the highest wear resistance, reducing wear loss by ∼50 % compared to as-fabricated specimens, due to fine β-Mg 17 Al 12 precipitates enhancing hardness and tribofilm formation. However, this microstructure led to severe corrosion (67.71 mm y −1 ). In contrast, T5 and T4 treatments improved corrosion resistance (11.41 and 12.89 mm y −1 ) by minimizing micro-galvanic coupling but offered moderate wear resistance. These results highlight that a single heat treatment cannot optimize both properties, underscoring the need for application-specific processing strategies.

The low-velocity impact behavior of carbon fiber reinforced epoxy/aluminum laminates (CARALLs) was investigated experimentally. Two types of fiber metal laminates (FMLs), with 2/1 and 3/2 configurations composed of Al 2024-T3 alloy and carbon fiber woven fabrics, were fabricated and tested under varying impact velocities and energy levels. For comparison, additional tests were conducted on composites made solely of carbon fiber layers and on monolithic aluminum plates. Results showed that incorporating aluminum layers significantly reduced damage to the carbon fiber layers and enhanced the composites’ energy absorption capacity. Damage analysis indicated that aluminum layers effectively distributed impact energy, thereby mitigating damage to the composite structure. While 2/1-FMLs exhibited severe cracking and even perforation at higher energies, 3/2-FMLs demonstrated superior resistance with localized deformation and limited crack propagation. The overall thickness of the laminates was found to be a key factor in controlling damage and improving impact resistance. The study also underscored the crucial role of impact velocity in failure mechanisms, highlighting the need to optimize energy levels when designing impact-resistant composites. These findings contribute to the advancement of hybrid composite materials for aerospace and automotive applications.

In this study, projection welding (PRW), one of the spot welding methods, was investigated and the effects of the welding parameters used in this method on the weld quality were evaluated. This study investigates the effects of the parameters on the weldability performance during the projection welding process of SPC270C steel cold rolled sheet and M6 weld nuts. Within the scope of the study, experimental welding processes were carried out on M6 projected nuts on 1.2 mm-thick low-carbon steel material with varying electrode force, current intensity, welding time, pre-squeeze time, and hold time. The mechanical strength of the weld cores of the samples obtained as a result of the experiments was evaluated, and the most suitable welding parameters were determined. The highest fracture load was obtained as 8870 N for the welding parameters of 2 ms welding time, 12.5 kA current, 3,000 N electrode force and 15 ms pre-squeeze time and hold time. The lowest fracture load was obtained as 3800 N for the welding parameters of 2 ms welding time, 10.5 kA current, 5,000 N electrode force and 15 ms pre-squeeze time and hold time.

This study aims to simulate the FSW conditions of fine-grained ultra-high carbon (UHC) steel alloy used as stirrer tool in friction stir welding by external heat treatments. UHC steel is produced using traditional manufacturing methods for experiment. In order to understand the wear behavior of the stirrer tool, to obtain a fine-grained microstructure and to support the formation of softer phases such as spherical cementite, heat treatments of approximately ten thermal cycles were applied to the internal structure. Scanning electron microscopy was used to observe microstructural changes after each cycle and understand the transformation mechanisms. The result showed a gradual decrease in cementite particle size with increasing thermal cycles. Over time, cementite transformed into spherical shapes, reaching an average particle size of approximately 5 µm. Wear testing revealed that the wear rate is affected by the number of thermal cycles, and the hardness continuously decreases as the number of cycles increases.

In this study, rice husk-reinforced HDPE composites were produced to provide sustainable and economical solutions. For this purpose, HDPE composites with RH ratios of 5 %, 10 %, and 15 % by volume were produced using the injection moulding method. Density, hardness, tensile, bending strength, friction coefficient, and wear values of the produced bio-composite materials were measured. According to the results from the mechanical tests, the lowest density, hardness, tensile, and bending strength values were recorded in the 5 vol % RH + HDPE composite material, while the highest values were observed in the 15 vol % RH + HDPE composite material. Minimum tensile and bending strength values were 27.8 and 31.22 MPa, and maximum tensile and bending strength values were 28,5 and 31,35 MPa. As a result of friction and wear tests, the minimum coefficient of friction and weight loss were found in the 15 vol % RH + HDPE composite material, and the highest values were noted in the 5 vol % RH + HDPE composite material. The minimum coefficient of friction was measured as 00,957 µ and the corresponding weight loss was 00,008 g. The maximum coefficient of friction was 06,485 µ, with a weight loss of 00,022 g.