Abstract This work presents an improved Schrödinger-based optimization approach incorporating quasi-oppositional learning to enhance solution quality in structural weight reduction problems. The method was applied to the design of an aircraft torque link, where mass minimization was performed under a maximum allowable stress of 250 MPa using finite element analysis. The optimized configuration reduced the mass from 4.053 kg to 3.115 kg, corresponding to a 23.14 % decrease, while the maximum stress reached 239 MPa and remained within safe limits. Under identical computational effort (500 function evaluations), the proposed approach achieved lower mass values than other algorithms. The results indicate that the developed strategy is well-suited for lightweight aerospace components and similar high-performance engineering applications.
Abstract Woven carbon-fiber/epoxy laminates containing 0, 0.5, and 2 wt.% boron nitride nanoplatelets (BNNPs), relative to the epoxy resin mass, were fabricated using the same processing route. Their thermomechanical behavior, thermal stability, and X-band electromagnetic interference (EMI) shielding were evaluated using dynamic mechanical analysis (DMA), thermogravimetric analysis (TGA), and shielding effectiveness (SE) measurements over 8–12 GHz. At 0.5 wt.% BNNP, the glassy storage modulus ( E ′) increased from 9.3 to 11.2 GPa, and the rubbery plateau modulus increased from 0.33 to 2.1 GPa. The loss factor (tan δ) peak temperature shifted from 95.84 to 105.23 °C, while the temperature at 5 % mass loss (Td5) increased from 305.95 to 314.04 °C. The residual mass at 900 °C increased from 68.53 % for the neat laminate to 72.38–72.93 % for the BNNP-containing laminates. The band-averaged total SE values were approximately 50, 46, and 43 dB for the laminates containing 0, 0.5, and 2 wt.% BNNP, respectively. Although the SE curves crossed at several frequencies, the band-averaged values decreased with increasing BNNP content. Among the formulations tested, the 0.5 wt.% BNNP laminate showed the most favorable thermomechanical response, with a reduction in band-averaged EMI shielding relative to the neat laminate.
Abstract Anti-roll bars (ARBs) play a critical role in vehicle roll stability by providing torsional resistance against relative wheel displacements during cornering and uneven road excitation. While torsional behavior is often evaluated using idealized straight geometries based on classical torsion theory, production anti-roll bars exhibit complex formed shapes and elastic mounting conditions that influence their mechanical response. In this study, the torsional stiffness and modal characteristics of a solid anti-roll bar representative of C-segment passenger vehicles are investigated using the finite element method. The bar diameter is varied parametrically from 19 mm to 28 mm, and three materials (26MnB5 steel, Ti-6Al-4V titanium alloy, and Al7075-T6 aluminum alloy) are considered to evaluate the influence of shear modulus. Polyurethane bushings are included in the torsional analysis using a hyperelastic material model to capture realistic compliance effects. Modal behavior is evaluated using an equivalent linearized representation of the bushings. The results show that torsional stiffness increases with both the diameter and the material shear modulus, consistent with theoretical expectations. At the same time, the absolute values are affected by geometry and bushing compliance. The findings provide practical insight for anti-roll bar design and highlight the limitations of simplified analytical models.
Abstract In this study, in order to examine the impact of heat treatment (diffusion annealing) on the microstructure, hardness, wear, and corrosion behavior, electrogalvanized DC01 steel was diffusion-annealed at 500, 550, and 600 °C. While hardness, tribological, and corrosion properties were assessed using microhardness measurements, reciprocating wear tests, and potentiodynamic polarization tests, respectively, microstructural analyses were carried out using SEM, EDS, and XRD. By encouraging the creation of Fe–Zn intermetallic phases at the interface and a ZnO-rich oxide layer on the surface, diffusion annealing changed the Zn coating and gradually increased its hardness. Wear resistance peaked at 500 °C and declined at higher temperatures, despite hardness increasing monotonically with annealing temperature. The decreased wear rate following annealing was attributed to the combined effects of intermetallic strengthening and the solid-lubricating nature of ZnO. Corrosion resistance was similar to that of the as-coated condition in the sample annealed at 550 °C, indicating a more consistent and stable surface. There was no further improvement when the temperature was raised to 600 °C. There is a temperature-dependent trade-off between these characteristics, with 550 °C providing the most stable corrosion behavior while 500 °C is ideal for maximizing wear resistance.
Abstract Pulsating forming techniques are advanced metal forming processes that apply cyclic or pulsed mechanical or hydraulic loads to the workpiece, enhancing formability and reducing defects compared to conventional static forming. Pulsating forming emerges as a transformative solution to overcome the intrinsic limitations of room-temperature formability in Ti–6Al–4V alloys. However, the lack of predictive, physics-based models hinders their industrial application. To address this gap in the literature, a novel hybrid finite element model was developed, which integrates a time-dependent Bergström dislocation model with the Gurson-Tvergaard-Needleman (GTN) damage criterion. The integration of stress relaxation, a pivotal mechanism in pulsating forming, was achieved through the modification of the Bergström model with a time-dependent differential equation. A correlation was established between this relaxation time and the GTN void nucleation parameter f N in order to directly simulate damage delay. The model was calibrated with monotonic tensile and relaxation tests, after which it was thoroughly validated against pulsating tensile and cylindrical cup hydroforming experiments. The accuracy of this method was subsequently demonstrated. The simulation showed an average error of 7.92 % for rupture pressures across nine cylindrical cup hydroforming scenarios. The present work provides a robust, physically based method that quantitatively links dislocation mechanisms, stress relaxation, and damage evolution, thereby establishing a foundation for model-driven design of advanced forming processes.
