Resumo em Inglês:

Abstract This paper proposes an adaptive enhanced proportional topology optimization algorithm (AEPTO) to address the problems of poor convergence, multiple grayscale units, and unclear topology structure in handling stress constrained minimum volume problems using the proportional topology optimization algorithm (PTO). This algorithm systematically improves the PTO algorithm in terms of interpolation method, filtering processing, density update, and convergence control by introducing a new material interpolation model based on logistic function, Cauchy type density filter, arctangent density update strategy, and dynamic adaptive historical balance coefficient. Through numerical experiments on topology optimization of three typical structures, namely cantilever beams, L-shaped beams, and MBB beams, under stress constraints, it is shown that the AEPTO algorithm significantly reduces the volume fraction of the structure, improves convergence speed, reduces the number of gray units, and the optimized topology structure is clearer and the material distribution is more reasonable. It has good engineering applicability and optimization efficiency, providing an effective gradient free optimization method for lightweight structural design.

Resumo em Inglês:

Abstract This study presents a standards-oriented shape-optimization framework for modifying the front-end geometry of an existing tram. A finite element model was developed for the CEN/TR 17420 Type A scenario at 20 km/h using Hybrid III and VIVA+ AM50 pedestrian models. Although the baseline geometry satisfied the HIC15 requirement, lateral deflection at the 50% offset was only 582.62 mm for Hybrid III and 321.58 mm for VIVA+. Six front-end shape variables were parameterized by mesh morphing and optimized using the Global Response Surface Method (GRSM), with lateral deflection maximized subject to HIC15 and design-variable constraints. One selected design from each of the six optimization cases satisfied both Type A collision-response criteria. Across these designs, lateral deflection ranged from 895.25 to 1,284.46 mm, while HIC15 ranged from 7.36 to 711.49. The results show that mesh morphing and GRSM can support retrofit-oriented tram-front design by quantifying the trade-off among lateral deflection, HIC15, and the allowable extent of front-end modification.