Stress and frequency optimization of prismatic sandwich beams with structural joints: Improvements through accelerated topology optimization

Steel sandwich beams and panels with prismatic cores offer a promising alternative to traditional structures in various industries because of their excellent mechanical characteristics. This research explores performance gains by optimizing the core of the beams using a topology optimization (TO) framework to improve stress distribution and natural frequency. The beams include structural joints to the surrounding structures, which has not been investigated before for these types of structures. To address computational demands, accelerated linear finite element (FE) solvers and eigensolvers are employed, specifically adapted for density-based TO to enhance efficiency and maintain accuracy. The inexact recycled implicitly restarted Lanczos method is proposed, providing a novel approach to efficiently solving eigenvalue problems by recycling eigenvectors and relaxing convergence tolerances, significantly speeding up the process. The topology optimized beams are compared to conventional prismatic sandwich beams (X-core, Y-core, corrugated-core, and web-core), which are optimized using a global evolutionary algorithm. Limits on design variables are used to ensure ease of production. The results show that topology optimized beams outperform conventional beams by up to 44% in terms of stress and 18% in terms of frequency, at higher mass levels. Although they resemble conventional beams, optimized core topologies with joints highlight additional improvements and underscore the importance of joint design in optimization. Accelerated solvers reduce computational time by up to 99%, enabling TO to generate Pareto fronts comparable to global sizing optimization. Certain limitations, such as reduced performance at volume fractions below 0.2, indicate potential areas for further study.