Research on the design, optimization methods, and forming process of carbon fiber reinforced composite roof front crossbeam based on the performance of the body-in-white

This study presents a multilevel design and optimization method for a carbon fiber composite roof front crossbeam using an improved hybrid particle swarm optimization–bacterial foraging optimization (PSO–BFO) algorithm. A finite element model of the body-in-white (BIW) was developed and experimentally validated. Stiffness and modal characteristics were evaluated, and four loading conditions were analyzed to establish requirements for laminate optimization. Measured mechanical properties of T700/WP-R2300 were used as material inputs. Free-size and size optimization determined the ply shapes and thicknesses, followed by stacking sequence optimization using the improved PSO–BFO algorithm. Compared with the original steel crossbeam, the optimized crossbeam achieved an 18.93% mass reduction, with increases of 39.72%, 30.67%, and 44.7% in roof compression, three-point bending, and axial tensile stiffness, respectively. For the BIW incorporating the optimized crossbeam, bending and torsional stiffness increased by 2.93% and 0.35%, respectively, while the first bending and torsional natural frequencies increased by 1.11% and 2.23% relative to the original BIW. Crossbeam specimens were fabricated, and three-point bending, modal, and whole-vehicle roof compression tests were conducted to evaluate the design. These results demonstrate the potential of the proposed method to reduce crossbeam mass while improving component and BIW performance.