Multiscale Modeling Of Hybrid Fiber Composite Vehicle Body Components And Research On Crashworthiness Under Bending Loads

Carbon Fiber Reinforced Plastics(CFRP)have crucial potential for improving the lightweight level of automobiles due to their high specific strength and stiffness.However,due to the high cost and poor toughness of CFRP materials,unstable local buckling and brittle fracture failure modes may occur when subjected to impact loads,resulting in a significant reduction in the crashworthiness of structures.In order to overcome the above shortcomings,carbon fibers can be combined with glass fibers with lower cost and better toughness to form hybrid fiber reinforced composites.If the hybrid fiber composite material is applied to the vehicle body structure design,it not only can better balance the lightweight effect and material cost,but also can improve the toughness of the material.Moreover,by optimizing the proportion of its component materials,the structure can generate deformation in a stable and controllable manner,thereby greatly improving the crashworthiness of the structure.Relying on the national key research and development program(2021YFB2501705),this paper takes carbon fiber/glass fiber hybrid fiber composites as the research object,and carries out multi scale analysis of crashworthiness of hybrid fiber composite body components by building a multi-scale model of hybrid fiber composites,and applies this model to the design of automobile B-pillar stiffeners.The main content of this article is as follows:(1)A multiscale model of hybrid fibers was established,and a stress amplification coefficient was introduced.The stress amplification coefficient was used to combine the microscopic stress with the macroscopic stress.Based on the microscopic stress,the microscopic damage failure and evolution of the fiber and matrix were performed,and the microscopic damage failure parameters were transferred to the macroscopic damage variables.The macroscopic damage variables were then updated to the macroscopic stiffness matrix,thereby achieving progressive damage failure calculation based on microscopic mechanics.By writing the multiscale model into the Vumat subroutine,the calculation is implemented on the ABAQUS/Explicit platform.(2)Experimental research on hybrid fiber composites was carried out.0° and 90° tensile tests were conducted on unidirectional pure carbon,pure glass,and carbon/glass hybrid fiber composites,and their macroscopic elastic parameters were measured.The microscopic fiber distribution of CFRP and GFRP was obtained through scanning electron microscope experiments,providing parameter support for multiscale microscopic modeling.A quasi static three point bending test was conducted to investigate the effects of different hybrid ratios on the bending resistance of laminated plates and the impact resistance of rectangular tubes.(3)The micro and macro models of hybrid fiber multiscale models were established in ABAQUS software,and the macro elastic parameters of hybrid fiber composites were predicted.Based on a multi scale finite element model,the three point bending and crushing process of a hybrid fiber rectangular tube was numerically simulated and verified by experiments.(4)Based on the validated multiscale finite element model,the effects of fiber mixing methods,ply number,and ply angle on the crashworthiness of rectangular tubes were studied.In addition,hybrid fibers are applied to the automobile B-pillar reinforcement plate and their crashworthiness is calculated.