Axial Crushing Performance Study Of Automotive Multi-cell Metal-CFRP Hybrid Thin-walled Tubes

With the continuous increase of vehicle ownership in the world,the probability of traffic accidents is increasing,and the amount of vehicle exhaust emission is also increasing with each passing day.The safety of automobiles and environmental pollution are imminent.The collision safety in the traditional automotive body design procdure depends on increase of the vehicle mass,whereas it induces more energy consumption and higher emission.Lightweight design focus on all-around exploring in the fields of new materials,new processes,new structures,etc.,and striving to balance of collision safety and environmental protection when designing automotive structures.The carbon fiber reinforced plastic(CFRP)owns a high fiber axial specific strength,and an excellent thin-walled energy absorbing structure can be obtained through a reasonable design,which especially conduces to fabrication of an automotive passive safety protection structure including a crash box.In this paper,aiming at the lightweight of automobiles,a novel automotive multi-cell Metal-CFRP thin-walled hybrid tubular structure was proposed and fabricated,and its axial crushing performance was systematically studied on the basis of simulation and experiment.Firstly,the superiority of the axial energy abrosbing performance of multi-cell filled circular tubular structures was numerically verified in terms of different section-geometry design schemes.Subsequently,the mechanical properties of CFRP used in this study were tested in terms of composite materials relevant guidelines in ASTM.The subsequent axial crushing experiment and simulation benchmark of CFRP single tubes verified the validity of FE modeling and the accuracy of corresponding mechanical parameters.Additionally,series of mutil-cell CFRP thin-walled hybird tubular structures were fabricated.The quasi-static axial crushing experiments aiming at hybird tubular structures with different cell numbers,wall thicknesses and cell diameters were conducted.The results show that the multi-cell CFRP hybird tube is a thin-walled structure with excellent axial crashing performance.Increasing cell numbers and wall thicknesses can effectively improve its axial crashing performance under a constant length-to-diameter ratio.In honeycomb-like design scheme,with more numbers and smaller tube diameters of outer cells,the superior axial crashing performance of the mulit-cell CFRP thin-walled hybird tube can be obtained.Finally,a multi-cell Metal-CFRP thin-walled composite tubular structure with different design parameter was further designed and fabricated.Combined with FE numerical simulation,the effects and rules of different design factors on the axial crashing performance of multi-cell Metal-CFRP thin-walled hybird tubular structures were analyzed and summarized in terms of the crush failure mode,the crushing peak curshing force and the specific energy absorbing,etc.The results show that the mutil-cell Metal-CFRP thin-walled tubular structure also owns an execellent axial crushing performance and a higher cost performance than the multi-cell CFRP hybrid tube.The material strength of cell and outer tube is the dominant influence factor for improving the peak curshing force and energy abosorbing,and owns a positive correlation.In addition,increasing number of inner cells conduces to improvement of the corresponding Metal-CFRP strucuteres crashing performance.In sum,the multi-cell Metal-CFRP hybird tube is an innovative thin-walled structure with excellent axial crushing performance,which can be effectively applied into the design procedure of actual anti-crashing energh absorbing structure of automobile body.