The Research On Crushing Response And Crashworthiness Under Axial Compression Of Thin-walled CFRP Tubes

As the lightweight and safety has become a popular trend of the car development,the composite materials stand out with its unique performance.More and more automotive structures apply composite materials instead of traditional metal materials,especially the fiber reinforced polymer which has been widely applied in the automotive parts.While the fiber reinforced composites are used in the energy absorbing structures,the safety performance of the composites should be noticed.Therefore,the crashworthiness of composite materials has been widespread concerned.The study on the composites is focused on the purpose of obtaining excellent composite structure which is able to absorb collision energy in a predictable and controlled manner.Based on the background,the axial crushing performance of the carbon fiber composite thin-walled tube was studied with experiments and numerical simulations.The main contents of this study are as follows:Firstly,the carbon fiber composite tubes are prepared using the winding forming process.The axial quasi-static compression tests are performed with a material testing system.The effect of fiber angle,diameter and number of layers on the crashworthiness of the tube was studied.The axial crushing performance of the winding tubes are evaluated comprehensively with the crashworthiness evaluation parameters,and the failure mechanism and morphology of the winding tubes are deeply researched to obtain the crashworthiness of the winding composite tubes.Then,the carbon fiber composite tubes are prepared by the rolling process.The axial quasi-static compression experiments are carried out based on the material testing machine.Similar to the winding tube,the angle,diameter and number of layers are studied.And the failure mechanism and morphology of the rolling tubes are discussed in detail,and the crashworthiness of the composite tubes is obtained.In addition,the crashworthiness of the winding tubes and the rolling tubes are compared in crushing response and failure mode respectively.The results show that the crashworthiness of the rolling tube is better than that of the winding tube.Further,the multi-shell finite element models of the carbon fiber composite tubes are established based on the Chang-Chang failure criterion of the composites in LS-DYNA.The modeling strategy of the debris wedge is proposed,the parameters of the failure model and interlayer contact algorithm for shells are determined.The simulation results are compared with the experimental results of the rolling tube.In particular,the layered failure mode of the tube is analyzed in detail,the results of which show that the model can precisely predict the axial crush response and failure modes,the numerical model has high accuracy and feasibility,and is able to provide reliable prediction for the experimental study in the following work.In this paper,some valuable conclusions have been drawn on the systematic study on the axial crushing response of carbon fiber composite tubes,which provides an addictive value for the application of composite thin-walled tube in engineering and further study.