Failure Of Abraided Composite Pin Under Dynamic Loading

As a kind of mechanical connection commonly used in complex composite structures,composite pins are often fractured and pulled out when subjected to dynamic loading such as impact,vibration and so on.However,studies on the dynamic strength and failure mechanism of composite pins are scanty,which has become a bottleneck of the wide application of composite structures.In this paper,according to the shear impact test of C/C braided composite pins,a dynamic failure criterion which is based on strain rate data is proposed.Meanwhile,the shear failure model of composite pins is established,and the impact of loading velocities and shear bands on the dynamic shear strength is also studied.In this section,the proposed criterion is verified by the comparison between the results from simulation and test.Furthermore,the proposed criterion is applied to the failure analysis of braided composite pins subjected to the harmonic dynamic loading,in order to predict the dynamic shear strength under this specific condition.The detailed contents of the study are listed as follows:(1)A dynamic failure criterion which is based on strain rate data is proposed to evaluate the dynamic strength of composite pins.Based on the results of impact tests of the C/C braided composite pins,the modified maximum stress criterion and the modified Tsai-Wu criterion are provided in this paper.(2)The shear failure model of composite pins is established,and the impact of loading velocities and shear bands on the dynamic shear strength is studied by using the modified criterion.By the comparison between the simulation and the test results,the proposed criterion is verified to be reliable.(3)The proposed criterion will be also applied to the failure analysis of C/C braided composite pins subjected to a harmonic dynamic loading,and the relationship between the failure strength and the loading frequency,the width of the shear band is predicted through the ABAQUS failure analysis.