Finite Element Analysis On Medium And Low Velocity Impact Responses Of 3-D Braided Composite

Compared with the traditional laminated composite materials,3-D braided composite materials overcome the disadvantages of easy layering and enhance the mechanical properties in the direction of thickness.3-D braided composites have higher specific strength and damage tolerance,stronger impact resistance and better overall structure.3-D braided composite materials in the process of preparation and application of the inevitable will be affected by a variety of impact load,so as to make the composite structure is a certain degree of failure,in order to avoid impact damage caused by security issues,and extend the service life of structures,it is crucial for the impact damage failure of 3-D braided composites.This paper aims to establish a full-size meso-structure model of 3-D braided composites by CATIA and ABAQUS/CAE,to explore the impact response characteristics of 3-D braided composites at different speeds and to explore the failure mechanism deeply.Main contents:(1)According to the real structural characteristics of 3-D braided composites,the preformed model was established by CATIA and the resin model was established by ABAQUS,assembly finished and then the full-size micro-structure finite element model of 3d braided composites was established.(2)Introducing the failure criteria of ductile and shear destructive materials and combining with ABAQUS/Explicit,the influence of velocity on the transverse and low speed impact response characteristics and failure mechanism of 3-D braided composite materials is discussed.(3)Compare the experimental results with the finite element calculation results to verify the effectiveness and correctness of the finite element model.Main conclusions:(1)The stress wave of 3-D braided composite material is reflected in the input bar for many times under the condition of transverse impact,which leads to the multiple impact of the input bar on the composite material model.In the process of four times of impact,it is found that there are multiple load peaks,and the load gradually decreases with the increase of impact times.The maximum load,displacement and absorbed energy increase with the increase of impact velocity.(2)The displacement and energy of the maximum load and the maximum load all increase linearly with the increase of impact velocity under low speed impact.The analysis shows that the stress is mainly concentrated in the impact area and the grip area at both ends.The sag occurs in the impact area and the degree of bending deformation and sag increases with the increase of impact velocity.(3)The comparison shows that the finite element calculation results are in good agreement with the experimental results,which verifies the validity and correctness of the 3-D braided composite finite element model.