Damage Simulation Of Composite Laminates Subjected To Low Velocity Impact

The composite structure is vulnerable to all kinds of damage, especially all kinds of low energy impact during the process of production and application, which will produce visual invisible damage in the laminates and degenerate the mechanics properties of composite. Composite laminate with damage is closely related to the structural safety and the life expectancy. So it is very important for structural safety assessment to evaluate the low-energy impact resistance and damage prediction of composite structures.In this paper, the damage prediction model of low velocity impact of composite laminates is established by using the finite element software ABAQUS. And the user material subroutine VUMAT including damage criterion and stiffness attenuation method is invoked during calculation. Then the damage accumulation process of composite laminates under repeated low velocity impact can be obtained. The main research contents are as follows:(1) A reasonable low speed impact experiment to a typical layer of composite laminated plate is designed. The tests include the preparation of the composite laminates,the engineering constants test, and the low-velocity impact. At the same time,the dynamic strain analysis system is used to collect strains during the impact, and nondestructive testing method,ultrasonic scanning microscope, is used to detect the delamination area. Among all the laminates, a part of the specimens are subjected to repeated low-velocity impacts. And then damage extension analysis of the laminated plate under the repeated low-velocity impact is implemented.(2) A laminated plate finite model of the low-velocity impact is built. It is necessary to establish the bonding layer between the layers in the FEM model to evaluate the delamination damage. At the same time, the H-R(Hashin-Rotem) damage criterion is written into VUMAT to analyze the low velocity impact damage. And in ABAQUS software, the repeated impact simulation is realized by using the restart method. And then compare the FEM results with the experiment results to revise and verify the accuracy and rationality of the simulation model.(3) The influence of different parameters on the dynamic response of the low-velocity impact is researched.These parameters include the energy of low velocityimpact, the contact area between the impact hammer and the surface of the laminate and the layer angle, etc. Comparative analysis of the damage propagation process and the dynamic response of laminated plate is carried out to predict the impact damage of the composite structure.