Research On Characteristics Of Damage Behavior Of Fiber Reinforced Composite Materials Under Impact Load

Fiber reinforced composites have been widely used in aerospace,automobile,ship and ordnance industry due to their high specific modulus,high specific strength and designability.Under complex working conditions,composite materials often bear a variety of impact loads.It may lead to the appearance of pits on the surface,and the internal damage of the structure which may be invisible.Therefore,it is of great scientific research value and engineering application value to study the damage failure behavior of fiber reinforced composites under impact load.In this paper,the damage behavior of composites is studied comprehensively from three different scales: material level,sample level and component level.At the material level,based on the continuum damage constitutive model proposed by Ladeveze,the strain rate effect is introduced to establish the rate-dependent damage constitutive model.It can accurately describe the different mechanical properties of composite materials under different strain rates.The main damage modes include fiber tensile rupture,fiber compression rupture,matrix microcracking and fiber/matrix debonding.Based on the damage constitutive model,a User subroutine VUMAT was developed,and the validity of VUMAT program in ABAQUS was verified by the single element test.At the sample level,the mechanical tests of laminates were carried out,including quasi-static tensile test and compression tests.Based on the VUMAT subroutine preliminarily verified,the tests were numerically simulated.The stress-strain curves obtained from the experiments and numerical simulation are basically in agreement,so the validity of the rate-dependent damage constitutive model established in this paper was verified,and the accuracy of the corresponding VUMAT subroutine was further verified.The damage model can accurately describe the damage failure behavior of three laminated plates.At the component level,based on the VUMAT subroutine,the impact problem of composite laminates is numerically simulated.On this basis,the finite element simulation of low-speed impact under different energy is carried out,and the influence of impact energy on dynamic response such as contact load,punch displacement and dissipated energy of laminated plates is discussed.The maximum displacement,maximum contact force and impact energy of punch are linearly related.The main damage modes of structure under low speed impact are matrix microcracking and fiber/matrix debonding.The rate-dependent damage constitutive model can be applied to the low-velocity impact problem.