DAMAGE OF COMPOSITE UNDER LOW-VELOCITY IMPACT AND APPLICATION OF MECHANICAL EQUIVALENT MODEL

The particularity and harmfulness of composite material damage caused by low-velocity impact makes it very important to assess the damage of aerospace structures. Through developed numerical model and experiment data, four aspects of application problems are solved in this paper: 1) By means of ABAQUS user subroutine VUMAT, which includes damage criterion and evolution, and by combining with a cohesive model, the damage of a laminate under low-velocity is simulated; 2) Damage tolerance design method requests the correct estimate of structures consisting of defects. By means of ABAQUS user subroutine USDFLD, which introduces damage criterion and material reduction, the ultimate strength of composite laminates including a circular hole under tension and compression loading is carried out; 3) Delamination has important influence on the compression of a composite laminate. By means of ABAQUS user subroutine UMAT combined with a cohesive model, which introduces damage criterion and stiffness reduction, the failure of the composite laminate as well as the prefabricated delamination under compression are simulated; 4) A mechanical equivalent model is proposed to solve the practical simulation of a co-curing structure. The model developed in this paper has obtained a good agreement with static structural experiment data and also been extended to the dynamic impact simulation.