PHYSICALLY BASED FAILURE CRITERIA FOR PREDICTION OF DAMAGE EVOLUTON IN COMPOSITE MATERIALS SUBJECTED TO IMPACT LOADING

This paper presents a newly developed 3D constitutive model for numerical simulation of the response of composite materials subjected to impact loading by means of explicit finite element analysis. The development was motivated by the requirements raised in aircraft and aeroengine manufacturing industries as a result of the deficiencies of constitutive models in commercial software. The research was inspired by the established methodology for experimental characterisation of composite materials at elevated rates of strain. The new material model relies upon the continuum representation of material behaviour within a representative volume element (RVE). The size of the RVE is given by the 'characteristic length ' of the finite element under consideration and the material orientation within this finite element. The element’s load carrying capacity is assessed by means of stress based failure criteria which address all experimentally observable failure modes. A damage mechanics approach is adopted in which the evolution of damage is determined by the rate at which the failure surfaces separating the admissible from inadmissible stress states are exceeded. The evolution of damage in specific materials is controlled by a set of physically based material parameters which define the rate at which the failure surfaces shrink, thus representing th