Effect of Nose Shape and Mass of the Impactor on Impact Damage of Laminated Composites.

Abstract : The investigation studied impact damage resistance of laminated composites caused by a low-velocity foreign object. Effects of material interfacial strength and impactor's mass and nose size on damage resistance were the study's concern. An analytical model was developed for predicting the dynamic response of composites during impact. The model consists of damage accumulation prediction and material degradation modeling. Damage accumulation criteria were adopted for predicting failure and mode of failure due to impact. Appropriate material constitutive relations were also proposed to relate strains to stresses for material that was inflicted with impact damage. The Hertzian contact law was modified by taking into account material degradation during impact. The proposed model and modified Hertzian contact law were implemented in a transient dynamic finite element analysis designated "3DIMPACT." The code predicts force response and damage accumulation of a composite during impact. Composites with and without toughening Interleaves were tested experimentally to verify the model and the computer code. The effect of the impactor' s size and nose radius was considered in verifying the code, very useful for evaluating impact resistance and for screening materials.