چكيده به لاتين
In this study, a strain rate dependent micromechanical model has been proposed to predict mechanical behvior of polymer matrix composites. First, in order to predict dynamic behavior of polymers under different loading conditions by combining the modified johnson-cook model in pure tensile and pure torsion, a generalized constitutive model has been presented to predict mechanical behavior of these materials under multi-axial loading conditions. Then, by implementing this model in ABAQUS user material subroutine, strain rate dependent mechanical behavior of polymers have been simulated under multi-axial loading conditons.
In order to validate the numerical simulation, experimental tensile tests of polymeric specimens with central holes were carried out at different strain rates. Comparison of experimental results with simulation around the hole shows that this model has an acceptable accuracy to predict strain rate dependent behavior of polymers under multi-axial stresses and strains. By combining the generalized dynamic constitutive model for neat polymers and the micromechanical plastic theory of Huang, strain rate dependent mechanical behavior of unidirectional composites under longitudinal and transverse tensile and in-plane shear loading conditions have been predicted. Then, by combining the strain rate dependent micromechanical model of unidirectional composites and a dynamic progressive failure criteria, a dynamic micromechanical constitutive model has been presented to predict strain rate dependent mechanical behavior of laminated composites.
A comparison of results predicted by the present model and experimental results shows that the model predicts the strain rate dependent mechanical behavior of laminated composites at different starain rates with a very good accuracy. Also, the present model is able to identify different failure modes of each ply of a laminate under static and dynamic loading conditions.
Keywords : micromechanical model, Strain rate, Fibrous composite, Generalized strain rate constitutive model
