Progressive Damage Modeling of Tensile Deformation of a Fiber Reinforced Composite Laminate under Strain Rate Effects

Finite element modeling provides an efficient approach to simulate the mechanical behaviors of composite materials. Many finite element models were built to predict the mechanical responses of composite materials under the static loading conditions. Such static-loading models of composite materials were too modest to predict their behaviors under the dynamic loading process, say varying strain rates. In this thesis, we established both macromechanical and micromechanical finite element models to simulate the progressive damages of fiber reinforced composite materials under varying intermediate strain rates.;With the application of the strain-rate-dependent composite properties, failure analysis and associated property degradations of failed composites, we were able to build a macromechanical finite element model to simulate the strain-rate-dependent mechanical behaviors of composite materials under intermediate strain rates. Through the comparison of our numerical results with experimental observations and modeling results reported in the literature, recommended values of mesh densities were presented and the correctness of our macromechanical mode was validated.;The model was further developed with a multicontinuum theory (MCT). Based on the macromechanical model, a micromechanical model was developed to study the effects of a MCT-based constituent stress interactive failure criterion on the numerical results of a tensile test on a composite coupon with varying strain rates. The MCT is based on a constituent volume average procedure and was used to calculate the stress and strain states of every constituent within the composite. Based on the stress information of the constituents, associated failure criteria and degradation rules were presented for the model.;By comparing the simulation results of the macromechanical and micromechanical models, we found some differences between them and further recommendations were given for modifying the present model to simulate the progressive damage dynamic responses of composite structures more precisely.