Investigation Of Dynamic Mechanical Behavior Of Pariculate-filled Composites

Particulate-filled materials are series of functional materials containing two or more materials. Their mechanical behaviors are sensitive to complex microstructures and complicated service environment. Especially, as for polymer-bonded particulate materials which experience viscoelastic deformation, investigating their mechanical responses under impact loading will give great more insight into the macro mechanical behaviors.In this paper, we mainly complete the following issues:(1) Based on Hopkinson Bar experiment, we proposed a macro homogeneous model by which we acquire mechanical responses of polymer-bonded particulate materials under high strain rates. A good agreement of the results between experiments and numerical simulations shows predictive capability of the model. And a CT imagebased micro damage model explicitly considering the micro features is formulated to represent macro behavior of polymer-bonded particulate materials. Cohesive elements which are widely used to quantify the damage or crack of material are inserted along element boundary to explicitly track crack paths and crack patterns. By applying revised stress-time curves extracted from macro model on the boundary of micro model, mechanical responses under various strain rates are obtained based on which we analyze the effects of microstructures and load velocity on mechanical behaviors.(2) A series of numerical models with various grain size, grain morphology and grain distribution laws are developed from which stress-strain curves under tension loading are extracted. The effects of microstructures on macro mechanical behavior are then investigated. Meanwhile, we observed the fracture process from micro cracks initiation to total failure of materials. We then can figure out which factor plays an important role in fracture mechanism.(3) A two-scale model was established with an initial edge crack in front of which microstructure was exactly considered and the other region was regarded as homogeneous material. Based on the two-scale cohesive model, the effects of microstructures and particulate/matrix interfaces on crack propagation paths and fracture resistance of particulate-filled materials are then analyzed.