颗粒增强金属基复合材料绝热剪切局部化中应变梯度效应

In this research, a general incremental micromechanical scheme for nonlinear.composites was developed. The advantage is that this scheme can reflect the effect of.the third stress invariant on the overall behavior of composites. To characterize theeffect of particle size on inelastic behavior of particle reinforced metal matrix composites (MMCp), a hybrid micromechanical model was proposed. By making use of split Hopkinson pressure and torsion bars, the effect of particle size on the formation adiabatic shear band in MMCp was performed. The experimental results show that adiabatic shear band is prone to occur in small- particle composite. To understand this size-dependent deformation localization behavior in MMCp, a train gradient-dependent constitutive equation of MMCp was developed. By using this.model and linear stability analysis, the role of strain gradient in adiabatic shear.banding in MMCp was investigated. The result demonstrate that higher strain gradient is a strong driving force for onset of adiabatic shear banding in MMCp. The theoretical result is in a good accordance with the experimental observations.

实验研究和理论相结合，揭示应变梯度对颗粒增强金属基复合材料绝热剪切变形局部化形成和发展的作用机制，建立应变梯度依赖变形局部化失稳准则；发展具有较可靠物理基础的应变梯度塑性理论及依赖复合材料均匀化理论。本项目将有助于丰富和发展应变梯度塑性理论及变形局部化理论。