More and more experiments have shown that particle-reinforced metal matrix composites (PMMC) exhibit obvious size effects. The aclassic plasticity theory does not contain internal length scale and cannot explain this size effect. In this paper, based on the Taylor relationship, the concept of "geometrically necessary dislocations" and the mechanism of dislocation multiplication, slippage and extinguishing, a constitutive equation for SiCp/Al composites related to strain gradient is established. The established equation is imported into Abaqus for simulation by writing a user subroutine Vumat. Combining the simulation and experimental results, the effects of stress, temperature, cutting force, strain gradient effect and its dimensional effect on cutting deformation during machining SiCp/Al composites are analyzed from the perspectives of material micro-plasticity mechanics and material dislocation theory. The results show that the presence of SiC particles changes the microstructure of the matrix material, and induce a high strain gradient in the matrix. This high strain gradient makes the material more prone to shear deformation localization. In the cutting process, the defects and breakage of the SiC particles themselves will lead to the formation of micro-cracks. The growth of micro-cracks in the shearing area is an important factor in the generation of chips. By comparing the simulation results with the experimental results, the modified constitutive model is closer to the experimental results, indicating that the established theoretical model based on the strain gradient can better reflect the cutting process of particle-reinforced metal matrix composites.

越来越多的实验表明，颗粒增强金属基复合材料（PMMC）表现出明显的尺寸效应。非经典塑性理论不包含内部长度尺度，无法解释这种尺寸效应。本文基于泰勒关系、“几何必要位错”的概念以及位错增殖、滑移和熄灭的机理，建立了与应变梯度相关的SiCp/Al复合材料的本构方程。通过编写用户子程序 Vumat 将建立的方程导入 Abaqus 进行仿真。结合仿真和实验结果，应力、温度、切削力的影响，从材料微塑性力学和材料位错理论的角度分析了应变梯度效应及其对SiCp/Al复合材料加工过程中切削变形的尺寸效应。结果表明，SiC颗粒的存在改变了基体材料的微观结构，并在基体中引起了高应变梯度。这种高应变梯度使材料更容易发生剪切变形局部化。在切割过程中，碳化硅颗粒本身的缺陷和破损会导致微裂纹的形成。剪切区微裂纹的生长是切屑产生的重要因素。通过将仿真结果与实验结果进行对比，修正后的本构模型更接近于实验结果，