基于离散元法的冷硬铸铁参数标定研究

Parameter Calibration of Chilled Cast Iron Based on the Discrete Element Method

摘要: 冷硬铸铁具有高硬度和高耐磨性，广泛用于轧辊、衬板等关键耐磨构件，但其高脆性使切削加工过程中易产生裂纹和崩边缺陷。为获得适用于冷硬铸铁切削仿真的离散元微观参数，建立了线性粘弹性摩擦键合平行键离散元模型，并通过单轴压缩和三点弯曲数值试验对模型参数进行了交叉验证标定。采用控制变量法分析了颗粒细观泊松比、滚动摩擦系数和颗粒刚度对弹性模量、抗压强度和抗弯强度的影响规律。结果表明，颗粒细观泊松比对弹性模量影响较小，在实际取值范围0.24~0.28内，抗压强度和抗弯强度波动均小于5%；滚动摩擦系数对弹性模量和峰值强度影响不显著；宏观弹性模量与颗粒刚度近似呈线性关系，可根据目标弹性模量反算颗粒刚度。研究结果可为冷硬铸铁切削过程离散元建模和参数标定提供依据。

Abstract: Chilled cast iron is widely used in key wear-resistant components such as rolls and liners because of its high hardness and excellent wear resistance. However, its high brittleness makes crack initiation and edge chipping likely to occur during machining. To obtain microscopic parameters suitable for discrete element simulation of chilled cast iron cutting, a linear viscoelastic frictional bonded parallel-bond discrete element model was established. The microscopic parameters were calibrated and cross-validated through numerical uniaxial compression and three-point bending tests. The effects of particle mesoscopic Poisson’s ratio, rolling friction coefficient and particle stiffness on elastic modulus, compressive strength and flexural strength were investigated by the control variable method. The results show that the particle mesoscopic Poisson’s ratio has little influence on the elastic modulus. Within the practical range of 0.24~0.28, the fluctuations of compressive strength and flexural strength are both less than 5%. The rolling friction coefficient has no significant effect on the elastic modulus or peak strength. The macroscopic elastic modulus is approximately linearly related to particle stiffness, which makes it possible to calculate particle stiffness from the target elastic modulus. The research results can provide a basis for discrete element modeling and parameter calibration of the cutting process of chilled cast iron.