采用簇单元(Cluster)方法, 建立了碳化硅陶瓷材料预应力加工的离散元模型; 通过离散元模拟和划痕实验, 研究了预应力条件对碳化硅陶瓷材料切削时裂纹的扩展规律的影响, 观察了陶瓷材料加工表面/亚表面的裂纹损伤情况. 离散元模拟与实验结果均表明: 当预应力大小在一定范围内, 随着预应力的逐渐增大, 径向裂纹的数目逐渐减少, 横向裂纹有替代径向裂纹的趋势, 并导致材料以较小的碎片的形式被去除; 采用预应力加工能有效降低加工损伤, 提高加工表面质量, 并且进一步证明应用离散元法模拟硬脆材料的加工是可行的.
The discrete element model (DEM) of SiC ceramic material for pre-stressed machining was established by using a cluster method. The processes of crack propagation on different pre-stressed machining conditions were investigated by means of DEM simulation and scratching test. Damages and cracks of surface/subsurface were also observed. Both DEM simulations and experimental results showed that, while the magnitude of pre-stress was controlled in a certain range, the number of radial cracks reduced as the increasing of pre-stress magnitude; and there was a trend that the radial cracks were replaced by the transverse cracks, so as to the SiC materials were removed in the form of smaller fragments. It could be seen that machining damage was decreased and surface quality was improved by applying the pre-stressed machining method, and it was further proved that discrete element method was feasible to simulate the machining process of brittle materials.
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