Finite Element Modeling of Brittle and Ductile Modes in Cutting of 3C-SiC
Finite Element Modeling of Brittle and Ductile Modes in Cutting of 3C-SiC
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DOI：
10.3390/cryst11111286
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发表时间：
2021-11-01
期刊：
影响因子：
2.7
通讯作者：
Hartmaier, Alexander
中科院分区：
文献类型：
--
作者：
Alam, Masud;Zhao, Liang;Hartmaier, Alexander
脆性陶瓷的加工是一项具有挑战性的任务，因为对刀具的要求非常高，加工表面的质量在很大程度上取决于所选择的工艺参数。通常，加工过程的效率随着切削深度或刀具的进给速率而增加。然而，对于脆性陶瓷，这容易导致非常粗糙的表面或甚至裂纹形成。从小切削深度获得的光滑表面到大切削深度获得的粗糙表面的过渡称为加工中的脆韧性过渡。在这项工作中，我们调查的机制，这种脆性到韧性的转变，金刚石切削本质上脆性的3C-SiC陶瓷与有限元建模。采用Drucker-Prager模型来描述材料的塑性变形，并通过逆方法确定材料参数，以匹配材料在纳米压痕下的变形行为，纳米压痕是与切割过程中发生的加载状态相似的加载状态。此外，损伤模型已被引入到描述材料分离过程中的加工过程中，也在亚表面区域的裂纹萌生。利用该模型对3C-SiC材料进行了金刚石刀具切槽模拟，分析了切槽变形和损伤机理。我们的研究结果揭示了作为切削深度的函数的韧性和脆性切削模式之间的一个明显的过渡。这个过渡的临界切削深度被发现是独立的前角，但是，表面粗糙度强烈依赖于刀具的前角。
Machining of brittle ceramics is a challenging task because the requirements on the cutting tools are extremely high and the quality of the machined surface strongly depends on the chosen process parameters. Typically, the efficiency of a machining process increases with the depth of cut or the feed rate of the tool. However, for brittle ceramics, this easily results in very rough surfaces or even in crack formation. The transition from a smooth surface obtained for small depths of cut to a rough surface for larger depths of cut is called a brittle-to-ductile transition in machining. In this work, we investigate the mechanisms of this brittle-to-ductile transition for diamond cutting of an intrinsically brittle 3C-SiC ceramic with finite element modeling. The Drucker-Prager model has been used to describe plastic deformation of the material and the material parameters have been determined by an inverse method to match the deformation behavior of the material under nanoindentation, which is a similar loading state as the one occurring during cutting. Furthermore, a damage model has been introduced to describe material separation during the machining process and also crack initiation in subsurface regions. With this model, grooving simulations of 3C-SiC with a diamond tool have been performed and the deformation and damage mechanisms have been analyzed. Our results reveal a distinct transition between ductile and brittle cutting modes as a function of the depth of cut. The critical depth of cut for this transition is found to be independent of rake angle; however, the surface roughness strongly depends on the rake angle of the tool.