In situ analysis of flow dynamics and deformation fields in cutting and sliding of metals
In situ analysis of flow dynamics and deformation fields in cutting and sliding of metals
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DOI：
10.1098/rspa.2015.0194
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发表时间：
2015-06-08
影响因子：
3.5
通讯作者：
Chandrasekar, Srinivasan
中科院分区：
文献类型：
--
作者：
Guo, Yang;Compton, W. Dale;Chandrasekar, Srinivasan
采用高速成像和粒子图像测速技术，对金属切削和滑动过程中的流动动力学、变形场和切屑颗粒的形成进行了现场分析。该模型系统是一个黄铜工件加载对楔形压头在低速。在大的负前角下，流动是稳定的，在压头前面形成材料的头部。没有材料去除和均匀应变层上的工件表面上的纯滑动政权的发展。当前角较小时，流动变得不稳定，由船首自由表面上的裂纹的形成和材料去除引起切割状态。裂纹萌生时船首表面的应变是恒定的。芯片形态，如离散颗粒，分段芯片和连续芯片与介观尺度粗糙度，所示出的是从一个通用的机制，涉及的船首裂纹的传播，但不同的距离朝向压头尖端。连续切屑形成中的简单剪切变形显示出小角度振荡也与船首裂纹有关。材料去除过程和韧性破坏的影响进行了讨论。
The flow dynamics, deformation fields and chip-particle formation in cutting and sliding of metals are analysed, in situ, using high-speed imaging and particle image velocimetry. The model system is a brass workpiece loaded against a wedge indenter at low speeds. At large negative rake angles, the flow is steady with a prow of material forming ahead of the indenter. There is no material removal and a uniformly strained layer develops on the workpiece surface-the pure sliding regime. When the rake angle is less negative, the flow becomes unsteady, triggered by formation of a crack on the prow free surface and material removal ensuing-the cutting regime. The strain on the prow surface at crack initiation is found to be constant. Chip morphologies, such as discrete particle, segmented chip and continuous chip with mesoscale roughness, are shown to arise from a universal mechanism involving propagation of the prow crack, but to different distances towards the indenter tip. The simple shear deformation in continuous chip formation shows small-angle oscillations also linked to the prow crack. Implications for material removal processes and ductile failure are discussed.