论文部分内容阅读
本文简要地概述了对热塑剪切带的演变所进行的解析研究,其中包括不稳定性的发生,不稳定性发生后剪切带的发展,以及剪切带的晚期行为。所讨论的情况是,在温度和应变速率有关的材料中所发生的简单剪切变形,而且热传导在其中是不可忽略的。倘若没有热流流出试件,那么在某临界状态前,可以存在一个均匀的剪切变形场。而达到该临界状态时,扰动便会导致不稳定性的发生。这便可以是狭窄剪切带的形成。剪切带在其早期的非定常变形流动中,可能变狭,并伴随升温和应变速率提高。热传导对剪切带的作用是使其变宽。对剪切带的晚期行为的分析,表明其宽度是塑性功率和热扩散二者相互平衡的某种表现。包含热-塑剪切带的试件的观察支持了上述结果。分析还指出,剪切带中是可能出现熔化现象的,这也已在电镜观察中看到。
This article provides a brief overview of the analytical study of the evolution of a thermoplastic shear band, including the occurrence of instabilities, the development of shear bands after instability, and the late behavior of shear bands. The case in question is the simple shear deformation that takes place in the material relating to temperature and strain rate, and the heat conduction is not negligible therein. If there is no heat flow out of the specimen, a uniform shear deformation field may exist before a critical state. When the critical state is reached, the disturbance will lead to instability. This can be the formation of a narrow shear band. Shear bands may become narrower in their earlier unsteady deformation flow with an accompanying increase in temperature and strain rate. The effect of heat conduction on the shear band is to widen it. The analysis of the late behavior of the shear band shows that its width is a manifestation of the balance between plastic power and thermal diffusivity. Observations of specimens containing thermo-plastic shear bands support the above results. Analysis also pointed out that the shear band may appear melting phenomenon, which has also been observed in electron microscopy.