STUDY ON INELASTIC CONSTITUTIVE EQUATIONS OF METALS CONSIDERING OF TEMPERATURE DEPENDENCY OF VISCOSITY AND AGING

考虑粘度和老化温度依赖性的金属非弹性本构方程研究

基本信息

批准号：
09650118
负责人：
KANEKO Kenji
金额：
$ 2.11万
依托单位：
SCIENCE UNIVERSITY OF TOKYO
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
1997
资助国家：
日本
起止时间：
1997 至 1998
项目状态：
已结题

项目摘要

Many studies on rate dependency of plastic flow of metals have been reported. In most of those studies, strain rate dependence of flow stress is considered to be due to only viscosity. On the other hands, some special facts that a flow stress decreases as a strain rate increases were recognized experimentally for Alminum-alloys. From the author's systematical experiments, it is found that the current theory having only viscosity function like a so-called overstress constitutive model, is not available for explaining a transient phenomena in flow stress observed at a sudden change in strain rate, and that the viscosity function derived from flow stress properties does not necessarily coincide with the viscosity function obtained from relaxation properties. In the previous report, taking into consideration of aging-like effect as well as viscosity, authors proposed a new viscoplastic constitutive models with aging.Apparent decrease in strain rate dependence of plastic flow stress can be observed at elevated temperature up to 500K, but much more decrease in relaxation behavior. It is found that the reason exists in a decrease of aging effect, and that a real viscosity property so much changes due to temperature for SUS316 stainless steel. On the other hand, for Ti which showes no aging at room temperature, strain rate dependency also decreases with increase of temperature, but the reason exists differently in increasing of aging, and real viscosity does not so change. Inelastic constitutive expressions with viscosity and aging considering its temperature dependence were proposed for these metals and its reliabilities were confirmed by comparing simulation results with the corresponding experimental results.It is also found that rate dependence is larger in axial loading than that in tosional loading for SCM435 steel in room temperature.

已经报道了许多关于金属塑性流动的速率依赖性的研究。在大多数这些研究中，流动应力的应变率依赖性被认为仅归因于粘度。另一方面，对于铝合金，通过实验认识到流动应力随着应变率增加而减小的一些特殊事实。作者通过系统的实验发现，现有的所谓过应力本构模型仅具有粘性函数的理论无法解释应变率突变时流变应力的瞬态现象，并且粘性从流动应力性质得到的函数不一定与从松弛性质得到的粘度函数一致。在之前的报告中，考虑到类老化效应以及粘度，作者提出了一种新的老化粘塑性本构模型。在高温至 500K 时，可以观察到塑性流动应力的应变率依赖性明显下降，但放松行为的减少更多。发现原因在于老化效果降低，并且SUS316不锈钢的实际粘度特性因温度而变化很大。另一方面，对于在室温下未表现出时效的Ti，应变速率依赖性也随着温度的升高而降低，但其原因在时效的增加方面有所不同，并且实际粘度没有如此变化。针对这些金属，提出了考虑其温度依赖性的粘度和老化的非弹性本构表达式，并通过将模拟结果与相应的实验结果进行比较，证实了其可靠性。还发现，SCM435 在轴向载荷下的速率依赖性大于在扭转载荷下的速率依赖性室温下的钢。