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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.

许多关于金属塑性流动的速率依赖性的研究已经被报道。在大多数这些研究中，流动应力的应变率依赖性被认为仅仅是由于粘度。另一方面，一些特殊的事实，即流动应力随着应变率的增加而减小，在实验上被认为是铝合金。从作者的系统实验中发现，目前的理论只具有所谓的超应力本构模型的粘性函数，不能解释在应变速率突变时观察到的流动应力的瞬时现象，并且由流动应力特性导出的粘度函数与由松弛特性得到的粘度函数并不一定一致。在以前的报告中，考虑了类时效效应和粘性，作者提出了一种新的具有时效的粘塑性本构模型，在500K以下的高温下，塑性流动应力的应变率依赖性明显降低，但松弛行为明显降低。研究发现，其原因在于时效效应的减弱，以及SUS316不锈钢的真实粘度随温度变化较大。对于室温下未出现时效的钛，应变速率依赖性也随温度的升高而降低，但其原因随时效程度的增加而不同，实际粘度变化不大。提出了考虑温度依赖性的粘性和时效的非弹性本构关系，并将模拟结果与相应的实验结果进行了比较，验证了其可靠性。此外，SCM435钢室温轴向载荷的速率依赖性大于扭转载荷。