权益分类	功能权益	普通用户	{{item.name}}会员
{{category.name}}	{{benefitItem.name}}

An analysis of cyclic stress-strain response correlated with static mechanical properties and development of new method for assessing fatigue life

与静态机械性能相关的循环应力-应变响应分析以及疲劳寿命评估新方法的开发

基本信息

批准号：
62460079
负责人：
HATANAKA Kenji
金额：
$ 4.48万
依托单位：
Yamaguchi University
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (B)
财政年份：
1987
资助国家：
日本
起止时间：
1987 至 1989
项目状态：
已结题

项目摘要

The cyclic stress-strain curve is necessitated to calculate a crack growth rate based on elastic-plastic fracture mechanics and to predict the fatigue life. In view of this, the purpose of the present study is to develop a new method for the numerical simulation of the cyclic stress-strain curve and for the fatigue life assessment based on it. The cyclic stress-strain response of copper was numerically simulated by introducing the dynamic dislocation mechanics. Then, this was applied to the cyclic stress-strain analysis of the circumferentially notched components and to the life estimation. The main results obtained are summarized as follows.(1),The cyclic stress-strain response was successfully calculated by using the static mechanical properties through the proposed method.(2) The stress-strain responses of the circumferentially notched components were calculated by means of elastic-plastic finite element method , where the constitutive equation stated in the item (1) was introduced into the F.E.M. calculations.(3) The change in the shape of the surface crack originated at trie notch root was successfully analyzed in terms of the elastic-plastic fracture mechanics. The transition from the semielliptical to circumferential crack, which occurred at the notch root in the crack extension process under a given test condition, was satisfactorily predicted in the proposed analysis.(4) The crack initiation life of the circumferentially notched components was evaluated on the basis of the finite element stress analysis. Consequently, it was revealed that the equivalent plastic strain generated at the notch root dominates the crack initiation life of the notched components where the multiaxial stress develops.(5) The low-cycle fatigue lives of the dully and acutely notched cylinder components were satisfactorily evaluated through the analysis of the growth of the surface and circumferential cracks.

循环应力-应变曲线是计算基于弹塑性断裂力学的裂纹扩展速率和预测疲劳寿命所必需的。鉴于此，本研究的目的是发展一种新的循环应力-应变曲线的数值模拟方法，并在此基础上进行疲劳寿命评估。然后，这是适用于循环应力-应变分析的周向缺口组件和寿命估计。所得主要结果概括如下。(1)通过该方法，利用静态力学性能成功地计算了循环应力-应变响应。(2)采用弹塑性有限元法计算了环向缺口构件的应力应变响应，其中将第（1）项所述的本构方程引入到有限元中。计算。(3)用弹塑性断裂力学成功地分析了缺口根部表面裂纹形状的变化。在给定的试验条件下，在裂纹扩展过程中发生在缺口根部的半椭圆裂纹到环向裂纹的过渡，在所提出的分析中得到了令人满意的预测。(4)在有限元应力分析的基础上，对环向缺口构件的裂纹萌生寿命进行了评估。因此，它揭示了在缺口根部产生的等效塑性应变占主导地位的多轴应力发展的缺口部件的裂纹萌生寿命。(5)通过对表面裂纹和周向裂纹扩展的分析，对钝缺口和尖锐缺口圆柱体构件的低周疲劳寿命进行了满意的评估。