Papers by Keyword: Cumulative Plastic Strain

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Authors: Shun Hua Zhou, Jing Shan Shi, Quan Mei Gong, Chang Ji
Abstract: Based on the dynamic triaxial test of typical soils in Hangzhou area, the existed empirical calculation formulas of cumulative pore pressure and cumulative plastic strain are analyzed to recharacterized variables such as the cyclic stress ratio and the static deviator stress, therefor the modified formulas are proposed. Parameters of cumulative deformation calculation model that suitable for this area are also determined according to dynamic triaxial tests. Thereafter the modified formulas is applied in a subway project under construction in Hangzhou. Results show that both the the cumulative plastic strain and cumulative pore pressure in dynamic triaxial test have the power exponential function relationship with the vibration number, and an inflection point appears in curve when amounts to approximately 1000. The improved formulas basicly tally with test results, of which the cumulative plastic strain formula coinsides better. The formulas work well in calculating the long-term settlement of subway projects in Hangzhou area.
Authors: Yong Liu, Jin Quan Xu, Yoshiharu Mutoh
Abstract: Fretting fatigue has grasped strong interest in last decades, some quantitative methods for the evaluation of fretting fatigue were developed. However, only very few studies have been reported on fretting wear, especially on its mechanical model and evaluation method. In this study, cumulative plastic strain is analyzed by FEM. To obtain accurate plastic strain, the shape change due to the plastic deformation has been taken into account. It is found that the cumulative plastic strain will be saturated after several hundred cycles at the initial fretting stage. Considering that fretting wear is very small during this early stage, as it can be observed from the fretting test, the wear at the contact interface before the saturation of cumulative plastic strain can be neglected. Since the saturated cumulative plastic deformation represents the stable deformation of the contact interface, it is proposed that the fretting wear can be characterized by the saturated cumulative plastic strain and accumulative shear stress. With this method, the wear profile of the specimen is predicted. By comparing FEM results with the experimental results of fretting wear, the proposed wear formulation is validated.
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