﻿ 一种疲劳损伤参数确定新方法<sup>*</sup>
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A novel method for determining fatigue damage parameters
LIU Xiaoxiao, WANG Yibing, ZHANG Zheng
School of Aeronautic Science and Engineering, Beijing University of Aeronautics and Astronautics, Beijing 100083, China
Received: 2017-07-05; Accepted: 2017-10-20; Published online: 2017-11-30 14:33
Foundation item: National High-tech Research and Development Program of China (2015AA034401)
Corresponding author. ZHANG Zheng, E-mail:jordanzzhang@buaa.edu.cn
Abstract: Fatigue fracture of metal materials is a common failure mode in engineering structures. Damage mechanics regards crack initiation as a progressive damage process, describing and conducting life estimates through the damage evolution equation. However, the parameters in the damage evolution equation need to be fitted according to the standard experimental data. This process usually requires multi-parameter fitting, which involves complicated operation, large computational amount and vague physical meaning. To avoid these problems, based on the theoretical basis of damage mechanics, a new method to determine the parameters of damage evolution equation was proposed. According to the properties of damage evolution equation and the characteristics of S-N curves, a single parameter method, which employs single parameter to determine the damage evolution equation, was proposed using mathematical method. The proposed method avoids the disadvantage of multi-parameter fitting at the same time and improves the calculation accuracy and speed, which provides an alternative for engineering analysis. Finally, a concrete example is given to demonstrate the effect of the proposed method.
Key words: damage mechanics     fatigue     evolution equation     parameter determining     S-N curves

1 损伤演化方程

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2 参数确定新方法 2.1 损伤参数p的确定

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2.2 损伤参数α的确定

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2.3 损伤参数D0的确定

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3 应用举例

 图 1 标准试样示意图 Fig. 1 Schematic diagram of standard specimen

 Kt=1 Kt=3 Kt=5 σn/MPa lg N σn/MPa lg N σn/MPa lg N 270 4.996 4 147 4.733 5 98 4.707 0 221 5.345 6 98 5.314 1 78 5.074 4 196 5.449 2 88 5.664 5 67 5.305 7 156 5.916 7 76 5.969 8 60 5.317 8 130 6.445 8 70 5.994 1 57 5.527 3

 Kt p α 1 1.021 2.505 67×10-5 3 1.112 3 4.304 6×10-4 5 0.389 9 2.867×10-4

 图 2 实验点与拟合曲线 Fig. 2 Test point and fitting curve
4 结论

1) 本文单一损伤参数确定法旨在充分利用实验(现象/曲线)的特征，在理论框架内建立损伤参数的物理含义，不仅确定参数的方法简明，拟合的计算量小，适用性更宽泛，同时可以准确地反映金属构件的疲劳性能。

2) 本文分别基于典型结构材料的标准件(棒件/板件)疲劳实验结果，进行了损伤参数的单一确定，与实验结果相比，取得了良好的一致性，也证明了本文方法的合理性和适用性。

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#### 文章信息

LIU Xiaoxiao, WANG Yibing, ZHANG Zheng

A novel method for determining fatigue damage parameters

Journal of Beijing University of Aeronautics and Astronsutics, 2018, 44(6): 1253-1257
http://dx.doi.org/10.13700/j.bh.1001-5965.2017.0448