基于全场等效损伤测试的寿命分析模型研究-固体力学专业论文.docxVIP

南京航空航犬人学硕十学位论文摘要 南京航空航犬人学硕十学位论文 摘要 本文是江苏省自然科学基金资助项目。材料的静力韧性是应办—应变图的 面积，表示材料断裂前吸收的功，它综合反映了材料的强度和延性性能。本文 研究了材料的静力韧性与疲劳损伤之间的关系，并在此基础上得到用韧性表示 的损伤表达式。本文以韧性耗散为损伤变量，通过预设的一组循环数，对其 中每一预定循环数进行不同应力水平的疲劳试验，测出材料的韧性变化 率，以此为损伤变量得到在该组循环数下损伤量与交变应力水平关系的 曲线族。该曲线族可以转换成相同损伤量下交变应力与循环数关系的等 效损伤线族，显示了损伤场全貌。然后在得出经验证合理的损伤线族方 程的基础上，在复杂加载下由损伤曲线计算损伤累积并得到剩余疲劳寿 命递推公式。伪了验证所得出的损伤线族方程在多级加载下的描述能力， 用该损伤线模型对LYl2CZ和30CrMnSiA两种材料的二级加载试验进行的 寿命预测与实验结果进行比较，预测疲劳寿命值与实验数据较好吻合， 结果令人满意。 本文的等效损伤曲线完全由实测得到，在等效损伤假设的前提下所 进行的损伤计算和寿命分析更为直接可信。凡卢一 ／ 吵 关键词：等效损伤；损伤累积；篷查垂窭；韧性耗散i 南京航空航大人学硕七学位论文Abstract 南京航空航大人学硕七学位论文 Abstract The project of thiS paper iS supported by Jiangsu Natural 7 Science fund．Material S statiC toughness iS the area of the Stress—stain chart，which means the work absorbed before its break． It integrative reflects the strength and the ductility of the material．ThiS paper studies the relationship between the statiC toughness and fatigue failure firstly，then getting the damage formula expressed by toughness．In this paper，fatigue test are performed on various alternative stress levels of a group of fixed cycle number．Meanwhile，the material toughness that is selected as fatigue damage parameter iS measured in the tests and a group of curves are obtained，which express the relevancy of the damage quantity and alternative stress 1evel．These curves are then transformed into equivalent damage curve family．Thus the full fatigue damage field is shown．In the paper，the damage cumulative model and the fatigue life formula are induced from the complex loading equivalent damage curves，which is based on the reasonable equivalent damage curve function．In order to examine the description of the gained damage 1inear equations under complex loading circumstances，a comparison of the theoretical 1ife prediction with the test results，which are obtained by testing the two material—LYl2CZ and 30CrMnSiA。iS made and it can be found that the data gained in the tests are well fit in with the damage equation．Thereby the equivalent da