拉扭双轴疲劳寿命预测方法研究

发布时间：2018-05-09 02:37

本文选题：多轴疲劳 + 不确定性　；参考：《湖南大学》2014年硕士论文

【摘要】：在实际工程问题中存在着大量的疲劳现象，且大部分情况下零部件所承受的载荷为多轴循环载荷，因而如何对多轴循环加载下的零部件进行更好的寿命预测成为疲劳领域内的热点研究之一。目前，国内外对于多轴疲劳的研究虽然有了一些进展，但由于多轴疲劳本身的复杂性，如今在理论和试验研究方面还不成熟，，对金属在多轴载荷下的疲劳寿命预测进行相关研究具有重要的理论和工程意义。本文在多轴疲劳寿命预测及其可靠性方面进行了一些尝试，相关研究工作如下：（1）基于现有的多轴疲劳准则，运用模糊理论，建立了一种多轴高周疲劳模糊准则。并结合材料的S-N曲线，可获得不同可靠度P下的多轴疲劳P-S-N曲线。该方法能够在一定程度上反映疲劳试验数据的分散性与不确定性。（2）提出了一种能够考虑加载路径对多轴低周疲劳寿命影响的路径载荷因子。借助该因子，构建了两种多轴低周疲劳寿命预测模型(拉伸型与剪切型)，使得预测模型能够较好地考虑应力比和相位角的影响。最后，运用大量试验数据对两种模型进行了验证。（3）基于等寿命曲线的思想，提出了一种新的多轴高周疲劳寿命预测方法。该方法在一定程度上考虑了多轴比例加载与材料固有属性之间的关系，而不是单纯依靠材料的单轴疲劳强度与剪切疲劳强度来预测比例加载下的结果。不仅如此，该方法还利用一组多轴非比例加载下的试验数据来考虑了不同材料之间对非比例的敏感程度。
[Abstract]:There is a large number of fatigue phenomena in practical engineering problems, and in most cases, the load of components is multiaxial cyclic load. Therefore, how to better predict the life of the components under multiaxial cyclic loading has become one of the hot topics in the field of fatigue. At present, although there has been some progress in the study of multiaxial fatigue at home and abroad, due to the complexity of multiaxial fatigue itself, the theoretical and experimental research is still immature. It is of great theoretical and engineering significance to study the prediction of fatigue life of metals under multiaxial loads. In this paper, some attempts have been made on the prediction of multiaxial fatigue life and its reliability. The related research work is as follows: 1) based on the existing multiaxial fatigue criterion and fuzzy theory, a multiaxial high cycle fatigue fuzzy criterion is established. The multiaxial fatigue P-S-N curves with different reliability P can be obtained by combining the S-N curves of the materials. This method can reflect the dispersion and uncertainty of fatigue test data to some extent. (2) A path load factor which can consider the effect of loading path on multiaxial low cycle fatigue life is proposed. With the help of this factor, two kinds of multiaxial low cycle fatigue life prediction models (tensile type and shear type) are constructed, which can better consider the influence of stress ratio and phase angle. Finally, a large number of experimental data are used to verify the two models. A new multiaxial high cycle fatigue life prediction method is proposed based on the idea of equal life curve. To some extent, this method considers the relationship between multiaxial proportional loading and intrinsic properties of materials, rather than simply relying on uniaxial fatigue strength and shear fatigue strength to predict the results under proportional loading. Not only that, but also a set of experimental data under multiaxial and non-proportional loading is used to consider the non-proportional sensitivity of different materials.
【学位授予单位】：湖南大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TH133.2

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