【作者】 高宇；

【导师】 朱顺鹏；

【作者基本信息】 电子科技大学 ， 机械（专业学位）， 2024， 硕士

【摘要】 疲劳破坏是重大装备结构常见的失效形式之一,而重大装备关键结构中往往存在不可避免的几何不连续特征(即缺口),这些部位发生应力集中现象所引起的缺口效应为疲劳破坏的主要起因,且尺寸效应与不确定性常伴随缺口效应出现而影响上述关键结构的疲劳强度和寿命。因此,建立综合考虑缺口效应、尺寸效应及不确定性的缺口结构疲劳分析方法和寿命预测模型对装备结构完整性设计与评定至关重要。结合高应力场法及Weibull分布,本文系统开展了基于场法的缺口结构疲劳分析方法与寿命预测模型研究,以综合考虑装备结构疲劳失效中的缺口效应、尺寸效应及不确定性,具体总结如下:1)针对疲劳缺口效应问题,如传统应力场强法有效损伤区确定复杂等难点,提出界限半径以改进传统应力场强法,并构建一套缺口结构通用疲劳寿命预测框架。将其他两种模型与提出模型对比后,结果表明提出模型预测缺口件疲劳寿命的效果较好。2)针对疲劳尺寸效应问题,提出两种模型对改进应力场强法进行尺寸效应修正:对于应力集中因子接近、缺口附近应力梯度变化程度较小的缺口结构,基于缺口深度进行尺寸效应修正的模型更简洁、准确;对于应力集中因子相差较大、缺口附近应力梯度变化程度较大的缺口结构,基于高应力场法进行尺寸效应修正的模型鲁棒性更强、适用范围更广。3)针对疲劳分散性问题,将改进应力场强法结合高应力场及Weibull分布提出缺口结构概率疲劳模型,并将模型应用于航空发动机压气机轮盘结构的疲劳寿命预测,对比其他模型后,结果表明提出模型对于轮盘结构的寿命预测效果较好,具备一定工程意义。更多还原

【Abstract】 Fatigue failure is one of the common forms of failure in major equipment structures,and there are often inevitable geometric discontinuities(notches)in the critical structures of major equipment.The notch effect caused by stress concentration in these areas is the main cause of fatigue failure,and size effects and uncertainties often accompany the notch effect,affecting the fatigue strength and life of the aforementioned key structures.Therefore,it is crucial to establish a fatigue analysis method and life prediction model for gap structures that comprehensively consider gap effects,size effects,and uncertainties for the design and evaluation of equipment structural integrity.Combining the high stress field method and Weibull distribution,this thesis systematically conducted research on the fatigue analysis method and life prediction model of notch structures based on the field method,in order to comprehensively consider the notch effect,size effect,and uncertainty in equipment structure fatigue failure.The specific summary is as follows:1)Regarding the issue of fatigue notch effect,such as the complexity of determining the effective damage zone using traditional stress field strength method,boundary radius was proposed to improve the traditional stress field strength method,and a universal fatigue life prediction framework for notch structures was proposed.After comparing the other two models with the proposed model,the results showed that the proposed model has a better effect on predicting the fatigue life of notched parts.2)Regarding the issue of fatigue size effect,two models were proposed to address the size effect in the improved stress field strength method.For notch structures with close stress concentration factors and smaller stress gradient changes near the notch,the model based on notch depth for size effect correction is simpler and more accurate;For notch structures with significant differences in stress concentration factors and significant changes in stress gradients near the notch,the model based on high stress field method for size effect correction has stronger robustness and wider applicability.3)Regarding the issue of fatigue dispersion,an improved stress field strength method combined with high stress field and Weibull distribution was proposed to propose a probabilistic fatigue model for notch structures.The proposed model was applied to predict the fatigue life of aircraft engine compressor disc structure.Compared with other models,the results showed that the proposed model has a good predictive effect on the life of disc structure and has certain engineering significance.更多还原