机械结构承载件疲劳状态的统计学分析

发布时间：2018-08-30 15:41

【摘要】：疲劳破坏是机械结构件失效的主要形式,结构件在受到循环载荷的作用下可能会发生疲劳甚至破坏。采用不同的疲劳分析方法,可对结构件疲劳损伤的特点进行分析。在实际工况下,结构件承受的载荷和工作环境十分复杂,并且机械结构件疲劳的发生存在很多随机性。因此,从数理统计的角度提出疲劳统计学分析方法,有望对机械结构件疲劳损伤进行有效评估。本文以机械结构疲劳状态为研究对象,根据结构件的材料特性和受载情况,采用数理统计方法对机械结构承载件的疲劳状态进行统计学分析。构建与结构件材料性质相一致的小构件疲劳试验装置,确定了四种不同的试验条件;利用有限元方法分析了试件的应力、应变,确定了结构件在受力情况下的易损伤部位,为合理布置光纤光栅传感器提供了依据。在传统的疲劳分析方法的基础上,分析了机械结构疲劳的影响因素,提出了机械结构件疲劳损伤的统计学分析方法。针对结构件所受载荷的特征,研究了试件在受力情况下应力、应变数据的变化规律,并且对试验数据进行均值处理。根据统计学疲劳损伤分析方法,对等价弹性模量试验数据进行线性回归分析和统计。结果表明,等价弹性模量的试验数据与试件的实际工作情况拟合比较好。采用假设检验,对试验数据进行了稳定性分析。当结构件出现疲劳时,等价弹性模量试验数据的总体均值检验显著。结果表明,当应力、应变和等价弹性模量在频率较高和振幅较大的情况下,结构件在较短试验时间发生疲劳而且疲劳速率变化比较大。通过对等价弹性模量数据的统计分析,获得了试件疲劳损伤与等价弹性模量的关系,确定了试件发生疲劳的时间点以及载荷的幅值和频率对疲劳的影响程度,并归纳出在不同试验条件下试件疲劳状态的变化规律。本文对机械结构件在不同试验条件下的应力、应变、等价弹性模量试验数据进行了分析,研究了弹性模量和结构件疲劳状态的关系,提出了一种评估机械结构件疲劳状态的统计学方法。研究结果可为机械结构件的疲劳分析提供理论和试验依据。
[Abstract]:Fatigue failure is the main form of failure of mechanical structural parts. Fatigue and even failure of structural parts may occur under cyclic load. Different fatigue analysis methods can be used to analyze the fatigue damage characteristics of structural parts. Under the actual working conditions, the load and working environment of structural parts are very complex, and there are many randomness of fatigue occurrence of mechanical structural parts. Therefore, from the point of view of mathematical statistics, the fatigue statistical analysis method is proposed, which is expected to effectively evaluate the fatigue damage of mechanical structural parts. In this paper, the fatigue state of mechanical structure is studied. According to the material characteristics and loading conditions of structural parts, the fatigue state of mechanical structural load-bearing parts is analyzed statistically by means of mathematical statistics. In this paper, a fatigue test device for small components is constructed, which is consistent with the material properties of structural parts, and four different test conditions are determined, and the stress and strain of the specimens are analyzed by using finite element method, and the vulnerable sites of structural members under stress are determined. It provides a basis for the reasonable arrangement of fiber Bragg grating sensors. On the basis of the traditional fatigue analysis method, the influencing factors of fatigue of mechanical structure are analyzed, and the statistical analysis method of fatigue damage of mechanical structural parts is put forward. According to the characteristics of the load on the structural parts, the variation law of the stress and strain data is studied, and the mean value of the test data is processed. According to the statistical fatigue damage analysis method, the test data of equivalent elastic modulus are analyzed by linear regression analysis and statistics. The results show that the experimental data of equivalent elastic modulus fit well with the actual working conditions of the specimen. The stability of the test data is analyzed by using hypothesis test. When fatigue occurs, the test results of equivalent modulus of elasticity are significant. The results show that when the stress, strain and equivalent elastic modulus are higher in frequency and amplitude, the fatigue and fatigue rate of the structural parts change greatly in a short test time. Based on the statistical analysis of the equivalent elastic modulus data, the relationship between fatigue damage and equivalent elastic modulus of the specimen is obtained, and the time point when fatigue occurs and the influence of the amplitude and frequency of load on fatigue are determined. The changes of fatigue state of specimens under different test conditions are also summarized. In this paper, the experimental data of stress, strain and equivalent elastic modulus of mechanical structural parts under different test conditions are analyzed, and the relationship between elastic modulus and fatigue state of structural parts is studied. A statistical method for evaluating fatigue state of mechanical structures is presented. The results can provide theoretical and experimental basis for fatigue analysis of mechanical structural parts.
【学位授予单位】：河南科技大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TH114

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