基于混沌分形理论的金属疲劳损伤过程的特征分析

发布时间：2018-06-23 06:28

本文选题：非线性超声 + 疲劳损伤　；参考：《振动与冲击》2017年21期

【摘要】：为了有效地分析金属疲劳损伤过程中裂纹扩展与演化的特征,提出利用混沌分形理论对蕴含疲劳裂纹扩展规律的超声非线性输出信号进行分析,用Lyapunov指数、K熵、关联维数等特征量对金属疲劳损伤过程的特性进行表征和评价。采用RITEC公司的RAM-5000系统获得具有不同疲劳损伤程度试件的超声非线性输出信号,计算疲劳过程中的Lyapunov指数、K熵、关联维数。分析结果表明金属疲劳损伤过程中超声非线性输出信号具有混沌特性;Lyapunov指数、关联维数、K熵等特征值随疲劳循环次数单调递增,当宏观裂纹出现后趋于饱和,说明疲劳损伤过程中试件内部的复杂程度和混沌特征逐渐增强;由疲劳过程中微裂纹的演化规律可知,混沌分形特征值可以有效地表征试件在疲劳过程中裂纹的变化规律和群体性行为。因此混沌分形理论可以有效地分析金属疲劳损伤过程中裂纹扩展与演化的特征,根据混沌分形特征值—疲劳循环次数的关系,为试件的疲劳寿命预测提供了一种新的分析方法。
[Abstract]:In order to effectively analyze the characteristics of crack propagation and evolution in the process of metal fatigue damage, the chaotic fractal theory is used to analyze the ultrasonic nonlinear output signals containing the law of fatigue crack growth. The characteristics of the fatigue damage process of metal are characterized and evaluated with Lyapunov, K entropy and correlation dimension. The RIT is used to evaluate the characteristics of the fatigue damage process. The RAM-5000 system of EC company obtains the ultrasonic nonlinear output signal with different fatigue damage test parts, and calculates the Lyapunov index, the K entropy and the correlation dimension in the fatigue process. The analysis results show that the ultrasonic nonlinear output signal has chaotic characteristics in the process of metal fatigue damage, and the eigenvalues of the Lyapunov exponent, correlation dimension and K entropy are with fatigue. The cycle times are monotonically increasing, and when the macro cracks appear to be saturated, the complexity and chaotic characteristics of the specimens are gradually enhanced during the fatigue damage process. It is known from the evolution law of the micro cracks in the fatigue process that the chaotic fractal characteristic value can effectively characterize the change law and mass behavior of the cracks in the fatigue process. Therefore, the chaotic fractal theory can effectively analyze the characteristics of crack propagation and evolution in the process of metal fatigue damage. According to the relationship of the chaotic fractal characteristic value - fatigue cycle times, a new analysis method is provided for the fatigue life prediction of the specimen.
【作者单位】：广西大学轻工与食品工程学院;广西大学机械工程学院;
【基金】：国家自然科学基金(51365006;51445013)
【分类号】：TG115.58

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