基于区间理论的不确定结构随机疲劳损伤估计方法

STUDY ON RANDOM FATIGUE ANALYSIS METHOD OF UNCERTAINTY STRUCTURE BASED ON INTERVAL THEORY

将结构体系中不确定参数定义为区间变量,在随机疲劳谱分析方法的基础上,提出一种计算平稳高斯荷载作用下不确定结构疲劳损伤的新方法。该方法采用区间参数模型定义结构的不确定性,应用功率谱密度描述外荷载的随机性;利用有理级数和单位对称区间显式表达结构区间频响函数和不确定结构在平稳高斯荷载作用下的动力响应区间;根据Tovo-Benasciutti疲劳损伤预测模型,计算不确定结构在随机荷载作用下的疲劳损伤区间期望率;并可通过调整相应不确定参数的单位对称区间近似估计该不确定参数不同不确定半径的疲劳损伤区间期望率。通过数值算例,将该文提出的随机疲劳区间分析方法与顶点法进行比较,验证了该方法的准确性和适用性。

Based on the random fatigue analysis by a spectral method, a new approach is proposed to evaluate fatigue damage of uncertain structure under stationary Gaussian load, in which interval variables are introduced to describe uncertain parameters of structural systems. In this proposed method, uncertainty of structure is defined by interval parameter variables, and randomness of external loads is described by probabilistic models. Interval frequency response functions of structure and dynamic response of uncertain structure under stationary Gaussian load are explicitly expressed by the Rational Series Expansions and the Extra Unitary Intervals. Interval expected fatigue damage rates of uncertain structure are calculated by the prediction model of the Tovo-Benasciutti fatigue damage under random loads. The changes of fatigue damage in given parameter intervals are approximately expressed by adjusting extra unitary intervals of corresponding uncertain parameters. Finally, two numerical examples are studied to illustrate the accuracy and the efficiency of the proposed method compared with the vertex method.