Global sensitivity analysis has predominantly focused on examining the effect of time-invariant parameters on the mechanical properties of fiber-reinforced composites, while ignoring degradation. However, fiber-reinforced composites are subject to degradation, which means that the physical system is dynamic. It is important to consider this dynamic behavior in sensitivity analysis. This paper presents a set of sensitivity indices based on the interval method to measure the influence of the time-invariant and time-variant parameters on the synthetic uncertainty of output in global sensitivity analysis for 2D triaxially braided composites (2DTBCs) considering degradation. To achieve this purpose, we represent time-variant uncertain parameter using an interval process and describe them with multiple uncorrelated interval variables using the interval Karhunen-Loève explansion method. We then introduce a two-dimensional interval process and similarity degree to define a new sensitivity index for time-invariant uncertain parameters. For time-variant uncertain parameter, a novel sensitivity index combining multi-dimensional interval process and similarity degree is proposed which considers the synthetic influence of the group of multiple uncorrelated interval variables. Additionally, an efficient sampling-based method is presented to estimate the global sensitivity analysis indices using the Monte Carlo method and Newton-Cotes formula. Finally, the feasibility and potential benefits of the proposed sensitivity indices are demonstrated by applying them to a 2DTBC made of carbon fiber reinforced polyether ether ketone with thermal ageing consideration.

中文翻译：

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区间过程退化编织复合材料的全局敏感性分析

全局敏感性分析主要集中于检查时不变参数对纤维增强复合材料机械性能的影响，而忽略了降解。然而，纤维增强复合材料容易降解，这意味着物理系统是动态的。在敏感性分析中考虑这种动态行为非常重要。本文提出了一组基于区间法的灵敏度指数，用于衡量考虑退化的二维三轴编织复合材料（2DTBC）全局灵敏度分析中时不变和时变参数对输出综合不确定性的影响。为了实现这一目的，我们使用区间过程表示时变不确定参数，并使用区间 Karhunen-Loève 解释方法用多个不相关的区间变量来描述它们。然后，我们引入二维区间过程和相似度来定义时不变不确定参数的新灵敏度指数。针对时变不确定参数，考虑多个不相关区间变量组的综合影响，提出一种结合多维区间过程和相似度的敏感性指标。此外，还提出了一种基于采样的有效方法，利用蒙特卡罗方法和牛顿-科特斯公式估计全局敏感性分析指数。最后，通过将所提出的灵敏度指数应用于由碳纤维增强聚醚醚酮制成的考虑热老化的2DTBC，证明了所提出的灵敏度指数的可行性和潜在好处。