Rotorcraft composite structures are required to satisfy desired reliability levels when analyzing the scatter of material properties at coupon and element levels in accordance with the Federal Aviation Regulations “FAR 29.573” and the Advisory Circular “AC 29.573”. By estimating the strength and life shape parameters from static and fatigue test results, load enhancement factors can be obtained. Thus, the uncertainties from the scatter of composite properties can be analyzed. However, depending on the Weibull parameter estimation and scatter analysis methods, the load enhancement factors may differ. Therefore, in this paper, improved Weibull parameter estimation and scatter analysis methods have been proposed. Baseline static and fatigue tests are conducted, and the test data are pooled to generate reliable shape parameters. The static-strength shape and fatigue-life shape parameters are evaluated for eight Weibull parameter estimation and three scatter analysis methods. Moreover, based on the strategies of the Weibull parameter estimation and scatter analysis methods, the load enhancement factors are evaluated as a function of test duration. Finally, the consequences of model selection on distribution fitting and the scatter analysis along with the effect of life factors and strength parameters on the load enhancement factors are discussed. As a result, more conservative load enhancement factors are obtained by applying various Weibull parameter estimation methods for the scatter analysis.

中文翻译：

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威布尔参数估计方法在复合材料散射疲劳评估中的应用

根据联邦航空条例“FAR 29.573”和咨询通告“AC 29.573”，在分析挂件和元件级别的材料特性散布时，需要旋翼机复合结构满足所需的可靠性水平。通过从静态和疲劳测试结果估计强度和寿命形状参数，可以获得载荷增强因子。因此，可以分析复合材料特性分散的不确定性。但是，根据威布尔参数估计和散点分析方法，负载增强因子可能会有所不同。因此，本文提出了改进的Weibull参数估计和散点分析方法。进行基线静态和疲劳测试，并汇集测试数据以生成可靠的形状参数。对八种威布尔参数估计和三种散射分析方法的静态强度形状和疲劳寿命形状参数进行了评估。此外，基于威布尔参数估计和散射分析方法的策略，负载增强因子被评估为测试持续时间的函数。最后，讨论了模型选择对分布拟合和散布分析的影响，以及寿命因素和强度参数对载荷增强因素的影响。因此，通过将各种 Weibull 参数估计方法应用于散点分析，可以获得更保守的负载增强因子。基于威布尔参数估计和散布分析方法的策略，负载增强因子被评估为测试持续时间的函数。最后，讨论了模型选择对分布拟合和散布分析的影响，以及寿命因素和强度参数对载荷增强因素的影响。因此，通过将各种 Weibull 参数估计方法应用于散点分析，可以获得更保守的负载增强因子。基于威布尔参数估计和散布分析方法的策略，负载增强因子被评估为测试持续时间的函数。最后，讨论了模型选择对分布拟合和散布分析的影响，以及寿命因素和强度参数对载荷增强因素的影响。因此，通过将各种 Weibull 参数估计方法应用于散点分析，可以获得更保守的负载增强因子。