Abstract Load cycle counting is an important tool for estimating the fatigue life of structures. Rainflow counting methods have been developed to count load reversals and extract load cycles from load time histories. Rainflow counting methods were originally developed to assess fatigue damage associated with mechanical cycling where time-dependent factors such as dwell time and loading rate were not considered significant contributors to fatigue failure. However, loading rate and hold times can be significant factors in some fatigue failures, such as solder interconnects under temperature cycling. In these cases, fatigue life models may require the load transition time and load hold times to account for time-dependent material changes, such as creep. This paper develops a new multi-parameter cycle counting algorithm that provides a range-based hold time estimation for use with time-dependent fatigue damage models. To show the applicability of the new method, the life of solder joints under a complex thermal cycling regime was estimated using the data extracted by the new multi-parameter cycle counting algorithm. This life estimate was then compared with test results and found to be within the estimated uncertainty bounds.

中文翻译：

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具有时间参数的循环计数算法的开发

摘要 载荷循环计数是估算结构疲劳寿命的重要工具。已经开发出雨流计数方法来计算负载逆转并从负载时间历史中提取负载周期。雨流计数方法最初被开发用于评估与机械循环相关的疲劳损伤，其中诸如停留时间和加载速率等时间相关因素不被认为是疲劳失效的重要因素。然而，加载速率和保持时间可能是某些疲劳失效的重要因素，例如温度循环下的焊接互连。在这些情况下，疲劳寿命模型可能需要载荷过渡时间和载荷保持时间来考虑随时间变化的材料变化，例如蠕变。本文开发了一种新的多参数循环计数算法，该算法提供了基于范围的保持时间估计，以用于瞬态疲劳损伤模型。为了显示新方法的适用性，使用新的多参数循环计数算法提取的数据估计了复杂热循环机制下焊点的寿命。然后将该寿命估计与测试结果进行比较，发现它在估计的不确定性范围内。