Multiaxial fatigue life prediction models rely on intrinsic parameters that provide the balance between arbitrary and reference stress/strain conditions. However, this balance may be compromised due to evolving damage mechanisms, causing initially determined model parameters to deviate from actual values, resulting in life prediction errors. Despite the significant impact of fatigue model parameters on prediction accuracy, this issue is often ignored, with many studies assuming constant parameters to simplify prediction algorithms and reduce computational costs. In this study, we introduce a novel approach to quantify the error introduced into fatigue life predictions by approximate methods for determining model parameters under multiaxial loading paths. For the first time, error estimation was conducted using a life-dependent method, revealing that the error is a function of the selected approximation method and the ratio of slope coefficients from S-N curves for torsional versus uniaxial loading. These findings provide a unique framework for selecting computationally efficient approximation methods while balancing life prediction accuracy. This balance is crucial in the design of metallic components using fatigue topology optimization and finite element analysis. The proposed methodology, validated across eight metallic materials subjected to various multiaxial loading paths, offers valuable insights into the trade-offs between computational cost and prediction accuracy, which are essential for optimized structural design.

中文翻译：

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在多轴疲劳寿命预测中用于有效模型参数估计的容错能力


多轴疲劳寿命预测模型依赖于在任意应力/应变条件和参考应力/应变条件之间提供平衡的固有参数。然而，由于损伤机制的演变，这种平衡可能会受到损害，导致最初确定的模型参数偏离实际值，从而导致寿命预测误差。尽管疲劳模型参数对预测精度有重大影响，但这个问题经常被忽视，许多研究假设参数恒定，以简化预测算法并降低计算成本。在这项研究中，我们引入了一种新的方法，通过确定多轴载荷路径下模型参数的近似方法量化疲劳寿命预测中引入的误差。首次使用寿命相关方法进行误差估计，揭示了误差是所选近似方法与扭转与单轴载荷的 S-N 曲线斜率系数之比的函数。这些发现为选择计算高效的近似方法提供了一个独特的框架，同时平衡寿命预测的准确性。这种平衡在使用疲劳拓扑优化和有限元分析设计金属组件时至关重要。所提出的方法在受到各种多轴载荷路径的 8 种金属材料中进行了验证，为计算成本和预测精度之间的权衡提供了有价值的见解，这对于优化结构设计至关重要。