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首页> 外文会议>ASME pressure vessels and piping conference;PVP2009 >DESIGN EVALUATION METHOD FOR RANDOM FATIGUE BASED ON SPECTRUM CHARACTERISTICS
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DESIGN EVALUATION METHOD FOR RANDOM FATIGUE BASED ON SPECTRUM CHARACTERISTICS

机译：基于谱特征的随机疲劳设计评估方法

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摘要

This paper shows the new design approach for random fatigue evaluation based on spectral characteristics. Fatigue damage under random loading is usually evaluated according to the following steps: 1. Decomposition of random wave to stress amplitude using the rainflow cycle counting method (RFC) 2. Evaluation of fatigue damage using Palmgren-Miner's linear summation rule. In design process, the fluctuation of load is usually characterized through power spectral density (PSD). Therefore, the design process is expected to be generalized if the fatigue damage is directly evaluated from the PSD together with S-N diagram of the material. In fact many properties related to fatigue damage, such as distribution of extreme values, can be derived theoretically from geometrical properties of PSD. However, concerning the distribution of stress amplitude counted by RFC, it is rather difficult to derive it theoretically due to its complicated procedure. In this paper, upper bound of stress amplitude distribution is confirmed for many random waves generated by numerical simulation for many types of PSD. Expressing the upper bound distribution by closed form function using PSD characteristics leads us to the direct evaluation of fatigue damage with safety margin if the fatigue damage by particular stress amplitude is approximated using some series expansion form. Simple approximation procedure of high cycle fatigue damage for austenitic stainless steel and ferritic steel will be proposed in the paper. Finally, design evaluation procedure for the fatigue damage evaluation from PSD together with S-N diagram is summarized.
机译：本文展示了一种新的基于光谱特征的随机疲劳评估设计方法。通常根据以下步骤评估随机载荷下的疲劳损伤：1.使用雨流循环计数方法（RFC）将随机波分解为应力振幅。2.使用Palmgren-Miner的线性求和规则评估疲劳损伤。在设计过程中，通常通过功率谱密度（PSD）来表征负载的波动。因此，如果直接从PSD评估疲劳损伤以及材料的S-N图，则可以预期设计过程将是通用的。实际上，理论上可以从PSD的几何特性中得出许多与疲劳损伤有关的特性，例如极值的分布。但是，关于由RFC计算的应力振幅分布，由于其复杂的过程，理论上很难推导出它。在本文中，通过对多种类型的PSD进行数值模拟生成的许多随机波，确认了应力振幅分布的上限。如果使用某些级数展开形式来估算由特定应力振幅引起的疲劳损伤，则使用PSD特性通过闭合形式函数表示上限分布，可以直接评估具有安全裕度的疲劳损伤。本文提出了奥氏体不锈钢和铁素体钢高周疲劳损伤的简单近似程序。最后，总结了基于PSD的疲劳损伤评估的设计评估程序以及S-N图。

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