Purpose

The purpose of this paper is to analyze the dependent competing failure reliability of harmonic drive (HD) with strength failure and degradation failure.

Design/methodology/approach

Based on life tests and stiffness degradation experiments, Wiener process is used to establish the accelerated performance degradation model of HD. Model parameter distribution is estimated by Bayesian inference and Markov Chain Monte Carlo (MCMC) and stiffness degradation failure samples are obtained by a three-step sampling method. Combined with strength failure samples of HD, copula function is used to describe the dependence between strength failure and stiffness degradation failure.

Findings

Strength failure occurred earlier than degradation failure under high level accelerated condition; degradation failure occurred earlier than strength failure under medium- or low-level accelerated condition. Gumbel copula is the optimum copula function for dependence modeling of strength failure and stiffness degradation failure. Dependent competing failure reliability of HD is larger than independent competing failure reliability.

Originality/value

The reliability evaluation method of dependent competing failure of HD with strength failure and degradation failure is first proposed. Performance degradation experiments during accelerated life test (ALT), step-down ALT and life test under rated condition are conducted for Wiener process based step-down accelerated performance degradation modeling.

中文翻译：

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具有强度失效和刚度退化失效的谐波传动相依竞争失效的可靠性分析

目的

本文的目的是分析谐波传动（HD）强度失效和退化失效的相关竞争失效可靠性。

设计/方法/方法

基于寿命试验和刚度退化实验，采用维纳过程建立HD的加速性能退化模型。模型参数分布通过贝叶斯推理和马尔可夫链蒙特卡罗（MCMC）估计，刚度退化失效样本通过三步采样方法获得。结合HD的强度破坏样本，利用copula函数描述强度破坏与刚度退化破坏之间的依赖关系。

发现

高加速条件下强度破坏早于退化破坏；在中低水平加速条件下，退化失效比强度失效发生得更早。Gumbel copula 是强度失效和刚度退化失效的相关建模的最佳 copula 函数。HD的相关竞争失效可靠性大于独立竞争失效可靠性。

原创性/价值

首次提出了具有强度失效和退化失效的HD依赖竞争失效的可靠性评估方法。对基于维纳过程的降压加速性能退化建模进行了加速寿命试验（ALT）、降压ALT和额定条件下寿命试验期间的性能退化实验。