航空结构环境振动试验裂纹分析

Analysis of cracks in vibration test for structure

某航空结构进行耐久振动环境试验时,发现裂纹。通过建立有限元模型,进行随机响应分析,得到结构最大RMS应力处的功率谱密度。利用信号分析理论,将危险部位应力功率谱还原为多个样本的应力时域数据。利用名义应力法对多样本应力时域数据进行疲劳寿命估算,得到每个样本的寿命值。对多个样本的寿命估算值进行正态单边容差参数统计,得到结构的寿命值。寿命估算结果与试验结果较好吻合。利用分析结果,对结构振动疲劳薄弱部位进行改进。改进后的结构顺利通过环境试验考核,解决了实际工程问题。

Cracks were found in the durability environmental test of an aviation structure.Based on the finite element model and random response analysis,the power spectral density at the maximum RMS stress of the structure is obtained.Using the theory of signal analysis,the stress power spectrum of the dangerous part is restored to the stress time domain data of multiple samples.To estimate the fatigue life of the multi-sample stress time domain data by S-N method,the life value of each sample is obtained.The NTL are performed on the estimated life values of multiple samples to obtain the life value of the structure.The life estimates are in good agreement with the test results.The weak parts of vibration fatigue of the structure are improved by using the analysis results.The improved structure passed the environmental test assessment and solved the actual engineering problems.