金属管线高温环境下的断裂失效分析

发布时间：2018-06-07 21:37

本文选题：金属管 + 断口分析　；参考：《力学与实践》2017年01期

【摘要】：超燃冲压发动机燃烧室试验台配置了大量金属管线,煤油作为燃料和冷却介质在其中输运,在实验过程中发生管线早期断裂失效,对此开展了分析。首先利用三维体视显微镜与扫描电镜进行了断口观察与分析,表明管线的开裂起源于焊缝根部,具有典型的多源起源特征;裂纹源区具有蓝色半圆形特征,表明存在焊接裂纹。同时,断口呈现明显的疲劳辉纹,间距为亚微米量级。根据辉纹间距与管材壁厚以及使用寿命分析,确定了疲劳载荷的频率范围;根据理论公式与有限元模态分析对管线的自振频率进行了估算,其结果与断口分析的结果吻合良好。以上研究结果表明管线断裂是典型的振动疲劳失效导致的。为此,建议在管线中部增加固定点约束,改变管线的自振频率以降低振幅,并改进焊接工艺,提高管线焊接质量。基于以上措施,有效解决了管线的早期断裂失效问题。
[Abstract]:A large number of metal pipelines are installed in the combustion chamber of scramjet combustion chamber, in which kerosene is transported as fuel and cooling medium. The early failure of pipeline fracture occurred during the experiment, and the analysis is carried out. First, the fracture surface was observed and analyzed by 3D stereoscopic microscope and scanning electron microscope. The results show that the cracking of pipeline originated from the root of weld and has the characteristic of multi-source origin, and the source region of the crack has blue semicircle characteristic, which indicates the existence of welding crack. At the same time, the fracture surface shows obvious fatigue striation, the distance is submicron order of magnitude. The frequency range of fatigue load is determined according to the analysis of gloss spacing, pipe wall thickness and service life, and the natural vibration frequency of pipeline is estimated according to theoretical formula and finite element modal analysis, and the results are in good agreement with the results of fracture analysis. The above results show that the pipeline fracture is caused by typical vibration fatigue failure. Therefore, it is suggested that the fixed point constraint should be added in the middle of the pipeline, the natural vibration frequency of the pipeline should be changed to reduce the amplitude of the pipeline, and the welding process should be improved to improve the welding quality of the pipeline. Based on the above measures, the problem of early fracture failure of pipeline is effectively solved.
【作者单位】：中国科学院力学研究所非线性力学国家重点实验室;中国科学院大学工程科学学院;中国科学院力学研究所高温气动国家重点实验室;
【分类号】：O346.1

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