飞机声疲劳裂纹扩展的分析方法研究

随着近年来各种大型、超高速飞行器的加速研制,发动机噪声越来越高,随之而来的结构声疲劳问题也越来越引起人们的重视。作为一种非常规的高周低应力振动疲劳问题,声疲劳裂纹扩展的处理是一项工程难题。分析了声疲劳裂纹扩展问题的主要技术难点,改进了虚拟裂纹闭合法(VCCT),并将其应用到某飞机结构声疲劳问题中,对某飞机结构在噪声载荷作用下的裂纹扩展情况进行了计算。结果表明,改进后的VCCT方法合理可行,具有一定的工程应用价值。不过由于材料在随机振动载荷作用下的裂纹扩展参数与静态(或准静态)下会有所差异,故对于分析中使用的材料参数,应该进行静-动转换或者通过专门的动态试验来测得。

Study on Crack Growth Analyzing Method of Sonic Fatigue for Airplane

As the rapid develop of many large and ultra high speed aircraft, the noise level of engine is getting higher. As a consequence, sonic fatigue problem for structures is causing more and more attention. Crack growth of sonic fatigue, which is a vibration fatigue problem with very low stress level but high cycles, is a difficult issue in engineering field. In this paper, The technical difficulty of crack growth in analysis for sonic fatigue is analyzed. Virtual Crack Closure Technique (VCCT) is improved and applied to this problem. The crack growth of a piece of aircraft structure under the excitation of noise load is studied using this method. The results show that the improved VCCT method is reasonable and applicable, and meaningful for engineering. However, the crack growth property of material under random vibration loading is different from that under static or quasi-static load. Either some static-dynamic conversion or special dynamic testing is needed to get these material properties.