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飞机机体结构疲劳裂纹的萌生与扩展几乎都发生在紧固件连接处,预测结构连接件的疲劳寿命具有重要意义。为了准确计算连接件疲劳寿命,提出了一种修正的局部应力应变法,该方法首先采用应力严重系数法和修正Neuber法分析连接件高应力区的应力、应变,然后利用Manson-Coffin方程计算疲劳寿命,此外考虑到在中、高周疲劳里表面加工和尺寸因素的影响是不能忽略的,对应变-寿命曲线的弹性段作了修正以使其同时适用于高、低周疲劳寿命的估算。以搭接件为算例进行疲劳寿命计算,并使用MTS Landmark试验机对搭接件进行疲劳试验。结果表明,采用此方法估算的连接件疲劳寿命与试验结果相比误差小于16%,证明了此方法的有效性。
Aircraft fuselage fatigue crack initiation and expansion almost always occurred in the fastener connection, prediction of structural fatigue life of connectors is of great significance. In order to accurately calculate the fatigue life of the connector, a modified local stress-strain method is proposed. Firstly, the stress and strain of the high-stress area of the connector are analyzed by using the method of stress severity factor and the modified Neuber method, then the fatigue is calculated by the Manson-Coffin equation In addition, taking into account the medium and high cycle fatigue in the surface processing and size factors can not be ignored, the strain - life curve of the elastic section has been modified to make it suitable for both high and low cycle fatigue life estimates. The fatigue life calculation is done by taking the overlap as an example, and the fatigue test is performed on the lap by using the MTS Landmark testing machine. The results show that the fatigue life of the connector measured by this method is less than 16% compared with the experimental results, which proves the effectiveness of this method.