C-T曲线通用性分析和试验研究

提出了疲劳寿命预腐蚀影响系数曲线(C-T曲线)通用性分析的C值直接对比法和C-T曲线参数统计对比法,并进行相关试验研究,得到了C-T曲线和载荷谱、应力水平以及裂纹尺寸基本无关的结论。C-T曲线是进行腐蚀条件下飞机结构疲劳寿命评定和分析的基础,为验证分析C-T曲线和载荷谱、应力水平以及裂纹尺寸的相关性,从C的定义和分布规律出发,提出了C值直接对比法和C-T曲线参数统计对比法,近似谱、不同恒幅应力水平以及不同指定裂纹尺寸下的预腐蚀疲劳寿命数据均表明了C-T曲线基本具有通用性;并进行了某型飞机结构主梁模拟试件在随机谱及恒幅谱下的预腐蚀疲劳试验,试验结果同样验证了上述结论,从而说明了C-T曲线的通用性。

Analysis and Test of Generality of C-T Curve

To analysis the generality of C-T curve of pre-corrosion factor(C) versus corrosion time(T), the method of comparing C value or comparing parameters of C-T curves is proposed, and the weak- correlation of C-T curve with fatigue load spectrum, stress level and crack size are gained from the testing result. C is the ratio of pre-corrosion fatigue life to un-corrosion fatigue life, and C-T curve is the basis of evaluating the fatigue life for aircraft structure in corrosive environment. To decrease the task for testing the C-T curve, two methods are used to analysis the correlation of C-T curve and the factors, such as fatigue load spectrum, stress level and crack size, and the generality is proved by the pre-corroded fatigue life of the same specimen under similar spectra, constant-stress levels, and different crack sizes. The fatigue test is performed under the spectrum and comstant amplitude loading, and the same conclusion is obtained, so the generality is gained.