含裂纹AL2024薄板剩余强度和剩余寿命的影响因素研究

机械构件在使用的过程中难免会造成各种裂纹缺陷。为了保证含裂纹结构的使用安全,本文基于韧性断裂准则和最大周应力准则建立了含裂纹结构的剩余强度和剩余寿命的分析模块。利用上述分析模块探索了裂纹深度和裂纹倾斜角对含裂纹AL2024铝板剩余强度和剩余寿命的影响能力,并利用回归分析分布拟合出了剩余强度和剩余寿命的表达式。研究结果表明：剩余强度和剩余寿命的分析模块准确可靠；剩余强度随裂纹深度和裂纹倾斜度成指数变化,裂纹深度从15 mm增加到40 mm,裂纹倾斜角从60°减小到0°过程中,剩余强度从249.50 MPa减小到79.78 MPa,说明从剩余强度上讲深裂纹和小倾角裂纹对结构危害较大；剩余寿命与裂纹深度和裂纹倾斜角也成指数关系,在研究范围内随裂纹深度的增大和裂纹倾斜角的减小剩余寿命从148871减小到4481,说明从剩余寿命上讲深裂纹和小倾角裂纹危害较大。研究结果表明深裂纹和小倾角裂纹对结构危害较大,在周期性检查过程中要特别注意；同时该方法对于结构剩余强度和剩余寿命的评估提供了有益的参考。

Study on influencing factors of residual strength and residual life of AL2024 sheets including cracks

Various cracks and defects may be produced in the using of mechanical components. The residual strength prediction program based on the ductile fracture criteria and the residual life prediction program based on the maximum circumferential stress criterion were built to ensure safe usage of various structures. The influence ability of crack depth and crack angle on the residual strength and residual life was explored using finite element programs, and then the corresponding formulas were fitted. The research results indicated that residual strength and residual life prediction programs proposed in the present work were accurate and reliable. The residual strength was exponential based on crack depth and crack angle at the range of research. The residual strength reduced from 249.50 MPa to 79.78 MPa, with crack depth rising from 15 mm to 40 mm and crack angle changing from 60° to 0°. Residual strength prediction results indicated that the deeper the crack and the larger the crack angle, the more dangerous the crack. The residual life of the structure was also exponential based on crack depth and crack angle. Residual life reduced from 148871 to 4481 with crack depth rising and crack angle reducing at the range of research. Similar conclusion was received that the deeper the crack and the larger the crack angle, the more dangerous the crack. This research indicated that deep cracks with small tilt angle should be paid more attention in the periodic inspections. This study provided a valuable reference for evaluating the residual strength and residual life.