摘要
局部应力应变法(LSSM)以危险点处的局部应力应变历程进行寿命评价,忽略了非比例附加强化及缺口附近应力梯度对疲劳损伤的影响.论文通过分析裂纹萌生面(临界面)上剪应力和正应力分布状态,提出一种计算缺口件多轴疲劳损伤影响区的数学计算方法,建立考虑法向正/剪应力梯度与非比例附加强化效应的寿命预估模型.首先,基于能量法和临界面理论,借助坐标变换原理将应变能密度最大的材料平面定义为临界面,建立确定裂纹萌生方向的计算方法.其次,以临界面上特定路径为积分方向,将缺口件三维问题转化为线性问题,简化计算过程.综合考虑峰值应力和等效应力场强对多轴疲劳寿命的贡献度,建立表征缺口件多轴疲劳损伤演化过程的损伤参量.最后,通过TC4合金和Q345钢多轴疲劳试验验证论文模型的可行性和精确度,并与LSSM法、FS模型、SWT模型进行对比分析.
Due to the combined action of complex loading and notch effect,the notched part of an actual engineering structure serves under multiaxial stress,which is prone to multiaxial fatigue failure.Therefore,it is of engineering significance to accurately evaluate the multiaxial fatigue damage process of notched specimens.For multiaxial conditions,the local stress-strain method(LSSM)uses the local stressstrain history at the dangerous point of a notch to predict the fatigue life,without taking into account the influence of non-proportional additional hardening or the stress gradient effect on fatigue damage.Based on the analysis of shear stress and normal stress distribution on the crack initiation plane(the critical plane),a mathematical calculation method is proposed to calculate the fatigue-damage-affected area of multiaxial notched specimen,and a life prediction model is established by considering shear/normal stress gradient and non-proportional additional strengthening effect.Firstly,based on the energy method and the critical plane theory,the material plane with the largest strain energy density is defined as the critical plane by using the coordinate transformation principle,and the calculation method to determine the direction of crack initiation is established.Secondly,taking a specific path on the critical plane as the integral direction,the three-dimensional problem of notched specimen is transformed into a linear problem to simplify the calculation process.Then,the contributions of peak stress and equivalent stress field intensity to multiaxial fatigue life are considered comprehensively,and the damage parameter representing the fatigue damage evolution process of multiaxial notched specimen is established.Finally,the feasibility and accuracy of the proposed model are verified by multiaxial fatigue tests of TC4alloy and Q345steel,and compared with the LSSM,the Fatemi-Socie model,and the Smith-Watson-Topper model.The multiaxial fatigue of notched specimens is a key problem in structural integrity assurance of modern equipment.The proposed method may shed light on improving structural performance and ensuring service safety,and has great theoretical significance for the establishment of multiaxial fatigue life criterion.
作者
刘俭辉
张子阳
资绒
易湘斌
Jianhui Liu;Ziyang Zhang;Rong Zi;Xiangbin Yi(School of Mechanical and Electronical Engineering,Lanzhou University of Technology,Lanzhou,730050;Xuzhou Heavy Machinery Co.,Ltd.,Xuzhou,221000;Gansu Precision MachiningTechnology and Equipment Engineering Research Center,Lanzhou,730050)
出处
《固体力学学报》
CAS
CSCD
北大核心
2023年第3期406-416,共11页
Chinese Journal of Solid Mechanics
基金
国家自然科学基金项目(51605212)
甘肃省科技计划项目(20JR10RA161)
兰州市人才创新创业项目(2021-RC-023)
兰州理工大学红柳优秀青年基金项目资助
关键词
多轴疲劳
寿命预测
应力梯度效应
非比例附加强化效应
multiaxial fatigue
life prediction
stress gradient effect
non-proportional additional hardening effect
作者简介
通讯作者:刘俭辉.E-mail:liujh@lut.edu.cn.
