各向异性损伤力学在螺纹疲劳寿命预估中的应用

Anisotropic Damage Mechanics with Application to Bolt Fatigue Life Estimation

引用损伤力学方法研究金属构件疲劳问题。在微结构力学模型基础上建立轴对称的各向异性疲劳损伤本构关系,通过有限元-附加力解法编制考虑各向异性损伤的有限元程序。应用引入门槛条件的损伤演化方程,并以损伤划分步长预估了构件疲劳裂纹形成与扩展寿命。用这一方法预估30CrMnSiNi2Aφ5和φ8螺栓全寿命。结果表明,理论S-N曲线与试验S-N曲线吻合良好并且门槛条件对修正低应力下疲劳寿命有很好的效果。本方法所需机时较少,可用于工程实际构件的高周疲劳寿命预估及抗疲劳优化设计。

Damage mechanics method is applied to investigate fatigue problems of metallic structure members.Adopting micro-structure model,the anisotropic damage coupled constitutive relations is established for axi-symmetric cases to design the procedure considering anisotropic damage with finite element-additional loading method.The damage evolution with a threshold value is utilized to predict the fatigue crack formation and propagation lives of structural members are with damage increment as step length.Then the fatigue life experiment of the bolts with 5mm and 8mm diameters made of 30CrMnSiNi2A are tested and the total lives are estimated the result shows that the theoretical S-N curves well coincide with the experimental ones,the threshold value modifies the agreement of fatigue lives between theoretical data and experimental ones at low stress level.