应力场强法中场径参数的研究

Study of field size parameter in stress field intensity approach

针对应力场强法中场径计算方法存在争议且不易求取的问题,基于应力场强法假设,研究了场径参数计算方法的理论依据;在考虑场径求取可行性的基础上,提出一种在任意载荷条件下确定试件场径的方法.给出了场径的求取步骤,选取6块不同应力集中系数的缺口试件在4种应力比下,按照步骤求取场径.对场径计算结果拟合并作图,由图所示分析影响场径大小的因素.得出结论:在相同应力比下,场径与应力集中系数呈很强的线性关系;在相同应力集中系数下,场径与应力比呈很强的二次曲线关系.通过实例对所提出的方法进行了验证,结果表明:由提出方法确定的场径计算得出的疲劳寿命更贴近于试验寿命,在保证安全的基础上提高了疲劳寿命预测的准确性.

Aiming at problems that the calculation method of the field size parameter of the stress field intensity was controversial and difficult to obtain,the theoretical basis of calculation approach of field size parameter was researched based on the assumption of the stress field intensity approach.Considering the calculation approach＇s feasibility,aapproach for determining the field size of component under arbitrary loading conditions was proposed.By given the calculating steps of the field size,the field size for 6selected notched specimens with different stress concentration factors in 4kinds of stress ratio was calculated.The figures were fitted by field size calculation results.By analyzing factors which affected the field size according to the figure,conclusions were as follows：field size had a strong linear relationship with the stress concentration factor under the same stress ratio,field size had a strong quadratic curve relationship with the stress ratio under the same stress concentration factor.The calculation approach of the field size parameter was verified through an example.The results showed that the fatigue life determined by the approach proposed was more close to the experiment life,and it improved the accuracy of life prediction on the basis of security.