基于应力场强法的场强半径规律研究

Research on the Law of Field Strength Radius Based on Stress Field Intensity Approach

针对应力疲劳试验费时长、耗资源和相关材料疲劳数据较为缺乏、难以获取的情况,本文对应力场强法假设进行延伸,以应力集中系数Kt不为1时的疲劳寿命数据为基准,研究不同Kt和不同应力水平下的场径参数求取方法,给出场径求取步骤。同时,利用5种不同Kt的缺口试件,在应力比为-1时的疲劳寿命数据支撑下,以Kt为1.5的标准缺口试件为基准,按照步骤求取在不同Kt和应力水平下的场径参数。得出结论:当应力比等于-1时,以Kt不为1的标准缺口件疲劳寿命数据为基准求取的场径,在一定范围内与Kt呈很强的线性关系,但在较大的范围时,场径与Kt不呈线性关系。Kt相同的缺口件的场强半径并不是一成不变的,而是会根据应力幅的改变而改变,且在弹性范围之内,不同Kt的缺口件场强半径随应力幅的变化规律是基本一致的。

In view of the fact that the stress fatigue test is time-consuming,resource-consuming and the fatigue data of related materials are scarce and difficult to obtain,the hypothesis of stress field strength method is extended in this paper.Based on the fatigue life data when the stress concentration coefficient Kt is not 1,the field diameter parameter calculation method under different Kt and different stress levels is studied,and the exit diameter calculation steps are given.At the same time,five notched specimens with different Kt were used to obtain field diameter parameters under different Kt and stress levels based on the standard notched specimens with Kt as 1.5,supported by fatigue life data when the stress ratio is-1.It is concluded that when the stress ratio is-1,the field diameter obtained based on the fatigue life data of standard notched parts where Kt is not 1 shows a strong linear relationship with Kt in a certain range,but does not show a linear relationship with Kt in a large range.The field strength radius of notched parts with the same Kt is not invariable,but will change according to the change of stress amplitude,and within the elastic range,the change law of field strength radius of notched parts with different Kt is basically consistent with the stress amplitude.