当量名义应力和变幅载荷下结构DFR的确定

EQUIVALENT NOMINAL STRESS AND DETERMINATION OF STRUCTURAL DFR UNDER VARIABLE AMPLITUDE

1.当量名义应力及K_f和DFR之间的关系 当量名义应力定义为:在变幅载荷作用下结构危险部位的局部应力-应变水平对应的相同寿命的常幅名义应力水平。当量名义应力水平的确定方法详见文献。计算当量名义应力时必须用到结构的疲劳强度减缩系数K_f。

The concept of Equivalent Nominal Stress (ENS), relationship between a structural Detail Fatigue Rating (DFR) and Fatigue Stress Concentration Factor (Kf) and the determination method of the structural DFR under variable amplitudes are presented. The ENS and the relationship between DFR and Kf are very important for structure fatigue analysis. When some structural ENS and locations come up to plastic condition, the ENS and the above relationship must be used to determine DFR under variable amplitudes. The tests and analytic examples show that the method presented in this paper is correct.