关键词: 抽油杆, 应力比, 疲劳极限, 疲劳强度, 许用安全系数

Abstract: This paper proved that the fatigue limit curve of the diagram is very safety by the study of the recommended-modified Goodmen-stress diagram of the API RP 11BR.According to the calculation of its allowable safety coefficient,the maximum allowable stress in the diagram was reduced with the increasing of component of the alternating stresses,it met the requirement of the allowable stress of the sucker rod,and met the conventional principle of the fatigue design.The paper suggested that the work range of the tensile safety of the recommended API diagram be extended to the work range of the tensile-compress safety that the stress ratio r is less than 0~-1,so as to calculate the parameters of the down section of the sucker rod.It was presented that the minimum fatigue limit was regarded as the allowable stress when the stress ratio r of the down section of the sucker rod is less than -1,and its stress strength condition is σ_min≥[σ_min].

Key words: sucker rod, stress ratio, fatigue limit, fatigue strength, allowable safety coefficient