基于可靠指标的密封螺栓静强度设计

考虑内压容器垫片密封螺栓静强度和载荷的模糊不确定性,应用模糊等效随机的信息熵理论,将密封螺栓的模糊静强度和模糊载荷分别等效为随机静强度和随机载荷;根据等可靠度的观点,确定了密封螺栓静强度在不同工况时的可靠指标,建立按可靠指标进行密封螺栓静强度设计的方法,得到其静强度安全系数。研究表明,(1)按静强度可靠指标得到了计算密封螺栓最小直径的公式。(2)密封螺栓在预紧、正常操作、气压试验与液压试验时,屈服强度的可靠指标分别为2.486 0、2.486 0、1.920 4与0.815 0,抗拉强度的可靠指标分别为5.644 6、5.644 6、5.644 6与4.270 0。(3)基于满足屈服和抗拉强度的可靠指标,螺栓屈服与抗拉强度的最小安全系数分别为1.45与1.90。

Design of Seal Bolt Static Strength Based on Reliability Index

Considering the fuzzy uncertainty of intrinsic pressure vessel gasket seal bolt static strength and the load,and applying the information entropy theory that fuzzy entropy was equal to probability entropy,the fuzzy static strength and fuzzy load variables were transferred into related random variable ones of seal bolt,respectively.According to the equal-reliability view point,the seal bolt static strength reliability index was defined in different operating modes.With the reliability index,the design method for determining bolt static strength is established,and the static strength safety factor is obtained.The research results show that:(1)According to the reliability index of the seal bolt static strength,the calculation formula of the bolt minimum diameter is obtained.(2)When pre-tight,normal operation,barometric pressure test or hydraulic pressure test,the reliability index of the bolt yield strength is 2.486 0,2.486 0,1.920 4 or 0.815 0,respectively;the tensile strength reliability index is 5.644 6,5.644 6,5.644 6 or 4.270 0,respectively.(3)Based on the reliability index’s satisfaction of the yield strength and tensile strength,the minimum safety factor of the bolt yield strength or tensile strength is 1.45 or 1.90,respectively.