金属垫片接触应力分布解析算法

Method for Calculating Distribution of Contact Stress of Metallic Gaskets

金属垫片密封是压力容器和管道中常见的密封形式,其失效极少是因强度不足引起的,泄漏是连接系统失效的主要原因。在真实螺栓法兰金属垫片连接结构中,垫片的局部接触应力对螺栓法兰连接结构密封性能的影响较垫片的平均压紧应力更大。笔者在Warters法的基础上,考虑了操作压力的影响,对法兰变形进行理论分析,推导了法兰偏转角的计算公式。根据法兰偏转角和金属垫片力学性能,提出了金属垫片接触应力分布的解析算法。解析计算得到的平均应力与数值模拟结果较为接近,但垫片外缘的最大应力小于数值模拟值,金属垫片接触应力的解析计算方法可作为一种保守的工程算法,可用于真实螺栓法兰金属垫片连接结构的设计。

Metallic gasket seals are widely used in pressure vessels and piping. The failure of sealing systems is mostly caused not by the strength of flanges or bolts but by the leakage of the connections. The leakage behavior of bolted flange connections is related to the gasket contact stress. In particular, the non-uniform distribution of this stress in the radial direction caused by the flange rotational flexibility has a major influence on the leakage tightness of bolted flange connections. Based on Warters method and considering the operating pressure, the deformation of the flange is analyzed theoretically, and the formula for calculating the angle of rotation of flange is derived, based on which and the mechanical property of the gasket material, the method for calculating the gasket contact stresses is put forward. The maximum stress at the outer flank of gaskets calculated by analytical method is lower than that by numerical simulation, but the mean stresses calculated by the two methods are nearly the same. The analytical method can be used as an engineering method for designing the metallic gasket connections.