椭圆封头不连续应力的讨论

摘要

根据椭圆封头近似椭圆壳的真正几何形状，分析计算 了椭圆封头的不连续应力．对于标准椭圆封头，其近似椭圆壳的总应力在过渡区 的内壁存在最大的经向拉应力σiφmax，但同时存在周向 压应力；过渡区的外壁存在最大周向压应力σoθmax， 但同时存在经向拉应力；第三强度理论相当应力在过渡区的内壁存在最大值σir3max．无论是σiφmax、σoθmax还是σir3max，其值均随厚径比的增 大而减小，其位置均随厚径比的减小而越靠近封头的联接边缘．与将椭圆封头的 近似椭圆壳作为椭圆壳处理的计算结果相比，封头近似椭圆壳的σiφmax、σoθmax、σir3max均较小，且差异随厚径比的增大而增大，当厚径比为0.04时，误差可达10%左 右；封头近似椭圆壳最大应力的位置一般更靠近联接边缘．%Based on the real geometry of the approximate ellipsoid of ellipsoidal heads, the discontinuous stresses are analyzed. For the standard ellipsoidal head, the maximum meridional tensile stress σiφmax and hoop compressive stress are in the inner surface of the knuckle region; the maximum hoop compressive stress σ0θmax and meridional tensile stress are in the outer surface of the knuckle region, and a maximum third-strength- theory equivalent stressσir3max is in the inner surface of the knuckle region.The values of σiφmax，σ0θmax and σiθmax decrease with the increase of the thickness-to-diameter ratio，and their positions are closer to joint circles with the decrease of the ratio. Compared with the results based on the ellipsoid, the values of σiφmax，σ0θmax and σir3max on the approximate ellipsoid are all smaller and their positions are generally closer to the joint circles. The differences increase with the increase of the thickness-to-diameter ratio, and the differences of maximum stress values raise up to approximate 10% when the ratio is 0.04.