Study on ultimate load of local thinning elbow of stainless steel
Local thinning of stainless steel elbow supplied from Malleable Iron Pipe Fittings Supplier is a common defect of elbow, but domestic and foreign researches on this kind of defect mainly focus on straight pipe, and few literatures have been reported on local thinning of stainless steel elbow. Through detailed finite element calculation and theoretical analysis, this paper studies the internal pressure and bending moment under the action of the local thinning to bend the influence of ultimate bearing capacity, as well as the internal pressure under the action of many local thinning the mutual interference effect and under the action of bending moment of straight pipe to elbow limit load of strengthening effect, and some experimental verification, get the following results:
1. Using the finite element method under the action of internal pressure limit load of local thinned elbow has carried on the systematic analysis and calculation, it is concluded that the local thinned elbow ultimate pressure is different from local thinning of the straight pipe, elbow of extreme pressure not only depends on the size of the local thinning, also associated with local thinned position and bending radius, such as using the calculation method for the evaluation of local thinned straight pipe elbow, are not safe or too conservative results; At the same time, the effect of thinning width on the ultimate load can not be ignored. On the basis of finite element analysis, the formula for calculating the ultimate pressure of local thinning elbow is given, and the results of the formula are in good agreement with the finite element calculation and experimental results.
2. Malleable Iron Pipe Fittings Manufacturer through finite element analysis, the mutual interference effect between multiple local thinning under internal pressure is studied. The study shows that the mutual influence of multiple local thinning is related not only to the spacing but also to the thinning depth. It is pointed out that when the thinning depth is shallow, the axial local thinning spacing is greater than 2 times the wall thickness, and the ultimate load of double local thinning is basically the same as that of single local thinning. When the depth of thinning is deep and the distance between axial local thinning is greater than 4 times the wall thickness, the ultimate load of double local thinning is basically the same as that of single local thinning, which complements the shortcomings of existing studies.
3. Through the finite element calculation, the strengthening effect of the straight pipe connected to the elbow on the ultimate bending moment is studied, and it is pointed out that the straight pipe connected to the elbow will increase the ultimate bending moment of the elbow, and the increase amount of the ultimate load of the elbow is different when the bending radius is different. When the length of the connecting straight pipe is greater than 3 times the pipe diameter, the strengthening effect of the straight pipe on the elbow will not increase. This study complements the research on the strengthening effect of straight pipe on elbow.
4. The influence of local thinning on the ultimate bending moment of stainless steel elbow was studied in detail through finite element analysis, and it was found that the ultimate bending moment of local thinning elbow under the action of internal bending moment was related to the position, size and bending radius of the local thinning elbow. The results show that the influence of geometric nonlinearity is significant under the action of bending moment. Based on the finite element analysis of local thinning of inner wall and large deformation, the formula for calculating the ultimate bending moment of local thinning bend under the action of external internal bending moment is given. The study fills a gap in the field.
