3D Primary Structure Method And Its Application Research In Nozzles

Stress classification method is a widely used method of design by analysis at present.The primary stress and the secondary stress are clearly defined in the code,however,it is impossible to distinguish between primary stress and secondary stress by using equivalent linearization only by means of the stress distribution curve,but the primary structure method is a good solution.The application of the primary structure method based on ANSYS in the plane model has become mature,but the research in the 3D field is still blank,and the literature has not been found at present.This article has made a breakthrough in the promotion of the application of a structural method to 3D structures.The analysis of the stress situation of cylindrical shell with nozzle is discussed and the stress checking method suitable for engineering is put forward.First,the application and analysis of the primary structure method in the plane model is introduced in this paper,taking the head-extension nozzle as an example.Introduce the use of this method to correctly judge the source,function and characteristic of the stress and make a reasonable classification of it.Second,the 3D structure of the elliptical head-nozzle structure is used as the debug model,and the constraint equations applicable to the 3D model are proposed and the correctness is verified.Then,the primary structure method is used to analyze the stress of cylindrical shell with nozzle structure.The results show that the original structure is a more reasonable primary structure,and the maximum membrane and bending stress at the inner wall of the connecting ring is primary stress.Based on the analysis results of this paper,the calibration standard for cylindrical shell with nozzle structure is revised,and the new allowable limit is used for stress checking and structural improvement.Last,according to the verification method in the project,the strength of each nozzle on the body of a clamp type vessel is evaluated to be qualified.However,the strength of the H1 nozzle does not meet the requirements under the revised calibration criteria,and the size needs to be redesigned.Then,through the construction of the primary structure of the furnace body,stress classification and evaluation are performed on the shell and the connecting pipe near the flange side.