Residual stresses and strains in the pipe after the pre–bending and local heating

Abstract

Annotation. Constructional elements made from bent steel pipes are widely used in chemical and aerospace sectors, civil engineering, the construction of pipelines and utility networks. Industrial bending machines are commonly used for bending pipes. However, for large pipe diameters and thicknesses such large machines cannot be used. Moreover, these are expensive machines and their use for bending pipe is not rational in a small volume. Because of this, the task of analyzing the effectiveness of the simpler ways to bend pipes is relevant, e.g. applying bending moment and local heating effect simultaneously. Thus, the purpose of the article is to build a model that allows to analyze bending of locally heated large–diameter pipe, when it is loaded by bending moment. Method of research consists of building of models of pipe bend by using the finite element method when the bending moment and local heating effect on the predetermined area are applied. Finite element model of the deformation of locally heated pipes that are bended by bending moment was built in software package ABAQUS. The mechanical behavior of the pipe material was described by the theory of ideal–plastic flow with a yield strength, which depends on the temperature. Scientific novelty lies in the fact that the model allows to determine the residual state of the pipe with specified geometric dimensions for a given program of thermopower loading. The constructed model has practical importance in the field of engineering calculations, which are used in the manufacture of building structures with curved large–diameter pipes. This allows to select the optimum configuration of the heated area and the loading mode to achieve the desired bending of the pipe when the restriction on the change of the wall thickness and cross–sectional ovalization are satisfied.