Method for analyzing residual stress of polyethylene pipe welded joint

Abstract

The invention provides a method for analyzing residual stress of a polyethylene pipe welded joint. The method comprises the following steps: carrying out a unidirectional stretching experiment and a stress relaxation experiment to obtain a tangent modulus and a yield limit value of a base material sample and a stress loading function curve of the base material sample under unit strain; establishing a viscoelastic constitutive model based on a generalized Maxwell equation and Pluronic series, and fitting the curve by adopting the model to obtain parameters of the model; establishing a basic material database of the polyethylene material according to the parameters, the thermophysical parameters and the thermodynamic parameters; establishing a geometric model, dividing grids, inputting thermal boundary conditions and force boundary conditions of each welding stage, and setting load steps and convergence parameters to obtain instantaneous temperature field data; and taking the instantaneous temperature field data as a preheating load, and adjusting input parameters by adopting a sequential coupling method to obtain the distribution condition of the residual stress. According to the method for analyzing residual stress of a polyethylene pipe welded joint, nondestructive analysis of the residual stress of the joint after the welding process is accurately and quickly realized.

Description

technical field [0001] The invention relates to the field of residual stress analysis, in particular to an analysis method for residual stress of welded joints of polyethylene pipes. Background technique [0002] In the safety classification of key nuclear power equipment, it is generally divided into one, two, three safety levels and non-safety levels according to the safety functions performed by each pressure-bearing equipment. Among them, the water supply circulation system widely used in nuclear power equipment also involves safety. Grade and non-safety grade, and it uses traditional metal pipes such as nickel-based alloy steel and austenitic stainless steel, but these pipes have poor anti-corrosion performance, serious fouling phenomenon, and are easily affected by erosion-corrosion, often not reaching the rated design It has already failed and destroyed during its lifespan, thus posing a great threat to the safe work of nuclear power plants. [0003] Due to its excel...

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