Distortions Generated by Welding Process Using ANSYS-FEA

The objective of this paper is to present both a methodology of detailed axisymmetric simulation of a small scale welding test using the ANSYS general purpose finite element computer code and a comparison with test data. To simulate this manufacturing process, an APDL (ANSYS Parametric Design Language) macro was developed and implemented. The methodology implemented deals with the major phenomena of the welding process from transient heat analysis to structural thermal-plastic analysis. The methodology is based on an axisymmetric approach and accounts for nonlinearities due to temperature-dependent thermal and mechanical material properties as well as surface contacts. It predicts, with reasonable accuracy, the real test measurements. CANDU* nuclear reactors use horizontal fuel channels housed in a large fabricated horizontal vessel called the calandria vessel. This calandria vessel has two end shields (each consists of double endplates), which provide support for the fuel channels as well as defining the basic reactor geometry. Each pair of double endplates is joined by tubes called lattice tubes. The lattice tubes, which are welded to the endplates, provide passages for the fuel channels and stiffness to the calandria vessel. To ensure that the distortions of the endplates due to welding satisfy the design requirements, small scale and large scale welding tests are performed. The initial small scale welding test consisted of welding a lattice tube to the associated section of an endplate. A larger scale welding test consists of welding a 2x6 array of lattice tubes to assess the accumulated distortion on the end plate. In order to develop a deep understanding of the distortions generated by welding, these welding tests are simulated using detailed finite element analyses. The detailed simulations include heat flow and elastic plastic analysis. Numerical simulations of the complete assembly, using coarse finite element models and elastic-only analyses of the endplate assembly, are also included as part of the design qualification effort.

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