Numerical simulation of temperature field and residual stress in multi-pass welds in stainless steel pipe and comparison with experimental measurements

A parametric study of residual stresses in multi-pass butt-welded stainless steel pipes

Simulation of welding has advanced from the analysis of laboratory setups to real engineering applications during the last three decades. This development is outlined and the directions for future research are summarized in this review, which consists of three parts. This part shows that the increased complexity of the models gives a better description of the engineering applications. The important development of material modeling and computational efficiency are outlined in Parts 2 and 3, respectively.

Finite element modeling and simulation of welding part 1: increased complexity

Simulation of welding has advanced from the analysis of laboratory setups to real engineering applications during the last three decades. This development is outlined and the directions for future research are summarized in this review, which consists of three parts. The material modeling is maybe the most crucial and difficult aspect of modeling welding processes. The material behavior may be very complex for the large temperature range considered.

Finite element modeling and simulation of welding. part 2: improved material modeling

The main emphasis of this review is on thermal modelling and prediction of laser welding in metals. However as similar techniques are employed to model conventional welding processes such as arc, resistance and friction, as well as related processes such as alloying, cladding and surface hardening, part of this review is given over to the modelling of these processes where appropriate. The time frame of the review is up to the year 2002.

Thermal modelling of laser welding and related processes: a literature review

FE-calculated stresses in a multi-pass butt-welded pipe—A simplified approach

Abstract In this contribution macroscopic modeling of phase transformations and mechanical behavior of low alloy steels are developed and investigated. Such modeling is of importance in simulations of transient thermo-mechanical processes which can cause phase transformations, examples from the railway industry include train braking induced frictional heating as well as rail grinding and welding operations. We adopt a modeling approach which includes phase transformation kinetics and individual constitutive models for the phases in combination with different homogenization methods. Algorithmic implementations of the isostrain, isostress and self-consistent homogenization methods are presented and demonstrated in finite element simulations of a laser heating experiment. Stress field results from the different homogenization methods are compared against each other and also against experimental data. The importance of including transformation induced plasticity in the modeling is highlighted, as well as the multi-phase stages of the heating and cooling.

/pdf/homogenization-based-macroscopic-model-of-phase-2suoxdjd.pdf

Homogenization based macroscopic model of phase transformations and cyclic plasticity in pearlitic steel


 The fabrication of ship hulls involves welding operations, one typical operation is fillet welding of stiffeners to plates (panels) a so-called T-joint. The residual stresses from the welding process will influence the fatigue life of the structure, and residual deformations will increase the risk for buckling of the panel and give poor fabrication tolerances which may complicate the assembly of a built-up structure.
 Though this weld geometry has been frequently studied in the literature both experimentally and numerically, the focus has been on the residual stress field and if residual deformations are studied, the angular distortion and the typical V-shape seen in the welded plate (panel) are reported. This benchmark focusses on the residual shape after two-pass fillet welding of a stiffener to a plate (T-joint and the influence of the constraints used during welding. The information of the full welding residual deformations may be useful for the fabrication of larger complex welded structures.
 The benchmark study clearly shows that careful consideration is needed when defining a reference plane for comparison of resulting deformations from FE-simulations and from experiments as well as good documentation of the actual boundary conditions and steps carried after the completion of the welding and before measuring residual deformations. The FE-simulations have shown that it is difficult to obtain the full antisymmetric, twisted shape of the plate as measured in the experiments, although a trend similar to the experiments can be seen as the plate tends to move upwards at the end of each weld pass, i.e a slight influence of the weld pass direction.

Benchmark Study of Welding Deformations in Stiffened Plate


 The classification society Bureau Veritas requires a structural assessment of composite materials structures to confirm the compliance with applicable rules, like 3-point bending tests. However, for sandwich panels with a low-density foam core, local phenomena like indentation and wrinkling may occur in the upper face sheet at the loading punch, thus the intended load capacity of the sandwich panel will not be reached. It is then proposed to perform complementary shear tests to capture the behaviour of the core of the sandwich panel.
 In the present paper, the load capacity in a 3-point bending test is simulated with emphasis on the influence of the constitutive modelling of the core foam, as calibrated against experimental results for shear tests. It is carried out as a benchmark exercise, with participation from three universities.
 The FE-simulations show that the shear test can be used to accurately model the load capacity of the core foam. However, for the 3-point bending test using specimen with a very high panel length / thickness ratio a large part of the load transfer is done in the upper face sheet with less involvement of shear in the core. Although core fracture is observed in the experiments, both the FE-simulated and experimentally found maximum load agree well with the load capacity as determined from analytical formula for local failure in the upper face sheet. The FE-simulated vertical displacement at maximum load differs though.

B.L. Josefson

Papers

A parametric study of residual stresses in multi-pass butt-welded stainless steel pipes

FE-calculated stresses in a multi-pass butt-welded pipe—A simplified approach

Homogenization based macroscopic model of phase transformations and cyclic plasticity in pearlitic steel

Benchmark Study of Welding Deformations in Stiffened Plate

Load Capacity of Sandwich Panel With Core Foam Evaluated by 3-Point Bending Test