Bai-Qiao Chen

Deformation measurements in welded plates based on close-range photogrammetry:

A global approach for measuring weld-induced deformations in plated structures is presented in this article. Three-dimensional deformation models of butt-welded plates were obtained before and after three welding tests by using close-range photogrammetry to generate the displacement field from sets of digital images. The procedure was validated against direct measurements of the deformations. A polynomial equation was found to be the best fitting to the surface of a butt-welded plate. Based on the modified Fourier series, a proposed function to represent complex surface was validated. A comparative study on the sampling element size was also included.

Validation of numerical simulations with X-ray diffraction measurements of residual stress in butt-welded steel plates

ABSTRACT The present work investigates experimentally and numerically the residual stress induced in the surface of thin steel plates subjected to single pass butt welding. First, the temperature history is calculated considering the temperature-dependent material properties in thermal analysis and some selected points are verified by measured temperature history recorded by thermocouple and data logger. Then the mechanical analysis of indirect thermo-mechanical analysis in numerical run is applied to calculate the induced residual stress of welding. The numerical results are validated with the experimental measurements. The experimental data, collected in the fusion zone, heat affected zone and at the edges of the transverse edges of the plate are measured by the technique of X-ray diffraction. In addition, the effect of the boundary conditions, element size and the width of the plate are also investigated and discussed and conclusions are presented.

Evaluation of multi-pass welding-induced residual stress using numerical and experimental approaches

ABSTRACT In the present work the welding-induced residual stresses in steel plates, due to multi-pass welding are investigated numerically and experimentally. The transient finite element model is developed to estimate the axial residual stresses induced by butt welding. Element birth and death technique is used to simulate the welding process in ANSYS. Plates with 6 mm thicknesses are modelled by one and three passes of welding to investigate the effect of multi-pass welding on the induced residual stress. An experimental study is performed to calibrate the numerical results for both thermal and mechanical analyses. The X-ray diffraction method is used for measuring the residual stress. A good agreement is achieved between numerical and experimental results. It is concluded that, multi-pass welding has significant effects on the residual stress distribution.