Spot welding

About: Spot welding is a research topic. Over the lifetime, 12491 publications have been published within this topic receiving 89845 citations. The topic is also known as: Spot_welding.

Prediction of laser-spot-weld shape by numerical analysis and neural network

Abstract: The finite element method (FEM) and neural network were applied for predicting the bead shape in laser spot welding of type 304 thin stainless steel sheets. The parameters of pulsed Nd:YAG laser spot welding such as pulse energy, pulse duration, sheet metal thickness, and gap between sheets were varied for various experiments and numerical simulations. The penetration depth and nugget size of spot welds measured for specimens without gap were compared with the calculated results to verify the proposed finite element model. Sheet metal thickness, gap size, and bead shape of the workpiece without gap were selected as the input variables for the back-propagation learning algorithm of the neural network, while the bead shape of the workpiece with and without gap was considered as its output variable. Various combinations of stainless steel sheet metal thickness were considered to calculate the laser-spot-weld bead shape of the workpiece without gap, which was then used as the input variable of neural network to predict the bead shape for various gap sizes. This combined model of finite element analysis and neural network could be effectively applied for the prediction of bead shapes of laser spot welds, because the numerical analysis of laser spot welding for the workpiece with gap between two sheets is highly limited.

The effect of mechanical loading on the contact resistance of coated aluminium

Abstract: Measurements of contact resistance, related to resistance spot welding, were made using pre-treated (coated) and abraded aluminium alloy strip. With conventional domed electrodes, the contact resistance was much larger at the sheet-to-sheet (faying) contact than at the electrode-sheet contact. The effect is believed to be associated with the role of sliding in breaking down contact resistance of sheet with an insulating surface film. When the coating was removed the difference between faying surface and electrode-sheet contact was much smaller. Macroscopic shear stresses are developed by electrode-sheet contact whereas no shear stresses are present at the faying surface. The hypothesis is supported by experiments made with asymmetrical electrode pairs which give rise to varying shear stresses in faying surface contact. Some implications for the control of spot welding of different aluminium surfaces are discussed.