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.

Effects of laser beam energy and incident angle on the pulse laser welding of stainless steel thin sheet

“…4 illustrates that the penetration depth, bead width and bead length all increase as the laser energy increases at the same incident angle of 30-75 • . It also indicates the slope of all characteristic length decrease as laser energy increases, similar results were found in Chang and Na's study [4]. Fig.…”

“…The hole due to material vaporization is assumed to be a conelike shape in the vertical welding [4], its volume is estimated by…”

“…For instance, Mazumder and Steen [1], Sonti and Amateau [2], and Frewin and Scott [3] investigated the shape and size of welding spot by numerical methods. Chang and Na [4,5] by experiments and numerical simulation predicted the dependence of the weld bead size of the laser spot welds on the parameters, laser pulse energy, pulse duration time, sheet metal thickness.…”

Review on experimental study of Nd:YAG laser beam welding, with a focus on aluminium metal matrix composites

“…Using the model researchers calculated temperature distribution, penetration depth, weld bead size and geometry which are in good agreement with experimental result. Chang and Na [68], reported the development of a combined model of finite element analysis and neural network for prediction of weld bead geometry during laser spot welding of AISI 304 stainless steel. Authors used heat conduction theory for finite element Methods and showed that thermal & mechanical aspects can be decoupled assuming that the dimensional changes during laser spot welding are insignificant.…”

Thermomechanical Modeling of Laser Spot Welded Solar Absorbers

“…Recently, a number of numeri cal models have been developed to study thermal and mechanical phenomena during laser processes. These models were used to evaluate temperature distributions and to predict the weld pool shape, the melting zone, and the dimensions of the HAZ [8][9][10][11][12][13][14][15][16][17][18][19][20][21][22], In some studies, a fully or sequentially coupled thermal-stress analysis was also carried out to determine the thermal deformations-distortions and the residual stress-strain fields [23][24][25][26][27][28][29][30][31][32][33][34][35][36][37][38]. Most of these investigations are limited to problems associated with continuous or single spot laser welding in butt-, lap-, or T-joint specimens; the mechanical effects of LSW in manufactur ing processes of large industrial structures, such as solar absorb ers, have not been investigated so far.…”