Simulation Of Laser Welding Research Articles

Inconel 718 laser welding simulation tool based on a moving heat source and phase change

Modern aerospace industry demands the union of different Inconel 718 parts ensuring the quality of the joint. Therefore, in the present work a novel fiber laser welding model that considers wobbling strategy is developed. The heat source model definition and solid-liquid phase change phenomena are taken into account as bead is considered liquid zone during the melting, getting a robust-but-simple tool for prediction of bead and heat affected zone geometries depending on process parameters. One of the main drawbacks is the maximum welded bead width, which is limited by the beam spot. In order to overcome this handicap, wobbling strategy allows covering a wider area by combining elliptical and linear motions. Optimal relation between these orbital and translation speeds is defined for minimum overlap among consecutive wobble rings. Likewise, temperature rise at welded joint is estimated by existing and modified heat source models after relying on experimental validation.

An octree-based adaptive mesh refinement method for three-dimensional modeling of keyhole mode laser welding

Numerical simulations of laser welding could provide unprecedented insight into the physical details of the welding process; however, it remains a central challenge to understand laser welding with a high-efficiency and high-resolution method. This paper reports an octree-based adaptive mesh refinement method for efficient process modeling of laser welding in three dimensions. Based on multiresolution analysis algorithm, we also propose a hybrid adaptive mesh refinement strategy depending on local temperature, fluid velocity, and volume of fluid (VOF) value of weld pool of laser welding. Using the proposed method, the predicted heat transfer, and fluid flow behaviors of weld pool are consistent with experimental and previous theoretical results. Spatter formation at the beginning stage of laser welding is observed with a grid resolution in tens of microns. Under certain circumstances, the liquid jet can be produced when the fluid speed near the top surface of the weld pool is 1m/s. The time for breakup of a liquid jet into spatters is about 0.065ms. Furthermore, using the method, we just need 7hours to complete a simulation of a 40-ms real laser welding process on a small workstation (2.60GHz CPU, 16 cores), comparing with 120hours needed using uniform grids. In a word, this method shows great potential for efficient computer simulation-based process optimization of laser material processing.

Simulation of laser welding using advanced particle methods

AbstractThe process of laser welding is modelled using the meshless Lagrangian Smoothed Particle Hydrodynamics (SPH) method. Significant physical effects during the welding process like heat conduction, surface tension, and the occuring phase transitions melting, solidification, and evaporation are considered in the model. By coupling an SPH code with a ray tracer that tracks the propagation of independent light rays in the capillary and calculates the locally absorbed intensity by means of geometrical optics, the laser‐material interaction is represented in detail, even for complex capillary geometries. Therefore, both heat conduction and deep penetration laser welding can be simulated using this co‐simulation approach. The model is able to predict the temperature distribution during the welding process and the dimensions of the resulting weld seam. Furthermore, the vaporisation threshold and deep penetration threshold can be estimated. The numerical results are validated by comparing the obtained threshold values with experimental data and an analytical approximation during seam welding of aluminum. (© 2016 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

Numerical analysis of effective thermal conductivity of plastic foams

This study is dedicated to the development of a numerical finite-element solution to determine the effective thermal conductivity of extruded polymeric foam with different levels of open and closed porosity. The implemented numerical method is derived from periodic homogenization techniques used for the simulation of laser welding of composite materials. For a validation purpose, it was applied to the calculation of the effective thermal conductivity of polyethylene extruded foam for which the input data (density, cell size and distribution, porosity ratio, and extinction coefficient) were characterized experimentally. The computed results were compared with experimental data obtained by the transient plane source technique and analytical results derived from the literature. The deviation from the experimental data is five times lower than that of analytical methods. Moreover, the proposed numerical solution allows reaching higher porosity ratio and makes it possible to reduce the computation time while ensuring the same compactness ratio regardless of the calculation.

Electrodynamic simulation of energy absorption in laser keyhole welding of zinc-coated and uncoated steel sheets

Laser beam absorption phenomena during laser welding of zinc-coated and uncoated DP 590 steel sheets were simulated using the finite-difference time-domain (FDTD) method for the Maxwell equations. For accurate simulations, the keyhole shapes that were measured using a coaxial observation method during multi-mode fiber laser welding of the above steels were used, and the beam divergence and focusing characteristics of the laser were accurately matched. Also, the wavelength enlargement method was used to deal with a large computational domain required for laser welding simulation. Absorption mechanisms, multiple reflection patterns, and heating patterns were found to be significantly different for the two steels because of the different keyhole shapes. Zinc-coated steel has a much lower keyhole absorptance than uncoated steel at the same experimental condition, which was experimentally validated by melt pool size measurement. Ray tracing simulations were also performed for comparison purposes.

원형 커버의 펄스 레이저 용접 후 부품 잔류변형 개선에 관한 유한요소해석

Molten zone shape of pulse laser welding is affected by welding conditions such as beam power, beam speed, irradiation time, pulse frequency, etc. and is divided into conduction type and keyhole type. It is necessary to design heat source model for irradiation of laser beam in the pulse laser welding. Shape variables and the maximum energy density value of the heat source model are different depending on the molten zone shape. In this paper, pulse laser welding simulation for joining of cylindrical part and circular cover was carried out. The heat source model for pulse laser beam with circular path was applied to the heat input boundary condition, radiative and conductive heat transfer were considered for the thermal boundary condition. For each phase, thermal and mechanical properties according to temperature were also applied to analysis. Analytical results were in good agreement with the molten zone size of specimen under the same welding conditions. So, the reliability of the welding simulation was verified. Finally, the improvements for reducing residual deformation after cover welding could be reviewed analytically.

INVITED] An overview of the state of art in laser welding simulation

The work presented in this paper deals with the laser welding simulation. Due to the rise of laser processing in industry, its simulation takes also more and more place. Nevertheless, the physical phenomena occurring are quite complex and, above all, very coupled. Thus, a state of art is necessary to summarize phenomena that have to be considered. Indeed, the electro-magnetic wave interacts with the material surface, heating the piece until the fusion and the vaporization. The vaporization induces a recoil pressure and deforms the liquid/vapor interface creating a vapor capillary. The heat diffused in the material produces thermal dilatation leading to mechanical stress and strain.As a complete simulation is too large to be computed with one model, the literature is composed by two kinds of models, the thermo-mechanical simulations and the multi-physical simulations. The first aims to find the mechanical stress and strain due to the welding. The model is usually simplified in order to reduce the simulation size. The second, compute the more accurately the thermal and the velocity fields. In that case authors usually search also the size of the weld bead and want to be totally self consistent.In this review, the major part of equations and assumptions needed to simulate laser welding are shown. Their effects on simulation results are illustrated for each simulation type. The paper aims to give sufficient knowledge and tools to allow a simulation of laser welding.

Multi-physical Simulation of Laser Welding

Abstract Laser welding is a highly demanded technology for manufacturing of body parts in the automotive industry. Application of powerful multi-physical simulation models permits detailed investigation of the laser process avoiding intricate experimental setups and procedures. Features like the degree of power coupling, keyhole evolution or currents inside the melt pool can be analyzed easily. The implementation of complex physical phenomena, like multi-reflection absorption provides insight into process characteristics under selectable conditions and yields essential information concerning the driving mechanisms. The implementation of additional physical models e. g. for diffusion discloses new potential for investigating welding of dissimilar materials. In this paper we present a computational study of laser welding for different conditions. Applied to a real case model predictions show good agreement with experimental results. Initial tests including species diffusion during welding of dissimilar materials are also presented.

Finite Element Simulation of Laser Welding of 904L Super Austenitic Stainless Steel

Experiments on Laser butt welding of 904L super austenitic stainless steel was conducted using diffusion cooled 3.5 kW slab CO2 laser welding system. The weld geometries such as bead width and depth of penetration were measured. The laser welding process has also been simulated using ANSYS a Finite Element Analysis tool. The effect of laser power, welding speed and focal point position on the bead geometry was investigated. The experimental plan was developed based on the Taguchi technique. The comparison of the results of the simulation indicates that Finite Element Method (FEM) can predict the responses adequately within the limits of welding parameters being used. It is suggested that FEM can be used as a tool for predicting the bead geometry at low values of heat input on laser welding.

Development of laser welding simulation code with advanced numerical models

Toward a standardization of laser welding repair processes and controlling a residual stress which is induced by laser welding, we constructed the fully parallelized laser welding simulation model using one-fluid model (in the simulation, solid, liquid and gas phase are simultaneously calculated by one set of governing equations) and some advanced numerical models. In the simulation, the base material is a pure aluminum which was included to the code as a physical parameter and we considered the surface tension force and its effect of a temperature gradient named Marangoni stress. As a result, reasonable results were obtained that is welding bead which is one of the representative behavior of a low power density laser welding and the appropriate shape of inside the molten pool. Therefore, the model can be applied to be practical laser welding problems.

Contribution to Numerical Simulation of Laser Welding

Contribution deals with numerical simulation of thermal and stress fields in welding tubes made of austenitic stainless CrNi steel type AISI 304 with a pulsed Nd:YAG laser. Process simulation was realised by use of ANSYS 10 software. Experiments were aimed at solution of asymptotic, standard and the so-called shell model. Thermally dependent properties of AISI 304 steel were considered. Thermal fields developed in the course of welding process and also shape of weld pool were assessed. Contribution is aimed at simulation of technological welding process with input parameters regarding the thermal and strain task and comparison of attained results with real experiment. The achieved results of numerical simulation were almost identical with a real weldment thermally affected by welding process.

ICONE19-43939 Phenomenological evaluation of laser-irradiated welding processes with a combined use of higher-accuracy experiments and computational science methodologies : (5) Numerical simulation of the welding processes with a multi-dimensional multi-physics analysis code SPLICE

It is quite important that the establishing the welding and solidification processes, generation of the residual stress, in a laser welding for various reactor components. In order to standardize laser welding repair processes and controlling a residual stress which is induced by laser welding, we constructed the fully parallelized laser welding simulation code using one-fluid model (solid, liquid and gas phases are simultaneously calculated by one set of governing equations) and some advanced numerical models, e.g., VSIA (Volume and Surface Integrated Average) based CIP finite volume method for the discretization, the THINC/WLIC scheme for an accurate interface capturing and the robust and stable pressure Poisson equation solver, AMG preconditioned BiCGSTAB method. In the simulation, the base material is a pure aluminum which was included to the code as a physical parameter and we considered the surface tension force and its effect of a temperature gradient named Marangoni effect. As a result, reasonable results were obtained that is welding bead which is one of the representative behavior of a low power density laser welding and the appropriate shape of the vertical cross section of the molten pool. Therefore, the model can be applied to practical laser welding problems and contribute the standardization of a laser welding repair technology.

Numerical simulation of laser welding of thin metallic plates taking into account convection in the welding pool

A new algorithm for numerical simulation of laser welding of thin metallic plates was developed here. It is based on the collocations and least squares method and a new quasi-three-dimensional model of laser welding process. Calculations for titanium plates were carried out. An influence of the convection on the welding process was investigated.

B211 レーザー照射による材料溶接シミュレーションに関する予備的検討(固液相変化を伴う伝熱現象IV)

At the commercial use stage in next generation nuclear energy systems such as sodium-cooled fast breeder reactors and advanced light-water reactors, securing maintenance and repair better than an equal to those of current water-cooled reactors is needed. Especially, establishment of a repair technology that secures the plant integrity for long-term operation period becomes indispensable. Then, experimental and analytical studies are started aiming at the world standardization of welding technology with a laser. As a part of those, in order to investigate the possibility of the laser welding simulation, melting characteristics of very small fine metal powders on a stainless steel plate were analyzed numerically. The fine metal powder is made of iron, and is heated by the laser beam, and then melts exceeding the melting temperature. This paper reports the predicted results of fine metal powders with the laser welding.

有限要素法によるレーザー溶接のシミュレーション 第1報 チタン板の溶接

有限要素法によるレーザー溶接のシミュレーション 第1報 チタン板の溶接