Numerical Simulation of Deformations in T-Joint Welded by the Laser Beam

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MODELOWANIE NUMERYCZNE ZJAWISK CIEPLNYCH I STRUKTURALNYCH W ELEMENTACH STALOWYCH SPAWANYCH DOCZOŁOWO WIĄZKĄ LASERA Yb:YAGThe numerical model of thermal and structural phenomena is developed for the analysis of Yb:YAG laser welding process with the motion of the liquid material in the welding pool taken into account. Temperature field and melted material velocity field in the fusion zone are obtained from the numerical solution of continuum mechanics equations using Chorin projection method and finite volume method. Phase transformations in solid state are analyzed during heating and cooling using classical models of the kinetics of phase transformations as well as CTA and CCT diagrams for welded steel. The interpolated heat source model is developed in order to reliably reflect the real distribution of Yb:YAG laser power obtained by experimental research on the laser beam profile.On the basis of developed numerical models the geometry of the weld and heat affected zone are predicted as well as the structural composition of the joint.Keywords: Laser welding, heat transfer, phase transformations, numerical modelling, Kriging method Praca dotyczy modelowania numerycznego zjawisk cieplnych i strukturalnych w procesie spawania laserem Yb:YAG z uwzględnieniem ruchu ciekłego materiału w jeziorku spawalniczym. Pole temperatury i pole prędkości ciekłej stali w strefie przetopienia otrzymano z numerycznego rozwiązania równań mechaniki ośrodków ciągłych metodą projekcji Chorina i metodą objętości skończonych. Przemiany fazowe w stanie stałym analizowano podczas nagrzewania i chłodzenia bazując na klasycznych modelach kinetyki przemian fazowych oraz wykresach CTA i CTPc-S. W celu wiarygodnego odzwierciedlenia rzeczywistego rozkładu mocy lasera Yb:YAG opracowano model interpolowany źródła, wykorzystujący badania doświadczalne profilu wiązki laserowej. Na podstawie opracowanych modeli numerycznych prognozowano geometrię spoiny i strefy wpływu ciepła oraz skład strukturalny złącza.

Section: Phase Transformation In Solid Statementioning

confidence: 99%

“…Obtained CHT and CCT diagrams as interpolation functions [33] are implemented into numerical algorithms with diagram of fractions of structural constituents (Fig. 8).…”

Section: Phase Transformation In Solid Statementioning

confidence: 99%

Numerical Modelling Of Thermal And Structural Phenomena In Yb:YAG Laser Butt-Welded Steel Elements

Кубяк¹,

Piekarska²,

Stano³

et al. 2015

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“…2). In solid state λ= λ (T) is defined according to data form the literature [23]. Much higher value of λ (T) is assumed at high temperatures, which corresponds to the motion of liquid material in the welding pool.…”

Section: Thermal Phenomenamentioning

confidence: 99%

“…The influence of maximum heating temperature is generally ignored. High heating rates as well as very high and various maximum heating temperatures of steel occur in the case of welding process using highly concentrated heat source of a high power like a laser beam heat source [17][18][19][20][21][22][23][24]. These factors affect the kinetics of phase transformation in the solid state.…”

mentioning

confidence: 99%

Modelling and Analysis of Phase Transformations and Stresses in Laser Welding Process / Modelowanie I Analiza Przemian Fazowych I Naprężeń W Procesie Spawania Laserowego

Piekarska¹

2015

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The work concerns the numerical modelling of structural composition and stress state in steel elements welded by a laser beam. The temperature field in butt welded joint is obtained from the solution of heat transfer equation with convective term. The heat source model is developed. Latent heat of solid-liquid and liquid-gas transformations as well as latent heats of phase transformations in solid state are taken into account in the algorithm of thermal phenomena. The kinetics of phase transformations in the solid state and volume fractions of formed structures are determined using classical formulas as well as Continuous-Heating-Transformation (CHT) diagram and Continuous-Cooling-Transformation (CCT) diagram during welding. Models of phase transformations take into account the influence of thermal cycle parameters on the kinetics of phase transformations during welding. Temporary and residual stress is obtained on the basis of the solution of mechanical equilibrium equations in a rate form. Plastic strain is determined using non-isothermal plastic flow with isotropic reinforcement, obeying Huber-Misses plasticity condition. In addition to thermal and plastic strains, the model takes into account structural strain and transformation plasticity. Changing with temperature and structural composition thermophysical parameters are included into constitutive relations. Results of the prediction of structural composition and stress state in laser butt weld joint are presented.

“…This is particularly important in the case of large-scale welded structures where operations of the deformation reduction are practically impossible [10]. A significant technological problem is the determination of the stress and strain generated at the interface of joined elements and adjacent zones [5,7,11].…”

Section: Introductionmentioning

confidence: 99%

Numerical Prediction Of Deformations In Laser Welded Sheets Made Of X5CrNi18-10 Steel

Piekarska

Кубяк

Saternus

et al. 2015

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The work concerns the numerical modelling of coupled thermal and mechanical phenomena occurring in the laser beam welding process. Commercial Abaqus FEA engineering software is adopted to numerical computations in order to perform a comprehensive analysis of thermo-mechanical phenomena. Created in Fortran programming language additional numerical subroutines are implemented into Abaqus solver, used to describe the power intensity distribution of the movable laser beam heat source. Temperature dependent thermomechanical properties of X5CrNi18-10 steel are adopted in the numerical analysis of stress and strain states. Mathematical and numerical models are verified on the basis of a comparison between selected results of computer simulations and experimental studies on butt-welded joints.Numerical simulations are presented for steel sheet with a thickness of 2 mm. Temperature distributions, the shape and size of melted zone as well as residual stress and deformations are presented for analyzed elements. Numerically determined deflections are compared with the measured deflection of welded joint.