Geometry Of Fillet Weld Research Articles

A comparative analysis of the impact of fillet weld geometry on residual stress distribution in nickel-based superalloy

A comparative analysis of the impact of fillet weld geometry on residual stress distribution in nickel-based superalloy

Assessing local stresses in scanned fillet weld geometry using bagged decision trees

This study addresses the limitations of current parametric equations and artificial neural networks (ANNs) in accurately predicting the stress concentration factor (SCF) of fillet welded joints stemming from the simplification of their real weld profiles. To improve the accuracy, this study introduces bagged trees for estimating local stresses. The dataset used as the foundation for training the bagged trees is extracted from the actual weld geometry of T-shaped joints. It is created via a digitalization process involving the extraction of actual geometric parameters from the joints, which are transformed into finite element models (FEMs). These models are then employed to determine the ratio between the simulated sectional stress and the nominal stress (σsec/∆σnom) under an axial loading condition. A comprehensive comparison is carried out among existing parametric equations, ANNs, and the proposed bagged trees. The results emphasize the inadequacy of idealized geometry models in accurately determining local stresses for real weld profiles. In contrast, bagged trees are a promising method for accurately computing sectional weld stresses (σsec) within real weld geometry.

Improved effective notch strain approach for fatigue reliability assessment of load-carrying fillet welded cruciform joints in low and high cycle fatigue

An improved effective notch strain (ENSN) approach is developed for the fatigue reliability assessment of load-carrying fillet welded cruciform joints in low and high cycle fatigue regions. The ENSN approach is improved in the ENSN estimation using an analytical approach, and the improvement is verified using some published experiments performed in the low cycle fatigue regime. The cruciform joint is modelled as a correlated two-component series-system, and various sources of uncertainties are considered. The fillet weld geometry uncertainty is modelled by correlated position variations of geometrical control points. To avoid iterative calls of the finite element analysis in the fatigue reliability assessment, response surface models are constructed, and they are used to approximate the influence of position changes. A critical fatigue notch factor is proposed to represent the fatigue resistance for a given fatigue loading and material, which allows a direct reliability approximation. The critical fatigue notch factor for an ice-induced fatigue loading is derived. The ENSN approach is more reasonable to be used for this type of fatigue loading than the high cycle fatigue approach. A cruciform joint subjected to ice-induced fatigue loading is assessed to demonstrate the application of the fatigue reliability assessment procedures.

Fatigue life investigation of non-load carrying fillet weld of structural offshore steel S460G2+M using experiment and FEM simulation

This research deals with the fatigue life investigation using experiment and FEM simulation on longitudinal fillet weld of structural offshore steel S460G2+M with a thickness of 10mm. The experimental fatigue test is conducted based on nominal stress (NS) approach while the simulation uses the effective notch stress (ENS) approach for fatigue life assessment. The investigation begins with the preparation of the longitudinal fillet weld fatigue specimen using Milling Machine based on the IIW fatigue specimen design recommendation and joined using the semi-automatic GMAW process following the AWS D1.1 procedure. Fatigue testing on non-load carrying fillet weld is conducted using the Instron Fatigue Machine with a stress ratio of 0.1 with constant amplitude loading and stress loading from 50%-75% of the yield strength of the base material. For the simulation approach, the 3D longitudinal fillet weld geometry is created using CAD based on the ENS design procedures of IIW where the sizes and dimensions are similar to the experimental fatigue specimen. The static elastic stress analysis of the model is conducted using MSC Marc/Mentat FEM software. Based on the IIW fatigue data evaluation, it is found that the natural mean curve of the longitudinal fillet weld obtained 146 MPa of FAT class which exceeds approximately 106% from the IIW FAT class recommendation for a longitudinal fillet joint. However, the characteristic curve of 97.7% failure probability of the parts only attained 95 MPa of FAT class, but still exceeds approximately 33% form the IIW FAT class. In the ENS fatigue assessment of the 3D longitudinal fillet weld, it is found that the model obtained 195MPa of FAT class which is inferior approximately 15 % from the FAT class recommendation of IIW. Also, it is found that both S-N curves of NS after conversion to ENS system have a good agreement with the S-N curve of ENS of 3D longitudinal fillet weld model and the IIW recommendation due to only 16 % and 34% lower as compared with the IIW FAT class recommendation for ENS.

Seismic performance of flange plate connections between steel beams and box columns

This paper presents analytical and experimental studies on the cyclic behavior of flange plate connection between a steel beam and a welded box column. Three full-scale specimens were tested to evaluate the effect of flange plate length and plate-to-flange fillet weld geometry on the seismic response of flange plate connection. Flange plate connection in the test specimens achieved the AISC seismic provision requirements for special moment frames. Then, the finite-element model developed using ABAQUS was validated using the test results. This model was subsequently used to further investigate the behavior of the test specimens.

A traction stress based shear strength definition for fillet welds

In this paper, a traction stress based shear strength definition is presented for correlating weldment test data obtained from standard specimens such as those stipulated by AWS B4.0 as well as for applications in general structural design applications when finite element methods are used. With this proposed approach, well-documented discrepancies in shear strength between transverse and longitudinal shear tests can now be reconciled, resulting in a single shear strength value regardless of specimen types and loading conditions. The method should provide a basis for achieving a quantitative weld sizing in fillet weld design for structural applications. The paper starts with a brief description of major issues associated with strength data interpretation using the conventional shear stress formula given in AWS B4.0 which is widely used by various industries. After posing a series of candidate static failure criteria, an existing finite element solution technique for dealing with stress concentration effects on fatigue is then extended for applications in determining stress parameters that can be related to shear strength in standard shear test specimens. A large amount test data are then analyzed to judge the most appropriate failure criteria for shear strength characterization of fillet welds. An analytical solution is also developed both for validating the proposed shear strength definition and for gaining theoretical insights, e.g. on stress/strength relationship as a function of fillet weld and fillet weld geometry.

Predicting Bead Geometry of 2F-Fillet Joint Welded by Small Wire SAW

The cost of development of WPS will be very expensive if the welding parameter is selected based on trial and error. Optimal welding condition cannot be easily guessed unless the operator has records of good welding. If a calculator that can predict the welding parameter for the desired bead geometry accurately, such tool will be extremely useful for any fabrication industry. This paper intends to investigate the correlation between the welding parameter and weld bead geometry of 2F position T-fillet carbon steel, when welded by 1.2 mm diameter wire submerged arc welding. Keeping only one parameter as variable, 2F fillet weld coupons are welded by SAW with a range of welding current, welding voltage and welding speed. Only weld bead geometry that complied with the quality requirement of code of practice AWS D1.1 is considered. The trendline graph is created to fit the correlation between the heat input and the fillet weld geometry. By incorporating the trendline formulas into the calculator, the weld bead geometry can be predicted accurately for any welding parameter. The mean absolute deviation (MAD) between the predicted geometry and the experimental results is less than 0.50mm.

Guaranteed fillet weld geometry from heat transfer model and multivariable optimization

Numerical heat transfer models of gas metal arc (GMA) fillet welding do not always predict correct temperature fields and fusion zone geometry. The inaccuracy results, to a large extent, due to the difficulty in correctly specifying several input parameters such as arc efficiency from scientific principles. In order to address this problem, a heat transfer model is combined with an optimization algorithm to determine several uncertain welding parameters from a limited volume of experimental data. The resulting smart model guarantees optimized prediction of weld pool penetration, throat and leg-length within the framework of phenomenological laws. A boundary fitted coordinate system was used to account for the complex fusion zone shape. The weld pool surface profile was calculated by minimizing the total surface energy. Apart from the direct transport of heat from the welding arc, heat transfer from the metal droplets was modeled considering a volumetric heat source. The Levenberg–Marquardt and two versions of conjugate gradient method were used to calculate the optimized values of unknown parameters. An appropriate objective function that represented the difference between the calculated and experimental values of the penetration, throat and leg-length was minimized. The calculated shape and size of the fusion zone, finger penetration characteristic of the GMA welds and the solidified free surface profile were in fair agreement with the experimental results for various welding conditions.

An analytical solution for transient temperature distribution in fillet arc welding including the effect of molten metal

This paper presents an analytical solution to predict the transient temperature distribution in fillet arc welding, including the effect of the molten metal generated from the electrode. The analytical solution is obtained by solving a transient three-dimensional heat conduction equation with convection boundary conditions on the surfaces of an infinite plate with finite thickness, and mapping an infinite plate on to the fillet weld geometry, including the molten metal with energy equation. The electric arc heat input on the fillet weld and on the infinite plate is assumed to have a travelling bivariate Gaussian distribution. To check the validity of the solution, flux cored arc (FCA) welding experiments were performed under various welding conditions. The actual isotherms of the weldment cross-sections at various distances from the arc start point are compared with those of the simulation result. As the result shows a good accuracy, this analytical solution can be used to predict the transient temperature distribution in the fillet weld of finite thickness under a moving bivariate Gaussian distributed heat source. The simplicity and short calculation time of the analytical solution provides the rationale for using the analytical solution to model the welding control systems or to obtain an optimization tool for welding process parameters.

引張りをうける十字すみ肉溶接継手の変形挙動と強度(第1報)

Progressive research program is undertaken to observe the mechanical behaviour in crusiform fillet welded joint under tension. Attension is forcussed, in particular, on the effect of geometry of fillet weld including its contour, size and penetration on plastic deformation and strength of welded joint. The present report explains experimentally the effect of contour of fillet weld. Model specimens, having profile of crusiform fillet welded joints, machined from a mild steel of 1.6 mm thick are used for the experiments. Strain distributions in fillet weld are measured by using the Moire method. The strain and stress distributions in fillet weld at several load levels are obtained for various fillet angle θf. Influence of the fillet angle θf and reinforcement of weld on the strength of fillet welded joint are determined.