Modeling Laser Travel and its Effects on Temperature Evolution in Laser Hardening of Hypoeutectoid Steel

2014 ◽  
Author(s):  
Suhash Ghosh ◽  
Chittaranjan Sahay
Keyword(s):  
Heat Source ◽  
Target Material ◽  
Processing Parameters ◽  
Small Time ◽  
Laser Hardening ◽  
Temperature Evolution ◽  
Fe Model ◽  
Aisi 4140 ◽  
Moving Plane ◽  
Variable Flux

To achieve a precise and controlled laser process, a thorough analysis of the thermal behavior of the material is necessary. The knowledge of the thermal cycles is important to ascertain suitable processing parameters, thus improving surface properties when the alloys are laser irradiated. In the present paper, a numerical simulation of the laser hardening process has been developed using the finite element (FE) code ABAQUS™ to solve the heat transfer equation inside the treated material (AISI 4140 steel). The thermal analysis is based on Jaeger’s classical moving heat source method by considering the laser beam as a moving plane (band/disc) heat source and the target material is a semi-infinite solid. However, the FE model, used to solve the governing equation, does not directly accommodate the moving nature of heat source. A reasonable approximation is to divide the laser travel on the substrate into many small time/load steps, and apply variable flux and boundary conditions in each time/load step. This approximates the quasi-steady state phenomena over the series of these time steps for the complete laser travel. This paper investigates the effects of the choice of time/load steps on the temperature evolution as well the computing times in the process.

Modeling Laser Travel and its Effects on Thermal Stresses in Laser Hardening of Steel

2015 ◽  
Author(s):  
Suhash Ghosh ◽  
Chittaranjan Sahay ◽  
Devdas Shetty
Keyword(s):  
Heat Source ◽  
Thermal Stresses ◽  
Target Material ◽  
Processing Parameters ◽  
Small Time ◽  
Laser Hardening ◽  
Fe Model ◽  
Aisi 4140 ◽  
Moving Plane ◽  
Variable Flux

To achieve a precise and controlled laser process, a thorough analysis of the thermal behavior of the material is necessary. The knowledge of the thermal cycles is important to ascertain suitable processing parameters, thus improving surface properties when the alloys are laser irradiated. In the present paper, a numerical simulation of the laser hardening process has been developed using the finite element (FE) code ABAQUS™ to solve the heat transfer equation inside the treated material (AISI 4140 steel). The thermal analysis is based on Jaeger’s classical moving heat source method by considering the laser beam as a moving plane (band/disc) heat source and the target material is a semi-infinite solid. However, the FE model, used to solve the governing equation, does not directly accommodate the moving nature of heat source. A reasonable approximation is to divide the laser travel on the substrate into many small time/load steps, and apply variable flux and boundary conditions in each time/load step. This approximates the quasi-steady state phenomena over the series of these time steps for the complete laser travel. This paper investigates the effects of the choice of time/load steps on the temperature and thermal stress evolution as well the computing times in the process.

scholarly journals Influence of Surface Preparation on the Interface of Al-Cu Joints Produced by Magnetic Pulse Welding

Metals ◽  
2020 ◽  
Vol 10 (8) ◽  
pp. 997 ◽  
Author(s):  
Omid Emadinia ◽  
Alexandra Martins Ramalho ◽  
Inês Vieira de Oliveira ◽  
Geoffrey A. Taber ◽  
Ana Reis
Keyword(s):  
Tensile Testing ◽  
Dissimilar Materials ◽  
Surface Preparation ◽  
Target Material ◽  
Processing Parameters ◽  
Magnetic Pulse ◽  
Magnetic Pulse Welding ◽  
Surface Conditions ◽  
Comprehensive Evaluations ◽  
Pulse Welding

Magnetic pulse welding can be considered as an advanced joining technique because it does not require any shielding atmosphere and input heat similar to conventional welding techniques. However, it requires comprehensive evaluations for bonding dissimilar materials. In addition to processing parameters, the surface preparation of the components, such as target material, needs to be evaluated. Different surface conditions were tested (machined, sand-blasted, polished, lubricated, chemically attacked, and threaded) using a fixed gap and standoff distance for welding. Microstructural observations and tensile testing revealed that the weld quality is dependent on surface preparation. The formation of waviness microstructure and intermetallic compounds were verified at the interface of some joints. However, these conditions did not guarantee the strength.

Predictive modeling of multi-track laser hardening of AISI 4140 steel

2008 ◽  
Vol 480 (1-2) ◽  
pp. 209-217 ◽  
Author(s):  
Ritesh S. Lakhkar ◽  
Yung C. Shin ◽  
Matthew John M. Krane
Keyword(s):  
Predictive Modeling ◽  
Laser Hardening ◽  
Aisi 4140 Steel ◽  
Aisi 4140

A Study on the Grinding Temperature Field for Titanium Alloy

2007 ◽  
Vol 339 ◽  
pp. 45-49
Author(s):  
W. Li ◽  
Tong Xing ◽  
Bao Xiang Qiu ◽  
Gang Xiang Hu ◽  
Yang Fu Jin
Keyword(s):  
Finite Element ◽  
Temperature Field ◽  
Heat Source ◽  
Simulation Software ◽  
Transient Temperature ◽  
Fe Model ◽  
Grinding Temperature ◽  
Wet Grinding ◽  
Dry Grinding ◽  
Grinding Temperature Field

A reasonable finite element (FE) model of grinding temperature field has been developed on the basis of analysis of the transient temperature field， and three kinds of boundary conditions are loaded on the element of a moving heat source. The study, which is based on the finite element principle, has been carried out using the numerical simulation software ANSYS. Many results have been obtained including three dimensional temperature distribution map. The simulated results under different conditions show good agreement with the experimental results. With the comparison of the dry-grinding and wet-grinding, the result shows that the wet-grinding temperature with a proper grinding fluid is rather lower than the dry-grinding temperature. Finally, the variable coefficient of convective heat transfer and the different form heat source have been discussed in detail.

scholarly journals Application of Artificial Neural Networks in Hybrid Simulation

2019 ◽  
Vol 9 (21) ◽  
pp. 4495 ◽  
Author(s):  
Mucha
Keyword(s):  
Finite Element ◽  
Real Time ◽  
Degrees Of Freedom ◽  
Computational Cost ◽  
Hybrid Simulation ◽  
Time Algorithm ◽  
High Accuracy ◽  
Small Time ◽  
Fe Model ◽  
Artificial Neural

Hybrid simulation is a technique for testing mechanical systems. It applies to structures with elements hard or impossible to model numerically. These elements are tested experimentally by straining them by means of actuators, while the rest of the system is simulated numerically using a finite element method (FEM). Data is interchanged between experiment and simulation. The simulation is performed in real-time in order to accurately recreate the dynamic behavior in the experiment. FEM is very computationally demanding, and for systems with a great number of degrees of freedom (DOFs), real-time simulation with small-time steps (ensuring high accuracy) may require powerful computing hardware or may even be impossible. The author proposed to swap the finite element (FE) model with an artificial neural network (ANN) to significantly lower the computational cost of the real-time algorithm. The presented examples proved that the computational cost could be reduced by at least one number of magnitude while maintaining high accuracy of the simulation; however, obtaining appropriate ANN was not trivial and might require many attempts.

Numerical and Experimental Studies of Residual Stresses in Multipass Welding of High Strength Shipbuilding Steel

2015 ◽  
Vol 59 (03) ◽  
pp. 133-144
Author(s):  
Guangming Fu ◽  
Tetyana Gurova ◽  
Marcelo I. Lourenco ◽  
Segen F. Estefen
Keyword(s):  
Neural Network ◽  
Numerical Simulation ◽  
Heat Source ◽  
Residual Stresses ◽  
Experimental Studies ◽  
Source Model ◽  
Fe Model ◽  
Offshore Platforms ◽  
Heat Source Model ◽  
Shipbuilding Industry

The article contributes, through numerical simulation based on models calibrated by experimental results, to better estimate residual stresses and distortions in welded structures representatives of ships and offshore platforms considering welding procedures relevant to shipyard current practices. A multi-pass welding is carried out to investigate the residual stresses in laboratory tests. The temperature at several positions on a plate sample is recorded with thermocouples and residual stresses are measured using an x-ray diffraction technique. Finite element (FE) models are developed in this study and experimentally validated. The three dimensional (3D) moving Goldak's double-ellipsoidal heat source model is employed in the simulations. A Levenberg-Marquardt neural network algorithm is employed to determine the geometric parameters of the heat source model. The technique based on neural network is applied to dimension the heat source later employed in the thermal analysis using 2D FE model to reduce the computer time of the numerical simulation and to make it feasible for shipbuilding industry applications. The numerical results of temperature and residual stress distribution are correlated with the experimental measurements. Finally, the effects of preheat and interpass temperatures on the residual stresses are investigated using numerical simulation. The effects of the transient releasing temperature on the residual stresses are also discussed.

Numerical Investigation on Interruption in the Welding Process Used in Shipbuilding

2015 ◽  
Vol 31 (04) ◽  
pp. 220-229
Author(s):  
Debabrata Podder ◽  
Sara Kenno ◽  
Sreekanta Das ◽  
Nisith Ranjan Mandal
Keyword(s):  
Residual Stress ◽  
Heat Source ◽  
Complex Geometry ◽  
Time Lag ◽  
Welding Process ◽  
Diffraction Method ◽  
Nonlinear Material ◽  
Fe Model ◽  
Temperature Dependent ◽  
Longitudinal Residual Stress

Interruptions in the welding process in shipbuilding are unavoidable because of complex geometry and human fatigue. This article presents an uncoupled three dimensional finite element (FE) modeling technique for bead-on-plate welding and an interruption in the welding process for low carbon and high notch toughness steel plate typically used in shipbuilding. The goal of the FE model was to successfully predict the effect of various time delays in the welding interruption on the residual stress distributions. The FE results are compared with the experimental results for the validation of the model. The experimental work was completed using the neutron diffraction method. The element birth-and-death algorithm was used in ANSYSW to simulate the filler metal deposition. A double ellipsoid heat source was used to simulate the heat source of the weld pool. The FE model considers the temperature dependent nonlinear material properties and uses the temperature-dependent combined coefficient of heat loss. The study found that weld interruptions in the welding process change the residual stress patterns and cause an increase in the maximum longitudinal tensile residual stresses. However, the maximum longitudinal compressive stress reduces as a result of interruptions in the weld process. This study found that a weld interruption duration of approximately 2 minutes is optimum for both fatigue and buckling strength. This study also analyzed the effect of preheat on longitudinal residual stress distribution and concluded that a suitable short time lag without any preheat is equivalent to preheat after a long welding interval.

Sign in / Sign up

Export Citation Format

Share Document