Modeling of Temperature Distribution in Laser Welding of Lapped Martensitic Steel M1500 and Softening Estimation

2016 ◽  
Vol 138 (11) ◽  
Author(s):  
Hongze Wang ◽  
Yansong Zhang ◽  
Kunkun Chen
Keyword(s):  
Temperature Distribution ◽  
Laser Welding ◽  
Thermal Contact ◽  
Carbon Diffusion ◽  
Element Model ◽  
Hardness Measurement ◽  
Vehicle Body ◽  
Thermal Contact Conductance ◽  
Martensitic Steels ◽  
Time Curve

With the implementation of more stringent emissions standards, ultrahigh strength steel has been increasingly used in vehicle body to reduce the carbon emissions, but softening in the heat-affected zone is one of the most serious issues faced with in welding of this steel. In this paper, a finite element model (FEM) was developed to estimate temperature distribution in laser welding of lapped martensitic steels M1500 considering the effect of interface. Three methods to characterize the effect of interface have been adopted. The comparison result shows that the method using two groups of contact elements with birth and death options could accurately characterize the thermal contact conductance properties of the interface before and after welding, respectively. Based on the simulated temperature–time curve, a carbon diffusion model was then developed to estimate the martensite tempering transformation in the softening zone. Maximum softening degree and location of the softening zone were estimated and validated by hardness measurement experiments.

Modelling of Heat Affected Zone Softening in Laser Welding of M1500

2015 ◽  
Author(s):  
Hongze Wang ◽  
Yansong Zhang
Keyword(s):  
Temperature Distribution ◽  
Laser Welding ◽  
Heat Affected Zone ◽  
High Strength Steel ◽  
High Strength ◽  
Element Model ◽  
Hardness Measurement ◽  
Vehicle Body ◽  
Ultra High Strength Steel ◽  
Heat Affected Zone Softening

With the implementation of more stringent emissions standards, ultra-high strength steel has been increasingly used in vehicle body to reduce the carbon emissions, but softening in the heat affected zone is one of the most serious issues faced with in welding of this steel. In this paper, a finite element model (FEM) was developed to estimate temperature distribution in laser welding of ultra-high strength steel M1500 and a carbon diffusion model was then developed to estimate the martensite tempering transformation in the softening zone based on the simulated temperature distribution results. Maximum softening degree, minimum hardness point position and boundary of the softening zone were estimated and validated by hardness measurement experiments. This work provides a better understanding of the mechanism for heat affected zone softening in laser welding of ultra-high strength steel.

Study on evaluation method of tube—fin thermal contact conductance

2010 ◽  
Vol 225 (2) ◽  
pp. 390-396
Author(s):  
D Tang ◽  
D Li ◽  
Y Peng ◽  
Z Du
Keyword(s):  
Contact Pressure ◽  
Evaluation Method ◽  
Thermal Contact ◽  
Element Model ◽  
Thermal Contact Conductance ◽  
Forming Process ◽  
Contact Conductance ◽  
Die Geometry ◽  
Novel Method ◽  
Tube Expansion

The thermal contact conductance (TCC) is one of the principal parameter in heat transfer mechanism of tube—fin heat exchangers. Because of the difficulties in experimental measurements, the tube—fin TCC has not been focused deeply. This article presents a novel method in evaluating the TCC of tube—fin heatexchanger. First, the tube—fin contact status is investigated with a finite-element model of tube expansion process. Distribution of contact pressure along the tube—fin interface is obtained from the simulation results. Then, experiments are carried out for the relationship between the contact pressure and the TCC. Combining the experiment result with the contact pressure distribution, the tube—fin TCC can be evaluated. Based on the method, effect of processing factors of the expansion forming process, such as expanding ratio and die geometry, are examined.

Influence of Temperature Distribution on Tighten Force in Tie-Bolt Fastened Rotor With Considering Thermal Contact Conductance

2015 ◽  
Author(s):  
He Peng ◽  
Ning Xu ◽  
Zhansheng Liu
Keyword(s):  
Surface Roughness ◽  
Thermal Expansion ◽  
Temperature Distribution ◽  
Contact Pressure ◽  
Thermal Contact ◽  
Thermal Contact Conductance ◽  
Axial Position ◽  
Contact Conductance ◽  
Pressure Surface ◽  
Axial Temperature

Tighten force has much influence on tie-bolt fastened rotor dynamics. Temperature distribution in tie-bolt fastened rotor results in thermal expansion of rotor and rods. The difference of thermal expansion between rotor and rods causes the variation of bolt load. With considering the thermal contact conductance, the thermal model of tie-bolt fastened rotor was established by finite element method and the axial temperature distribution was obtained. The influences of surface roughness, nominal contact pressure and axial position of contact on axial temperature distribution were analysed. Based on temperature distribution in the tie-bolt fastened rotor, the variation of tighten force was investigated. Results show that nominal contact pressure, surface roughness and axial contact arrange have different influences on the variation of tighten force with temperature.

scholarly journals Two-dimensional finite element analysis investigation of the heat partition ratio of a friction brake

2018 ◽  
Vol 232 (12) ◽  
pp. 1489-1501 ◽  
Author(s):  
Le Qiu ◽  
Hong-Sheng Qi ◽  
Alastair Wood
Keyword(s):  
Heat Flux ◽  
Finite Element ◽  
Finite Element Model ◽  
Thermal Contact ◽  
Element Model ◽  
Partition Ratio ◽  
Thermal Contact Conductance ◽  
Interface Temperature ◽  
Two Dimensional ◽  
Heat Partition

A two-dimensional coupled temperature–displacement finite element model is developed for a pad-disc brake system based on a restricted rotational pad boundary condition. The evolution of pressure, heat flux, and temperature along the contact interface during braking applications is analysed with the finite element model. Results indicate that different rotational pad boundary conditions significantly impact the interface pressure distribution, which in turn affects interface temperature and heat flux distributions, and suggest that a particular pad rotation condition is most appropriate for accurately modelling friction braking processes. The importance of the thermal contact conductance in the analysis of heat transfer in friction braking is established, and it is confirmed that the heat partition ratio is not uniformly distributed along the interface under normal and high interface thermal conductance conditions.

Anisotropic Heat Conduction Effects in Proton-Exchange Membrane Fuel Cells

2006 ◽  
Vol 129 (9) ◽  
pp. 1109-1118 ◽  
Author(s):  
Chaitanya J. Bapat ◽  
Stefan T. Thynell
Keyword(s):  
Thermal Conductivity ◽  
Temperature Distribution ◽  
Thermal Contact ◽  
Current Collector ◽  
Gas Diffusion ◽  
Thermal Contact Conductance ◽  
Contact Conductance ◽  
Gas Diffusion Layers ◽  
Diffusion Layers ◽  
Anisotropic Thermal Conductivity

The focus of this work is to study the effects of anisotropic thermal conductivity and thermal contact conductance on the overall temperature distribution inside a fuel cell. The gas-diffusion layers and membrane are expected to possess an anisotropic thermal conductivity, whereas a contact resistance is present between the current collectors and gas-diffusion layers. A two-dimensional single phase model is used to capture transport phenomena inside the cell. From the use of this model, it is predicted that the maximum temperatures inside the cell can be appreciably higher than the operating temperature of the cell. A high value of the in-plane thermal conductivity for the gas-diffusion layers was seen to be essential for achieving smaller temperature gradients. However, the maximum improvement in the heat transfer characteristics of the fuel cell brought about by increasing the in-plane thermal conductivity is limited by the presence of a finite thermal contact conductance at the diffusion layer/current collector interface. This was determined to be even more important for thin gas-diffusion layers. Anisotropic thermal conductivity of the membrane, however, did not have a significant impact on the temperature distribution. The thermal contact conductance at the diffusion layer/current collector interface strongly affected the temperature distribution inside the cell.

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