Numerical Simulation of the Influence of Different Surface Morphologies on Molten Pool Flow under Moving Heat Source

2021 ◽  
Vol 904 ◽  
pp. 9-13
Author(s):  
Jie Yin ◽  
Zhen Yu Zhao ◽  
Hou Ming Zhou ◽  
Kai Li ◽  
Hao Zhou
Keyword(s):  
Heat Source ◽  
Surface Topography ◽  
Capillary Force ◽  
Molten Pool ◽  
Moving Heat Source ◽  
Element Analysis ◽  
Thermocapillary Force ◽  
Initial Shape ◽  
Transient Model ◽  
Laser Polishing

In order to study the influence of different initial topography on the molten pool flow under a moving heat source, the finite element analysis method was used to establish a two-dimensional transient model of laser polishing to simulate the evolution of the surface topography of the material during laser polishing. In the simulation process, a moving laser beam was used as the heat source, and the free surface of the actual material was profiled through a three-dimensional profiler. A very similar simulation model surface was constructed, coupled with the flow field and temperature field in the laser polishing process, and the capillary force was considered comprehensively. Combined with thermocapillary force. The results show that under the combined action of capillary force and thermocapillary force, the surface of the polished material has a peak-filling effect, which makes the surface of the material achieve a good polishing effect. The initial shape will affect the polishing effect, the greater the curvature, the faster the flow rate of the molten pool. In molten pools with large spatial curvatures, capillary forces dominate. Keywords: Laser polishing; molten pool; surface topography; numerical analysis; capillary force; thermocapillary force.

Role of Capillary and Thermocapillary Forces in Laser Polishing of Metals

2017 ◽  
Vol 139 (4) ◽  
Author(s):  
Chi Zhang ◽  
Jing Zhou ◽  
Hong Shen
Keyword(s):  
Capillary Force ◽  
Molten Pool ◽  
Continuous Wave ◽  
Flow Behavior ◽  
Marangoni Effect ◽  
Cost Effective ◽  
Underlying Mechanism ◽  
Thermocapillary Force ◽  
Laser Polishing ◽  
Coupled Heat Transfer

As one of emerging novel surface treatment techniques, laser polishing offers a cost-effective and efficient solution to reduce surface roughness of precision components at micro-/mesoscale. Although it has been applied for industrial and biomedical purposes, the underlying mechanism has not been fully revealed. This paper presents a study to understand the basic fundamentals of continuous wave fiber laser polishing of Ti6Al4V samples. A two-dimensional numerical model that coupled heat transfer and fluid flow is developed to illustrate the molten flow behavior. The roles of capillary and thermocapillary flow in the process of laser polishing are investigated to assist the understanding of the contributions of surface tension (capillary force) and Marangoni effect (thermocapillary force) in the polishing process. Capillary force dominates the molten pool at the initial stage of melting, while thermocapillary force becomes predominant when the molten pool fully develops.

scholarly journals In-Situ Laser Polishing Additive Manufactured AlSi10Mg: Effect of Laser Polishing Strategy on Surface Morphology, Roughness and Microhardness

Materials ◽  
2021 ◽  
Vol 14 (2) ◽  
pp. 393
Author(s):  
Jiantao Zhou ◽  
Xu Han ◽  
Hui Li ◽  
Sheng Liu ◽  
Shengnan Shen ◽  
...  
Keyword(s):  
Surface Quality ◽  
Molten Pool ◽  
Surface Defects ◽  
Polished Surface ◽  
Transient Model ◽  
Surface Evolution ◽  
Powder Bed ◽  
Laser Polishing ◽  
Surface Morphologies

Laser polishing is a widely used technology to improve the surface quality of the products. However, the investigation on the physical mechanism is still lacking. In this paper, the established numerical transient model reveals the rough surface evolution mechanism during laser polishing. Mass transfer driven by Marangoni force, surface tension and gravity appears in the laser-induced molten pool so that the polished surface topography tends to be smoother. The AlSi10Mg samples fabricated by laser-based powder bed fusion were polished at different laser hatching spaces, passes and directions to gain insight into the variation of the surface morphologies, roughness and microhardness in this paper. The experimental results show that after laser polishing, the surface roughness of Ra and Sa of the upper surface can be reduced from 12.5 μm to 3.7 μm and from to 29.3 μm to 8.4 μm, respectively, due to sufficient wetting in the molten pool. The microhardness of the upper surface can be elevated from 112.3 HV to 176.9 HV under the combined influence of the grain refinement, elements distribution change and surface defects elimination. Better surface quality can be gained by decreasing the hatching space, increasing polishing pass or choosing apposite laser direction.

Temperature Field Due to a Moving Heat Source: A Moving Mesh Finite Element Analysis

1985 ◽  
Vol 52 (2) ◽  
pp. 274-280 ◽  
Author(s):  
Z.-B. Kuang ◽  
S. N. Atluri
Keyword(s):  
Finite Element ◽  
Temperature Field ◽  
Heat Source ◽  
Process Zone ◽  
Surrounding Medium ◽  
Moving Mesh ◽  
Transient Temperature ◽  
Moving Heat Source ◽  
Element Analysis ◽  
External Agent

The transient temperature field (as seen by a moving observer) due to a moving heat source, such as the process zone near a dynamically propagating crack tip or an external agent as in the case of welding, is analyzed by a moving-mesh finite element procedure. The effects of the temperature-dependent material properties, and of the loss of heat to the surrounding medium through convection and radiation, are studied. Situations under which conditions in the process zone may be labeled as “isothermal” or “adiabatic” are explored. Estimates of temperature rise near the tip of a crack propagating at realistic speeds in structural steels are made.

Finite Element Analysis of Thermal Effect on Large Thick Titanium Alloy Electron Beam Welding with Different Focus

2012 ◽  
Vol 152-154 ◽  
pp. 665-671 ◽  
Author(s):  
Bing Gang Zhang ◽  
Guo Qing Chen ◽  
Wei Guo ◽  
Ming Xiao Shi
Keyword(s):  
Finite Element ◽  
Titanium Alloy ◽  
Temperature Gradient ◽  
Heat Source ◽  
Molten Pool ◽  
Electron Beam Welding ◽  
Element Model ◽  
Peak Temperature ◽  
Element Analysis ◽  
Simulated Temperature

A composite heat source model composed of Gaussian surface heat source and rotational paraboloidal body heat source have been established to simulate the temperature field of 20mm TA15 titanium alloy. The results show that the simulated peak temperature of molten pool during surface focus welding is 3200°C, while the simulated peak temperature of molten pool during lower focus is 2700°C, and the whole surface temperature of surface focus welding is higher than that of lower focus welding, while the whole inner temperature of surface focus welding is lower than that of lower focus. The simulated temperature gradient in the direction of depth during surface focus welding is large, but the simulated temperature gradient in the direction of depth during lower focus welding is small. The simulated result was verified by the thermocouple and contrast of weld cross section morphology. The simulated thermal cycle curves are well consistent to the results tested by thermocouple, and there is a good consistency between the simulated molten pool morphology and the real weld morphology, they verify the accuracy of finite element model.

scholarly journals Numerical Simulation and Verification of Laser-Polishing Free Surface of S136D Die Steel

Metals ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 400
Author(s):  
Hao Zhou ◽  
Houming Zhou ◽  
Zhenyu Zhao ◽  
Kai Li ◽  
Jie Yin
Keyword(s):  
Numerical Simulation ◽  
Surface Morphology ◽  
Molten Pool ◽  
Orthogonal Experiment ◽  
Material Surface ◽  
Beam Radiation ◽  
Transient Model ◽  
Laser Polishing ◽  
Die Steel ◽  
Pool Depth

As a novel polishing technology, polishing by laser beam radiation can be used to improve the sample surface finish without causing material losses. In order to study the effect of laser polishing on the surface morphology of S136D die steel, an L16(44) orthogonal experiment was designed to describe the variation trend of surface roughness with energy density. The two-dimensional transient model of laser polishing was established to simulate the evolution process of material surface morphology during laser polishing by combining numerical simulation with the experiment. The model uses a moving laser heat source to study the effects of capillary pressure and thermocapillary pressure in the laser polishing process. The experimental results show that the minimum roughness can be reduced to 0.764 μm, and the error between the actual molten pool depth and the simulated molten pool depth is 5.3%.

scholarly journals Analysis of hyperbolic Pennes bioheat equation in perfused homogeneous biological tissue subject to the instantaneous moving heat source

2021 ◽  
Vol 3 (4) ◽  
Author(s):  
Ali Kabiri ◽  
Mohammad Reza Talaee
Keyword(s):  
Heat Source ◽  
Closed Form ◽  
Method Comparison ◽  
Closed Form Solution ◽  
Form Solution ◽  
Temperature Profiles ◽  
Moving Heat Source ◽  
Bioheat Equation ◽  
Perfusion Rate

AbstractThe one-dimensional hyperbolic Pennes bioheat equation under instantaneous moving heat source is solved analytically based on the Eigenvalue method. Comparison with results of in vivo experiments performed earlier by other authors shows the excellent prediction of the presented closed-form solution. We present three examples for calculating the Arrhenius equation to predict the tissue thermal damage analysis with our solution, i.e., characteristics of skin, liver, and kidney are modeled by using their thermophysical properties. Furthermore, the effects of moving velocity and perfusion rate on temperature profiles and thermal tissue damage are investigated. Results illustrate that the perfusion rate plays the cooling role in the heating source moving path. Also, increasing the moving velocity leads to a decrease in absorbed heat and temperature profiles. The closed-form analytical solution could be applied to verify the numerical heating model and optimize surgery planning parameters.

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