Transient Thermal Analysis

A Study of Lethal Effects of High Power Laser over Various Materials by Transient Thermal Analysis using Finite Element Method

Abstract: This paper describes the lethal effects of Laser during its interaction with metals. In this paper we discuss the thermal analysis for studying the changes in physical properties of different metals and alloys name copper (Cu), Aluminum (Al) and Stainless Steel (SS) using finite element analysis (FEA) technique. The ANSYS WORKBENCH 14 software was used along with 3D CAD (Computer-Aided Design) solid geometry to simulate the behavior of temperature distribution under thermal loading conditions. A comparative study is also done to simulate the effect of beam- combining.
Introduction:
A high power fiber laser

The solid model Fig 2. The solid model split into hexagonal patterned circles for applying heat load
The top face of the Fig 1 is heated by Laser. The top surface of another model has a hexagonal patterned six circles and one circle at the centre as shown in Fig 2. The heat flux is non- uniform over that face. Other five faces of the solid exchange heat by convection with the surrounding air environment. The fact that the top and bottom faces have the same heat transfer coefficient means that the temperature of the solid is symmetric about a vertical plane that bisects the length of the solid. Similarly, the two sides have identical heat transfer coefficients which create a symmetry plane that bisects the breadth.
These planes further subdivide the solid into four quadrants in such a way that the temperature solution in each quadrant is identical. Hence, we need to solve the heat conduction problem in only any one of the quadrants.
Thermal

FEA Treatment of Thermal Modeling
The basis for thermal analysis in ANSYS is a heat balance equation obtained from the principle of conservation of energy. The finite element solution performed via Mechanical APDL calculates nodal temperatures, and then uses the nodal temperatures to obtain other thermal quantities. The ANSYS program handles all three primary modes of heat transfer: conduction, convection, and radiation. Mesh was created in Ansys. The mesh had 144005 elements. The fine meshing is shown in Fig 3.
Results: The transient thermal analysis was carried using Ansys Workbench 14.0 and the results were obtained for various time periods. Fig 4 shows the results for Aluminium for all three laser configurations after 60 seconds. Similarly, Fig 5 and Fig 6 show the results for Copper and Stainless Steel respectively. A comparative graph of temperature variation with depth for three materials for 1 KW laser configuration is plotted in Fig 6. A comparative graph for maximum temperature variation with time for different materials for 1KW laser configuration is plotted in Fig