Simulation of Thermal Images

1. Simulation of Thermal Images ECE 673 Summer 2003 Presented by Vijaya Priya Govindasamy

2. Outline • Objective • Proposed Approach • Implementation • Results • Conclusion • Scope of improvement

3. Objective • To understand the way the simulation tool works for complex models • To define complex models for simulation in MuSES • To understand the sensitivity of different parameters in running the simulation and their effect on simulation of complex models • To reason out the solution obtained at the end of the simulation (Do you see what you would expect to see)

4. Need for Simulation • Reduces the time and cost of developing prototypes for test purposes • Gives more flexibility in controlling the parameters • Infrared prediction measurements are accurate and faster

5. MuSES • MuSES – Multi-service Electro-optic Signature • MuSES is a thermal modeling tool, used to model the steady state and transient distribution of heat over complex surface descriptions of component systems. • MuSES models 3-D conduction, convection, and multi-bounce radiation. • The output from MuSES is the temperature map of the component system which can be viewed using the integrated post-processor

6. Parts and Elements • Parts vs. Elements • collections of elements that have the same properties, materials, and surface conditions. • The thermal results are solved for the individual elements, but all properties (e.g. part type, materials, thickness, convection coefficient, etc.) are assigned at the part level. • The properties applied to the part will also apply to all of the elements assigned to that part. • Elements vs. Nodes • One or more thermal nodes, depending on the part type • Thermal results are calculated for each of the thermal nodes

7. MuSES Interface Source: MuSES Manual

8. MuSES Solution Procedure • Group geometry • Assign material properties • Set boundary conditions • Set solution parameters • Run simulation • Run signature simulation(optional) • View results using post-processor

9. Meshing Requirements • The characteristics of a good quality mesh for import into MuSES are: • All adjacent polygons share common vertices (equivalenced mesh) • All polygons are 3 or 4-sided (triangles or quads) • All polygons are convex • All polygons have an aspect ratio near unity(e.g. no long and skinny polygons) • Polygons are spread uniformly across thesurface (e.g. avoid fans of polygons) • No overlapping or repeated facets • Surface mesh only (e.g. thin plates represented by their exterior surface only)

10. Poor Mesh • MuSES treats overlapping and adjacent vertices as unconnected parts • The polygons should be uniform with aspect ratio of unity • Overlapping elements should be embedded on the host surface Overlapping elements Unconnected parts Source: MuSES Manual

11. Previous Work Exhaust System Model Car Underbody Model Source: http://imaging.utk.edu/~priya/ece671

12. Part Types • Assigned temperature parts • Temperature curves are assigned for such parts • Surface condition and Bounding box condition are assigned • Calculated Temperature parts • Only initial temperature value is given • Convective heat coefficient value is assigned • Temperature values are calculated as a result of numerical solution • Surface condition, Material properties and Bounding box condition are assigned

13. Properties • Material Type • Given for calculated parts • Based on the type of material the numerical solution is carried out • Thickness • Does not mean anything with the geometry • Used only for calculation • Surface condition • Defines the emmisivity property • Paint codes are also used • Convective coefficient • The value of ‘H’ is given for calculated parts • Used in numerical solution

14. Property Definition • Sample Property Definition • Engine Interior • The temperature is very high due to combustion • Engine Exterior • In real time the coolant fluid reduces the outside temperature Engine Temperature curve

15. Property Definition • Sample property definition • Muffler Interior • Exhaust gas temperature • Muffler Exterior • Outside heat loss to the environment – convection & radiation Muffler Temperature curve

16. Solution Analysis • Start time and End time • Step size • Tolerance slope and Tolerance • View factor rays • Number of iterations • Accuracy of the solution • Convergence parameter

17. Original Geometry • Under body • Engine • Muffler • Transmission • Inverter • Radiator • Catalytic converter • Starter Motor • Batteries • Intake and Exhaust Manifold • Wheels • Upperbody

18. Simulation result of Upper Body

19. SimulationresultofUnderBody

20. Construction of model Reasonable temperatures Medium complexity Tolerance slope of solution convergence - 5e-007 Assumptions Construction of the model

21. Solution Justification Simulation result of Upper Body & Under body

22. Temperature Curves Catalytic converter Engine Muffler

23. Simulation of Thermal Images • Bidirection Reflectance Distribution Function • Displays the image as seen through a sensor • Uses the radiosity solution, environmental conditions and viewing geometry • Requires use of paint code at least by one surface • Two step process • First step: Computes radiances • Second step: Ray tracing

24. Thermal Images of Upper Body Car Upperbody Infrared prediction View 1 View 2

25. Thermal Image of Under Body Infrared Prediction of Car Under body

26. Thermal Image Results and Statistics

27. Thermal Image Results and Statistics

28. Simulation of Toyota Model • Total number of parts when downloaded :281 • Reduced to 17 parts • Additional parts • Transmission • Complete drive train • Gas tank • Discs and Drums • Shock Absorbers

29. Toyota Model Toyota Tundra Pickup Undercarriage Source:http://www.3dcadbrowser.com/browse.aspx?category=52

30. Error Report • Time taken for view factor calculation – more than 72 hours • Following error generated after 3 days • This TDF file was written with MuSES Pro 7.0.0 • Model statistics: • Elements: 467262 • Vertices: 1401798 • Parts: 16 • Opened `d:\priya-MuSES\toyota.tdf' • There are 934525 thermal nodes in the model • Assigning radiation patches... • Computing view factors... • View factor calculation completed • Out Of Memory adding radiation nodes to the solver. • Please close some applications and try again.

31. Error Report

32. Scope of improvement • Problems associated with computer memory has to be solved • Simulation of laser scanned 3d models of real elements

33. Report Revisited • Abstract (1/1) • Introduction (5/5) • Background • Proposed Approach • Theory and Methods(6/6) • Thermal Imaging • MuSES • Simulation of Thermal Images • Experimental Results(5/5) • Conclusion(1/1) • Reference(1/1)

34. Thank You