Spring 2002, METBD452 - FEA Heat Transfer Applications

Prof. Dave Johnson, dhj1@psu.edu, Penn State - Erie, The Behrend College

Project Assignment

Concepts:

• Conduction and Convection Heat Transfer
• Heat Flux Loading
• (Optional) Convection using Surface Effect finite elements
• Transient Thermal Analysis
• Stepped/Ramped loading, automatic time stepping, convergence issues
• Time History Postprocessing
• Time History Animation
  

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  The figure above shows the cross-section of a tractor trailer brake drum, i.e. it is an axisymmetric structure. This part is heated by friction from the brake shoe inside the straight cylinder wall. All surfaces (except the adiabatic base and the area under the brake shoe are cooled by forced convection to ambient (70 F) air when the truck is moving. This assumes that the clearance between the brake shoe and the drum does not permit significant air flow for cooling in that region.
  The drum material is cast iron with:

• themal conductivity of 0.00065 BTU/sec-in-F
• density of 0.246 lbm/cu.in
• specific heat of 0.13 BTU/lbm-F
  The transient thermal loading imposed on this structure is shown below and simulates two cycles of braking and acceleration. In this situation, the truck slows, then speeds up again. As it slows, the heat input at the brake shoe is applied and the forced convection decreases. Then, when the brake is removed, the forced convection increases (as the truck speeds up).

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  Perform a thermal transient analysis of this problem to determine the maximum temperature occuring in the brake drum during the operating cycle. Also, include in your report, the time which shows the highest drum wall temperature and report the location of the hot spot. Assume that the drum is at 70 F at the beginning of the analysis.

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  Report, should include:

• A plot (or plots) showing the model and boundary conditions.
• A time history plot of heat flux and film coefficient b.c.'s to confirm the model loading matches the analysis requirements.
• A time history plot of the temperature under the center of the brake pad, on the ID of the drum.
• A plot illustrating the convergence behavior of the solution (Integration Time Step size).
• Appropriate hand calculations (intergration time step, estimate model temperature after 30 sec.)
• Prepare an animation (showing temperature contours over time) to show the process (in class - homework grade). Use "fixed" contour scaling so all the images have the same contour legend.
• Include the annotated log file, showing the model generation and solution.

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  Reminder: All project reports will be typed, and include:

• a cover page with course name, project name, team names, and date
• a brief objective statement (2-3 sentences, maximum)
• a summary of procedures (bulleted items: assumptions, data, analysis steps)
• a conclusion statement (what was learned, perhaps an evaluation of the design)
• a copy of the project statement (this web page) may be attached.

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