A Two-material Topology Optimization Method for the Design of a Passive Thermal Control Interface

Open Access
Author:
Thurier, Pierre F
Graduate Program:
Aerospace Engineering
Degree:
Master of Science
Document Type:
Master Thesis
Date of Defense:
July 25, 2014
Committee Members:
  • George A Lesieutre, Thesis Advisor
  • Mary I Frecker, Thesis Advisor
  • James Hansell Adair, Thesis Advisor
Keywords:
  • Topology optimization
  • Thermo-mechanical
  • Thermal control
  • contact
  • compliant mechanisms
  • two-material
  • design
Abstract:
Many spacecraft thermal control systems in use today have active sensing and heating elements; passive systems could be simpler and lighter. Thermal control of a two-dimensional equipment sandwich panel could be achieved by enhancing or preventing contact at internal heat-conduction interfaces. Such contact could be established by exploiting differences in the coefficients of thermal expansion of two materials. This study investigates a two-material topology optimization method for the design of a structure under combined thermal and mechanical loading. Thermal loads of interest consist of high and low heat fluxes associated with electronic components, sunk to a fixed thermal bus temperature, and are coupled to mechanical behavior through the coefficients of thermal expansion. Using a SIMP interpolation scheme, algorithms were developed to optimize the topology of three phases: one material having a high coefficient of thermal expansion and thermal conductivity; one material with a low coefficient of thermal expansion and thermal conductivity; and void ("no material"). The governing thermal and mechanical equations are solved using a four-noded finite element formulation. Optimization of the design compliance was used as a benchmark problem for these algorithms. A highly conductive face sheet was introduced to improve the distribution of heat into the structure, and prevent numerical instabilities in the optimization process. Tests on the thermo-mechanical model demonstrated the ability of the algorithm to account for thermal expansion, as well as the effects of thermal gradients. The implementation of the 2-material topology optimization approach demonstrated the importance of the mismatch in the materials properties on optimal topologies. Finally, a thermal contact model, based on a unilateral contact approach, was developed. Results for the design of cellular contact-aided compliant mechanisms showed the ability of the algorithm to generate patterns and features that could be used in a future final design. Further developments could focus on improving the algorithms and the design of the compliant mechanisms.