Accession Number : ADA321073

Title :   Design of Materials with Extreme Thermal Expansion Using a Three-Phase Topology Optimization Method,

Corporate Author : PRINCETON UNIV NJ

Personal Author(s) : Sigmund, Ole ; Torquato, Salvatore

PDF Url : ADA321073

Report Date : MAY 1996

Pagination or Media Count : 40

Abstract : Composites with extremal or unusual thermal expansion coefficients are designed using a three-phase topology optimization method. The composites are made of two different material phases and a void phase. The topology optimization method finds the distribution of material phases optimizing an objective function (e.g., thermoelasticity) subject to certain constraints, such as elastic symmetry or volume fractions of the constituent phases, within a periodic base cell. The effective properties of the material are found using numerical homogenization based on finite element discretization of the base cell. To benchmark the design method we first consider two-phase designs. Our optimal two-phase microstructures agree well with rigorous bounds and so-called Vigdergauz microstructures that realize the bounds. For three phases, the optimal microstructures are compared with new rigorous bounds and again it is shown that the method yields designed materials with thermoelastic properties close to the bounds. The three-phase design method is illustrated by designing materials having maximum directional thermal expansion (thermal actuators), zero isotropic thermal expansion (thermal actuators), zero isotropic thermal expansion, and negative isotropic thermal expansion. It is shown that materials with effective negative thermal expansion coefficients can be obtained by mixing two phases with positive thermal expansion coefficients and void.

Descriptors :   *MATERIALS, *THERMAL EXPANSION, THERMAL PROPERTIES, MICROSTRUCTURE, OPTIMIZATION, CELLS, FINITE ELEMENT ANALYSIS, NUMERICAL ANALYSIS, ELASTIC PROPERTIES, VOIDS, PHASE, TOPOLOGY, ISOTROPISM, SYMMETRY, YIELD, MIXING, ACTUATORS, TEMPERATURE COEFFICIENTS, TWO PHASE FLOW, HOMOGENEITY, DIRECTIONAL, DENMARK, THERMOELASTICITY.

Subject Categories : Thermodynamics

Distribution Statement : APPROVED FOR PUBLIC RELEASE