High-Temperature Material Lattice Combining Low Thermal Expansion, High Stiffness and Strength

摘要

Low or near zero thermal expansion is a desirable property for structures undergoing high heat fluxes and thermal stresses. A number of lattice concepts have been investigated to solve this issue. Unfortunately they do not display high stiffness and strength, are too complicated to allow for ease of fabrication, or are not proven at high enough temperatures from practical use on extreme temperature environments. A bi-material lattice that combines low or near zero thermal expansion with high stiffness over a wide temperature range has been introduced and discussed in previous research. This concept was effectively modeled and tested using an aluminum alloy, 7075-T6, and a titanium alloy, Ti-6Al-4V. The main objective of this research is to prove this bi-material lattice concept can be applied to higher temperature combinations of material capable of 1000 deg C while still maintaining high strength and stiffness. Criteria for materials selection are presented. Three configuration concepts are analyzed via finite element calculations. Results show that the bi-material lattice can be used with high temperature materials up to 1000 deg C but some adjustments in topology are required to achieve that temperature in a Ni - Nb metallic lattice.