Out of Plane Coefficient of Thermal Expansion and Its Influence on Reflector Thermal Distorsions

摘要

A test program was carried out to measure the out of plane coefficient of thermal expansion (CTE) of spaceborne reflectors which require micron-order stability. Analytical models to predict the test results and to study the influence on the reflector thermal distortions were developed. Parametric studies to define the range of increasing importance for the out of plane coefficient of thermal expansion were carried out. Results show that finite element techniques can be reliably used for CTE prediction. The value of out of plane CTE is very high, aluminum dominated. Influence of the CFRP facing laminates translates into transverse effects higher than produced by aluminum alone, due to Poisson's ratio constraining effects. For antenna distorsions, simple models providing meaningful results can be made to support preliminary design phases.