Thermomechanical evaluation of a glass-epoxy composite for astronomical optical devices

Abstract

Astronomical devices, such as optical benches, carry high precision instrumentation work at low temperatures (−150 °C). To fulfill engineering requirements, glass-epoxy composite trusses are proposed. To evaluate the performance of this solution, thermomechanical characterization is carried out by means of dynamic mechanical analysis (DMA), thermogravimetric analysis (TGA), flammability tests, and tensile test and Scanning Electron Microscopy (SEM) observations. Two family of coupons are tested; first one environmentally aged for 10 years and second one recently fabricated, both at 20, 0 and −20 °C. Ageing influence is more noticeable on thermal behavior as Tg and self-extinguish capacity are lower. Ultimate tensile strength and maximum strain are lower for the aged coupons (16–25%), but there is not a remarkable difference in terms of stiffness. Also, coupons mechanically tested at −20 °C show a slight increment in strength. These results show that ageing of glass-epoxy composites must be considered when high performance devices are conceived to be fabricated with.