Impact Behavior of Glare Hybrid Laminate Under Extreme Thermal Conditions

Abstract

Artificial bodies intentionally placed into low orbit around the earth (LEO) are exposed to critical thermal and mechanical in-service conditions, e.g. severe thermal cycling and micrometeoroid impact. To better understand the response of Glare™-5 2/1 fiber-metal laminate under such conditions, pristine test coupons were subjected to low-energy ballistic impact (21 J) at the temperatures of-196 and 100 °C. Another set of test pieces went through the same experimental conditions, except that they were first submitted to 1,200 thermal shock cycles from-196 to 100 °C. Thermally conditioned specimens exhibited higher resistance to externally visible damage in both test temperatures. On the other hand, internal failure mechanisms characterized via microscopy and X-ray CT inspection techniques have shown that specimens submitted to cryogenic impact after repeated thermal cycling presented the best impact resistance, being age hardening of outer 2024-T3 Al-alloy sheets a possible enhancing factor; besides, residual thermal stresses in the core glass fiber-reinforced epoxy matrix, associated to the post-cure of the latter may have led to higher interlaminar strength.

Quasi-Static Indentation Response of Galvanized Iron Toughened Glass Fiber/Epoxy Laminates

“…The first development of FMLs was ARALL (Aramid fiber reinforced aluminum laminate) at Delft University of Technology in the 80"s. Later on, CARALL (Carbon fiber reinforced aluminum laminate) and GLARE (glass fiber reinforced aluminum laminate) were invented in order to improve ARALL laminates. GLARE has a structural efficiency of 72% higher than monolithic aluminum, saving approximately 1 ton of weight of an aircraft [2]. Today, GLARE is not only being used as lower wing and pressurize fuselage skin panel, but also applied in cargo floors, engine cowlings, patch repair, stringers, cargo containers, and seamless tubes, due to its excellent properties [3].…”