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.