Mechanics and Durability Branch.pdfVIP

1/12 CRYOGENIC INSULATION BONDLINE STUDIES FOR REUSABLE LAUNCH VEHICLES= T. F. Johnson Mechanics and Durability Branch E. S. Weiser Advanced Materials and Processing Branch NASA Langley Research Center Hampton, VA 23681-2199 P. G. Duong Boeing Corporation Huntington Beach, CA 92647 ABSTRACT Cryogenic insulations bonded to metallic substrates were characterized under simulated mission conditions representative for a reusable launch vehicle. The combined thermal and mechanical test consisted of 50 to a 100 cycles. These combined thermal and mechanical cycles simulated flight missions with temperatures ranging from -423°F to 450°F and a maximum mechanical tension load ranging from 20,000 lbs. to 97,650 lbs. The combined thermal and mechanical (uniaxial tension) test apparatus (1 ft. by 2 ft. Test Apparatus) developed at the NASA Langley Research Center, was used to perform cyclic tests on cryogenic insulations bonded to tank wall substrates. No visual delamination or degradation was observed in the cryogenic insulation-to-metallic substrate bondline or butt joints between cryogenic insulation panels. In addition, after cyclic testing was performed, residual property results from tension-pull and closed-cell content tests of the cryogenic insulations indicated a decrease in the bondline strength and closed-cell content. INTRODUCTION The Reusable Launch Vehicle (RLV) Program is a partnership between the National Aeronautics and Space Administration (NASA) and aerospace industry. The goal of the RLV Program has been to develop a vehicle that is fully reusable with greatly reduced operational cost1, 2, 3. The thermal protection system (TPS), the insulated cryogenic propellant tanks, crew/payload compartments, engines, and control systems require careful consideration for the vehicle to be viable since future launch vehicles must be fully reusable to reduce the cost of space access. However, one of the most crucial issues being considered is the development of durable, l