Permeability Test Measurement of Composite Material for Reusable Launching Vehicles (RLV)

Polymer composites are replacing metals over the time due to their light weight, high strength to weight ratio, excellent physical and thermal properties. Hence, they are ideal candidates where weight is of particular concern. One such application is reusable launch vehicles (RLV). Use of polymer Composite materials instead of conventional metal alloys for fuel tank reduces weight of launching vehicle so that more payloads can be carried into space, thereby reducing cost per kilogram of payload. Polymer composites at room temperature show familiar properties but when they are exposed to low temperature, properties change rapidly and show abnormal behavior. Material becomes brittle as temperature is lowered and fails even at low stresses. It becomes further complex when fibrous polymeric composites are used at cryogenic temperatures. In this context, the suitability of polymer composites at low temperature in RLV has to be addressed since during fuelling with liquid hydrogen, the temperature of tanks drops to cryogenic temperature (20K). Polymer matrix composites are wellknown class of engineering plastics, capable of withstanding such extreme thermal cycling and low velocity impacts, while retaining their impermeability