Mechanical and physical properties of the Echo II metal-polymer laminate

Abstract : Results of a comprehensive investigation of the physical and mechanical properties of the Echo II material are reported. The Echo II material (an aluminum - mylar - aluminum composite film) was subjected to a variety of tests and environmental controls designed to evaluate its properties under anticipated service conditions. This test program included the determination of creep and relaxation properties, peel strength, electrical conductivity, and uniaxial and biaxial stress properties. A major portion of these results represents room temperature testing; however, for several specific programs, data were obtained at both freezing and elevated temperatures which simulated actual service conditions. Additional tests were performed on material which had been exposed to electron radiation of various energies and total exposures. Similar tests were performed on individual components of the film; that is, the mylar, the aluminum, and the adhesives. In addition to laboratory tests on small samples of the composite film, biaxial strain data were obtained from a full size balloon used in a Static Inflation Test performed at Lakehurst, New Jersey. Test results including a failure analysis performed on several full scale balloons which failed prematurely are also reported.