The nonlinear biaxial characterization of balloon film - Texas A&M University (TAMU) Scholar

© 1996 by Winzen Engineering, Inc. Sufficient experimental data have been collected over the past few years to permit the characterization of various polyethylene thin films typically used hi the construction of stratospheric balloons. This model of the strain response for linear low density polyethylene is based on the constitutive theory proposed by Schapery which has its origins in the thermodynamics of solids. The films considered here have a nominal thickness of 20 microns and are typically loaded by low pressures which produce a two dimensional state of stress. The approach taken here is based on the creep compliance of the material which has been determined as a function of time, temperature and stress and expressed hi terms of a “reduced” tune. In addition to an accurate nonlinear model, the limits of the region where this material may be considered to be a thermorheologically simple material is shown by the definition of a “proportional limit”. The effects of viscoelastic properties on the strain of a typical long duration balloon vehicle are shown to be sensitive to the temperature and duration of the launch procedure.

The nonlinear biaxial characterization of balloon film Conference Paper