AIR FORCE FLIGHT DYNAMICS LAB WRIGHT-PATTERSON AFB OH
The empirical development of nylon material subroutines for use in computer analysis of parachute system dynamics is discussed. The subroutines account for material plasticity, creep and hysteresis. They predict peak forces and strains accurately or - 5 and are valid over broad ranges of strain rate three decades and tensile load zero to minimum breaking strength. The strain rate sensitivity of nylon is shown to be a manifestation of material creep. Previous models are simplistic by comparison and have been, in general, unsatisfactory. A package of data processing computer programs also developed provides the capability to quickly generate additional subroutines for similar materials from limited test data.