Stress and Deflections in Type II and Type IV Airdrop Platforms

摘要

Severe stress conditions may develop during the extraction and parachute deployment phases of an airdrop with a stressed platform. The platform stresses and deflections during that dynamic loading period are computed by treating the platform as a planar network of beams rigidly connected at the joints. Stiffness properties of the beams in the network are calculated approximately using standard methods and then refined to more exact values by comparing measured deflections under static loading to computed deflections. These stiffness properties are then used in the analysis of the dynamic load. Equations of motion are written for each degree of freedom using a lumped mass representation for the loads. Deflections at the joints of the network are obtained by solving the equations of motion using the Runge-Kurt-Gill numerical procedure. Stresses are then determined from the deflections. (Author)