Investigation of Rapidly Deployable Plastic Foam Systems. Volume II. Nonlinear Deformation and Local Buckling of Kevlar Fabric/Polyurethane Foam Composites

摘要

Volume I of this report (1) presents the findings of a study conducted to develop a low-density polyurethane foam system that is deployable within 5 seconds, and (2) documents a study of foam/fabric cylinders as potential structural members. An especially fast-reacting foam formulation was devised, hardware for delivery and mixing of foam chemicals was designed and evaluated, various geometric shapes of constant volume that the foam could be formed into were invesigated, and the impact loading characteristics of the foam at various times soon after generation were studied. Fabrication of fabric foam cylinders was also studied. Volume II of this report documents a study of fabric-skinned, foam-filled cylindrical beams and an analytical/experimental study of their bending properties. Results of the studies show that a low-density polyurethane foam system that will deploy within 5 seconds is practical to generate and to form into geometrically shaped lightweight fabric bags. The foam exhibits good impact absorption properties very quickly after formation; these properties can be used to attenuate rapidly applied loads of low to intermediate velocities. Finally, the fabric/foam composite beams possess interesting structural qualities commensurate with the fabric and foam used in making them. The analytical and experimental results compare very well. The analysis identified several factors of the mechanics involved that must be included in calculations to predict the loading response of such composites. (Author)