Long-Term Tropic Environmental Exposure of Army Standard Family (ASF) rigid Wall Honeycomb Sandwich Panels

Abstract : Modular building concepts for lightweight, transportable tactical shelters incorporate such features as adhesively bonded sandwich wall construction of nonmetallic honeycomb core and aluminum skins. Tactical shelters are used in many locations throughout the world and consequently are subjected to a wide variety of environmental conditions. Experience has demonstrated that the hot-humid environment of the tropics is the most demanding on adhesively bonded shelter walls. The purpose of this investigation was to establish a physical and structural properties data base for tactical rigid wall honeycomb sandwich panels with long-term exposure to the tropical environment. Thirty-two sandwich panels were fabricated and subjected to the tropical environment at the U.S. Army Tropic Test Center in the Republic of Panama. Panels were of standard configuration, panels with hardware (latches, inserts, and repair patch), panels with no polysulfide sealant, and panels with simulated damage. Both Nomex and Kraft paper cores were included. Upon withdrawal from tropical exposure, each panel was weighed to assess moisture pickup, visually inspected for corrosion, local bulges, fungus growth, and sealant deterioration, and coin tap tested for delamination. Subsequently, each panel was machined into specimens and the effects of the tropical exposure determined. Test included: drum peel, flatwise tension, flatwise compression, sandwich flexure, insert pullout and torque, and sealant durometer.... Tactical shelters, Tropical exposure, Adhesive bonded, Testing, Honeycomb sandwich.