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The US Army helmet has evolved from sheet steel, to 29�layer Kevlar, to the current Kevlar/Twaron advanced combat helmet. The helmet liners have also changed from compressed paper fibers, plastic, and rayon to sophisticated suspension�webbing systems with chin straps. Exposure to brain�injuring shock waves from explosions is a current concern. A variety of materials and designs have been proposed for helmet liner systems, including: air� and fluid�filled (water or glycerin) chambers, layered composites with interfaces that reflect some of the incoming energy, foamed or cellular materials, aerogel, solid glass beads, hollow glass beads, and others. Select several of these and discuss the related pros and cons.
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Degarmo's Materials And Processes In Manufacturing
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