Progress of auxetic and semi-auxetic materials

Auxetic materials with negative Poisson\u27s ratios, display the unique behavior owing to their micro-structure or geometrical build. Auxetic materials resist deformities when subjected to uniaxial, biaxial, and shearing stresses. Cellular based materials are known for their excellent impact and shock energy absorption. When foams are incorporated with auxetic geometry, their impact energy absorption increases. Combination of auxetic materials with conventional materials yield semi-auxetic materials. Ideally, layered structures where facing materials are metallic sheets sandwiching polymeric foam cores are popular. The auxetic materials can be combined with conventional materials to obtain P-N-P and N-P-N semi-auxetic sandwiched structures with diverse potential in several applications like automotive, aerospace, sports equipment, and protective armors