| Literature review: materials with negative poisson's ratios and potential applications to Aerospace and Defence (2006) | |||||||||||
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| Modern technology requires new materials of special properties. One of the reasons for interest in materials of unusual mechanical properties comes from the fact that they can be used as matrices to form composites with other materials of other required properties, e.g. electric, magnetic, etc. A new field of endeavour is to study materials exhibiting negative Poisson’s ratio (NPR). These types of materials get fatter when they are stretched, or become smaller when compressed, in contrast to conventional materials (like rubber, glass, metals, etc.). Large-scale cellular structures with NPR property were first realised in 1982 in the form of two-dimensional silicone rubber or aluminium honeycombs deforming by flexure of the ribs (Gibson, et al, 1982 & 1988). In 1987, Lakes first developed the NPR polyurethane foam with re-entrant structure (Lakes, 1987a and 1987b). This polymeric foam had a Poisson’s ratio of -0.7. These new types of materials were named auxetics by Evans (Evans, et al, 1991). “Auxetics” comes from the Greek word auxetos, meaning “that which may be increased”. Studies and experiments have demonstrated that auxetic materials (i.e., materials with NPR) can improve mechanical properties, including shear resistance, indentation resistance and fracture toughness, compared to conventional materials from which they are made. These auxetic materials also offer very good sound and vibration absorption and could have many potential applications to aerospace and defence areas. This report briefly reviews the latest advances in research work in auxetic materials, structural mechanisms, properties and applications, particularly in aerospace and defence. Indeed, these new types of materials have a lot of potential applications to Defence such as personal protective equipments (e.g., protective clothing, body armour, bullet-proof vest, etc) and others (e.g., “smart” sensors, sonar, panels etc). Also, these materials could potentially be used to build completely new structures with special functions. However, more research work needs to be done for further understanding of these materials and applications to real components. Also, for future work it is necessary to collaborate with researchers from textile, chemical & biological areas to explore the potential applications for protecting military personnel from injury, or chemical and biological attacks.. An auxetic material exhibits exceptional features, which are different from a conventional material. That is, the auxetic material gets fatter when it is stretched, or becomes smaller when it is compressed, because it has a negative Poisson’s ratio. This report briefly reviews the latest advances in research work in auxetic materials, structural mechanisms, properties and applications, particularly in aerospace and defence.. DSTO-AVD | |||||||||||
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