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首页> 美国政府科技报告 >Computational Investigation of Impact Energy Absorption Capability of Polyurea Coatings via Deformation-Induced Glass Transition.
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Computational Investigation of Impact Energy Absorption Capability of Polyurea Coatings via Deformation-Induced Glass Transition.

机译：聚脲涂层冲变吸收能力的变形诱导玻璃化转变计算研究。

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摘要

A number of experimental investigations reported in the open literature have indicated that the application of polyurea coatings can substantially improve blast and ballistic impact resistance/survivability of buildings, vehicles and laboratory test plates. While several potential mechanisms (e.g., shock-impedance mismatch, shock-wave dispersion, fracture- mode conversion and strain delocalization) have been proposed for the observed enhancement in the blast-wave/projectile-energy absorption direct experimental or analytical evidence for the operation of these mechanisms has been lacking. Recently, it has been proposed that transition of polyurea between its rubbery- state and its glassy-state under high deformation-rate loading conditions is another possible mechanism for the improved ballistic impact resistance of polyurea-coated structures/test plates. In the present work, an attempt is made to provide computational support for this deformation-induced glass transition based energy-dissipation/absorption mechanism. Towards that end, a series of finite-element analyses of the projectile/coated-plate interactions are carried out using a transient non-linear dynamics finite-element approach. The results obtained are used to assess the extent of energy absorption and to identify the mode of failure of the test plate as a function of the imposed impact conditions. The results obtained show that the mechanical response of polyurea under impact conditions is a fairly sensitive function of the difference between the test temperature and the glass transition temperature. Specifically, when this difference is large, polyurea tends to display high-ductility behavior of a stereotypical elastomer in its rubbery-state. On the other hand, when the test temperature is closer to the glass transition temperature, polyurea tends to transform into its glassy-state during deformation and this process is associated with viscous type energy-dissipation.

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