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原文传递 STIR: Mechanisms of Enhancing Impact Resistance of Layered Materials Using Thin Polymeric Interfaces.

题名：	STIR: Mechanisms of Enhancing Impact Resistance of Layered Materials Using Thin Polymeric Interfaces.
作者：	Xu, L. R.
关键词：	Layers, Failure (mechanics), Impact, Polymers, Impact loads, Stress waves, Compression waves, Crack propagation, Composite materials, Laminates, Adhesives, Impact resistance, Polymeric interfaces, Impact damage reduction, Youngs modulus, Compressive stress waves
摘要：	This project provides a fundamental understanding on an innovative material design, i.e., implanting thin interfaces inside layered materials to enhance impact resistance. Its technical merit is simplifying a complicated problem to discover key parameters in controlling failure mechanisms. Four mechanisms related to impact damage reduction or impact resistance increase were found. First, thin interfaces lead to reduction of the maximum impact force of layered materials, and for some layered polymer specimens, the reduction was up to 60%. Second, low Young's moduli of thin interfaces are necessary conditions to reduce the maximum impact force. Third, impedance mismatch and shear modulus mismatch of the thin interfaces and the adjacent bonded materials are key factors to change dynamic stress and wave distributions. Fourth, under high impact loading, dynamic crack initiation leads to strong tensile stress wave ahead of dynamic cracks. After major stress wave is reflected from the thin interface due to the above property mismatch, fast compressive stress wave suppresses slow crack propagation. The above research outcomes will be beneficial to many layered materials including composites laminates and layered armor. Since composite materials have extensive applications, this project will have significant impact inside and outside Department of Defense.
报告类型：	科技报告