Accession Number : ADP004700

Title :   Improved Extensional Modulus Measurements for Polymers and Metal Matrix Composites,

Corporate Author : NAVAL SURFACE WEAPONS CENTER SILVER SPRING MD

Personal Author(s) : Madigosky,W.

Report Date : NOV 1984

Pagination or Media Count : 12

Abstract : An improved resonance apparatus for rapid and reliable materials characterization is described. The apparatus accurately determines the propagation constants of an extensional acoustic wave by exciting a bar of material at one and by a noise source while the other is allowed to move freely. Miniature accelerometers measure the accelerations at the two locations. A dual channel Fast Fourier Transform spectrum analyzer is used to obtain the amplitude and phase response as a function of frequency from which the complex Young's modulus can be obtained. Young's modulus and loss factor measurements have been successfully measured in materials ranging from soft polymers to rigid metal matrix composites. For viscoelastic materials the method of fractional derivatives is found to successfully model the complex modulus throughout the transition region, and suggests that the four independent constants used are indeed related to the measurable physical properties and chemical composition of the material. (Author)

Descriptors :   *DAMPING, *METAL MATRIX COMPOSITES, *POLYMERS, *MEASUREMENT, ACOUSTIC WAVES, FAST FOURIER TRANSFORMS, SPECTRUM ANALYZERS, VISCOELASTICITY

Distribution Statement : APPROVED FOR PUBLIC RELEASE