Accession Number : AD0664658

Title :   DYNAMIC MEASUREMENT OF THE HARDNESS OF PLASTICS.

Descriptive Note : Technical memo.,

Corporate Author : HARVARD UNIV CAMBRIDGE MASS ACOUSTICS RESEARCH LAB

Personal Author(s) : Walking,Robert A.

Report Date : MAY 1963

Pagination or Media Count : 120

Abstract : A device is described for measuring the force-displacement relations prevailing when a small, rigid, spherical indenter slides over the plane surface of a piece of plastic material. A sinusoidally varying force, superimposed on a static bias force, is applied to the indenter by a magnetostrictive, bimetallic, laterally vibrating bar. The resulting displacement of the indenter into the material is measured by a small seismic pickup. The pickup is capable of detecting peak displacements as small as 50 angstroms at frequencies above 100 c/s, even in the presence of low-frequency displacements more than 100 times as large. The effective stiffness, defined as the ratio of the variational force to the variational displacement, was measured for a blank, seven-inch phonograph record composed of a vinyl chloride-acetate copolymer.

Descriptors :   (*PLASTICS, HARDNESS), TEST METHODS, TEST EQUIPMENT, LOADS(FORCES), PLASTIC PROPERTIES, VINYL PLASTICS, MECHANICAL PROPERTIES

Subject Categories : Plastics
      Test Facilities, Equipment and Methods
      Mechanics

Distribution Statement : APPROVED FOR PUBLIC RELEASE