DYNAMIC MEASUREMENT OF THE HARDNESS OF PLASTICS
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.
Document Details
- Document Type
- Technical Report
- Publication Date
- May 01, 1963
- Accession Number
- AD0664658
Entities
People
- Robert A. Walking
Organizations
- Harvard University