Lawrence G Robertson

US Patent:

8286498, Oct 16, 2012

Filed:

Aug 9, 2010

Appl. No.:

12/852562

Inventors:

Lawrence M. Robertson - Albuquerque NM, US
Emil V. Ardelean - Albuquerque NM, US
James C. Goodding - Albuquerque NM, US
Vit Babuska - Albuquerque NM, US

Assignee:

The United States of America as represented by the Secretary of the Air Force - Washington DC

International Classification:

G01N 3/08

US Classification:

73826

Abstract:

A standard tensile test device is improved to accurately measure the mechanical properties of stranded cables, ropes, and other composite structures wherein a witness is attached to the top and bottom mounting blocks holding the cable under test. The witness is comprised of two parts: a top and a bottom rod of similar diameter with the bottom rod having a smaller diameter stem on its upper end and the top rod having a hollow opening in its lower end into which the stem fits forming a witness joint. A small gap is present between the top rod and the larger diameter portion of the bottom rod. A standard extensometer is attached to the top and bottom rods of the witness spanning this small witness gap. When a force is applied to separate the mounting blocks, the gap in the witness expands the same length that the entire test specimen is stretched.