ISSN: 1945-7553
CODEN: JTEVAB
Page Count: 11

The Linearity of Clip Gages Used in Fracture Mechanics Tests

Smith, DJ
Lecturer, University of Bristol, Bristol,

Gordon, JR
Edison Welding Institute, Columbus, OH

(Received 10 November 1988; accepted 23 June 1989)

Abstract

The measurement of displacement in fracture toughness tests is generally accomplished using clip gages. This paper describes an experimental study to examine the performance of a number of clip gages. It is shown that double cantilever clip gages exhibit a non-linear response. The degree of non-linearity is shown to vary with temperature. In relation to fracture mechanics test methods it is demonstrated that in some instances relaxation of the test standards is required to-encompass the gage performance. Where data can be stored digitally, the non-linear response can be accounted for using a third-order polynomial calibration. An analytical study shows that the non-linearity is inherent for the large displacements often incurred in fracture mechanics tests.

Keywords:
fracture mechanics, displacement transducer, clip gage, fracture toughness, crack tip opening displacement

Paper ID: JTE12447J
DOI: 10.1520/JTE12447J
ASTM International is a member of CrossRef.