Strain Measurement for Materials of Low Modulus of Elasticity by Wire Strain Gage

Abstract

This paper presents a numerical and experimental analysis of the influence of wire strain gage on strain for materials with low modulus of elasticity. A numerical analysis was made using two-dimentional model and the finite element method was applied. The results were compared with those obtained by the photoelastic analysis and the bending test.
The results are as follows
(1) When the strain of materials with low modulus of elasticity is measured by the wire strain gage, the wire strain gage stiffens the base materials.
(2) This stiffning effect increases with an increasing stiffness ratio, E_g/E_m, where E_g and E_m are modulus of elasticity of the wire strain gage and the base material, respectively.
(3) For example, in the case of plastics, the strain measured by the wire strain gage is about 80% of true strain.