Strain measurement from the strain gauge is partially affected by carrier and adhesive materials and their thickness. Effect of adhesive layer thickness has been addressed in this paper. Well characterized tensile experiments have been conducted using Al 6061-T6 specimens attached with strain gauges at mid length of the specimen and strain gauges are attached with different materials namely epoxy and polyurethane to understand the effect of adhesive layer thickness in strain measurement. The strain at a location has been noted for one particular adhesive layer thickness value (0.13 mm) and similar experiments have been carried out with different adhesive thickness values (0.16 mm, 0.18 mm and 0.26 mm). The results obtained from experiments have been compared with analytical results from Basic Strength of Materials approach. Good agreement is seen between the experimental and analytical results. It has been observed that the thickness of the adhesive layer plays significant role for getting accurate strain.

Metal foil strain gauges are most widely used for the stress analysis in engineering structures. Typical strain gauge system includes strain sensitive grid, carrier material, and adhesive layer. Strain measurement from the strain gauge is partially affected by carrier and adhesive materials and their thickness. In the present work, a Finite Element Model is developed in order to study the effect of both adhesive layer and carrier thickness on strain measurements while using strain gauges. To understand the behavior of the adhesive material, mechanical characterization is done on bulk adhesive specimen. Finite Element Analysis (FEA) is carried out with different materials namely epoxy and polyurethane. Initially a single element foil loop is considered for the analysis and further this is extended to metal foil strain gauge with nine end-loops. Finally, the strain variation through thickness of adhesive layer, carrier and strain sensitive grid is obtained from FEA. The results thus obtained are compared with analytical results from Basic Strength of Materials approach.