Sensitivity of the shear gage to normal strains

This paper documents an experimental study: that was conducted to demonstra te the sensitivity of the shear gage to the presence of normal strains. The shear gage is a specially designed strain gage rosette that measures the a verage shear strain in the test section of notched specimens such as the lo sipescu, Arcan and compact shear specimens. These specimens can have compli cated stress states with high shear and normal strain gradients. To evaluat e the sensitivity of the shear gage to normal strains, shear gages were tes ted on an Arcan specimen. The Arcan specimen is a notched specimen that can be loaded in pure shear (90 deg), pure tension (0 deg) and at intermediate 15- deg increments. The shear modulus for an aluminum specimen was determi ned at each of these loading angles. It was found that the gages display ne arly zero sensitivity to normal strains (epsilon(x), epsilon(y)). Moire int erferometry was used to document the shear and normal strain distributions in the test section and to provide an independent method for determining th e average shear strain. These results reinforce the robust nature of testin g with the shear gage.