Shear Modulus Testing Patterns Vishay Micro-Measurements Special Purpose Sensors - Shear Modulus Testing Shear Modulus Sensors are specifically designed to accommodate the unique specimen geometries and strainfield distributions encountered when testing composite materials for shear properties. Two popular specimens for in-plane shear modulus testing of composites are the Iosipescu and compact designs. The test section for both types is described as the area between two opposing notches. The Iosipescu specimen has a distance between the notch roots of 0.45 in (11.4 mm); for the compact design this distance is 0.75 in (19 mm). Both of these specimens have an inherently nonuniform shear-strain distribution in their test zone. Determining shear modulus requires extracting an average shear-strain value from this nonuniform strain field. Since strain gages have the unique characteristic of integrating the surface strain field under their grids, average specimen strain is automatically obtained by spanning the entire length of either specimen's test section. The planar configuration, with side-by-side grids, is constructed with a standard N2 backing and Option SP61 (beryllium-copper lead ribbons and polyimide film encapsulation). The stacked configuration is produced with a special backing, A2. This backing is similar to N2 but is fully encapsulated with a polyimide film and includes integral berylliumcopper lead ribbons (like those provided by Option SP61). The stacked configuration is offered to best simulate strain measurement at a point. The stacked gages are supplied in a quarter-bridge arrangement so that independent gage measurements can be made if necessary. When connected in a half-bridge circuit, the stacked construction inherently provides temperature compensation and insensitivity to normal strains. Due to the increased stiffness of a stacked sensor, compared to one having only a single layer, an evaluation of the test conditions and requirements should be made to ensure that the gage will not compromise accuracy by significantly reinforcing low-modulus and/or thin specimens. Two 500 0.4%, 45 shear-gage configurations are available for both the Iosipescu and compact specimen designs. DIMENSIONS GAGE PATTERN AND DESIGNATION Insert Desired S-T-C No. in Spaces Marked XX. N2A-XX-C032A-500/SP61 N2P-08-C032A-500/SP61 MATRIX GAGE LENGTH OVERALL LENGTH GRID WIDTH OVERALL WIDTH Length Width 0.032 0.81 each section 0.462 0.031 0.79 each section 0.197 0.500 0.257 5.00 12.7 6.5 0.197 0.800 0.257 5.00 20.3 6.5 11.73 For use with Iosipescu specimens. N2A-XX-C032B-500/SP61 N2P-08-C032B-500/SP61 0.032 0.81 each section 0.762 19.35 0.031 0.79 each section For use with compact specimens. 3X A2A-XX-C085C-500 A2P-08-C085C-500 0.085 2.16 each section 0.445 0.070 0.200 0.500 0.260 11.30 1.78 5.08 12.7 6.6 0.745 0.070 0.200 0.805 0.260 18.92 1.78 5.08 20.4 6.6 For use with Iosipescu specimens. A2A-XX-C085D-500 A2P-08-C085D-500 0.085 2.16 each section For use with compact specimens. 3X www.vishaymg.com 106 micro-measurements@vishay.com Document Number: 11525 Revision 10-Jan-03