micro-measurements@vishay.com
Shear Modulus Testing Patterns
Vishay Micro-Measurements
Document Number: 11525
Revision 10-Jan-03
www.vishaymg.com
106
Special Purpose Sensors - Shear Modulus Testing
Shear Modulus Sensors are specifically designed to
accommodate the unique specimen geometries and strain-
field 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.
Two 500Ω ±0.4%, ±45° shear-gage configurations are avail-
able for both the Iosipescu and compact specimen designs.
The planar configuration, with side-by-side grids, is con-
structed with a standard N2 backing and Option SP61 (beryl-
lium-copper lead ribbons and polyimide film encapsulation).
The stacked configuration is produced with a special back-
ing, A2. This backing is similar to N2 but is fully encapsu-
lated with a polyimide film and includes integral beryllium-
copper 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 nor-
mal strains. Due to the increased stiffness of a stacked sen-
sor, compared to one having only a single layer, an evalua-
tion of the test conditions and requirements should be made
to ensure that the gage will not compromise accuracy by sig-
nificantly reinforcing low-modulus and/or thin specimens.
DIMENSIONS
GAGE PATTERN
AND DESIGNATION GAGE OVERALL GRID OVERALL
Insert Desired S-T-C No. in Spaces Marked XX. LENGTH LENGTH WIDTH WIDTH Length Width
N2A-XX-C032A-500/SP61
0.032 0.462 0.031 0.197 0.500 0.257
N2P-08-C032A-500/SP61
0.81 11.73 0.79 5.00 12.7 6.5
each section each section
N2A-XX-C032B-500/SP61
0.032 0.762 0.031 0.197 0.800 0.257
N2P-08-C032B-500/SP61
0.81 19.35 0.79 5.00 20.3 6.5
each section each section
A2A-XX-C085C-500
0.085 0.445 0.070 0.200 0.500 0.260
A2P-08-C085C-500
2.16 11.30 1.78 5.08 12.7 6.6
each section
A2A-XX-C085D-500
0.085 0.745 0.070 0.200 0.805 0.260
A2P-08-C085D-500
2.16 18.92 1.78 5.08 20.4 6.6
each section
For use with Iosipescu specimens.
MATRIX
For use with compact specimens.
For use with Iosipescu specimens.
For use with compact specimens.
3X
3X
