Compressive shear testing is simply the pushing apart of a material specimen by applying compressive force from opposite sides in a parallel plane. In this way, the material is stressed in a sliding motion.
Typically it is used to test adhesive bonds and layered composites where it is the compressive equivalent of a 'tensile lap shear test'.
It is also used as a test method to determine the internal strength of a material that is designed to bear shear forces.
A compressive shear test may be single-shear, where one part is pushed down across another. Alternatively, it can be double-shear, where a bonded section is pushed out from between the sections on either side.