Shear Strength

Shear Strength:
1. Shear strength of plastic material is defined as the ability to withstand the maximum load required to shear the specimen so that the moving portion completely clears the stationary portion. Forcing a standardized punch at a specified rate through a sheet of plastics until the two portions of the specimen
completely separate carries out shear strength test.
2. Shear strength data is of great importance to a designer of film and sheet products that tends to be subjected to shear loads. Most large molded and extruded products are usually not subjected to shear loads.
SHEAR STRENGTH: The maximum load required to shear a specimen in such a manner that the resulting pieces are completely clear of each other.
Unit is lb / inch².
TEST METHOD
Test Method for shear strength of plastics by punch tool (ASTM D 732).

Shear strength is calculated as follows:

                                          Force required to shear the specimen
Shear strenggth (psi) = -----------------------------------------------------------
                                         Area of sheared edge

Area of sheared edge = (circumference of punch) x (thickness of specimen)
Calculate shear strength in MPa determined by dividing the load required to shear shear the specimen by the area of the sheared edge, which shall be taken as the product of the thickness of the specimen by the circumference of the punch.
A shear tool of the punch type, which is so, constructed that the specimen is rigidly clamped both to the stationary block and movable block so that it cannot be deflected during the test. 

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