Scope:

ASTM D3846 test provides in-plane shear strength evaluation of reinforced thermosetting sheet plastics with randomly oriented fiber reinforcement. ASTM D3846 involves the application of compressive load to a notched specimen of uniform width. This test is used for those materials for which enough data cannot be generated by the Short Beam Strength method in ASTM D2344

Test Procedure:

For the ASTM D3846 test, the specimen is first measured for its length, width, and thickness between the notches, and then it is placed in the fixture. Two parallel specimen slots 6.4 mm (0.250 inches) apart are fixed onto opposite faces of the test specimen. To provide a controlled location for loading, the specimen slots are kept deep enough to pass the center point of the laminate specimen. After this, bolts of the fixture are tightened applying a specific torque. The specimen is then loaded, and a speed of 1.3 mm/min (0.050 in/min) is maintained till failure is achieved. Finally, Shear Strength is calculated using the measured shear area. It is similar to ASTM D695-15 Test Method for Compressive Properties of Rigid Plastics.

Specimen size:

Test specimens are usually 12.7 mm (0.5 inches) by 79.5 mm (3.13 inches) by 2.54 to 6.6 mm (0.100 to 0.260 inches) thick.

Data:

The maximum shear load value is divided by the products of the width of the specimen and the length of the failed area to obtain the In-Plane Shear Strength in MPa (psi). 

Conclusion:

ASTM D3846 is a standard test method for in-plane shear strength of reinforced plastics.