ASTM D3164 Lap-Shear Sandwich Tension Testing

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ASTM D3164 Lap-Shear Sandwich Tension Testing

ASTM D3164 standard methodology for evaluating the load bearing capacity of composite materials in lap shear sandwich construction is a common industry practice.

ASTM D3164 helps users compare plastic adherends in single lap shear adhesive joint applications. The test method serves the increased need to test adhesively bonded plastics as a result of their inherent advantages over mechanically fastened joints, which includes the alleviation of stress risers and stress cracking.

What Is Lap Shear Testing?

Shear testing forces are applied parallel to the upper and lower faces of the test specimen and can be either tension or compression based. Shear test strength and stiffness results in tension mode may vary widely from compression mode. Shear tests are commonly performed on adhesives, fasteners including bolts, machine screws and rivets.

Lap shear test samples are economical, practical and easy to make. They are the most popular sample type for development, evaluation, manufacturing quality control and comparative studies used for adhesives and bonded products. They are tested in tension.

Why Perform Tests According to ASTM D3164?

ASTM D3164 can be used to produce comparative shear strength data for joints made from a number of plastics. This test can be used to provide data for R&D, engineering design, quality control, acceptance or rejection under specifications, and for other purposes.

The misuse of strength values obtained from lap shear joint as design stress allowable values for structural joints could lead to product failure, property damage, and injuries.

Test Machines for Lap Shear Tests per ASTM D3164

Given that the standard D3164 test is based on 12.7 mm (0.5 in) adherand overlap x 1 in wide specimen geometry, and assuming the maximum shear stress is 1400 psi, then the tensile load required would be 700 lbf. If purchasing a new machine, then a minimum safety factor of 3:1 would result in a need for a 2000 lb capacity load frame.