Lap Shear Strength Test of Adhesively Bonded Plastics ASTM D3163. Lap Shear Adhesion Test for Fiber Reinforced Plastics (FRP) ASTM D5868.

Lap Shear Test Scope:
Lap Shear determines the shear strength of adhesives for bonding materials when tested on a single-lap-joint specimen. The test is applicable for determining adhesive strengths, surface preparation parameters and adhesive environmental durability. There are a variety of ASTM single-lap-joint shear tests including ASTM D1002 which specifies lap shear for metal to metal, ASTM D3163 for plastics joints, and ASTM D5868 for fiber reinforced plastics (FRP) against itself or metal.

Test Procedure:
For ASTM D3163 for adhesively bonded rigid plastic, two specimens are bonded together with adhesive and cured as specified. The test specimens are placed in the grips of a universal testing machine and pulled at 1.3 mm/min (0.05 in/min) until failure. ASTM D5868, for fiber reinforced plastic, specifies a loading rate of 13 mm/min (0.5 in/min).

Specimen Size:
Two specimens, each 25.4 x 101.6 mm (1" x 4") are bonded together with adhesive so that the overlap is sufficient to provide failure in the adhesive, and not in the substrate. Typical overlaps are 12.7 mm and 25.4 mm (0.5" and 1"). Adhesives are applied as specified by the adhesive manufacturer recommendations.

Maximum, minimum and average values of failure load
Failing Stress in megapascals (pounds force per square inch)
Type of failure (cohesive, adhesive, or substrate)


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