Summary of Test
Shear joints impose uniform stresses across the bond area which results in the highest possible joint strength. ASTM D1002 is commonly performed to measure the shear strength of adhesives that are used to bond metals. This test is similar to ASTM D3163 which is for adhesives that bond rigid plastic substrates, and also ASTM D3164 which is for plastic adhesives that are used to bond both plastic and metal substrates. All three of these specifications use a single lap joint (lap shear) specimen to determine the shear strength of adhesives. This is a quick summary to decide if this test is right for you, and to point out what equipment you need to perform the test.
Prior to conducting ASTM D1002, it is important to read the entire specification in the relevant ASTM publication.
Recommended Equipment
Breaking load should be between 15 and 85% of machine capacity. This rule may be antiquated as there should be no trouble going to the full scale capacity of a machine. Many strong adhesives require a 10,000 pound (50kN) capacity testing machine (ADMET eXpert 2613). Most common is a 2,000 pound (10kN) testing machine (ADMET eXpert 2611).
Vise grips with serrated inserts are commonly used for lap shear tests. The serrated grip inserts are designed to dig into the material and prevent it from slipping. If slippage occurs with a vice grip, self-tightening grips of pneumatic or wedge design may be used. The grip inserts should be aligned so that the centerline of the grip assembly is aligned with the adhesive bond. Proper alignment is achieved with vice grips by adjusting the grip inserts from side to side so that the center line of the upper and lower grips pass through the adhesive.
When using wedge grips that do not have the ability to offset the centerline, spacers are needed for a proper test.
Testing Procedure
- To perform ASTM D1002, first calculate the amount of shear area in square inches or square millimeters. This will be used to calculate the speed of test and convert the force reading into a stress reading.
- Load each end of the specimen into tensile grips. Apply a force at a controlled rate to the specimen until it breaks and record the maximum force and type of joint failure. ASTM D1002 specifies a load control rate found in the test standard. A cross head control rate that approximates the loading rate and also is an acceptable mode of control.
Just Ask!
Questions about running ASTM D1002 on your system?
