What shear tests exist for adhesive materials?

Shear tests for adhesive materials are of two main types:

• Tests on bulk samples of adhesive
• Tests on samples that consist of a joint, i.e. two adherends bonded together

Bulk samples can take the form of:

• Rods or beams subjected to a torsional load
• Beams containing notches - Iosipescu type sample
• Plates containing notches - Arcan method

Joint samples can take the form of:

• Butt joints made from either solid or hollow cylinders, subjected to a torsional load
• Stepped adherends bonded together - e.g. the 'thick adherend shear test' (TAST)
• Plates bonded on the edge - Arcan method

The single lap joint loaded in tension is often referred to as a 'lap-shear test'. Although this is a relatively quick and easy test, it does not give true shear data for the adhesive material, because of bending in the sample, and the generation of tensile, peeling stresses, which complicate the stress state in the bondline.

Further information

• Additional details of the various shear tests, along with their advantages, disadvantages and preferred methods, are given in the best practice guide ' Determining mechanical properties of adhesive materials'.
• Examples of shear test standards are presented in the FAQ ' What standards exist for shear testing of adhesives?'.

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