ISO 4587 Adhesive Lap-Shear Strength of Rigid-to-Rigid Bonded Assemblies

ISO 4587 adhesive lap-shear bond strength is one of the most common tests that is done on assemblies. This test determines how strong an assembly will be when it comes into contact with another object or surface. It also helps to predict where there might be a weak spot in the assembly and what the risk of failure is likely to be.

What Is ISO 4587?

ISO 4587 is used to determine the shear strength of rigid to rigid adhesives in single lap shear joint applications. These adhesives are applied to bond a variety of joints and components. Testing is important to characterize and compare the strength of different adhesives.

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 ISO 4587?

ISO 4587 is a lap shear test which is performed to determine the shear strength of an adhesive that is applied to two rigid plates and pulled to failure. It can be used to compare between adhesive types or different lots within the same adhesive. ISO 4587 is comparative in nature, and not correlated to real world performance. Different environmental conditions and joint geometries contribute to the variation of adhesive performance.

Important Considerations when Testing According to ISO 4587

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.

ISO 4587 Test Specimens

Two rigid substrates are used for ISO 4587. The specific types of substrates vary considerably frombrass, copper, aluminum, titanium, steel, plastic and composites. A single lap shear geometry consists of two identical substrates with a defined overlap section where adherend is applied.

Test Machines for Lap Shear Tests per ISO 4587

Our universal test machines serve multiple adhesive testing applications and are capable of performing all quasi static tension/compression tests, such as tensile, peel, adhesion, and flexural testing. The machine force capacity should be chosen by taking into account the highest force needed over the lifetime of the equipment. Machines feature a uniform constant rate of loading (CRL) and rate of extension (CRE), or constant velocity control mode. Force measurement complies with ISO 7500-1.

The controller needs to be set so that the specimen is controlled at a stress rate of 8.3 to 9.7 MPa (1200 to 1400 psi) of shear area per minute. The tensile force applied to the specimen translates into a shear stress applied to the area of the adhered area (0.5 square inches).

What Grips Are Required for ISO 4587?

ISO 4587 is a test performed on rigid specimens bonded via a lap joint, which causes the ends of the specimen to be offset from the load line of the test. Load string alignment is a unique gripping challenge associated with single lap shear testing. The geometry of the test specimen naturally causes the two clamped ends of the specimen to be offset. Side loading occurs if the grip selection does not account for that offset. G154 and G240G mechanical vise action grips and several models of pneumatic vise action grips have integrated offsets which allow you to manually adjust the jaw faces to the left or right. This functionality is important so that the operator can ensure that the applied force coincides with the center line of the load string.

This setup requires mechanical grips with offset jaw faces to account for this overlap to ensure a true shear force application.