ASTM D2293 Creep Properties of Adhesives in Shear by Compression Loading

Scope:

When evaluated on a standard specimen and exposed to particular parameters of temperature and compressive stress in a spring-loaded testing apparatus, the ASTM D2293 test technique includes the assessment of the creep properties of adhesives for bonding metals. This test method is valuable for comparing adhesive creep properties in research and development, especially when those qualities are impacted by changes in adhesive formulation or projected service circumstances, such as temperature, moisture level, and loading time. 

Procedure:

The specimen is centered within the slot between the washer and bushing of the equipment to conduct an ASTM D2293 creep test. Tightening the nut compresses the spring between the two bushings to the appropriate load. By deflecting the spring to a certain amount, the correct load may be applied. With a calibrated microscope and a 10X objective lens, the average displacement of fine razor scratches over the centers of both sides of the lap joints is measured to determine the total deflection. If the spring force is allowed to continue compressing the specimen, the initial deflection noticed will be followed by a steadily rising deflection over time. 

These deflections are measured periodically with the calibrated microscope for as long as the ASTM D2293 test is allowed to continue or until the adhesive joint fails to provide a complete history of the creep behavior. 

Video 01: Demonstration of a creep testing machine

Specimen size:

Bonded specimens with a length of 6.35 mm (1⁄4 inches) on either side of the shear area shall be used in the ASTM D2293 test method.

Data:

As per the ASTM D2293, the total observed average deflection, the magnitude and duration of the compressive stress, and the test temperature for each specimen are recorded and reported at the end of the testing process.

Conclusion:

When evaluated on a standard specimen and exposed to particular parameters of temperature and compressive stress in a spring-loaded testing apparatus, the ASTM D2293 test technique includes the assessment of the creep properties of adhesives for bonding metals.