Scope:

The ASTM D3433 test method is used to determine the fracture strength of adhesives in bonded metal junctions during cleavage. This test method determines the attribute G1c (opening mode fracture toughness), which describes a material’s resistance to slow-stable or run-arrest fracturing in a neutral environment. The ASTM D3433 is also utilized for acceptance and production quality control criteria, but only where a strong foundation for specifying minimum G1c values exists.

The test is used in research and development to determine the impacts of the adhesive composition, processing variables, and environmental effects on service performance in quantitative terms. It’s also utilized in service evaluation to see whether an adhesive system is suitable for a certain application where maximum defect sizes can be determined with certainty.

Test procedure:

The ASTM D3433 test method involves cleavage testing bonded specimens by causing a crack to extend in a direction normal to the crack surface using a tensile force. The load vs. load-displacement across the bond line is autographically recorded. Equations derived from elastic stress analysis of specimens of the type described are used to obtain the G1c and G1a values from this load. The efficacy of this test procedure for determining G1c and G1a values is contingent on the occurrence of a sharp-crack condition in the bond line in a sufficiently large specimen.

The ASTM D3433 test method evaluates the fracture strength of a bonded joint, which is decided by the adherend surface condition, adhesive, adhesive-adherend interactions, primers, adhesive-supporting scrims, and other factors.

Video 01: ASTM D3433 Double cantilever beam specimen loading clevis set

Specimen size:

Contoured double-cantilever, bonded specimens are used in the ASTM D3433 test method.

Data:

Individual G1c and G1a (fracture toughness to start to crack and fracture toughness from arrest load) values for each specimen is reported according to the ASTM D3433 test method. All three maximum, minimum, and average values for G1c, and G1a, and the nature of the failure are reported.

Conclusion:

The ASTM D3433 test method is used to determine the fracture strength of adhesives in bonded metal junctions during cleavage.