ASTM D5041 Fracture strength in Cleavage of Adhesives in Bonded Joints

Scope:

The standard ASTM D5041 describes the fracture strength testing of flat adhesively bonded reinforced plastic specimens, by imposing cleavage stresses for crack propagation and specimen failure. Cleavage testing is performed by forcing a wedge into the pre-cracked extremity of the adhesive bond-line of a composite double cantilever beam specimen, under specified conditions. The wedge displaces the adherend plates on either side, as it penetrates between the plates. The energy stored as the plastic plates bend, drives the crack growth. The crack length is measured at regular intervals throughout the test duration. Fracture energy is correlated to the crack length, wedge displacement, longitudinal modulus, and thickness of plates. The test provides a good quality check of the adherend surface preparations, as it reflects the  performance of the entire bonded system and not just the adhesive. Rapid crack propagation indicates defective surface preparation. The ASTM D5401 test is also used to screen various adhesives that will be used in bonding reinforced plastic plates.

Procedure:

The ASTM D5041 test can be performed on any testing machine with a drive mechanism capable of imparting a constant and controlled velocity to a movable crosshead member. The specimen comprises two flat plates bonded by an intermediate adhesive layer. The specimen is fastened vertically onto a steel support baseplate. A stainless steel wedge with a removable tip is used to perform the cleavage. The base of the wedge is attached to the movable crosshead member of the testing machine by a threaded coupling. A notch is provided at the leading edge of the specimen, to initiate crack propagation on the sample. The wedge is driven through a specified speed and the crack propagation is measured.

Video 01: ASTM D5041 Cleavage fracture strength test fixture (SS)

Specimen size:

A typical specimen for ASTM D5041 testing would be 200 mm long and 25 mm wide with an adherend plate of approximately 2 mm thickness.

Result:

The ASTM D5041 fracture strength is reported in megapascals or gigapascals.

Conclusion:

The standard ASTM D5041 describes the fracture strength testing of flat adhesively bonded reinforced plastic specimens, by imposing cleavage stresses for crack propagation and specimen failure.