ASTM D1781 determines the peel resistance of adhesive bonds between two materials with different physical properties. For example it measures the peel resistance between:
a relatively flexible adherend and a rigid adherend
a relatively flexible facing of a sandwich structure and its core
In each case the surface adherend is relatively flexible and the backing material is very rigid. In order to peel the flexible material from the rigid backing material and accurately measure the peel strength, a special device called a climbing drum peel fixture (shown) is used. The peel fixture ensures that only “peeling” forces are applied to the flexible adherend/rigid adherend interface thus ensuring accurate measurement of peel resistance.
Honeycomb structural panels are a common adhesive assembly that requires ASTM D1781 testing. These panels provide high stiffness and strength with low weight for aerospace and industrial applications. The adhesive used for the sandwich panel construction is critical to ensure structural integrity. Testing can be complicated due to high adhesion strength and the dimensional rigidity of the core section, and the fact that the facing panels are not completely flexible.
Prior to conducting ASTM D1781, it is important to read the entire specification in the relevant ASTM publication.
The climbing drum peel fixture with sample is mounted in the test frame.
Apply a tensile load at a constant rate of crosshead separation and determine the average peeling load between 1in and 6in of adherend separation. The corresponding amount of crosshead movement is dependent on the geometry of the climbing drum peel fixture.
Calculate and report the average peel torque. To ensure compliance, please read read the entire ASTM D1781 test specification prior to testing.