Shear Test
Flexural loading applied to a specimen with an initial crack at the mid-plane acts as the primary means for evaluating Mode II interlaminar fracture. The end notched flexure configuration utilizes a three-point bending setup to create sliding shear stresses at the crack tip. In composite packaging materials, this test determines the resistance of the interface to sliding failure.
The crack is placed at one of the outer supports where the shear force is highest.
Mechanical Response
Loading the beam causes the two halves of the notched end to slide against each other as the entire structure bends. This movement mimics the stresses a laminated board experiences when it passes through a set of nip rollers or a tight curve on a conveyor. If the end notched flexure test shows a low resistance to shear, the material might delaminate during the creasing process.
Process Optimization
Results from these measurements guide the selection of adhesive chemistry for high-barrier films. Stronger shear resistance prevents the layers from shifting during the high-pressure sealing of aseptic containers. This specific geometry remains a standard tool for research into the bonding performance of bio-based resins and recycled fibre blends where interface consistency is difficult to maintain.
