To determine T-peel strength, the ISO 11339 test standard can be applied for product optimization.
Testing and Simulation of T-Peel Strength
Knowing the force required to progressively separate two bonded, flexible adherends gives engineers an understanding of the direct measure of the adhesive bond strength in a bonded joint.
Therefore, quantifying an adhesive’s peel resistance provides greater product insight, facilitating optimization processes, and may form part of a product qualification or specification.
The T-peel strength test determines the stress needed for a peeling mode to commence and maintain a defined rate of adhesive failure.
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Testing Procedure
The test method uses a T-type specimen to determine the relative peel resistance of adhesive bonds between flexible substrates. T-peel refers to the shape created when placing the ends of two flexible substrates into the testing machine grips.
When characterizing the average force needed to separate two bonded materials, material strength is determined at a constant speed and rate. This is then divided by the average force applied throughout the test per unit width of the bonded samples.
When performing the T-peel test on a bonded flexible-to-flexible substrate assembly, the unbonded ends of substrates are subjected to the necessary force.
There is no fixed angle between the bond line and the orientation of the applied force. Each unbonded end of the T-shaped specimen is braced in the testing machine’s grips, ensuring that it is aligned correctly to distribute force evenly across the entire width of the bond line.
The adherends are separated at a constant rate so that progressive separation occurs along the bond line.
For aluminum adherends, the test standard establishes a separation rate of 100 mm/min. The applied force is recorded against the distance of separation. The test does not stop until at least 150 mm of the adhesive bond line has been separated.
Test Parameters
Test specimens comprise two flexible sand-blasted aluminum adherends, prepared and bonded together. Specimens are either prepared individually or cut from bonded panels. The desired width is 25 mm, as stated in the ISO 11339 standard. A minimum of five specimens is recommended.
Data Provided
The T-peel strength provides the data relating to the average peel force, as well as revealing the maximum and minimum peeling forces throughout the testing of an adhesive assembly.
Tips for Modeling and Simulation
While T-peel test results do not usually act as a direct input for finite element simulation of adhesive joints, this test is useful for simulations like Cohesive Zone Modeling (CZM), either as an experimental target value for an inverse calibration method or as a parameter for model validation.
An inverse calibration method necessitates parametric simulation of the experiment and repeating the CZM parameters until the simulated results correspond with the received data.
This information has been sourced, reviewed and adapted from materials provided by Huntsman Advanced Materials.
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