• composite bonding
• creep
• digital image correlation
• structural adhesive

Structural adhesives employed in bonded joints are polymers, whose deformation and stress exhibit time and temperature rate dependence. Creep is the tendency of a solid material to slowly move or deform permanently under the influence of stress. Understanding creep behavior of adhesive materials is critical to establish the life and the durability of adhesively bonded structures.
This research aims at the experimental characterization of adhesively bonded joints creep deformation through the application of a full field measurement system.
The project can be divided in 3 parts:
1) design and manufacturing of test facilities and specimens,
2) preliminary tests to assess specimen, fixture and measurement method tests repeatability and consistency,
3) carrying out of creep tests on adhesive materials: creep properties are obtained by subjecting adhesively bonded aluminum butterfly shaped specimens to biaxial loads using an Arcan fixture and a heat chamber.

The objective is to characterize adhesive creep response in a joint configuration which is tested under a controlled stress state and at the same time is close to real joints behavior. Such data could be used for validating the analytical predictions on single lap bonded joint behavior, showing at the same time the possibility for a computational model to be comparable to the tests results. On the other hand the use of full field measurements will guarantee a deep analysis of the whole joint adhesive section, which could not have been possible with traditional mechanical measurement systems.