STORY: The Mechanical Engineering and Materials Science departments at the University of California Santa Barbara (UCSB) have extensive test equipment and labs at their disposal. As a graduate student, I had access to and experience with various test methods and machines, allowing me to study and rate materials not only for my research but for my projects. For one of my research projects, I needed to conduct open hole compression (OHC) tests, but our test machines were not configured to accept the fixture that is commonly used for this sort of test. Therefore, I designed and machined a slimmer, cheaper, simpler, lighter (yet equally accurate) fixture that was used for a Boeing research project. Data obtained from tests with my fixture was published in several articles and presented at several conferences.

In my research with the FAA, I will conducted several peel and shear tests to compare bond strengths. To ensure that the bonded specimens that I made were aligned properly, I designed and built a bonding jig that constrains any size panel up to about 16" x 16" while its adhesive sets up.

SPECS: UCSB's test labs include test machines and fixtures for tension, compression, torsion, 3-point bend, 4-point bend, fatigue, and other mechanical tests. For the Boeing OHC tests, the compression machine was not equipped with hydraulic grips large enough to hold the standard, thick OHC fixture. I was forced to come up with a slimmer design, limited by the size of the gap of the opened grips. I machined the new fixture out of A-2 tool steel, hardened it, and tested it thoroughly, confirming that it gave results that matched those obtained with the other fixture. Additionally, the test specimens that were used in my fixture were less than half the size of those typically used, allowing testers to cut more samples out of a panel, thereby achieving more data points (often a concern, considering the generally high cost of composite materials).

The FAA research for my dissertation concerned the strength of adhesively bonded composite joints, as used in aircraft structures. To compare bond strengths, I ran several tests with various materials and pre-bond surface preparation methods.

TECH DETAILS : Read more about my composites research.

SPONSORS: Shop facilities and research work from UCSB Mechanical & Environmental Engineering. Research grants provided by Boeing and the FAA.