Interface Failure Analysis of Triangular Rollable and Collapsible (TRAC) Booms

Characterizing the interface bond of thin-ply composites is important for assessing the overall structural integrity. Due to the flexibility of thin composite laminates, it is not feasible to carry out mode I double cantilever beam (DCB) and mode II end notch flexure (ENF) tests, due to the large geometric changes undergone during testing. To reduce the compliance during testing, thick aluminum substrates are bonded to the two free-surfaces of the test laminates. DCB and ENF tests are specifically carried out in this configuration. A specific glass fiber plain weave interface of a 7-ply composite structure is tested. µCT imaging shows the presence of periodic voids of size scales of 200 µm, and local delaminated regions of 0 . 7 − 5 . 6 mm. The former is attributed to capillary effects from the glass tows, while the latter is due to insufficient resin flow during the two-cure manufacturing process.