Preliminary Report on Super Composite Beam and Split Cylinder Experiments

摘要

These experiments had two main objectives: (1) explore and demonstrate whether the bending- extension (b-e) coupling effect of graphite/ epoxy two-layered cross-ply laminate has the potential to substantially improve (e.g., reduce fundamental natural frequencies of) low-frequency, wall-driven composite projectors (such as the slotted cylinder projector), and (2) provide experimental data to confirm theoretical predictions (made with previously derived analytical solutions) on b-e coupled composite beams with simple supports. Vibration tests were conducted on the flat and curved shapes of bare- beam and actuator-beam specimens, with two-layered and near-symmetric graphite/ epoxy cross-ply laminated composites. All bare-beam specimens were tested with free vibration, whereas all actuator-beam specimens were tested with forced vibration. Additionally, all flat specimens were tested in both the simply- supported and the free-free boundary conditions, whereas all curved specimens were tested only in the free-free boundary conditions (due to the setup of the current testing fixtures for simple supports).