Mechanical Coupling due to Composite Structural Damage and Repair

The research described examines the relationship between damage/repair scenarios and the resulting effect on the coupled response of the structure. The monocoque is simplified as a box beam and damage is simulated by introducing a hole in one side of the tube. Repair is simulated by adding plies to an undamaged area of the beam side. Composite beam samples were manufactured and tested using a 3-axis coordinate measurement machine (CMM), to experimentally verify the computer numerical predictions of the deformed shape. The beams were loaded with a combined torsion-bending load using an eccentric tip load and rigidly fixing the opposite end. Structural coupling was observed by computing the distortion center of the beam profile at cross-sections along its length and comparing the results to the undamaged/unrepaired beam. The experimental results correlate well with the finite element simulations and generally follow the predictions of the analytical model. It is found that both torsion-bending coupling and asymmetric torsional stiffness occur for both the damaged case and after structural repair.