Active Vibration Control of Cantilever Structures by Integrating the Closed Loop Control Action into Transient Solution of Finite Element Model and an Application to Aircraft Wing

In this work, the active vibration control (AVC) of a cantilever beam with an end mass is considered first, and studied experimentally and through simulation. Laplace transform method, Newmark method, and ANSYS are used for finite element simulations. An impulse force applied to the mass and the velocity actuation applied to the base are assumed to be disturbance and controlling input, respectively. The displacement of the mass taken as the feedback signal in simulations. Four strain-gauges located near the bottom point, connected with Wheatstone bridge, and the output voltage of a load-cell amplifier (LCA) is used as the feedback signal in experiments. Strain feedback is considered in experiments because it is easy to implement, cost effective and applicable in applications. Experimental displacement signals obtained from the top of the beam are compared with the output signals from LCA and it is observed that they are approximately linearly dependent. Velocity input is generated with a servo motor driven linear actuator in experiments. The closed loop control is achieved by a personal computer with Adlink-9222 PCI DAQ card and a C program in the experiments. The integration of the closed loop control action into the transient solution with Newmark method and ANSYS is implemented in simulations. The input reference value is taken as zero for vibration control. The instantaneous value of the feedback signal at a time step is subtracted from zero to find the error signal value and the error value is multiplied by the control gain to calculate the controlling signal. The simulation results obtained with Newmark method and ANSYS are in good agreement with the analytical results obtained with Laplace transform method. Simulation results are also in acceptable agreement with experimental results for explaining the behaviour of the success of AVC depending on the control gain, Kp. After verifying ANSYS solutions, ANSYS procedure is applied to an aircraft wing as a real complex cantilever structure. The wing with a length of 810.8 mm, 13 ribs with a length of 300 mm and NACA 4412 aerofoil is considered in the study. It is observed that AVC of real engineering structures can be simulated by integrating control action into transient solution in ANSYS.