Numerical and Experimental Investigation of the Design of a Piezoelectric De-Icing System for Small Rotorcraft Part 1/3: Development of a Flat Plate Numerical Model with Experimental Validation

Abstract

The objective of this research project is divided in four parts: (1) to design a piezoelectric actuator-based de-icing system integrated to a flat plate experimental setup and develop a numerical model of the system with experimental validation, (2) use the experimental setup to investigate actuator activation with frequency sweeps and transient vibration analysis, (3) add ice layer to the numerical model and predict numerically stresses for different ice breaking with experimental validation, and (4) bring the concept to a blade structure for wind tunnel testing. This paper presents the first objective of this study. First, preliminary numerical analysis was performed to gain basic guidelines for the integration of piezoelectric actuators in a simple flat plate experimental setup for vibration-based de-icing investigation. The results of these simulations allowed to optimize the positioning of the actuators on the structure and the optimal phasing of the actuators for mode activation. A numerical model of the final setup was elaborated with the piezoelectric actuators optimally positioned on the plate and meshed with piezoelectric elements. A frequency analysis was performed to predict resonant frequencies and mode shapes, and multiple direct steady-state dynamic analyses were performed to predict displacements of the flat plate when excited with the actuators. In those steady-state dynamic analysis, electrical boundary conditions were applied to the actuators to excite the vibration of the plate. The setup was fabricated faithful to the numerical model at the laboratory with piezoelectric actuator patches bonded to a steel flat plate and large solid blocks used to mimic perfect clamped boundary condition. The experimental setup was brought at the National Research Council Canada (NRC) for testing with a laser vibrometer to validate the numerical results. The experimental results validated the model when the plate is optimally excited with an average of error of 20% and a maximal error obtained of 43%. However, when the plate was not efficiently excited for a mode, the prediction of the numerical data was less accurate. This was not a concern since the numerical model was developed to design and predict optimal excitation of structures for de-icing purpose. This study allowed to develop a numerical model of a simple flat plate and understand optimal phasing of the actuators. The experimental setup designed is used in the next phase of the project to study transient vibration and frequency sweeps. The numerical model is used in the third phase of the project by adding ice layers for investigation of vibration-based de-icing, with the final objective of developing and integrating a piezoelectric actuator de-icing system to a rotorcraft blade structure.

Electromechanical Resonant Ice Protection Systems: Energetic and Power Considerations

“…It shows that clamped boundary conditions require more power for de-icing than free boundary conditions. In this study [24,26], fractures were obtained in clamped conditions with high voltage (from 300 to 600 Vpp (Peakto-peak voltage)) confirming the much higher voltage requirements of clamped conditions.…”

Experimental Study of a Piezoelectric De-Icing System Implemented to Rotorcraft Blades

“…The position of the first actuator patch is circled in red, showing that the patch overlaps two different anti-nodes. As observed in the previous study on the flat plate [17], an actuator overlapping two anti-nodes resulted in a suboptimal excitation of the resonant mode and when the structure was not optimally excited, the resulting vibration amplitude was weak, and the results of the numerical modeling were less accurate. Moreover, the power consumption increased with an increase in the frequency of excitation since power is linearly dependent on the frequency (see Equation ( 1)).…”

“…A similar ABAQUS FEA-based numerical model, as developed and validated in the previous investigations by [17,19], was developed to replicate the structure and boundary conditions of the blade-based testing setup. The blade geometry was designed to replicate as accurately as possible the experimental setup.…”

“…With a longer profile spanwise, it is believed that the blade should have higher flexibility, and vibration would be favored. Moreover, the actuators used in this study would be more fit to be anti-nodes of the first vibration modes for a longer blade, since the ideal length of an actuator corresponds to the size of the anti-node, and larger actuators diminish the efficiency of the system [17], resulting in a more efficient excitation of the structure. Finally, the very low angular speed at which the de-icing tests were performed, as well as the small radius of rotation, did not yield tangential speeds representative of the reality.…”

“…The present study represents an incremental improvement and complexification of previously presented experimental and Finite-Elements Analysis (FEA)-based numerical investigations where the principle of the proposed design method was demonstrated using a simple flat plate structure. The results of these experiments were published in [17][18][19], where a comprehensive literature study was presented, and the optimal integration and excitation of the actuators, the steady-state and transient vibration response and the stresses involved in icebreaking were extensively studied experimentally and numerically. In this new study, the developed and demonstrated concept was applied to a more complex structure, e.g., a rotating small-scale 22.9 cm (9 inches) long blade setup.…”