Carlos De Marqui Junior

Effect of pseudoelastic hysteresis of shape memory alloy springs on the aeroelastic behavior of a typical airfoil section

The literature on aeroelasticity includes studies on the use of smart materials as sensors and actuators in vibration control problems. Although different smart materials are available, shape memory alloys have received growing attention in aerospace applications. The hysteretic response of shape memory alloys exhibiting pseudoelasticity provides energy dissipating and damping capabilities for these materials, and therefore, the effectiveness of the pseudoelastic behavior of shape memory alloys has been investigated for passive structural vibration control. However, its effect on the aeroelastic behavior of lifting surfaces has not been covered in the literature. Hence, this article addresses the modeling and analysis of a 2-degree-of-freedom typical aeroelastic section with shape memory alloy springs introduced through the pitch degree of freedom. A state-space model is employed for the simulations of the coupled system, and a two-state approximation to Theodorsen aerodynamics is used for the determination of the aerodynamic loads. The effects of the hysteretic behavior of the shape memory alloy springs on the aeroelastic behavior of the typical section are investigated at the flutter boundary and at post-flutter regime.The literature on aeroelasticity includes studies on the use of smart materials as sensors and actuators in vibration control problems. Although different smart materials are available, shape memor...

Applied self-powered semi-passive control for a 2-degree-of-freedom aeroelastic typical section using shunted piezoelectric materials

The use of smart materials in vibration control problems, including aeroelastic response, has been investigated in several researches over the last years. Although different smart materials are available, the piezoelectric one has received great attention due to ease of use as sensors, actuators, or both. The main control techniques using piezoelectric materials are the active and passive ones. In the case of aeroelastic control, passive piezoelectric networks have a weak capability of improving the flutter stability margin. Although active systems can achieve good vibration control performance, the amount of external power and added hardware are important issues for active aeroelastic control. In this article, the self-powered semi-passive piezoelectric control of a wind tunnel model aeroelastic response is presented as an alternative to active and passive systems. Linear and nonlinear aeroelastic cases are examined using a test apparatus that allows for experiments of pitch and plunge degrees of freedom of a typical section. Piezoelectric coupling is introduced onto the plunge degree of freedom, and two different semi-passive control schemes are employed: the synchronized switch damping on short circuit and the synchronized switch damping on inductor. An autonomous and self-powered switching circuit is employed, providing a useful self-powered method of aeroelastic control.

Effect of constitutive model parameters on the aeroelastic behavior of an airfoil with shape memory alloy springs

The effects of the pseudoelastic hysteresis of shape memory alloy springs on the aeroelastic behavior of a typical airfoil section are numerically investigated for six different sets of alloy constitutive properties. A two-degree-of-freedom (namely, plunge and pitch) typical section is modeled. Shape memory alloy helical springs are considered in the pitch degree-of-freedom based on classical phenomenological models modified by the pure shear assumption. Tension–compression asymmetry and nonhomogeneous distributions of shear strain, shear stress and martensitic fraction in the cross-sectional area of the coiled shape memory alloy wire are considered. A linear model is used to determine the unsteady aerodynamic loads. Attractive alloy characteristics, which can enhance the aeroelastic behavior of the typical section at the flutter boundary and at the post-flutter regime, are identified and discussed in detail.

Aeroelastic control of non-rotating and rotating wings using the dynamic stiffness modulation principle via piezoelectric actuators

Carleton University’s Rotorcraft Research Group is working on the development of an active rotor control system that incorporates a mechanism for helicopter blade pitch dynamic stiffness modulation at the root, the Active Pitch Link. This system overcomes stroke limitations of smart material and attains superior performance for helicopter rotor-induced vibration reduction. The system was tested at the whirl tower facility and this article reports the achievements obtained with a dynamically similar hinged rotor blade model. Up to 100% reduction in the transmitted loads occurred at the target 2/rev frequency when the blade was excited by a transversal jet to mimic the asymmetric flow of the helicopter rotor in forward flight. An open-loop control algorithm optimized to a target higher-harmonic frequency of the rotor also minimized the impact on the rotor fundamental cyclic control frequency at 1/rev. In another experiment at University of São Paulo, semi-passive control techniques using shunted piezoelectric materials were investigated for the aeroelastic control of fixed wings. Flutter oscillations of a typical section were controlled out over a range of airflow speeds. Finally, the similarity between both control techniques is discussed and recognized that they are based on a dynamic stiffness modulation control principle.

Linear and nonlinear aeroelastic energy harvesting using electromagnetic induction

Transforming aeroelastic vibrations into electricity for low-power generation has received growing attention over the past couple of years. The goal is to convert wind energy into electricity for powering small electronic components employed in wireless applications such as structural health monitoring. The potential applications of interest for aeroelastic energy harvesting range from lifting components in aircraft structures to several other engineering problems involving wireless electronic components located in high wind areas. This paper investigates linear and nonlinear aeroelastic energy harvesting using electromagnetic induction. A two-dimensional airfoil with plunge and pitch degrees of freedom (DOF) is considered. The electromagnetic induction is introduced to the plunge DOF by means of a coil-magnet combination and the nonlinearities are introduced through the pitch DOF. The governing dimensionless aeroelastic equations are given with electromagnetic coupling and a resistive load in the electrical domain. The effects of several dimensionless system parameters (electromechanical coupling, load resistance, and coil inductance) on the dimensionless electrical power as well as the dimensionless linear flutter speed are investigated. After considering the linear problem, combined nonlinearities are investigated to improve the electrical output. A cubic stiffness of the hardening type is combined with the free play nonlinearity to make the resulting nonlinear oscillations bounded with acceptable amplitude over a wide range of airflow speeds. The results and the dimensionless simulations presented in this work can be employed for designing and optimizing scalable aeroelastic energy harvesters for wind energy harvesting using electromagnetic induction.© 2011 ASME

Design of an experimental flutter mount system

Aeroelastic instabilities may occur in aircraft surfaces, leading then to failure. Flutter is an aeroelastic instability that results in a self-sustained oscillatory behaviour of the structure. A two-degree-of-freedom flutter can occur with coupling of bending and torsion modes. A flexible mount system has been developed for flutter tests in wind tunnels. This apparatus must provide a well-defined 2DOF system on which rigid wings encounter flutter. Simulations and Experimental Tests are performed during the design period. The dimensions of the system are determined by Finite Element analysis and verified with an Aeroelastic Model. The system is modified until first bending and torsion modes become the first and second modes and other modes become higher than these. After this, a Modal Analysis is performed. An identification algorithm, ERA, is used to determine modes shape and frequencies from experimental data. Detailed results are presented for first bending and torsion modes, which are involved in flutter. The flutter mechanism is demonstrated by Frequency Response Functions obtained in several wind tunnel velocities until flutter achievement and by a V-g-f plot obtained from an identification process performed with an extended ERA. Mode coupling, damping behaviour and the self-sustained oscillatory behaviour are verified characterising flutter.

Energy analysis of semi-passive control for an aeroelastic plate-like wing using shunted piezoelectric materials:

The use of piezoelectric materials in vibration control problems has been widely investigated over the last years. The main control techniques using piezoelectric materials are the active and passive ones. In the particular case of aeroelastic control, passive piezoelectric networks have a weak capability of improving the flutter envelope. Although active systems can achieve good control performance, the potential large amount of power required for actuation is an important issue. The synchronized switch damping techniques were developed to overcome the drawbacks of passive and active control. These nonlinear techniques increase the electromechanical conversion and enhance the shunt damping. In this article, an energy flow analysis is employed to investigate the effects of two switch damping techniques on the aeroelastic behavior of a plate-like wing in two case studies. In the first one, the energy flow analysis is presented for the base excitation condition without aerodynamic influence. The working principle of switch damping techniques and the energy return phenomenon are discussed. In the second case, the energy flow analysis is employed to discuss the aeroelastic evolution and semi-passive control effects over a range of airflow speeds.

Adaptive locally resonant metamaterials leveraging shape memory alloys

Locally resonant metamaterials leveraging shape memory alloy (SMA) springs are explored in this work in an effort to develop adaptive metamaterial configurations that can exhibit tunable bandgap properties as well as enhanced damping capabilities. An analytical model for a locally resonant metamaterial beam in transverse vibrations is combined with an SMA model for the resonator springs to investigate and leverage the potential of temperature-induced phase transformations and stress-induced hysteretic behavior of the springs. Two case studies are presented for this new class of smart metamaterials and the resulting finite metastructures. In one case, SMA resonators operate in the linear elastic regime, first at low temperature (martensitic behavior) and then at high temperature (austenitic behavior), demonstrating how the bandgap can be tuned to a different frequency range by altering the SMA elastic modulus with temperature. In the second case, the SMA springs are kept at high temperature at all times to operate in the nonlinear regime, so that the hysteresis associated with the SMA pseudoelastic effect is manifested, yielding additional dissipation over a range of frequencies, especially for the modes right outside the bandgap.Locally resonant metamaterials leveraging shape memory alloy (SMA) springs are explored in this work in an effort to develop adaptive metamaterial configurations that can exhibit tunable bandgap properties as well as enhanced damping capabilities. An analytical model for a locally resonant metamaterial beam in transverse vibrations is combined with an SMA model for the resonator springs to investigate and leverage the potential of temperature-induced phase transformations and stress-induced hysteretic behavior of the springs. Two case studies are presented for this new class of smart metamaterials and the resulting finite metastructures. In one case, SMA resonators operate in the linear elastic regime, first at low temperature (martensitic behavior) and then at high temperature (austenitic behavior), demonstrating how the bandgap can be tuned to a different frequency range by altering the SMA elastic modulus with temperature. In the second case, the SMA springs are kept at high temperature at all times to...

Linear and Nonlinear Modeling and Experiments of a Piezoaeroelastic Energy Harvester

In this paper a piezoaeroelastically coupled lumped-parameter model for energy harvesting due to flow excitation is presented. A two-dimensional airfoil having two degree of freedom, i.e. pitch and plunge, is investigated. Piezoelectric coupling is considered for the plunge degree of freedom. Therefore an additional electrical degree of freedom is added to the problem. A load resistance is considered in the electrical domain. The unsteady aerodynamic loads are obtained from a time domain lumped vortex model. Two case studies are presented here. First the interaction of piezoelectric energy harvesting and a linear aeroelastic typical section is investigated for a set of electrical load resistances. Time domain responses for pitch and plunge as well as for the electrical outputs (voltage, current and electrical power) are presented. The linear model predictions are compared against experimental results. Later a concentrated nonlinearity (free play) is added to the pitch degree of freedom and the typical section is used to investigate LCO for piezoelectric energy harvesting.Copyright

Self-Powered Active Control for an Aeroelastic Plate-Like Wing Using Piezoelectric Material

This paper presents the self-powered active control of elastic and aeroelastic oscillations. A plate-like wing with two piezoelectric layers on the bottom surface and one piezoelectric layer on the top surface is modeled along with an electrical circuit. The direct piezoelectric effect of the bottom layer is used for mechanical to electrical energy conversion. The electrical circuit calculates the control voltage to be applied into the top piezoelectric layer that works as an actuator. The required actuation energy is fully supplied by the harvested energy. The control voltage is obtained from a Linear Quadratic Regulator (LQR) control law. Three cases are investigated. In the first one the harmonic base excitation of the cantilevered wing is considered, the suppression of flutter oscillations is investigated in the second case and the atmospheric turbulence induced vibrations problem is presented in the third case. The performance of the self-powered controller is similar to the performance of a conventional active controller with limited control voltage.© 2014 ASME