Application Cases

Experiment Name: Active Deformation Experimental Verification of Scaled Morphing Wing Model

Research Direction:
This study introduces a design scheme for a scalable morphing wing model suitable for low-speed wind tunnel testing. It includes simulation results of active deformation under a 1500 V driving voltage for the scaled model after bonding with Macro Fiber Composite (MFC) actuators. This chapter applies theory to practice by conducting ground experiments where varying voltages are applied to examine the active deformation of the scaled model. These experiments serve as validation for the simulations, demonstrating the feasibility and reliability of the computational methods. Additionally, wind tunnel experiments are conducted to explore the driving performance of MFC actuators under wind loads.

Test Equipment:
Voltage amplifier, MFC actuator, laser displacement sensor, data acquisition card, computer, etc.

Figure 1: Structural Block Diagram of the Ground Experimental System

Experimental Procedure:
To validate the active deformation simulation results of the scaled model, this study designs ground experiments for the active deformation of the wing-scaled model. The ground experimental system includes both software and hardware components.

The hardware for the ground experiments includes:

• A deformable scaled wing model bonded with MFC actuators polarized at a 45° angle (including a composite resin skin).

• A voltage amplifier/driver.

• A control computer.

• A laser displacement sensor for measuring deformation at the wingtip of the scaled model.

• A multifunctional data acquisition card.

In the ground experiments, the scaled model is fixed to the experimental platform using a diamond-shaped support frame. The voltage control program is implemented using LabVIEW. After programming the digital control signal for output voltage in LabVIEW, it is converted into an analog control signal (i.e., D/A conversion) via a USB data acquisition card. The output voltage value is transmitted to the voltage amplifier/driver, which amplifies the voltage by 200 times and applies it to the piezoelectric fiber composite MFC actuators. When voltage is applied to the actuators, deformation occurs under the influence of the electric field. This deformation is transmitted through the bonding layer between the MFC actuators and the composite skin, causing deformation in the scaled wing model. The deformation in the Z-direction is recorded using a laser displacement sensor, and the corresponding twisting angle is calculated.

Experimental Results:
During the experiments, the leading edge and trailing edge points at the wingtip of the scaled model were selected as displacement measurement points. The Z-direction displacements of these two points under the driving force of the piezoelectric fiber actuators were measured to determine the twisting angle during active deformation. The voltage loading method was manual, using a stepwise approach from 0 V to 1500 V in 100 V increments. The Z-direction displacement values were measured, with data recorded 5 seconds after each loading step. Multiple measurements were taken, and the average values were used. Figure 2 compares the experimentally measured displacement values with the simulated values from the scaled model under actuator driving, adjusted using a correction factor based on the thermal analogy method.

Figure 2: Comparison of Active Deformation Simulation Results and Actual Deformation When Three Groups of MFCs Are Simultaneously Powered

As shown in the figure, the experimentally measured deformation displacement values align well with the simulation results. Therefore, the thermal analogy method with the correction factor is suitable for static displacement analysis of active deformation structures driven by piezoelectric actuators. However, at voltages above 1300 V, the experimental deformation displacement slightly exceeds the simulated values. This discrepancy may occur because, as the voltage load on the MFC approaches its critical value, the polarization of the electric field becomes more pronounced compared to lower voltages, resulting in a stronger driving effect than the linear relationship with voltage.

Figure 3: Relationship Between MFC Actuator Location and Active Deformation at the Trailing Edge of the Wngtip

Figure 3 illustrates the relationship between the location of the piezoelectric fiber actuators and the magnitude of active deformation. As shown, due to the fixed fuselage and the higher stiffness of the metal structure, the farther the MFC actuators are from the root position, the greater the active deformation they produce. This observation aligns with the simulation results.

Figure 4: Relationship Between Voltage Loading Speed and Active Deformation at the Trailing Edge of the Wingtip (Using the Middle Group as an Example)

In the experiments, the voltage loading method involved linear growth until reaching the desired voltage, after which it remained constant. Figure 4 shows the relationship between voltage loading speed and the magnitude of active deformation when linear voltages are applied at growth rates of 50 V/s, 100 V/s, and 150 V/s. As shown, the loading speed has little effect on the deformation magnitude, with minimal deviation in deformation across the three loading speeds. Therefore, in practical engineering applications, the ideal loading speed can be selected based on other factors or specific requirements.

Voltage Amplifier Recommendation: ATA-2161

Figure: ATA-2161 High-Voltage Amplifier Specifications