Shunted piezoelectric metamaterial-based UAV wing for vibration wave attenuation

Abstract

The present invention relates to a shunted piezoelectric metamaterial-based UAV wing designed for coupled flexural and torsional vibration attenuation under aerodynamic loads. The UAV wing assembly incorporates a box beam (104) embedded within an airfoil structure (102), where piezoelectric patches (106) are periodically bonded on the upper and / or bottom surfaces. Each patch is coupled to a resonant shunt circuit (108), forming shunted-piezoelectric patches that selectively attenuate vibrations across the range of frequencies. The periodic arrangement of these patches along the elastic axis introduces Bragg and local bandgaps, enabling high-frequency and low-frequency ranges of vibration attenuation. The resonance frequency of shunt circuits is tunable through inductance adjustments, optimizing local bandgap performance for different aerodynamic conditions. The interaction between the shunted metamaterial wing and aerodynamic loads forms a new aeroelastic bandgap in a very low-frequency range, and further broadens the Bragg and local bandwidth for wider frequency ranges of vibration suppression. The attenuation performance of these bandgaps improves with increasing airflow velocity. This innovation provides a lightweight, energy-efficient, and adaptive solution for improving structural integrity, flight performance and endurance.

Description

SHUNTED PIEZOELECTRIC METAMATERIAL-BASED UAV WING FOR VIBRATION WAVE ATTENUATION FIELD OF INVENTION

[0001] The present invention relates to an unmanned aerial vehicle (UAV) wing integrated with piezoelectric metamaterials and resonant shunt circuits. More specifically, the present invention provides shunted piezoelectric metamaterial -based UAV wing structure designed to attenuate coupled flexural -torsional vibrations under aerodynamic loads by forming bandgaps.BACKGROUND OF THE INVENTION

[0002] Unmanned Aerial Vehicles (UAVs) have gained widespread adoption in military, industrial, and commercial applications, performing critical tasks such as surveillance, mapping, environmental sensing, and reconnaissance. Despite advancements in UAV technology, one of the primary challenges remains limited flight endurance, which is largely constrained by the power supply provided by onboard batteries. To enhance flight endurance, UAVs are designed with lightweight airframes that minimize power consumption while maintaining structural robustness.

[0003] To achieve weight reduction, UAV wings often incorporate flexible structures that provide durability and adaptability to aerodynamic forces. However, these flexible wing structures are highly susceptible to vibrations caused by external and internal disturbances, including weather turbulence, bearing faults, maneuvering, wind shear, and landing-induced shocks. These vibrations generate flexural and torsional wave propagations, which can significantly impact structural integrity, flight endurance and performance, and control accuracy.

[0004] To mitigate these effects, researchers have explored both active and passive vibration control techniques. Active control methods utilize sensors, actuators, and control systems to actively suppress vibrations. While effective, these systems require additional power sources, increasing UAV weight and power consumption, which contradicts the goal of lightweight design and extended endurance. Passive techniques, on the other hand, rely on advanced composite materials and structural modifications to absorb and dampen vibrations. While passive methods need no additional energy, are cost-effective and simple in design, andprovide inherent stability, they are often ineffective at attenuating low-frequency vibrations, which are particularly detrimental to UAV performance.

[0005] Recent advancements in metamaterials have demonstrated their potential for attenuating low-frequency and high-frequency vibrations without requiring external power sources. Metamaterials are artificially engineered structures designed to exhibit properties that do not naturally occur in conventional materials, with applications initially developed in optics and later extended to elastic wave control. These materials create bandgaps that block or attenuate specific vibration frequencies, making them highly effective for vibration and wave mitigation in aerospace structures.

[0006] Therefore, there exists a need in the art for providing a piezoelectric metamaterial UAV wing integrated with passive shunt circuits to address the limitations of conventional passive methods while avoiding the drawbacks of active control techniques. This approach leverages the piezoelectric metamaterial effect to passively attenuate both low-frequency and high-frequency vibrations without adding significant weight or requiring external power.OBJECTS OF THE INVENTION

[0007] An object of the invention is to attenuate coupled flexural and torsional vibrations in UAV wings across both low-frequency and high-frequency ranges using a shunted piezoelectric metamaterial approach which improves structural reliability, flight performance and endurance.

[0008] Another object of the invention is to utilize shunted piezoelectric metamaterials for creating the local and Bragg bandgaps which effectively attenuates the desired vibration and wave propagation across wider frequency ranges.

[0009] Another object of the invention is to attenuate coupled flexural -torsional vibrations in the very low-frequency range by forming an aeroelastic bandgap, where local and Bragg bandgaps are difficult to achieve, which arises from the interaction between the piezoelectric metamaterial wing and aerodynamic loads.

[0010] Another object of the invention is to eliminate the need for external power sources which makes the vibration attenuation system cost-effective, and self-sustaining.

[0011] Another object of the invention is to minimize additional mass while enhancing vibration control, ensuring that UAV endurance and maneuverability are not compromised.

[0012] Another object of the invention is to enhance the flight endurance of UAVs by reducing unwanted structural vibrations which improves energy efficiency and control accuracy.

[0013] Another object of the invention is to provide a lightweight, passive vibration control solution that surpasses conventional passive methods by effectively targeting the wide range of low-frequency vibrations.

[0014] Another object of the invention is to offer an innovative, scalable, and adaptable solution for UAVs in various aerospace and defense applications which improves operational reliability and efficiency.SUMMARY OF THE INVENTION

[0015] The summary is provided to introduce aspects related to a shunted piezoelectric metamaterial-based UAV wing for attenuating coupled flexural and torsional vibrations under aerodynamic loads. This summary is not intended to identify essential features of the claimed subject matter nor is it intended for use in determining or limiting the scope of the claimed subject matter.

[0016] In one embodiment, the present invention provides a device for attenuating coupled flexural-torsional vibration in an Unmanned Aerial Vehicle (UAV) wing under aerodynamic loads, comprising: a box beam embedded in an airfoil structure of a wing assembly, wherein box beam comprises: two or more piezoelectric patches, wherein each piezoelectric patch is periodically bounded on bottom surface or upper surface or both of them inside the box beam; and a resonant shunt circuit coupled to each of the piezoelectric patch to form a shunted piezoelectric patch, wherein the two or more shunted-piezoelectric patches are periodically attached along the elastic axis of the wing assembly, wherein the resonance frequency of each of the shunted-piezoelectric patches is adjusted according to desired frequencies of vibration attenuation, to trap and dissipate energy from the vibrations at the wing assembly.

[0017] In an embodiment, the wing assembly with periodically placement of minimum of twoor more shunted-piezoelectric patches provides a shunted piezoelectric metamaterial wing.

[0018] In a further embodiment, the resonant shunt circuits act as bending resonators to attenuate flexural vibrations at their resonance frequency.

[0019] In a further embodiment, the interaction between the shunted piezoelectric metamaterial wing and aerodynamic loads results in the attenuation of both flexural and torsional vibrations simultaneously.

[0020] In a further embodiment, the resonant shunt circuits are tuneable by adjusting inductance of shunt circuits to selectively attenuate the coupled flexural and torsional vibrations at a specific frequency range.

[0021] In a further embodiment, the periodic placement of shunted-piezoelectric patches along with the wing assembly creates Bragg bandgaps for attenuating the high-frequency vibration and a local bandgap for attenuating the desired low-frequency vibrations.

[0022] In a further embodiment, a piezoelectric metamaterial wing interacted with aerodynamic loads introduces a new aeroelastic bandgap for attenuating very low-frequency vibrations.

[0023] In a further embodiment, the bandwidth of Bragg bandgaps and the local bandgap is broadened due to interaction of metamaterial wing with aerodynamic loads.

[0024] In a further embodiment, the attenuation performance of aeroelastic, Bragg and local bandgaps is proportional to the airflow velocity over the wing.

[0025] In another embodiment, the present invention provides a method for attenuating coupled flexural -torsional vibrations in an Unmanned Aerial Vehicle (UAV) wing under aerodynamic loads, comprising: providing a box beam embedded in an airfoil structure of a wing assembly, wherein a box beam comprising two or more piezoelectric patches periodically bounded on bottom surface or upper surface or both of them inside the box beam to form the piezoelectric metamaterial wing, and a resonant shunt circuit coupled to each of the piezoelectric patch to form a shunted piezoelectric patch, wherein the two or more shunted-piezoelectric patches are periodically attached along the elastic axis of the wing assembly; and adjusting the resonance frequency of each of the two or more shunted-piezoelectric patches tomatch the desired frequencies of vibration attenuation, to trap and dissipate energy from the vibrations at the wing assembly.

[0026] In an embodiment, the wing assembly with periodically placement of minimum of two or more shunted-piezoelectric patches provides a shunted piezoelectric metamaterial wing.

[0027] In one aspect, the method comprises attenuating flexural vibrations by the resonant shunt circuit which acts as a bending resonator.

[0028] In another aspect, the method comprises attenuating both flexural and torsional vibrations by interaction between the shunted piezoelectric metamaterial wing and aerodynamic loads.

[0029] In another aspect, the method comprises adjusting the inductance of shunt circuits to selectively attenuate the vibrations at a specific frequency range.

[0030] In an embodiment, the periodic placement of shunted-piezoelectric patches along with the wing assembly creates Bragg bandgaps for high-frequency vibration attenuation and a local bandgap for attenuating the desired low-frequency vibrations.

[0031] In a further embodiment, a piezoelectric metamaterial wing interacting with aerodynamic loads introduces a new aeroelastic bandgap for attenuating very low-frequency vibrations.

[0032] In a further embodiment, the bandwidth of Bragg bandgaps and the local bandgap is broadened due to interaction of metamaterial wing with aerodynamic loads.

[0033] In a further embodiment, the attenuation performance of aeroelastic, Bragg and local bandgaps is proportional to airflow velocity over the wing.

[0034] Other aspects and advantages of the invention will become apparent from the following description, taken in conjunction with the accompanying drawings, illustrating by way of example the principles of the invention.BRIEF DESCRIPTION OF THE DRAWINGS

[0035] The accompanying drawings constitute a part of the description and are used to provide further understanding of the present invention. Such accompanying drawings illustrate the embodiments of the present invention which are used to describe the principles of the present invention. The embodiments are illustrated by way of example and not by way of limitation in the figures of the accompanying drawings in which like references indicate similar elements. It should be noted that references to “an” or “one” embodiment in this invention are not necessarily made to the same embodiment, and they mean at least one. In the accompanying drawings:

[0036] Figure 1 illustrates a metamaterial wing structure of a UAV in accordance with an embodiment of the present invention.

[0037] Figure 2 illustrates a box beam within the airfoil structure of the UAV metamaterial wing in accordance with an embodiment of the present invention.

[0038] Figure 3 depicts a graphical representation of bandgaps for coupled flexural -torsional vibrations in an UAV metamaterial wing under aerodynamic loads in accordance with an embodiment of the present invention.

[0039] Fig.4 illustrates a flowchart providing a brief overview of the UAV metamaterial wing and its bandgap formation for attenuating the coupled flexural -torsional vibrations in accordance with an embodiment of the present invention.

[0040] A more complete understanding of the present invention and its embodiments thereof may be acquired by referring to the following description and the accompanying drawings.DETAILED DESCRIPTION OF THE INVENTION

[0041] The detailed description set forth below in connection with the appended drawings is intended as a description of various embodiments of the present invention and is not intended to represent the only embodiments in which the present invention may be practiced. Each embodiment described in this invention is provided merely as an example or illustration of the present invention, and should not necessarily be construed as preferred or advantageous over other embodiments. The detailed description includes specific details for the purpose ofproviding a thorough understanding of the present invention. However, it will be apparent to those skilled in the art that the present invention may be practiced without these specific details.

[0042] Approximating language, as used herein throughout the specification and claims, may be applied to modify any quantitative representation that could permissibly vary without resulting in a change in the basic function to which it is related. Accordingly, a value modified by a term or terms, such as “less than,” “approximately” etc. is not limited to the precise value specified. In some instances, the approximating language may correspond to the precision of an instrument for measuring the value.

[0043] The present invention discloses a UAV wing with shunted piezoelectric metamaterials for attenuating the coupled flexural and torsional vibrations under aerodynamic loads. The interaction of aerodynamic loads with piezoelectric metamaterial wing creates a new bandgap (aeroelastic bandgap) for attenuating the very low-frequency vibrations along with the Bragg and local bandgaps due to shunted piezoelectric patches. Further, the aeroelastic bandgap is actively tuned with airflow or UAV velocities. In general, the present invention shows that the multiple and tunable bandgap formations can be achieved due to the combined effect of aerodynamic flow and piezoelectric metamaterial to efficiently attenuate the coupled flexural and torsional vibrations in UAV wings. The UAV wing described in the present invention provides the piezoelectric metamaterial wing without significant increase in the overall weight of wings, develop the transfer matrix formulation for vibration and wave propagation analysis that includes aerodynamic effects, and explore the new bandgap formations, due to interaction of piezoelectric metamaterials with aerodynamic flow, for attenuating coupled flexural and torsional vibrations in a UAV wing.

[0044] In accordance with an embodiment of the present invention, Figure 1 illustrates an airfoil structure (102) of a UAV wing (100). This embodiment provides insights into the structural design of the UAV wing. The UAV wing assembly comprises an airfoil structure (102) with an embedded box beam (104). The box beam (104) provides structural integrity and houses periodically two or more piezoelectric (piezo) patches (106). The box beam (104) is designed as a closed-section structure, typically composed of lightweight composite materials such as carbon fiber or aluminum alloys. It consists of four walls — top, bottom, front, and rear — which together form a hollow, stiffened structure. This configuration enhances the wing’s resistance to both bending and torsional loads, making it particularly effective for high-performance UAV applications where weight reduction and structural integrity are critical.

[0045] The two or more piezoelectric patches (106) are thin, flat layers of piezoelectric material bonded onto the internal surfaces of the box beam (104). Specifically, each piezoelectric patch (106) is periodically bounded on bottom surface or upper surface or both of them inside the enclosed section of the box beam (104). The two or more piezoelectric patches (106) convert mechanical strain energy into electrical energy via the direct piezoelectric effect. Each piezoelectric patch (106) exhibits inherent capacitance, denoted as Cp, which enables energy storage in the form of electrical charge on its surfaces. The placement of the two or more piezoelectric patches (106) is periodic along the elastic axis of the wing assembly within the box beam (104). The periodically placement of two or more piezoelectric patches (106) is crucial for achieving vibration attenuation across wider frequency ranges through the formation of bandgaps.

[0046] Each piezoelectric patch (106) is coupled to a resonant shunt circuit (108), forming a shunted piezoelectric patch. The resonant shunt circuit consists of a resistor-inductor (RL) network that connects with the inherent capacitance of the patch to attenuate the desired frequency ranges of vibrations. The resonant shunt circuits (108) act as bending resonators to attenuate flexural vibrations at their resonance frequency. The resonant shunt circuits (108) are tuneable by adjusting inductance of the resonant shunt circuit to selectively attenuate the vibrations at a specific frequency range.

[0047] The two or more shunted-piezoelectric patches are periodically attached along the elastic axis of the wing assembly. The wing assembly with periodically placement of minimum of two or more shunted-piezoelectric patches provides a shunted piezoelectric metamaterial wing that creates bandgaps for attenuating the vibrations across desired frequency ranges. The interaction between the shunted piezoelectric metamaterial wing and aerodynamic loads results in the attenuation of both low-frequency and high frequency vibrations.

[0048] The resonance frequency of each of the shunted-piezoelectric patches is adjusted according to desired frequencies of vibrations attenuation, to trap and dissipate energy from the vibrations at the wing assembly. Also, the periodic placement of the two or more shunted-piezoelectric patches along with the wing assembly creates Bragg bandgaps for attenuating the high-frequency vibration and a local bandgap for attenuating the desired low-frequency vibrations.

[0049] Figure 2 illustrates a box beam (204) structure within the disclosed UAV wing, showing the placement and configuration of the two or more piezoelectric patches (206) and resonant shunt circuits (208) as described in the present invention. The figure 2 depicts a structural element of the box beam (204) embedded within the wing's airfoil (as shown in Figure 1). The box beam’s (204) cross-sectional shape provides high stiffness and strength, essential for wing integrity.

[0050] The figure 2 shows the two or more piezoelectric patches (206) bonded onto the internal surfaces of the box beam (204). Specifically, each piezoelectric patch (206) is periodically bounded on bottom surface or upper surface or both of them inside the enclosed section of the box beam (204). As depicted in Figure 2, the two or more piezoelectric patches (206) is on the bottom surface. The length of a single unit cell (ZMC) is a repeating segment along the span of the box beam (204). The said unit cell contains a piezoelectric patch (206) and a resonant shunt circuit (208), and its periodic arrangement creates bandgaps that help in vibration attenuation for wider frequency ranges. The length (Zp) of the piezoelectric patch (206) is mounted inside the box beam (204). In Figure 2, Ziu,and twindicates the width, depth, and thickness of the box beam (204) cross-section, respectively. The ithand (i+l)threpresent the current unit cell and the next unit cell in the periodic arrangement along the beam’s span. The zj (z,3) axis represents the vertical direction in the coordinate system and used to define displacement or position of components such as piezoelectric patches, and overall beam geometry. The xi (x,l) axis represents the spanwise direction along which the unit cells are periodically arranged and this is the primary axis along which the vibration control system is structured. They? (y,2) axis represents the chordwise direction, perpendicular to both xi (spanwise) and zj (vertical) and used for defining cross-sectional properties of the wing. The tprepresents the placement thickness of two or more piezoelectric patches (206) inside the box beam (204). wprepresents the width of the piezoelectric patch (206) along the beam cross-section.

[0051] In the present invention, the wing length (Lw), box beam width (bw) and depth (dw) define the geometry and modular design of the wing structure. The periodic arrangement of unit cells (i'hand (i+l)th)' along xi ensures the formation of bandgaps for vibration suppression across wider frequency ranges. The piezoelectric patch dimensions (wp, lp, tp) influence the tuning capability of bandgap characteristics. The coordinate system (xi, y2, z ) is essential for defining the geometry and displacement of piezoelectric metamaterial wing for analyzing the flexural and torsional vibrations.

[0052] Each piezoelectric patch (206) is connected to a resonant shunt circuit (208), represented by the symbol Zsuin the Figure 2. The resonant shunt circuit (208) is a passive electrical circuit for vibration attenuation without the requirement of external electrical energy. The direct piezoelectric effect converts the mechanical vibrations into electrical energy. The piezoelectric patch (206) has inherent capacitance (Cp) that can store the electrical energy as charges on the patch surfaces. The electrical charges are dissipated through resonant shunt circuits (208). The resonant shunt circuit is resistor-inductor (RL) circuit with the inherent capacitor of the piezoelectric patch. The effect of resonant shunt circuit can be seen as equivalent to that of tuned vibration absorber.

[0053] The resonant shunt circuit (208) coupled to each of the piezoelectric patch (206) to form a shunted piezoelectric patch, wherein the two or more shunted-piezoelectric patches are periodically attached along the elastic axis of the wing assembly. The piezoelectric shunt circuits act as bending resonators only for attenuating the flexural vibrations at their resonance frequency. However, torsional vibrations are also attenuated due to the interaction between the shunted piezoelectric metamaterial wing and aerodynamic loads. The resonance of an electrical circuit can be tuned at any disturbance frequency by changing the circuit inductance. Therefore, a resonant shunt circuit (208) can attenuate the vibration waves at its resonance frequency.

[0054] The resonant shunt circuit comprises an inductor and a resistor, forming an RL circuit. The inherent capacitance of the piezoelectric patch (206) itself acts as the capacitor in the RLC circuit. The figure 2 indicates that the two or more shunted piezoelectric patches are periodically attached along the elastic axis of the wing assembly.

[0055] When the UAV wing experiences vibrations (flexural or torsional), the box beam (204) structure deforms. This deformation induces strain in the two or more piezoelectric patches (206) bonded to its interior surfaces. Due to the direct piezoelectric effect, the strain in the piezoelectric patches (206) generates an electrical charge. This charge is proportional to the mechanical stress experienced by the patch. The generated electrical charge flows through the resonant shunt circuit (208) connected to the patch. The resonant shunt circuit is tuned (by adjusting the inductance) to resonate at a specific frequency. When the vibration frequency matches the resonance frequency of the shunt circuit, maximum energy is transferred from the vibrating patch to the circuit. The energy dissipated in the resistive element of the resonant shunt circuit is converted into heat, effectively damping the vibrations of the wing. This process is passive, requiring no external power source. The periodic arrangement of the two or moreshunted piezoelectric patches along the box beam (204) creates a metamaterial structure. This periodicity leads to the formation of bandgaps as discussed in Figure 3, which are frequency ranges where vibration and wave propagation is attenuated.

[0056] Figure 3 illustrates a graphical representation of bandgaps of the disclosed piezoelectric metamaterial wing as a function of frequency. It visually demonstrates the characteristics (such as bandgap position, bandwidth and attenuation performance) of bandgaps, which are frequency ranges where vibrations are significantly attenuated.

[0057] The graph of Figure 3 represents the bandgaps for coupled flexural -torsional vibration in the UAV wing under aerodynamic loads. Due to the periodic structure of the piezoelectric metamaterial wing (as detailed in Figure 2), desired frequency ranges emerge where vibration propagation is prohibited or strongly attenuated. These are the bandgaps. Within the highlighted bandgap regions in Figure 3, the attenuation level (min|a|) is significantly higher, indicating that vibrations within these frequency ranges are effectively suppressed. A higher peak within a bandgap corresponds to higher vibration attenuation.

[0058] The formation of different types of bandgaps are Aeroelastic Bandgap, Local Bandgap and Bragg Bandgaps are shown in figure 3. Aeroelastic Bandgap attenuates very low-frequency vibrations (e.g., below 50 Hz) and is created when a piezoelectric metamaterial wing interacts with aerodynamic loads. It’s particularly important for attenuating very low-frequency vibrations that can arise from gusts or changes in flight conditions. As airflow velocity increases, the attenuation performance of aeroelastic bandgap improves, leading to faster vibration attenuation. Further, the periodic placement of two or more shunted-piezoelectric patches along with the wing assembly creates Bragg bandgaps for attenuating the high-frequency vibration and a local bandgap for attenuating the desired low-frequency vibrations. The existence of multiple Bragg bandgaps (e.g., around 600 Hz and 2400 Hz) ensures suppression of high-frequency structural vibrations. The local bandgap (e.g., approximately 1500 Hz) effectively suppresses desired low frequency vibrations.

[0059] The interaction of metamaterial wings with aerodynamic loads can broaden the bandwidth of the Bragg bandgaps and local bandgap, making them effective over a wider frequency range. The attenuation performance of aeroelastic, Bragg and local bandgaps is proportional to the airflow velocity over the wing. The position, bandwidth and attenuationperformance of bandgaps, particularly the local bandgap, can be tuned by adjusting the electrical components (inductance and resistance) of electrical shunt circuits. This allows the vibration attenuation system to be optimized for specific vibration frequency ranges.

[0060] The width of the bandgap determines the range of frequencies attenuated, and the peak indicates the level of attenuation. For effective vibration suppression, the bandgaps need to be designed (by proper selection of unit cell length, piezoelectric material, patch geometry, and circuit parameters) to match the frequencies of the vibrations that need to be suppressed. The aerodynamic loads on the wing significantly influence the bandgap characteristics, as shown in Figure 3, by the presence of the aeroelastic bandgap and the broadening of other bandgaps (local and Bragg). The shunted piezoelectric metamaterial approach enhances the UAV wing’s performance and endurance, reducing the structural vibrations without additional mass or external energy. The tunable nature of the resonant shunt circuits (108) allows the vibration suppression characteristics to be adapted to different flight conditions.

[0061] Figure 4 illustrates a flowchart 400 for attenuating coupled flexural and torsional vibration in an Unmanned Aerial Vehicle (UAV) wing under aerodynamic loads, in accordance with an embodiment of the present invention. In this regard, each block may represent a module, segment, or portion of code, which comprises one or more executable instructions for implementing the specified logical function(s). It should also be noted that in some alternative implementations, the functions noted in the blocks may occur out of the order noted in the drawings. For example, two blocks shown in succession in Figure 4 may in fact be executed substantially concurrently or the blocks may sometimes be executed in the reverse order, depending upon the functionality involved. Any process descriptions or blocks in flow charts should be understood as representing modules, segments, or portions of code which include one or more executable instructions for implementing specific logical functions or steps in the process, and alternate implementations are included within the scope of the example embodiments in which functions may be executed out of order from that shown or discussed, including substantially concurrently or in reverse order, depending on the functionality involved. In addition, the process descriptions or blocks in flow charts should be understood as representing decisions made by a hardware structure such as a state machine.

[0062] At step 402, a box beam (104) is embedded within the airfoil structure (102) of a UAV wing assembly. This box beam comprises two or more piezoelectric patches (106) periodicallybounded on bottom surface or upper surface or both of them inside the box beam (104) to form the piezoelectric metamaterial wing. A resonant shunt circuit coupled to each of the piezoelectric patch (108) to form a shunted piezoelectric patch. The two or more shunted-piezoelectric patches are periodically attached along the elastic axis of the wing assembly. This configuration transforms the wing into a piezoelectric metamaterial wing, enhancing its capability to mitigate coupled flexural and torsional vibrations.

[0063] At step 404, The wing assembly with periodically placement of minimum of two or more shunted-piezoelectric patches forms a shunted piezoelectric metamaterial wing, creating bandgaps that effectively attenuate vibrations across low-frequency and high-frequency frequency ranges. The interaction of metamaterial wing with aerodynamic loads attenuates the very low-frequency vibrations by forming the aeroelastic bandgap. The resonance frequency of each shunted-piezoelectric patch is adjusted to match desired frequency of vibration attenuation. By tuning the resonance frequency, the system effectively traps and dissipates energy from the vibrations at the wing assembly.

[0064] Additionally, the method comprises attenuating flexural vibrations through the resonant shunt circuit, which acts as a bending resonator. Furthermore, it includes attenuating both flexural and torsional vibrations simultaneously through the interaction between the shunted piezoelectric metamaterial wing and aerodynamic loads. Another aspect of the method includes adjusting the inductance of the resonant shunt circuit to selectively attenuate vibrations within a specific frequency range. The periodic placement of shunted-piezoelectric patches along the wing assembly creates Bragg bandgaps for high-frequency vibration attenuation and a local bandgap for desired low-frequency vibration attenuation. The method further specifies that a piezoelectric metamaterial wing interacting with aerodynamic loads introduces a new aeroelastic bandgap for attenuating very low-frequency vibrations. Additionally, the bandwidth of Bragg bandgaps and the local bandgap is broadened due to the interaction of the metamaterial wing with aerodynamic loads. Finally, the attenuation performance of aeroelastic, Bragg, and local bandgaps is proportional to the airflow velocity over the wing, enhancing the overall vibration attenuation efficiency of the UAV wing structure.

[0065] This method ensures improved vibration suppression in UAV wings, contributing to increased fatigue life, and enhanced flight performance and endurance. The effectiveness of vibration attenuation is further influenced by airflow velocity, making it adaptable for varying flight conditions.

[0066] One of the technical advantages of the present application is that it attenuates desired low frequency and high-frequency vibrations through a shunted piezoelectric metamaterial approach, combining the benefits of both conventional passive and active methods, i.e., it does not rely on external energy, making it cost-effective and without significant mass addition. The piezoelectric metamaterial creates bandgaps that effectively attenuate the coupled flexural-torsional vibrations across the broader frequency ranges. Also, the present invention simultaneously enhances the flight endurance and performance of UAVs.

[0067] The terms “or” and “and / or” as used herein are to be interpreted as inclusive or meaning any one or any combination. Therefore, “A, B or C” or “A, B and / or C” may mean “any of the following: A; B; C; A and B; A and C; B and C; A, B and C.” An exception to this definition will occur only when a combination of elements, functions, steps or acts are in some way inherently mutually exclusive.

[0068] Any combination of the above features and functionalities may be used in accordance with one or more embodiments. In the foregoing specification, embodiments have been described with reference to numerous specific details that may vary from implementation to implementation. The specification and drawings are, accordingly, to be regarded in an illustrative rather than a restrictive sense. The sole and exclusive indicator of the scope of the invention, and what is intended by the applicants to be the scope of the invention, is the literal and equivalent scope of the set as claimed in claims that issue from this application, in the specific form in which such claims issue, including any subsequent correction.

Claims

WE CLAIM:

1. A device for attenuating vibration and wave propagation across desired frequency ranges in an Unmanned Aerial Vehicle (UAV) wing (100) under aerodynamic loads, comprising:a box beam (104) embedded in an airfoil structure (102) of a wing assembly, wherein box beam (104, 204) comprises:two or more piezoelectric patches (106, 206), wherein each piezoelectric patch (106, 206) is periodically bounded on bottom surface or upper surface or both of them inside the box beam (104, 204); anda resonant shunt circuit (108) coupled to each of the piezoelectric patch (106, 206) to form a shunted piezoelectric patch, wherein the two or more shunted- piezoelectric patches are periodically attached along the elastic axis of the wing assembly,wherein the resonance frequency of each of the shunted-piezoelectric patches is adjusted according to desired frequency range of vibrations attenuation, to trap and dissipate energy from the vibrations at the wing assembly.

2. The device as claimed in claim 1, wherein the wing assembly with periodically placement of minimum of two or more shunted-piezoelectric patches provides a shunted piezoelectric metamaterial wing.

3. The device as claimed in claim 1, wherein the resonant shunt circuits act as bending resonators to attenuate flexural vibrations at their resonance frequency.

4. The device as claimed in claim 1, wherein the interaction between the shunted piezoelectric metamaterial wing and aerodynamic loads results in the attenuation of both flexural and torsional vibrations simultaneously.

5. The device as claimed in claim 1, wherein the resonant shunt circuits are tuneable by adjusting inductance of the shunt circuit to selectively attenuate the coupled flexural and torsional vibrations at a specific frequency range.

6. The device as claimed in claim 2, wherein the periodic placement of shunted-piezoelectric patches along with the wing assembly creates Bragg bandgaps for attenuating the high-frequency vibration and a local bandgap for attenuating the desired low-frequency vibrations.

7. The device as claimed in claim 1, wherein a piezoelectric metamaterial wing interacted with aerodynamic loads introduces a new aeroelastic bandgap for attenuating vibrations in a very low-frequency range.

8. The device as claimed in claim 6, wherein the bandwidth of Bragg bandgaps and the local bandgap is broadened due to interaction of metamaterial wing with aerodynamic loads.

9. The device as claimed in claims 7 and 8, wherein the attenuation performance of aeroelastic, Bragg and local bandgaps is proportional to the airflow velocity over the wing.

10. A method (400) for attenuating vibrations and wave propagations across desired frequency ranges in an Unmanned Aerial Vehicle (UAV) wing under aerodynamic loads, comprising:providing (402) a box beam (104, 204) embedded in an airfoil structure (102) of a wing assembly, wherein a box beam (104, 204) comprising two or more piezoelectric patches (106, 206) periodically bounded on bottom surface or upper surface or both of them inside the box beam (104, 204) to form the piezoelectric metamaterial wing, and a resonant shunt circuit (108, 208) coupled to each of the piezoelectric patch (106, 206) to form a shunted piezoelectric patch, wherein the two or more shunted-piezoelectric patches are periodically attached along the elastic axis of the wing assembly; andadjusting (404) the resonance frequency of each of the shunted-piezoelectric patches to match the desired frequency range of vibration attenuation, to trap and dissipate energy from the vibrations at the wing assembly.

11. The method as claimed in claim 10, wherein the wing assembly with periodically placement of minimum of two or more shunted-piezoelectric patches provides a shunted piezoelectric metamaterial wing.

12. The method as claimed in claim 10, comprising:attenuating flexural vibrations by the resonant shunt circuit which acts as a bending resonator.

13. The method as claimed in claim 10, comprising:attenuating both flexural and torsional vibrations simultaneously through the interaction between the shunted piezoelectric metamaterial wing and aerodynamic loads.

14. The method as claimed in claim 10, comprising:adjusting inductance of the shunt circuit to selectively attenuate the coupled flexural and torsional vibrations at a specific frequency range.

15. The method as claimed in claim 11, wherein the periodic placement of shunted-piezoelectric patches along with the wing assembly creates Bragg bandgaps for high-frequency vibration attenuation and a local bandgap for attenuating the desired low-frequency vibrations.

16. The method as claimed in claim 10, wherein a piezoelectric metamaterial wing interacting with aerodynamic loads introduces a new aeroelastic bandgap for attenuating very low-frequency vibrations.

17. The method as claimed in claim 15, wherein the bandwidth of Bragg bandgaps and the local bandgap is broadened due to interaction of metamaterial wing with aerodynamic loads.

18. The method as claimed in claims 16 and 17, wherein the attenuation performance of aeroelastic, Bragg and local bandgaps is proportional to airflow velocity over the wing.

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