Compliant Edge Morphing Airfoil Structure for Rotorcraft
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Solution Overview
Problem
Designing an adaptive control surface for rotorcrafts poses challenges in efficiently distributing local actuation power to achieve specified shape changes while meeting power, weight, packaging, and survivability constraints, particularly in achieving shape morphing, stall elimination, and dynamic response.
Innovation Solution
An edge morphing arrangement for an elongated airfoil with a deformable cover and compliant web structures, actuated by a linear or rotatory drive mechanism, allowing for 0° to 10° flap motion at rates exceeding 7 Hz, utilizing composite materials like GFRP for increased lift and reduced weight, and optimizing the D-spar location for actuator placement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a rigid control surface is used, then structural integrity is maintained, but adaptability to achieve shape morphing is lost
Solution Approach 1:
The control surface employs a deformable cover made of flexible material that can change shape while maintaining structural integrity. This flexible shell approach allows the surface to morph between different configurations (0° to 10° flap motion) without compromising strength, directly resolving the contradiction between adaptability and structural integrity
Solution Approach 2:
The control surface transitions from a static rigid structure to a dynamic deformable structure that can actively change its shape in response to actuation. The deformable cover with compliant web structures enables real-time shape adaptation while maintaining sufficient structural strength through controlled flexibility
2Adaptability or versatility
If a complex actuator system is used to achieve precise shape control, then shape morphing capability is improved, but device complexity increases
Solution Approach 1:
The patent replaces complex mechanical actuator systems with an ultrasonic piezoelectric actuator that uses piezoelectric effect to generate precise shape control. This substitution reduces mechanical complexity while achieving the required shape morphing precision through direct piezoelectric-driven deformation of the compliant structure
Solution Approach 2:
The system achieves shape control by changing physical parameters (electrical voltage to piezoelectric actuator) rather than through complex mechanical linkages. The ultrasonic piezoelectric actuator converts electrical signals directly into mechanical deformation, simplifying the actuation system while maintaining precise control capability
3Strength
If the D-spar is positioned forward for structural support, then strength is improved, but packaging space for actuators is reduced
Solution Approach 1:
The actuator system is nested within the airfoil structure itself, with the ultrasonic piezoelectric actuator integrated into the deformable cover assembly. This nesting approach allows the actuator to be positioned within the existing structural volume without requiring additional space that would conflict with forward D-spar positioning for structural support
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution provides a 35% increase in retreating blade lift without stall, reduces weight, and enhances rotorcraft top speed, payload, and altitude capabilities, while maintaining structural integrity and minimizing power consumption.
Implementation Method 1
the deformable cover being formed of a deformable compliant material configured to deform to a substantial degree
Implementation Method 2
a first compliant web structure deformable to a substantial degree coupled at an upper end to the interior of the upper portion of the deformable compliant cover
Implementation Method 3
The flap can be actuated at rates up to (and exceeding) 7 Hz to provide once per rev flap positioning
Data Source
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AI summary
An edge morphing arrangement for an airfoil having upper and lower control surfaces is provided with a rib element arranged to overlie the edge of the airfoil. The rib element has first and second rib portions arranged to communicate with respectively associated ones of the upper and lower control surfaces of the airfoil. A first compliant linkage element has first and second ends and is disposed between the first and second rib portions of the rib element, the first and second ends are each coupled to the interior of a respectively associated one of the first and second rib portions. There is additionally provided a driving link having first and second driving link ends, the first driving link end being coupled to the interior of a selectable one of the first and second rib portions in the vicinity of the coupling of the respectively associated end of the first compliant linkage element. The second end is arranged to receive a morphing force, and the rib element is deformed in response to the morphing force. Multiple rib elements can be arranged substantially parallel to one another and configured to morph at respective operating ratios. Additionally, an overlying skin has a thickness that varies over the span.