Actuator System with Negative Stiffness for Rotor Blades
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Solution Overview
Problem
The design of powerful, lightweight actuator systems for active aerodynamic surfaces in rotary-wing and tilt-rotor aircraft poses challenges due to added weight and complexity, which affects vibration reduction, noise reduction, and performance improvements.
Innovation Solution
The use of linear actuators with a span-wise orientation and cross-axis flexure pivot elements that create a negative stiffness spring effect, counteracting centrifugal forces and reducing actuator power requirements, while allowing for larger motors and improved mass distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If actuator systems are added to operate active elements on blades or wings, then vibration reduction, noise reduction, and performance improvements are achieved, but weight and complexity increase
Solution Approach 1:
The patent utilizes centrifugal force generated by rotating masses to counterbalance the weight and inertial forces of the actuator system. By strategically placing counterweights on the rotor blade, the system offsets the additional weight of actuators, thereby reducing the net increase in rotating mass while maintaining vibration reduction and performance enhancement capabilities
Solution Approach 2:
The actuator system is designed to utilize the rotational energy and centrifugal forces already present in the helicopter rotor system to power the active elements. The actuators are configured to be driven by the rotor's rotation itself, eliminating the need for separate power sources and reducing overall system weight and complexity
2Power
If powerful actuator systems are designed to manipulate aerodynamic surfaces, then performance improvements are achieved, but device complexity increases
Solution Approach 1:
The actuator system is designed with multi-functionality, where a single actuator mechanism performs multiple functions: it controls the active aerodynamic elements, provides vibration reduction, and contributes to noise reduction. This universal approach consolidates what would otherwise require separate systems, thereby maintaining high power output while reducing overall device complexity
Solution Approach 2:
The patent merges the actuator mechanism with the rotor blade structure itself, integrating the actuation system into the existing blade architecture. By combining the actuator, linkage, and aerodynamic surface control into a unified integrated system, the design achieves powerful actuation capability while minimizing the number of discrete components and reducing system complexity
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
This approach reduces the mass of the actuator system, enhances motor power, and improves aerodynamic performance by counteracting aerodynamic forces, thereby reducing noise and vibration while maintaining performance enhancements.
Implementation Method 1
cross-axis flexure pivot elements that create a negative stiffness spring effect, counteracting centrifugal forces
Implementation Method 2
counteracting centrifugal forces
Data Source
AI summary
A method and apparatus is provided, including an actuator system that may be connected to a wing frame for controlling an active element. The actuator system may include sliding elements movable along an axis parallel to the span-wise axis of the wing. The sliding elements may be connected to fixed elements and a crank element, the crank element generally comprising a beam element and a cross-axis flexure pivot element. The beam element may be offset from the pivot element so that the crank element is rotatable about the pivot element with a negative stiffness under an external force that tends to pull the sliding elements away from the fixed elements.