Friction Disk Inerter Assembly for Aircraft Flutter Damping
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Solution Overview
Problem
Aircraft flight control surfaces experience undesirable resonance and flutter due to aerodynamic loads and hydraulic actuator dynamics, which existing dampers and inerters fail to adequately mitigate.
Innovation Solution
Inerters with friction disk assemblies are introduced, featuring a threaded shaft, inerter rod, and a friction disk assembly that generates a shear stress in an inerter fluid to dampen motion by resisting acceleration and creating a frictional torque, effectively mitigating resonance and flutter in aircraft hydraulic systems.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If existing dampers and inerters are used to mitigate resonance and flutter, then some damping effect is achieved, but the damping effectiveness is insufficient to adequately mitigate the undesirable resonance and flutter
Solution Approach 1:
The friction disk assembly is segmented into multiple friction disks (e.g., three disks) arranged in series, each contributing to the overall damping effect. This segmentation allows for increased total frictional torque without requiring a single large, complex component, thereby improving damping effectiveness while maintaining manageable system complexity
Solution Approach 2:
The friction disk assembly dynamically adjusts the frictional torque based on the relative motion between the rotating portion and fixed portion. As the motion velocity changes, the frictional torque automatically adjusts, providing optimal damping across varying operating conditions and enhancing overall damping effectiveness
2Reliability
If the friction disk assembly is designed to generate high frictional torque through shear stress in the inerter fluid, then damping effectiveness is improved, but the device complexity increases due to the additional components and mechanisms required
Solution Approach 1:
The friction disk assembly merges multiple functions into a single integrated component: it provides frictional damping through the friction disks, transmits torque through the inerter fluid, and couples the rotating and fixed portions. This merging reduces the number of separate components needed and simplifies the overall system architecture while maintaining high damping effectiveness
Solution Approach 2:
The assembly utilizes hydraulic principles by employing an inerter fluid that transmits force and generates shear stress. The fluid-based torque transmission is more compact and efficient than mechanical gear or belt systems, reducing complexity while achieving the required frictional torque for effective damping
3Reliability
If the rotating portion rotates at a velocity directly proportional to the linear velocity of terminal translation, then the damping force is optimized for the intended application, but the manufacturing precision requirements increase to ensure accurate velocity proportionality
Solution Approach 1:
The velocity proportionality is achieved by designing the friction disk assembly with specific geometric parameters (disk radius, number of disks, fluid viscosity) that can be adjusted to match the desired damping characteristics. By changing these parameters during design, the system achieves optimal damping for the intended application without requiring extreme manufacturing precision, as the parameters can be tuned within normal tolerances
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 inerter with friction disk assemblies effectively dampens motion and reduces resonance and flutter in aircraft flight control surfaces, enhancing the stability and operational bandwidth of hydraulic actuators and aircraft systems.
Implementation Method 1
rotation of the rotating portion relative to the fixed portion creates a shear stress in the inerter fluid that generates a frictional torque that opposes the rotation of the rotating portion relative to the fixed portion
Implementation Method 2
The friction disk assembly and the inerter fluid together are configured to damp a motion of the second terminal relative to the first terminal
Data Source
AI summary
Inerters with friction disk assemblies, and aircraft hydraulic systems and aircraft including the same. An inerter comprises an inerter housing containing an inerter fluid, a threaded shaft extending within the inerter housing and fixed relative to the first terminal, and an inerter rod extending at least partially within the inerter housing and fixed relative to the second terminal. The inerter further includes a friction disk assembly that, together with the inerter fluid, is configured to damp a motion of the second terminal relative to the first terminal. The friction disk assembly includes a fixed portion and a rotating portion, and is configured such that rotation of the rotating portion generates a frictional torque that opposes the rotation of the rotating portion. In some examples, the inerter is a component of a hydraulic actuator, an aircraft hydraulic system including the hydraulic actuator, and/or an aircraft including the aircraft hydraulic system.