Tunable Blade Assembly With Adjustable Mass for Resonance Control
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Solution Overview
Problem
Rotatable blades in flight vehicles vibrate excessively when their rotating speed and excitation frequency coincide with their predefined natural frequency, leading to potential structural damage and reduced performance.
Innovation Solution
A tunable blade assembly with an adjustable mass within a cavity in the blade to alter its natural frequency and reduce vibrations, using actuators and controllers to adjust the mass's location and amount.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the blade is fabricated with predetermined shape, weight, and stiffness to achieve a predefined natural frequency, then the blade structure is simple and manufacturing is easy, but the blade cannot adapt to different operating conditions and excessive vibrations occur when rotating speed coincides with natural frequency
Solution Approach 1:
The patent applies the dynamics principle by making the blade mass adjustable rather than fixed. A tunable mass is positioned within the blade that can be moved to different locations along the blade length, allowing the natural frequency to be dynamically tuned to match different operating conditions and rotational speeds, thereby preventing resonant vibrations.
Solution Approach 2:
The patent implements parameter changes by varying the position of the tunable mass along the blade to change the natural frequency parameter. This allows the blade to adapt to different operating conditions by adjusting the mass position, effectively changing the dynamic characteristics of the blade without altering its physical structure.
2Object-affected harmful factors
If the blade mass is increased to reduce vibrations, then vibration reduction is achieved, but the overall blade weight increases which affects flight vehicle performance
Solution Approach 1:
The patent uses parameter changes by adjusting the position of an existing tunable mass rather than increasing overall blade mass. By moving the mass to optimal positions, the natural frequency is tuned to avoid resonance, reducing vibrations without adding extra weight to the blade structure.
Solution Approach 2:
The patent extracts the vibration control function from the blade structure itself by using a separate, movable mass that can be positioned independently. This allows vibration reduction through strategic mass placement rather than increasing the overall blade mass, maintaining lightweight design while achieving vibration control.
3Reliability
If a fixed mass is added to the blade to alter natural frequency, then vibration control is achieved, but the blade cannot adapt to changing operating conditions and the device complexity increases
Solution Approach 1:
The patent applies dynamics by making the mass position dynamic rather than fixed. The tunable mass can be moved to different positions along the blade to adjust the natural frequency in real-time, allowing the blade to adapt to changing rotational speeds and operating conditions while maintaining effective vibration control.
Solution Approach 2:
The patent implements periodic action by adjusting the mass position in response to periodic changes in operating conditions. The system can periodically tune the natural frequency to match the rotational speed, ensuring continuous vibration control as operating conditions change during flight vehicle operation.
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 effectively reduces blade vibrations, enhances structural life, and improves passenger comfort by changing the resonant frequency, allowing for improved vehicle performance and reduced overall weight.
Implementation Method 1
the blades are fabricated in a predetermined shape, weight, and stiffness, which produces blades having a predefined natural frequency. During operation of the flight vehicle, the blades are excited by external forces which causes the blades to vibrate. Vibration of the blades may become excessive if the rotating speed and/or excitation of the blades approaches or coincides with the predefined natural frequency of the respective blades.
Implementation Method 2
a tunable control assembly which includes a mass adjustable inside of the cavity of the blade to reduce the vibrations in the blade
Data Source
AI summary
An example blade assembly includes a blade extending along a longitudinal axis between a root end and a tip end spaced from the root end, wherein: the blade is configured to rotate concurrently with a hub and rotation of the blade generates vibrations in the blade, and the blade defines a cavity spaced from the tip end; and a tunable control assembly including a mass adjustable inside of the cavity of the blade to reduce the vibrations in the blade.