Self-Locking Aircraft Strut for Windmilling Vibration Control
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Solution Overview
Problem
Conventional aircraft support structures, such as soft struts, fail to effectively manage high loads and vibrations during abnormal events like windmilling, leading to increased displacement and stress on adjacent systems, and existing solutions like snubbing features introduce additional vibrations and shocks.
Innovation Solution
The implementation of self-locking or self-actuating support structures that can transition between a soft and hard state in response to predetermined displacements, loads, or rotations, allowing them to isolate vibrations during normal conditions and withstand high loads during abnormal events.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If soft struts are used to reduce vibration and noise transmission during normal operations, then vibration isolation is improved, but stiffness is insufficient during high-vibration events like windmilling
Solution Approach 1:
The support structure incorporates a locking assembly that can transition between unlocked and locked states, dynamically changing the structural characteristics from flexible to rigid based on operating conditions. During normal operations, the structure remains flexible for vibration isolation; during high-vibration events, the locking assembly engages to provide increased stiffness
Solution Approach 2:
The system changes the physical state of the support structure by transitioning from a soft, flexible state during normal operations to a hard, rigid state during abnormal events. This parameter change is achieved through the locking assembly that alters the structural stiffness in response to displacement, load, or rotation thresholds
2Force
If snubbing features are incorporated to reduce high loads during abnormal events, then load resistance is improved, but additional vibrations and shocks are introduced
Solution Approach 1:
The invention removes the snubbing features (such as shear pins) that were previously incorporated into soft support structures. By extracting these harmful elements, the patent eliminates the source of additional vibrations and shocks that snubbing features introduced while attempting to reduce high loads
Solution Approach 2:
The patent converts the potential harm of using snubbing features by eliminating them entirely and replacing them with a locking assembly that provides load resistance without generating additional vibrations. The locking mechanism engages cleanly to resist loads without the violent shearing action of traditional snubbing features
3Strength
If the support structure transitions to a locked state during high-vibration events, then stiffness is improved, but displacement capability is reduced
Solution Approach 1:
The support structure dynamically adjusts its characteristics based on operating conditions. During normal operations, it maintains flexibility and displacement capability in the unlocked state. During high-vibration events, it transitions to a locked state with increased stiffness, automatically adapting to the changing operational requirements
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
These support structures effectively reduce the transmissibility of loads and vibrations, maintaining shock absorption and vibration isolation during normal operations while enhancing stiffness to counteract resonance and high vibrations during abnormal events, thereby improving the robustness of aircraft systems.
Implementation Method 1
This effectively increases the stiffness of the attachment mounts, and shifts the rigid-body natural frequencies of the system away from the excitation frequency. This reduces the dynamic motion of the supported equipment, as well as the loads through the supporting structure and mounts.
Data Source
Figure 1
Figure 2A~2B
Figure 2C
AI summary
Aircraft support structures, systems, and methods are disclosed. In one embodiment, an aircraft system includes a rotating component and a support (e.g. strut) that supports the rotating component. The support includes a locking assembly (P1) that is configured to lock, automatically, an inner member (214) of the support with respect to an outer member (208) of the support for stiffening the support in response to reaching or exceeding a predetermined threshold amount of displacement, load, stress, or rotation. The aircraft support structures, systems, and methods herein utilize self-locking and self-unlocking supports (e.g. struts) for increasing or decreasing a stiffness of the support.