Actuator Load Path Failure Detection Using Vibration Strain Gauges
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Solution Overview
Problem
Existing actuators lack effective means to detect and identify the failure of the primary load path, leading to potential failure of the secondary load path, which is critical in systems like trimmable horizontal stabiliser actuators for aircraft.
Innovation Solution
A system utilizing strain gauges mounted on the static portion and nut assembly of the actuator to measure vibrations, comparing these measurements to identify failure of the primary load path, and activating an alarm or notifying users when such failure occurs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a secondary load path is provided for backup, then reliability is improved, but the ability to detect primary load path failure deteriorates due to lack of monitoring means
Solution Approach 1:
The patent implements feedback by using strain gauges to continuously monitor the load path and provide real-time information about the structural state. The system compares vibration signals from the static portion and moving portion to detect changes indicating primary load path failure, enabling timely notification and maintenance planning.
Solution Approach 2:
The patent introduces an intermediary detection system consisting of strain gauges and a processor that mediates between the mechanical load path and the control system. This intermediary layer enables indirect detection of primary load path failure through vibration analysis without directly interfering with the load transmission function.
2Difficulty of detecting and measuring
If strain gauges and vibration monitoring are added, then detection capability is improved, but device complexity increases
Solution Approach 1:
The patent applies multi-functionality by using the actuator's existing structural components (static portion, moving portion, screw shaft, nut assembly) for both their primary mechanical function and as mounting structures for the detection system. The strain gauges utilize the existing load-bearing structures as their substrate, eliminating the need for separate dedicated sensor mounting structures.
Solution Approach 2:
The detection system leverages the actuator's own operational vibrations and load-induced deformations as the measurement signal source. The system uses the actuator's normal operation to generate the very signals that enable failure detection, eliminating the need for separate excitation sources or additional active components.
3Measurement precision
If vibration measurements are compared between static and moving portions, then failure identification accuracy is improved, but processing requirements increase
Solution Approach 1:
The patent applies partial action by focusing the comparison analysis specifically on vibration characteristics rather than analyzing all possible mechanical parameters. The system selectively monitors vibration signals from strain gauges mounted on critical portions, comparing only the relevant dynamic characteristics to identify failure conditions, rather than performing comprehensive analysis of all actuator parameters.
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
Enables timely detection and notification of primary load path failure, ensuring safe transfer of load to the secondary path, thereby maintaining system integrity and functionality.
Implementation Method 1
a first strain gauge configured to be mounted to the static portion and to measure vibrations of the static portion and a second strain gauge configured to be mounted to the nut assembly and to measure vibrations of the nut assembly
Data Source
AI summary
A system for identifying a failure of the primary load path in an actuator. The system includes a first strain gauge configured to be mounted to a static portion and to measure vibrations of the static portion and a second strain gauge configured to be mounted to a nut assembly and to measure vibrations of the nut assembly. The system comprises a processor configured to identify a failure of the primary load path by comparing the measured vibrations of the static portion and the measured vibrations of the nut assembly.