Actuator Load Path Monitoring via Strain Gauge Vibration Signatures

Solution Overview

Problem

Existing actuators lack effective means to detect and identify the failure of the primary load path, leading to potential structural instability and failure in critical applications like aircraft trimmable horizontal stabiliser actuators.

Innovation Solution

Incorporation of a strain gauge, such as a piezoelectric strain gauge, to measure vibrations in the actuator, coupled with a processor to identify the failure of the primary load path by detecting the engagement of a secondary load path through shock or vibration signatures.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a secondary load path is provided for failure conditions, then reliability is improved, but device complexity increases due to additional components and monitoring requirements

Engineering Contradiction:

Improveactuator reliabilityVSAvoidactuator complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The strain gauge is installed and configured before failure occurs to detect the transition from primary to secondary load path. This preliminary monitoring capability allows the system to identify failure conditions and activate the secondary load path without requiring complex real-time decision-making circuits or additional actuators.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent replaces complex mechanical failure detection mechanisms with a strain gauge-based sensing system. Instead of using intricate mechanical linkages, switches, or sensors to detect load path failure, the system uses strain measurement combined with Fourier transform analysis to identify the engagement of the secondary load path, thereby reducing mechanical complexity.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Difficulty of detecting and measuring

If strain gauge monitoring is implemented, then detection capability is improved, but device complexity increases due to additional sensing and processing components

Engineering Contradiction:

Improvefailure detection capabilityVSAvoidmonitoring system complexity

Core Design Contradiction:

Difficulty of detecting and measuringVSDevice complexity

Solution Approach 1:

The patent replaces complex mechanical failure detection mechanisms with a strain gauge-based sensing system. Instead of using intricate mechanical linkages, switches, or sensors to detect load path failure, the system uses strain measurement combined with Fourier transform analysis to identify the engagement of the secondary load path, thereby reducing mechanical complexity.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The strain gauge measures vibrations inherent to the actuator's normal operation, and the processor uses Fourier transform analysis to extract failure signatures from these existing signals. The system leverages the actuator's own operational vibrations as the measurement medium, eliminating the need for separate test signals or additional sensing infrastructure.

Inventive Principle:

Principle #25Self-service

3Measurement precision

If Fourier transform analysis is used to identify failure signatures, then measurement precision is improved, but processing complexity increases

Engineering Contradiction:

Improvefailure signature detection precisionVSAvoidsignal processing complexity

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The patent replaces complex mechanical failure detection mechanisms with a strain gauge-based sensing system. Instead of using intricate mechanical linkages, switches, or sensors to detect load path failure, the system uses strain measurement combined with Fourier transform analysis to identify the engagement of the secondary load path, thereby reducing mechanical complexity.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

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 real-time detection and notification of primary load path failure, ensuring safe transition to the secondary load path, thereby enhancing the reliability and safety of actuators in critical systems.

Implementation Method 1

The strain gauge is a piezoelectric strain gauge

Methodology Applied

Scientific EffectPiezoelectric effect: Piezoelectric Effect

Data Source

PatentUS20250206441A1System for an actuator

Publication Date: 2025.06.26 GOODRICH ACTUATION SYST

AI summary

A system for identifying a failure of the primary load path in an actuator. The actuator includes a screw shaft and a nut assembly moveable along the screw shaft. The nut assembly comprises a primary nut for transmitting load through the actuator along a primary load path, and a secondary nut for transmitting load through the actuator along a secondary load path. The nut assembly is configured such that, in normal operation, the secondary nut is not engaged with the screw shaft and load is transmitted through the actuator along the primary load path, and such that, upon failure of the primary load path, the secondary nut is configured to engage the screw shaft and transmit load through the actuator along the secondary load path. The system includes a strain gauge configured to be mounted to the actuator and to measure vibrations of the actuator.