Aircraft Structure Prognostics via Strain Sensor Correlation
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Solution Overview
Problem
Current methods for prognosing damage or defects in mechanical aircraft structures, especially composite structures, are expensive and not very accurate, as they do not provide real-time monitoring of physical and mechanical conditions, making it difficult to predict and prevent unexpected failures.
Innovation Solution
A method that uses strain sensors and a mathematical model to correlate actual strain data with theoretical data, allowing for real-time evaluation of a structure's soundness or defectiveness by estimating deformation under operative loads and comparing it with a finite element model, enabling continuous and reliable monitoring of mechanical conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If historical recording of events and fatigue estimation methods are used to prognosticate damages, then the prognostic can be performed without real-time monitoring, but the accuracy and reliability of damage detection deteriorates
Solution Approach 1:
The patent replaces complex historical data recording and fatigue estimation systems with a simplified strain sensor-based monitoring system. Strain sensors directly measure mechanical deformation, substituting indirect historical analysis with direct physical measurement, thereby improving prognostic accuracy while reducing system complexity
Solution Approach 2:
The structure itself provides the monitoring data through its strain response under load. By instrumenting the structure with strain sensors, the system uses the structure's own mechanical behavior as the monitoring signal, eliminating the need for external historical data collection and complex estimation algorithms
2Measurement precision
If comprehensive historical recording and detailed fatigue analysis are performed, then more complete damage information is obtained, but the cost and time required for prognostic increases
Solution Approach 1:
The strain sensor system enables continuous real-time monitoring of structure deformation during service. This continuous measurement provides persistent damage detection capability without requiring periodic interruptions for detailed analysis, thereby achieving high measurement precision without time loss
Solution Approach 2:
The system performs preliminary strain measurement and comparison with reference values continuously during normal operation. By detecting deviations early through real-time strain monitoring, the system identifies damage before it progresses to critical levels, enabling early intervention without requiring time-consuming detailed investigations
3Reliability
If real-time strain correlation with theoretical models is performed, then continuous monitoring of structure conditions is achieved, but calculation complexity increases
Solution Approach 1:
The patent segments the structure into discrete measurement points using strain sensors at critical locations. This segmentation allows monitoring of key structural responses without requiring full-field measurement, simplifying calculations while maintaining reliability through strategic placement of sensors at locations most indicative of overall structure health
Solution Approach 2:
The system creates a simplified digital representation (finite element model) that copies the essential mechanical behavior of the physical structure. This computational model replicates the structure's strain response characteristics, enabling real-time comparison with actual sensor data without requiring complex calculations on the full geometric detail of the actual structure
4Measurement precision
If heavy calculation loads are used for detailed strain analysis, then more accurate deformation estimation is obtained, but the system cannot be implemented on board aircraft during service
Solution Approach 1:
The patent applies partial action by using a limited number of strategically placed strain sensors rather than comprehensive full-field measurement. This selective monitoring captures the essential deformation characteristics needed for accurate assessment while generating minimal data that requires only simple calculations, enabling on-board implementation without sacrificing measurement precision
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
This approach allows for accurate and cost-effective continuous monitoring of mechanical structures, enabling real-time assessment of defects and preventing unexpected failures, even during service conditions, without heavy calculation loads, and can be applied on board aircraft.
Implementation Method 1
a limited number of strain sensors located in relevant points... actual strain data... measured by the provided sensors
Implementation Method 2
An estimated deformation of the structure under test as a function of a given operative load is obtained through the model of the structure, interpolating or extrapolating to the whole structure starting from a limited number of actual values of strain
Data Source
AI summary
A method for prognostics of a structure subject to loads, particularly an aircraft structure, includes, detecting the state (strains) of the structure at multiple primary points and additional points. The loads acting on the structure associated with the state detected in the primary points are determined. Based on the determined loads, the state of the structure in the additional points is estimated. The estimated state of the structure is compared with the state detected in the additional points. A soundness state of the structure is assessed if the estimated and detected values of the state quantity are in agreement, or a defectiveness state of the structure if such values differ.