EFPI Sensor Embedded in Propeller Blade Composite for Stress Monitoring
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Solution Overview
Problem
Current methods for manufacturing lightweight propeller blades using composite materials face challenges in measuring and monitoring residual stresses and integrity during production and operation, leading to potential defects and undetected damage, which can affect the blades' structural health and useful life.
Innovation Solution
Incorporating Extrinsic Fabry-Perot Interferometric (EFPI) sensors between layers of the propeller blade's composite structure to monitor residual stress build-up and microstrain, allowing for real-time data collection and analysis to determine structural integrity, and transmitting this information to a controller for output and maintenance decision-making.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If EFPI sensors are embedded in the blade composite structure to monitor residual stress and microstrain, then measurement precision and reliability are improved, but device complexity and manufacturing difficulty increase
Solution Approach 1:
The EFPI sensor is embedded within the blade composite structure during manufacturing, with the sensor optically coupled to a cavity in the spar. The sensor cavity is formed by removing foam material, creating a nested configuration where the sensor is integrated into the existing blade structure rather than added as a separate component.
Solution Approach 2:
An adhesive layer is introduced as an intermediary between the EFPI sensor and the blade composite structure. The adhesive optically couples the sensor to the cavity in the spar, providing both mechanical bonding and optical transmission while protecting the sensor during manufacturing processes.
2Manufacturing precision
If multiple layers of fiberglass cloth are hand stitched to form the blade shell, then manufacturing precision is improved, but ease of manufacture deteriorates due to labor intensive processes
Solution Approach 1:
The adhesive-coated fiberglass layers are self-bonding. The thermoplastic adhesive is activated by heat and pressure during the molding process, causing the layers to bond to each other and to the spar automatically without requiring manual stitching or additional fastening operations.
3Ease of manufacture
If thermoplastic adhesive is activated by heat and pressure to bond fiberglass layers, then ease of manufacture is improved by eliminating hand stitching, but reliability deteriorates due to potential internal layer damage from excessive heat
Solution Approach 1:
The EFPI sensor provides real-time feedback on the stress and strain conditions within the blade during the adhesive bonding process. By monitoring the optical interference patterns, the manufacturing process can be controlled to ensure that heat and pressure are applied within safe limits that prevent damage to the fiberglass layers while still achieving adequate bonding.
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 EFPI sensors provide reliable, non-destructive monitoring of propeller blades, enabling early detection of damage and wear, predicting remaining useful life, and optimizing maintenance schedules, thus enhancing operational safety and reducing material waste.
Implementation Method 1
Incorporating Extrinsic Fabry-Perot Interferometric (EFPI) sensors between layers of the propeller blade's composite structure to monitor residual stress build-up and microstrain
Data Source
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Figure 3A~4
Figure 5
AI summary
A blade for a propeller including a blade composite structure includes a Fiber Bragg Grating (FBG) or an Extrinsic Fabry-Perot Interferometric (EFPI) sensor embedded in the blade composite structure. The sensor is configured to receive a signal from a controller operatively connected to the FBG or EFPI sensor, and transmit a signal, responsive to the received signal, to a processor operatively connected to the sensor. The signal response is indicative of a stress measurement indicating a structural characteristic of the blade composite structure. The signal response provides information to determine, based on the signal response, whether the structural characteristic of the blade composite structure is within a predetermined limit indicative of structural integrity of the blade composite structure.