Propeller Blade Spar Core Reinforcement for Thermal Stress
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Solution Overview
Problem
Modern propeller blades experience thermal stresses due to differences in coefficients of thermal expansion between the foam spar core and the structural layer, leading to potential structural integrity issues under varying operational temperatures.
Innovation Solution
A reinforced spar core is introduced, featuring a combination of conventional and reinforced sections bonded together with adhesive or overlapping fiberglass prepreg, and wrapped with braided carbon layers for enhanced shear, axial, and bending resistance, along with a resin-impregnated joining layer for improved structural integrity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of moving object
If a foam spar core is used in propeller blades, then the blade achieves light weight and effectiveness, but thermal stresses develop due to coefficient of thermal expansion differences between the foam core and structural layer
Solution Approach 1:
The patent applies composite materials by combining foam core with carbon fiber reinforced polymer (CFRP) structural layers. The foam provides lightweight core structure while the CFRP layers provide strength and thermal stability, creating a composite spar core that mitigates thermal stress issues while maintaining light weight.
Solution Approach 2:
The patent implements local quality by creating a reinforced section within the spar core that has different properties than the rest of the core. This reinforced section, positioned at the blade root where thermal stresses are most severe, contains additional carbon fiber layers and adhesive bonding to specifically address the thermal stress problem in the critical stress zone.
2Ease of manufacture
If conventional foam spar core is used, then manufacturing is simple, but structural integrity deteriorates under varying operational temperatures
Solution Approach 1:
The patent applies segmentation by dividing the spar core into distinct sections: a reinforced section at the blade root and a conventional foam core section at the blade tip. The reinforced section contains additional structural layers (carbon fiber braids, adhesive layers) while the tip section uses conventional foam, allowing manufacturing to be simplified in non-critical areas while providing enhanced strength where needed.
3Reliability
If reinforced sections with multiple layers are added to spar core, then structural integrity and thermal stress resistance improve, but device complexity increases
Solution Approach 1:
The patent implements local quality by concentrating the reinforced multi-layer structure only in the blade root section where thermal stresses are most severe, while the blade tip maintains a simpler conventional foam core structure. This localized reinforcement improves structural integrity in the critical stress zone without unnecessarily complicating the entire spar core.
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 reinforced spar core mitigates thermal stresses and enhances the structural integrity of propeller blades, ensuring reliable operation across a wide range of temperatures.
Implementation Method 1
bonded together with adhesive or overlapping fiberglass prepreg
Implementation Method 2
wrapped with braided carbon layers for enhanced shear, axial, and bending resistance
Implementation Method 3
along with a resin-impregnated joining layer for improved structural integrity
Data Source
Figure 1~2
Figure 3
Figure 4
AI summary
A propeller blade spar core (150) includes a leading edge spar foam section (202a) surrounded by a first structural layer (204a), a trailing edge spar foam section (202b) surrounded by a second structural layer (204b), and a third structural layer (206) surrounding both the first and second structural layers (204a,204b).