Aviation Fuel Tank Rigid Wall Crash Energy Absorption
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Solution Overview
Problem
Current fuel tanks for aviation, particularly those designed for crash-worthy helicopters, face challenges in meeting government standards for crash resistance due to limited energy absorption capabilities of thermosetting composite materials, which often require additional weight from flexible inner tanks to compensate.
Innovation Solution
The development of rigid tank wall constructions using thermoplastic resin matrices with specific fiber reinforcement patterns, such as twill weave, enhances energy absorption, allowing for a reduction or elimination of the flexible inner tank, thereby achieving weight savings while maintaining crash resistance standards.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Shape
If thermosetting composite materials are used for the rigid outer tank, then the tank provides a constant predictable shape and facilitates attachment to aircraft components, but the material has limited elongation before breaking and does not absorb sufficient energy to meet crash standards
Solution Approach 1:
The patent uses a composite material system combining a thermoplastic resin matrix with continuous fiber reinforcement (such as carbon fiber, glass fiber, or aramid fiber) in a woven fabric form. This composite structure provides both the required structural integrity and shape stability while enabling sufficient energy absorption through the ductile thermoplastic matrix that can deform and absorb impact energy.
Solution Approach 2:
The patent changes the material parameters by selecting a thermoplastic resin matrix with specific mechanical properties including elongation at break of at least 5%, tensile strength of at least 50 MPa, and flexural strength of at least 80 MPa. These parameter changes enable the rigid tank to absorb sufficient energy during crash while maintaining its shape and structural function.
2Strength
If a flexible inner tank is added inside the rigid tank to improve crash resistance, then the tank assembly becomes more crash resistant, but the weight of the system increases
Solution Approach 1:
The patent extracts and eliminates the flexible inner tank component from the traditional two-tank system. By using a thermoplastic-based rigid tank construction that inherently provides sufficient energy absorption and crash resistance, the design removes the need for the additional flexible inner tank, thereby reducing overall system weight while maintaining required safety performance.
3Strength
If the thickness of the flexible inner tank is increased to provide greater crash resistance, then crash resistance improves, but the weight of the system increases
Solution Approach 1:
The patent eliminates the flexible inner tank entirely by using a thermoplastic rigid tank construction that provides sufficient crash resistance on its own. This extraction of the unnecessary component avoids the weight penalty associated with increasing flexible tank thickness while maintaining the required energy absorption capability.
Solution Approach 2:
The patent employs a composite material system with thermoplastic resin matrix and continuous fiber reinforcement that achieves the required crash resistance in a single rigid tank structure. This composite construction provides both strength and energy absorption without requiring additional flexible layers, thereby avoiding weight increase.
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 use of thermoplastic resin matrices with advanced fiber reinforcement in the rigid tank walls significantly improves energy absorption, enabling fuel tanks to meet crash resistance standards with reduced weight, offering a lighter and more efficient solution compared to traditional thermosetting materials.
Implementation Method 1
thermoplastic resin matrices with advanced fiber reinforcement in the rigid tank walls significantly improves energy absorption
Data Source
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AI summary
Embodiments of the present invention relate generally to fuel tanks for aviation, and particularly to construction of rigid tank walls (100) that have been found useful in absorbing energy of a magnitude expected during a crash. In some aspects, the rigid tank wall construction includes particular materials, such as a thermoplastic resin matrix. According to the invention, the rigid tank wall construction includes a twill weave pattern.