Flexible Aerostructure Joining for Thermal Expansion
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Solution Overview
Problem
Traditional rigid connection methods for joining aerostructures, such as wings to fuselages, fail to accommodate thermal expansion differences between components, leading to overstressing and inefficiencies in hypersonic vehicles due to added weight and drag from thermal protection systems.
Innovation Solution
The use of flexible connection elements, such as thin metal alloy plates aligned in a linear array with a rigid connection element, allowing for differential thermal growth by flexing in the chordwise direction to accommodate linear distance differences between aerostructure parts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If traditional rigid connection methods are used to join wings to fuselage, then structural strength is maintained, but thermal expansion differences cause overstressing of the connection
Solution Approach 1:
The connection system transitions from a static rigid structure to a dynamic system where flexible plates can change their mechanical properties. The flexible plates remain rigid under normal operational loads to maintain structural strength, but become flexible under thermal expansion conditions to accommodate differential growth between the wing and fuselage, thus resolving the contradiction between maintaining strength and accommodating thermal stress.
Solution Approach 2:
The flexible plates undergo parameter changes in their mechanical properties based on thermal conditions. At elevated temperatures, the plates change from a rigid state to a flexible state, allowing them to accommodate thermal expansion differences. This parameter change enables the connection to maintain both strength under normal conditions and flexibility under thermal stress, resolving the contradiction between these two requirements.
2Strength
If thermal protection systems are added to minimize internal structure temperature, then structural integrity is protected, but vehicle weight and drag increase significantly
Solution Approach 1:
The patent extracts and removes the heavy thermal protection system from the wing structure by implementing a hot structure design. The flexible connection plates are specifically designed to accommodate thermal expansion, which allows the wing to operate at elevated temperatures without requiring traditional thermal protection materials. This extraction of the TPS significantly reduces vehicle weight while maintaining structural integrity through the thermal-resilient connection design.
3Strength
If thermal protection systems are used to protect internal structure, then structural integrity is maintained, but cross-sectional area and wing thickness increase adding drag
Solution Approach 1:
The patent removes the thermal protection system that would otherwise increase wing thickness and vehicle cross-sectional area. By extracting this unnecessary protective layer and replacing it with a hot structure design featuring flexible thermal-resilient connections, the wing maintains structural integrity without the added drag penalties of thicker structures and larger cross-sectional areas.
4Force
If rigid connections are used to transfer wing loads to fuselage, then load transfer efficiency is high, but thermal growth overstresses the connection
Solution Approach 1:
The connection system dynamically adapts its mechanical properties based on thermal conditions. Under normal temperature conditions, the flexible plates maintain rigid characteristics for efficient load transfer. Under thermal expansion conditions, they transition to a flexible state that accommodates differential growth between the wing and fuselage, thereby resolving the contradiction between load transfer efficiency and stress reduction.
Solution Approach 2:
The flexible plates change their mechanical parameters in response to thermal conditions. At elevated temperatures, they transition from a high-stiffness state optimized for load transfer to a more compliant state that accommodates thermal growth. This parameter change enables the connection to maintain both efficient load transfer and reduced thermal stress, resolving the contradiction between these two performance requirements.
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 method enables efficient joining of aerostructures with reduced weight and drag by allowing thermal expansion while maintaining structural integrity, distributing loads effectively without the need for significant spars, thus enhancing the performance of hypersonic vehicles.
Implementation Method 1
The second aerostructure part expands linearly at a greater rate when exposed to heat than the first aerostructure part resulting in a difference in linear distance between the first aerostructure part and the second aerostructure part
Implementation Method 2
the flexible connection elements are configured to flex to accommodate for this linear distance difference
Data Source
AI summary
Methods of joining a first aerostructure part with a second aerostructure part are disclosed, for example, methods of joining an airplane wing or control surface to an airplane fuselage or joining fins to a rocket body. The method comprises aligning a plurality of connection elements in a linear array within the second aerostructure part, wherein the connection elements comprise a plurality of flexible connection elements and at least one rigid connection element, and attaching the first aerostructure part to the second aerostructure part at a plurality of connection points with the plurality of connection elements. The second aerostructure part expands linearly at a greater rate when exposed to heat than the first aerostructure part resulting in a difference in linear distance between the first aerostructure part and the second aerostructure part and the flexible connection elements are configured to flex to accommodate for this linear distance difference.