Shape Memory Alloy Control Surface Actuation
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Solution Overview
Problem
Existing hydraulic systems used to actuate control surfaces in aircraft are heavy, occupy valuable space, and increase aerodynamic drag due to their external placement.
Innovation Solution
A compact actuation system utilizing shape memory alloy extensible coupling members heated by a selective heating system to rotate control surfaces, reducing the number of moving parts and allowing for internal placement, thereby minimizing weight and drag.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If hydraulic systems are used to actuate control surfaces, then reliable actuation is achieved, but weight increases and valuable space is occupied
Solution Approach 1:
The patent replaces the traditional hydraulic mechanical actuation system with a shape memory alloy-based actuation system. The shape memory alloy members directly convert thermal energy to mechanical motion through phase transformation, eliminating the need for hydraulic pumps, reservoirs, valves, and associated mechanical linkages. This substitution dramatically reduces weight while maintaining actuation reliability through the inherent reliability of shape memory alloy phase transformation.
Solution Approach 2:
The patent utilizes parameter changes in the shape memory alloy material, specifically the temperature-dependent phase transformation between austenite and martensite phases. By controlling the temperature of the shape memory alloy members through heating elements, the material undergoes reversible phase changes that directly produce the mechanical motion needed for control surface actuation, eliminating complex mechanical transmission systems.
2Ease of operation
If hydraulic actuators are disposed on the outside surface of the wing in fairings, then actuation function is achieved, but aerodynamic drag increases
Solution Approach 1:
The patent merges the actuation system with the aircraft structure by integrating shape memory alloy members directly into the wing and control surface assemblies. The extensible coupling members are positioned within the structural framework of the wing and control surfaces, eliminating the need for external fairings and associated aerodynamic drag. The actuation function is achieved through the phase transformation of the shape memory alloy members that are structurally integrated rather than externally mounted.
3Ease of operation
If traditional hydraulic actuators are used, then control surface actuation is achieved, but device complexity increases
Solution Approach 1:
The patent extracts and eliminates the complex hydraulic subsystem components (pumps, reservoirs, valves, hoses, filters) from the actuation system. Only the essential elements remain: shape memory alloy members and simple heating elements. This extraction of unnecessary complexity maintains the ease of operation for control surface actuation while dramatically simplifying the overall device architecture.
Solution Approach 2:
The shape memory alloy members are self-actuating through phase transformation driven by simple heating elements. The material inherently converts thermal energy to mechanical work without requiring complex control mechanisms, hydraulic pressure regulation, or mechanical feedback systems. This self-service capability of the shape memory alloy reduces device complexity while maintaining ease of operation for control surface actuation.
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 system achieves a more compact and lightweight actuation mechanism that reduces aerodynamic drag and allows for internal placement, enhancing fuel efficiency and reliability.
Implementation Method 1
each one of the extensible coupling members in the pair comprising a shape memory alloy
Implementation Method 2
when respectively heated, the first one or the second one of the extensible coupling members cause the control surface to articulate
Data Source
Figure 1~2b
Figure 3
Figure 4
AI summary
The present invention provides a vehicle having a main body, a control surface pivotably coupled to the main body for changing the direction of travel of the vehicle, and an actuation system for driving a vehicle control surface to articulate about the pivot point. The actuation system comprises: at least one pair of extensible coupling members, each one of the pair of extensible coupling members comprising a shape memory alloy; and a heating system. The heating system is arranged to heat a first one of the extensible coupling members or a second one of the extensible coupling members in response to a vehicle control input received by the actuation system, wherein, when respectively heated, the first one or the second one of the extensible coupling members cause the control surface to articulate in the opposite direction to the other. The present invention also provides a method of actuating a control surface of a vehicle.