Sail Batten Shape Memory Control for Weight Reduction
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Solution Overview
Problem
Existing sail control devices employing shape memory systems face challenges in achieving dynamic control without increasing sail weight, as they require excessive shape memory material for structural resistance, leading to poor performance.
Innovation Solution
The use of pairs of shape memory systems operably connected to sail battens on opposite sides, extending along at least 75% of their length, allowing for controlled curvature adjustment through adjustable traction forces, without affecting the sail's overall structure and weight.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If shape memory material is used to make sail battens with adequate structural resistance, then structural strength is improved, but sail weight increases leading to poor performance
Solution Approach 1:
The batten is divided into two parts: a lightweight core structure (such as a hollow tube or channel) and shape memory alloy elements (wires or ribbons) that are wrapped around or attached to the core. The core provides the primary structural resistance, while the SMA elements provide shape control and additional reinforcement only where needed, significantly reducing the total weight compared to a fully SMA batten.
Solution Approach 2:
The invention uses composite construction combining lightweight materials (such as aluminum, carbon fiber, or hollow plastic tubes) with shape memory alloy elements. The core structure provides structural resistance while the SMA elements provide active shape control, creating a lightweight composite batten that maintains strength while minimizing weight.
2Measurement precision
If shape memory systems are arranged on opposite sides of the batten, then dynamic control precision is improved, but device complexity increases
Solution Approach 1:
The shape memory systems on opposite sides of the batten are configured with different properties (such as different wire diameters, different lengths, or different activation temperatures) to create asymmetric control. This allows independent adjustment of the batten's curvature in different directions, enabling precise dynamic control of the sail shape while maintaining a relatively simple overall system structure.
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 configuration enables dynamic sail control with precise bending adjustment, improving performance by maintaining structural integrity and reducing weight, while allowing for automatic or manual control based on environmental conditions.
Implementation Method 1
When elements made of a shape memory alloy are thermally actuated they are shortened by a well predictable percentage which is up to about 8%-9% depending on the material and amount of heat. Among the class of shape memory materials suitable for the purposes of the present invention there are shape memory polymers and shape memory alloys. It is known that filiform components made of a shape memory alloy undergo shortening upon heating when their structure is subject to a phase change from martensitic (low temperature phase) to austenitic (high temperature phase).
Implementation Method 2
Shape memory alloys featuring electrical resistivity and transition temperatures particularly suitable to be heated due to Joule effect by employing power sources typically present on sailboats, such as for example batteries, will preferably be chosen.
Data Source
AI summary
Sails for sailboat wind propulsion comprising shape memory systems containing shape memory elements are described. The shape memory systems are arranged in correspondence to the sail battens, extending along them and operably connected to the sail opposite faces or directly to the battens so as to face the opposite faces of the sail. A control apparatus and method of said sails is also described.