Curve® The working principle of bending actuators

CompActive’s Bending Actuators Curve® use shape memory alloys to realize novel adjustment functionality. This video explains in catchy animations how bending actuators efficiently use the motion of shape memory alloy wires.
This allows morphing solutions to be implemented without mechanics, motors, gears or levers. The operating principle allows robust, absolutely silent and very fast adjustment functions. Similar to bimetals but quite different – bending actuators from CompActive are the high-performance drives of tomorrow and an elegant alternative to solenoids, electric motors and pneumatics.

Cross-Industry Applications of the Technology

Active Aero Wheel by CompActive

For decades the automotive industry has been working on concepts to minimize the annoying air resistance at the fast spinning wheel. This makes up a considerable proportion of the total air resistance. The designs of newer electric vehicles show that closed rim designs with smaller openings are gaining ground for reasons of efficiency and range. The air resistance can be reduced in the single-digit percentage range, but nothing more. Only the complete closure of the rim can completely stop airflow and the damaging rotor effect of the wheel. This, however, is in conflict with the necessary cooling of the brake chamber when necessary, e.g. after a downhill pass.

Actuator modules from CompActive now allow several ventilation flaps to be integrated into the rim, which open automatically due to the waste heat from the braking system and initiate cooling through the wheel surface. Since they do not require a power source, they can also be easily applied to the rotating components: The two-dimensional bending actuators provide sufficient travel and the necessary robustness of an element that is moved in a rapidly rotating manner in road traffic.

Smooth Motion for Light and Laser

Quality light sources are expensive and are therefore used wisely. In most cases, their position is static, which means an adjustment – from room lighting to work surface focus or from spot to indirect lighting – is only possible by switching one lamp “off” and the other lamp “on” – cumbersome and costly, isn’t it?

Moving a light source in a way that is pleasing to the viewer, however, is not easy. The high projection lengths of the light beams make every discontinuity of the movements visible. Unpleasant jumps in speed and position or vibrations easily become visible. Conventional mechanical solutions with many relative movements in gears and mechanics inevitably lead to such effects. In particular, when a pleasant, slow motion is desired, discontinuities occur more intensively as a result of stick-slip effects.

CompActive’s bending actuators provide absolutely continuous deformation and movement due to their material-integrated and friction-free system. This also allows distance measuring systems e.g. for autonomous driving with high measuring lengths above 100 m to be pivoted over a defined angle without missing important information from the environment due to the sampling rate of the measuring device or due to mechanical jumps.


Whether it is modern optical measurement technology or residential lighting, test our bending actuators! Our solutions are noiseless, which the interactive light in the SmartHome should certainly be too…

Fast and Silent Actuator for Lid Opening - Touchless Functions - More Comfortable

Think about the lid of your kitchen garbage can, the handles of your drawers sticking out, the flap of the garbage can at your central station, the lid of the buffet at your favorite hotel… wouldn’t it be nice if things would move by themselves?

If you want to reduce hand movements for people, you have to be at least as fast as the movement itself. It is expected that there will be no loss of comfort elsewhere, such as noise or vibrations.
This is where two major advantages of bending actuators come into play:

1. They can be very fast: The large deflection of the bending actuators are generated by a solid-state actuator, a shape memory alloy (SMA). The activation can be as fast as desired, whether with 12 V in the range of seconds or with 48V in the range of milliseconds.


2. They are absolute noiseless and vibration-free: without gears and bearings, there are no starting points where noise or vibration could occur. So every function runs frictionless and smooth!

 

Planar bending actuators based on shape memory alloys - Handheld Demonstrator

Handheld demonstrator of a bending actuator based on shape memory alloys.

Distributed Actuation of Vortex Generators with bending actuators based on shape memory alloy wires

Adaptive Vortex Generators enable improving the aerodynamic efficiency of almost every aeroplane. They provide the possibility to reduce the minimum airspeed without any disadvantages for the efficiency of the cruise flight. The implementation of this functionality with a conventional mechanic system is limited by the boundary conditions of the application – a limited availabe space, a minimum weight and the implementation of multiple small adjusting elements.
By the use of Actuation modules with integrated wires made from shape memory alloys allow for a bending, spread over an area of the component. The active area without the actuation module has to be flexible or, in other words, thin, since the application of the actuation module stiffens the area. Afterwards, the actuation, i.e. the bending of the component, is initiated by direct heating via applied electrical current.

Flight Test – Active Vortex Generators with SMA-bending actuators

Actuation modules with integrated wires made from shape memory alloys allow for a bending, spread over an area of the component. The active area without the actuation module has to be flexible or, in other words, thin, since the application of the actuation module stiffens the area. Afterwards, the actuation, i.e. the bending of the component, is initiated by external heating or by direct heating via applied electrical current. With high degree of design freedom due to the 3D printing technology, new movement principles can easily be developed and tested. Furthermore, a subsequent transfer to high volume manufacturing processes such as injection molding is possible.

Active under floor panel with bending actuators

With surface-integrated SMA bending actuators, a static vehicle under floor panel becomes an under floor panel with active ventilation flap – without complex mechanics, with low installation space and without kinks. The actuator modules are applied to the cut flap of the under floor panel by using an adhesive film and rivets and are activated either by external heat or by Joule heating.

Main Details:
• Vent size: 220*100 mm²
• Actuator weight: 3*4 g
• Actuator thickness: 2.8 mm

Ventilation flaps based on protagonist-antagonist - SMA-actuator

In an electronically adjustable ventilation flap usually used in automotive engineering, in addition to the actual ventilation duct and flap, the motor, gear and mechanics are also installed, which together require a volume in the larger two-digit cm³ range. In order to achieve a minimum installation space, an actuator system made of shape memory alloys based on the material-integrated protagonist-antagonist principle was developed in cooperation with a partner. The actuator system was integrated directly into the flap and distributed over the surface. The use of the protagonist-antagonist actuators thus permits a more compact design without sacrificing setting options.

High Speed Catapult - Bending actuator with shape-memory-alloy

High-Speed-activation within a few milliseconds (<< 30 ms).

Active aerodynamic profile - surface-integrated bending actuator with shape memory alloy

The advantages of the flat bending actuators with shape memory alloys, especially for aerodynamic applications, are illustrated by this active aerodynamic profile, which changes its shape at the “push of a button”. The required installation space is minimized by the direct integration of the actuator into the lower profile. The lightweight construction potential of the scalable actuator principle is illustrated here: A profile section with a width of 30 mm is able to lift a weight of 120 g by 10 mm at a mass of 40 g. In particular, the closed and continuously curved outer contour offers the innovative aerodynamic shape adaptation and visually appealing design solutions.

How to Use

CompActive-Sample Actuator - easy to use

This video explains how easily the CompActive sample actuator can be controlled and activated.

Planar bending actuators based on shape memory alloys meet 3D printing

Actuation modules with integrated wires made from shape memory alloys allow for a bending, spread over an area of the component. The active area without the actuation module has to be flexible or, in other words, thin, since the application of the actuation module stiffens the area. Afterwards, the actuation, i.e. the bending of the component, is initiated by external heating or by direct heating via applied electrical current. With high degree of design freedom due to the 3D printing technology, new movement principles can easily be developed and tested. Furthermore, a subsequent transfer to high volume manufacturing processes such as injection molding is possible.

Curve® Modules - Assembly Instructions

The video explains with various examples how the Curve actuator modules can be easily mounted on individual components. Example material classes shown are: Fiber-reinforced plastic composites (GFRP, CFRP), steel, components from 3D printing (FDM, SLS). When using the actuator modules, the user does not have to deal with the shape memory alloys (SMA) themselves; the demanding electrical and mechanical connection is already solved for the user within the module. In addition to the video, recommendations for suitable material combinations can be found in the online application notes for the respective actuator modules 1910H, 3920M, 2940L.