Completely new solutions for production technology and automotive engineering become possible by structural integration of active materials, so-called smart materials such as piezoceramics, shape memory alloys or rheological fluids. The Fraunhofer IWU offers holistic solutions from feasibility studies to functional models up to manufacturing technologies for adaptronic solutions.
Piezoceramic materials
Piezoceramics are materials with a high maturity level and are applied, for example, as injectors for diesel and gasoline engines with low fuel consumption or as ultrasonic sensors in medical engineering. Piezoceramic materials feature a separation of charge under the influence of deformation caused by external force. If the material deforms, electrically charged areas form either at the topside, the bottom side or at opposing lateral surfaces. The reaction times are extremely short and also allow for excitation and reception of high-frequency oscillations up to a range of GHz in addition to quasi-static operation. Applications such as ultrasonic transducers and electromechanical transformers are derived from these characteristics.
Thermal shape memory alloys (SMA)
Thermal SMAs facilitate elegant solutions to use occurring thermal energy for causing the effect of shape memory without requiring additional energy. Thus actuators, which are often used in automotive engineering, for example, can be severely simplified. They can even be enhanced by temperature-controlled additional functions in drives. Moreover, thermal SMAs have a striking advantage compared to conventional solutions – their weight is extremely low in relation to their power density.
Magnetic shape memory alloys (MSM)
MSMs can change up to 12% of their shape under the influence of a magnetic field. They are highly suitable to be applied as actuators or sensors and for generating small amounts of electric energy. Significant advantages of MSM actuators lie in their work output relation to the operational frequency, energy efficiency and service life.
Electrorheological and magnetorheological fluids
Dielectric elastomer actuators (DEA), a subdomain of electro-active polymers (EAP), can be applied as actuators, sensors and for converting energy. Furthermore, DEAs are light and exhibit a very compact design, they switch rapidly and silently. Energy harvesting modules, which are made of DEA materials and used for generating electric energy from sources such as vibrations or oscillations, are predicted to have an efficiency of above 80%, which makes them significantly superior to conventional technologies and solar modules.
Optical shape memory alloys
Currently optical shape memory materials are available as light intensive shape memory polymers. Similar to thermal shape memory polymers, the material can be converted from an amorphous state (flexible and elastic) into a crystalline state (stiff). In this case the light acts as the trigger. The action of light influences the crosslinking density, which means that it has an impact on the elastic properties of the material. By specifically increasing the crosslinking points in the manufacturing process, the current shape of the material is fixed. When this fixing is dissolved later, the material “remembers” its original geometrical condition.
Fraunhofer Institute for Machine Tools and Forming Technology