Energy-Efficient Compliant Structures with Functional Spring-Damper-Characteristics

• Applicants: Professor Dr.-Ing. Ulf Kletzin; Professorin Dr.-Ing. Lena Zentner
• Subject Area: Engineering Design, Machine Elements, Product Development
• Term: from 2013 to 2019
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 203302371

Usually vibrations and jerky movements are undesirable in technical systems because of an increasing of dynamic loads on the one hand and different transmission properties on the other hand. In engineering, especially medical and automotive engineering, compensation is often achieved using springs, dampers and spring-damper devices with linear or non-linear characteristics. Additionally to compensation, such devices in prostheses, machines, apparatus and vehicles provide a dependency of transmission by deflection and velocity. Currently complex spring-damper devices are combined with actuators, sensors and control algorithms to reach a deflection and velocity dependency. The focus of this research project is the fundamental investigation of passive, compliant structures with functional materials, which yield comparable deflection- and velocity-dependent behavior such as complex active devices. In contrast to intelligent materials (smart materials) the term functional material summarizes materials with passively changing properties, meaning that no additional energy is needed for the change. The purpose of the project is to design compliant structures with functional spring-damper characteristics adapting to changing environmental conditions without the need of any additional energy to make systems energy-efficient and to save resources. This should be done by a combination of normal springs and compliant structures, which are filled with a functional material. Consequently, new energy-efficient elements will be built up to reduce the complexity, the required installation place, the weight and the power demand of conventional devices. These new elements and devices adapt in only a mechanical way and energy-efficient to changing environmental conditions. Investigating in fundamentals of functional materials with load-dependent properties (deflection, velocity or temperature) and purposeful geometrical design is the basis for an adaptive behavior of energy-efficient elements. Parasitic heat (heat due to friction) or external heat sources (changing ambient temperature) are possibilities to realize temperature-dependent features. Ongoing work to the first project period, where the velocity-dependent behavior of the used functional materials was modeled and experimentally investigated, is the modeling and the investigation of the temperature-dependent properties. For verification of functional spring-damper properties in energy-efficient, compliant structures demonstrators will be built up and tested.

• DFG Programme: Research Grants