Actively Combating Vibrations
Technical progress, lightweight construction, vibrations and noise are all closely correlated. Adaptive structural components could provide a remedy: they can help to actively reduce machine or vehicle vibrations and consequently also the noise.
Adaptronics will help to expand engineering capabilities and revolutionize the design of structures. Examples include active interfaces, active struts and active mounting of components.
Quelle: Fraunhofer LBF
Time to leave the bus station. The driver starts the engine and its rumbling motor sound is joined by strong mechanical vibrations within the structure. Especially the side panels of the bus vibrate, emitting a loud droning noise. "The bus example shows how closely vibrations and noise are related," explains Tobias Melz of the Fraunhofer Institute for Structural Durability and System Reliability LBF in Darmstadt. Scientists from five Fraunhofer Institutes are working together in a project entitled FASPAS (Function Consolidated Adaptive Structures Combining Piezo and Software Technologies for Autonomous Systems) to create single-source solutions for smart or adaptive tool and vehicle components, covering the whole spectrum relevant to adaptronics from materials science to system reliability.
Adaptive components detect mechanical vibrations and actively counteract them, e.g. by means such as destructive interference or active damping. This is made possible by directly integrating active or multifunctional materials, such as piezoelectric ceramics or magnetostrictive alloys that can be used as sensors as well as actuators, into the mechanical components. Acting as sensors, these materials report the sensed vibrations to a control unit, which analyzes the disturbance and calculates the optimal actuator signal needed to actively control the vibration. This actuator signal is then induced into the mechanical structure via the active material, which now acts as an actuator. In this manner, the active system can dampen the vibrations, isolate the source or even completely cancel the vibrations. Numerous technical systems can be optimized by applying this principle.
At stand E30 in Hall 2 of the Hanover Trade Fair, Fraunhofer researchers will demonstrate state-of-the-art adaptive components for automotive and tool construction. Examples include active interface structures that isolate unwanted vibrations from sensitive components. In cars, these interfaces can be mounted between the chassis and vehicle body to actively reduce especially high frequency vibrations, such as those generated by road-surface contact. Consequently, passenger comfort and safety is enhanced.
A second example is an active strut of a 3POD manufacturing machine. "The strut contains sensors and actuators that reduce torsional and flexural vibrations in the structure. This improves both the stiffness and lightweight characteristics," explains Melz. "The use of adaptive components enables us to improve manufacturing accuracy of machine tools and to increase comfort and handling of cars while at the same time optimizing lightweight design and enhancing functional capabilities of structures." Additionally, a structure integrated actuator system for axial vibration control, piezoelectric actuator and sensor systems as well as two test structures that demonstrate active online vibration control will be exhibited
