On a high-potential variable flexural stiffness device

Markus Henke; Gerald Gerlach

doi:10.1117/12.2016928

17 May 2013 On a high-potential variable flexural stiffness device

Markus Henke, Gerald Gerlach

Proceedings Volume 8763, Smart Sensors, Actuators, and MEMS VI; 876312 (2013) https://doi.org/10.1117/12.2016928
Event: SPIE Microtechnologies, 2013, Grenoble, France

Abstract

There are great efforts in developing effective composite structures for lightweight constructions for nearly every field of engineering. This concerns for example aeronautics and spacecrafts, but also automotive industry and energy harvesting applications. Modern concepts of lightweight components try to make use of structures with properties which can be adjusted in a controllable was. However, classic composite materials can only slightly adapt to varying environmental conditions because most materials, like carbon or glass-fiber composites show properties which are time-constant and not changeable. This contribution describes the development, the potential and the limitations of novel smart, self-controlling structures which can change their mechanical properties - e.g. their flexural stiffness - by more then one order of magnitude. These structures use a multi-layer approach with a 10-layer stack of 0.75 mm thick polycarbonate. The set-up is analytically described and its mechanical behavior is predicted by finite element analysis done with ABAQUS. The layers are braided together by an array of shape memory alloy (SMA) wires, which can be activated independently. Depending on the temperature applied by the electrical current flowing through the wires and the corresponding contraction the wires can tightly clamp the layers so that they cannot slide against each other due to friction forces. In this case the multilayer acts as rigid beam with high stiffness. If the friction-induced shear stress is smaller than a certain threshold, then the layers can slide over each other and the multilayer becomes compliant under bending load. The friction forces between the layers and, hence, the stiffness of the beam is controlled by the electrical current through the wires. The more separate parts of SMA wires the structure has the larger is the number of steps of stiffness changes of the flexural beam.

Citation Download Citation

Markus Henke and Gerald Gerlach "On a high-potential variable flexural stiffness device", Proc. SPIE 8763, Smart Sensors, Actuators, and MEMS VI, 876312 (17 May 2013); https://doi.org/10.1117/12.2016928

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