Non-linear Mechanical Behaviour of Metallic Micro-wires under Dynamic Axial Loads

Metallic micro-wires (diameter a parts per thousand 10 mu m) are widely used to suspend reference bodies and isolate them from micro-seismic vibration because of their low bending and torsional stiffness. They make it possible to realize torsion/swing low-resonant frequency oscillators, spectrally separable from the higher frequency physics of interest. In this study, metallic micro-wires are used to provide both seismic isolation through flexural compliance and high-speed actuation thanks to axial stiffness. An experimental apparatus is realized to characterize the dynamic response of a 25 mu m diameter tungsten wire used to actuate a suspended mass (10(-2) kg) subjected to accelerations up to 0.2 m/s(2). A theoretical non-linear model taking into account flexural and axial behaviour of the wire is developed and validated experimentally. Such a model makes it possible to predict the actual motion of the object, which significantly differs from that of the actuator.