Vibration IPMCs

The other research area involves developing IPMC applications. So far the focus has been mostly on actuators, artificial muscles, and sensors. For instance, Nafion-based accelerometers have been used as vibration sensors [Sadeghipour et al. (1992)], and IPMCs have been used as micropumps [Guo et al. (1996)]. Researchers introduced the possibility of using IPMCs as artificial muscles in robots [Shahinpoor et al. (1998)] and as energy harvesters for battery charging systems [Dogruer et al. (2007)]. 

It is clear that the Pt/Pd IPMCs have some advantages over the conventional Pt IPMCs when it comes to electromechanical actuation. Also mechanoelectrical transduction was measured by using a shaker assembly, programmed to produce sinusoidal mechanical vibration with 12.7 nun displacement. The preliminary results show that the produced voltage of a Pt/Pd IPMC is nearly twice the amplitude of the signal produced by a Pt IPMC. This enhancement of the mechanoelectrical transduction characteristic is likely due to the improved surface conductivity of Pt/Pd IPMCs. 

For the beam dynamics G(s), it suffices to use the first vibration mode of the beam since the actuation bandwidth of an IPMC actuator is relatively low, typically under 10 Hz ... 

A simple one-dimensional model of electrically-induced dynamic deformation or vibration of a cantilever beam made with such IPMC artificial muscle strips is given by the following equations ... 

The tensile strength and stress of the IPMC are measured in the same manner as those of the IP. The bending stiffness of a fully hydrated IPMC sample is estimated using the free oscillation attenuation method. By bending the sample to the appropriate initial displacement, the free vibration response can be recorded. The natural frequency of the cantilever, is obtained from the fast Fourier transform of the free vibration response curve. The stiffness of the IPMC, Egg, is determined using Eq. 4, which is based on the thin cantilever beam theory of material mechanics ... 

Back to die lice bending case, in order to accommodate the vibration dynamics of the beam, we cascade G(s) to H s), as illustrated in Fig. 6. As the output of G s) represents the bending displacement (as that of/f(s) does), G s) will have a dc gain of 1. Since the actuation bandwidth of an IPMC actuator is relatively low (under 10 Hz), it often suffices to capture the mechanical dynamics G(s) with a second-order system (first vibration mode) ... 

Fig. 14 (Left) A patterned IPMC and right) schematic of the IPMC imdetgoing torsional vibration (Reproduced from Cha et al. 2013b)...

Blocking force of an IPMC can be determined by using a load cell with suitable operating range. As the measured forces are typically in the range of millinewtons, even the shghtest vibrations can affect the experimental results. 

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