Active vibration control of a beam instrumented with MWCNT/epoxy nanocomposite sensor and PZT-5H actuator, robust to variations in temperature

Abstract

Multi walled carbon nano tube (MWCNT)/epoxy nanocomposite strain sensor and piezoelectric actuator pair are used in active vibration control (AVC) of a smart cantilevered beam. Due to different coefficients of thermal expansion of MWCNT and epoxy, the resistance of carbon nanotube/epoxy based strain sensor changes nonlinearly with change in temperature. The temperature dependence of CNT based strain sensor is modelled by fitting a polynomial curve on the experimentally obtained characterization data of CNT/epoxy strain sensor. Using augmented constitutive equations of piezoelectricity, finite element model of smart cantilevered beam instrumented with collocated nanocomposite strain sensor and PZT-5H actuator is derived. Effect of temperature on PZT-5H actuator is also considered in derivation of the control law. Active vibration control of the first mode of a smart cantilevered beam instrumented with collocated CNT based strain sensor and PZT-5H actuator is performed at ambient temperature and at temperature slightly away from the ambient temperature for two cases: (1) without considering the temperature dependence of CNT composite strain sensor in Kalman observer and (2) considering the temperature dependence of CNT composite strain sensor in Kalman observer. Simulations are also performed to visualize the behaviour of smart beam when the beam is subjected to a temperature impulse. This paper suggests a novel AVC strategy using MWCNT/epoxy strain sensor and PZT-5H actuator patch that is robust to variations in temperature.