Active Vibration Control of a Flexible Cantilever Beam by Applying Thermal Bending Moment

Abstract

Digital vibration control of a flexible cantilever beam using a thermal bending mo ment caused by the temperature gradient across the section of the beam is attained both by experi ments and simulations. Foil strain gauges bonded on the surfaces of the beam are used as an actuator which is capable of producing a thermal gradient. Thermal bending moments are applied in the proper sense to a flexible cantilever beam having very low natural frequency so that active control of the first mode bending vibration is realized. Experimental results show that the damping ratio is increased by about ten times. Simulations are based on the theoretical analysis in which the equation of state is derived from the equation of bending vibration for the beam, considering the heat flow on both upper and lower surfaces. A linear control law is determined based on the digital optimal regulator theory. A minimal order state observer is used to estimate a state variable which is not available in the measurements. Experimental results are consistent with the simulated ones.