Nonlinear dynamic strain analysis on rotor blade structures with embedded piezoceramic sensors for active vibration control

摘要

In this paper, a relative index method is proposed to analyze the nonlinear Von Karman strain effectson a rotor blade structure with embedded piezoceramic sensors. Although other qualitative andquantitative methods are available for nonlinear strain analysis, these methods have inherentdrawbacks. The proposed relative index method circumvents the drawbacks of both qualitative andquantitative methods. Firstly, it measures the nonlinear effect and converts it into a numerical value.The value is in the range of zero to one in which zero corresponds to negligible effects and oneindicates the highest severity of the nonlinear effects. In addition, to generate the index value, thismethod takes the whole picture of nonlinear effect response into consideration. The results of using the relative index method show that at any given mode of vibration thenonlinear effect on the sensor is relatively negligible at a high rate of rotation rather than on low. Theresults also indicate that the nonlinear effect increases at lower modes of vibration but its effect on thesensor almost levels off at higher modes. Moreover, if comparing index value of given modes ofvibration with the index value of its preceding modes, the effect of nonlinearity decreases. In addition,the results also suggest that at any given instantaneous speed of rotation the level of the nonlineareffect diminishes with the higher acceleration/deceleration operation of the blade.