Finite element analysis of superharmonic and subharmonic vibrations of plates excited by intensive ultrasonic pulses

Based on the experimental observation of superharmonic and subharmonic vibrations of steel plates excited by intensive ultrasonic pulses,a finite element modeling is established and transient dynamic analyses are performed by an explicit finite element method.A piezoelectric-thermal analogy method and an interface contact-impact algorithm are used to simulate the high-power ultrasonic transducer excitation and the dynamical interaction between the transducer horn tip and the plate surface,respectively.By analyzing the vibration velocity waveforms,vibration frequency spectra and contact force time histories obtained in the simulations,it can be found that the waveform distortion of the contact forces between the horn tip and the plate surfaces is the main reason for the generation of the superharmonic vibrations. On the other hand,the intermittent contact between the horn tip and the plate is the reason for subharmonic vibrations in the plates.The numerical simulations agree with that of the experimental results.