An alternative explanation of forming force reduction for forming process submitted to vibration: Influence of the waveform in the viscoplastic domain

This article addresses the effects of vibrations on a viscoplastic workpiece applied during the forging process. To achieve this goal, a phenomenological model based on the slice method combined with a Norton–Hoff viscoplastic law is developed. It allows to study the impact of vibration on the reduction of the mean forging load which has been experimentally observed before, and demonstrates that the sensitivity to strain rate is a key parameter. Moreover, based on the model, a new waveform of the vibrations is proposed that enhance the mean forging load reduction. Finite element simulations and experiments have been performed to evaluate the validity of the model in the case of sinusoidal and triangular waveforms, and are in good agreement with the analytical model's predictions.