Analytical modeling of ultrasonic surface burnishing process: Evaluation of through depth localized strain.

Highlights • Analytical model of plastic strain based on contact mechanic theorem in ultrasonic burnishing process has been proposed. • Values of plastic strain and relevant distribution have been verified by numerical simulation. • The obtained results of through depth applied strain were completely in line with variation of through depth hardens. Abstract During surface treatment process, microstructure change beneath the surface layers and relevant mechanical properties depend to amount of work hardening occurs through depth of the treated samples. In the present work, an analytical model of surface plastic strain based on contact mechanic theorem is proposed to analyze the ultrasonic burnishing parameters. The model comprises effect of factors such static force, feed rate, ball diameter and ball material as well as ultrasonic vibration parameters such as amplitude and frequency. To incorporate effect of feed rate, two important parameters such as linear coverage coefficient and overlapping ratio have been defined and contributed in the model. The through depth localized plastic strain has been verified by 3D finite element simulation model for different parameter combination. Since, in surface treatment process such as ultrasonic burnishing the surface hardness and microstructure is directly influenced by the plastic strain, a series of experiments have been carried out and through depth hardness profiles has been obtained. It was found from the results that the through depth plastic strain distribution is consistent well with that derived from FE simulation. According to the analytical model, surface plastic strain and relevant affected depth increases by increase of static force and vibration amplitude. Also, it decreases by increase of ball radius and feed rate. On the other hand, it was found that using tungsten carbide ball significantly enhances the surface plastic strain compared to the ball made of steel and silicon nitride. The analytical model of strain and relevant affected depth was completely in line with the variation of through depth hardness and relevant hardened depth. Graphical abstract Image, graphical abstract [ABSTRACT FROM AUTHOR]