Study on fracture behaviors of nanocomposite ceramics under a high cycle stress

Abstract

In order to clarify the fracture behaviors of nanocomposite ceramics under ultrasonic vibration-aided grinding, the stress under ultrasonic was analyzed by non-local elastic theory. A similarity model of bending fracture experiment was built to allow online observation of fracture process, according to the actual conditions of fracture damage under ultrasonic vibration-aided grinding and the similarity law. The experiments validated the theoretical analysis: as the ultrasonic frequency increases, fatigue life is distinctively shorter, and the fatigue crack extends faster and is more stable; the deflection angle decreases as the ultrasonic frequency increases, and it is biggest (47.53°) under 19.9 kHz; the phase transition occurs in the fracture process and the amount of phase transformation increases with the increase in ultrasonic frequency and zirconia content, and it can reach the maximum value when the zirconia content is about 25% and then declines; the greater the ultrasonic frequency, the more obvious the transgranular fracture, the more microcracks on the crystal layers, and the more smooth the fracture surface.

Mechanism of online dressing for micro-diamond grinding wheel during the ultrasound-aided electrolytic in-process dressing grinding

“…At the same time, the ultrasonic cavitation and other functions of ultrasonic can accelerate the scouring of grinding fluids on grinding wheel, making grinding chip off quickly, which improves the truing effect of the grinding wheel to a certain extent. 19 Based on the characteristics of ELID grinding technology and ultrasonic vibration grinding, to complement each other, this paper proposed the combination of ELID grinding and ultrasonic vibration dressing, namely ultrasound-aided ELID grinding. The method would improve the finishing effect of the grinding wheel in the realization of online dressing, increase machining efficiency and quality of the grinding wheel, and finally results in an efficient mirror continuous finishing technique.…”