Tensile fracture test of nanocomposite ceramics under ultrasonic vibration based on nonlocal theory

Abstract

Based on non-local theory, the dispersion characteristics of ultrasonic vibration in Specimen tension are analyzed, and the effects of ultrasonic frequency and amplitude on the wave dispersion are obtained through theoretical analysis. Tensile tests were carried out using an ultrasonic vibration system and specimens, and the test process as well as test parts were observed and analyzed. The influence of the ultrasonic vibration on fracture properties and the change of grain micro-organization under different loading conditions were verified by experiments. The introduction of ultrasonic vibration changes the internal stress of the ceramic fracture, affects the hardness of the workpiece, and also leads to the scattering of particles, which leads to the aggravation of ultrasonic attenuation and phase velocity dispersion. SEM and XRD analyses showed that with the increase in ultrasonic frequency and amplitude，the trans -granular fracture was more obvious, the micro-cracks and dimples increased, and micro-pores increased in size and number. The tensile stress produced by ultrasonic vibration will induce the transformation from T-phase ZrO2 particles to M-phase ZrO2 particles and absorb strain, which greatly improves the plastic mechanical properties of nanocomposite ceramics. Due to the inherent phase transformation toughening mechanism, the material improves the plastic mechanical properties under the ultrasound excitation, and it is easier to achieve ductile domain processing.