Horn failure prediction in presence of internal defect in ultrasonic machining process through numerical investigation

Ultrasonic machining is an advanced machining process which is applied for the machining of tough and fragile materials viz. glass, ceramics, etc. The ultrasonic horn is a most essential component used to transfer the longitudinal mode of vibration to the ultrasonic tool through a transducer. This investigation has considered the design of two different profiles of ultrasonic horns (cylindrical & stepped) using tungsten carbide material in dynamic conditions. Modal analysis is performed to calculate the mode shapes and natural frequencies of both the horn profiles. The dimension of the horns under the frequency of 20 kHz is considered. The analysis is performed using ANSYS 18.1 workbench interface. Harmonic response analysis is executed to compute the stress and deformation behaviour of both the horn profiles. After the stresses are generated, a defect is introduced at the maximum stress point in both the horn design. The defects are generated in three different orientations, viz. along the longitudinal axis, perpendicular axis, and another one is inclined with respect to the oscillation of the horn. The maximum stress is generated in the stepped horn that is 370.55 MPa, where the defect is located at perpendicular to the longitudinal axis with respect to the oscillation of the horn. The current analysis can be considered as the tool to understand the behaviour of the horn in the presence of a defect in ultrasonic machining.