# Rotating Sonotrode Design for Ultrasonic-Assisted Arc Welding of Metal Materials

## TL;DR

This paper introduces a new rotating sonotrode design to improve ultrasonic-assisted arc welding by reducing defects and optimizing performance.

## Contribution

A novel rotating sonotrode with a groove and double thin ends is designed to enhance ultrasonic welding of metals.

## Key findings

- The groove significantly reduces the resonant frequency of the sonotrode.
- Elliptical transition mode effectively reduces stress concentration.
- Double-position joint perforation adjusts resonant frequency and amplification factor effectively.

## Abstract

In the process of the ultrasonic-assisted arc welding of metal materials, traditional ultrasonic application methods, such as the low-frequency impact of ultrasonic horns on a base material, can easily cause the non-fusion defect. In order to solve this problem, a rotating sonotrode with a groove and double thin ends was designed in this study. The ultrasonic vibration is transmitted into the weld pool by the rolling of the sonotrode on both sides of the weld. The resonant frequency was set at 50 kHz. Firstly, based on the Mindlin theory, a rotating sonotrode without a groove was designed by solving the frequency equation and by conducting a finite element simulation. Secondly, the effects of the groove, perforation, and transition mode on the resonant frequency, stress distribution, and amplification factor were investigated by finite element simulation. Finally, the optimum rotating sonotrode with a groove was obtained. The results show that the size of a rotating sonotrode that has a small frequency error can be obtained by using the discrete interval solver method combined with finite element simulation. The groove can significantly reduce the resonant frequency. The stress concentration can be effectively reduced by using the elliptical transition mode. The resonant frequency and amplification factor of a rotating sonotrode with a groove could be effectively adjusted by a method of double-position joint perforation. The final resonant frequency was 49.721 kHz and the amplification factor was 3.02. This study provides an effective design method for a sonotrode with double thin ends and a groove structure.