Ultrasonic assistance is widely used in manufacturing, both for conventional (e. g. grinding, drilling) and non-conventional (e. g. EDM) processes. Ultrasonic machining is also used as a stand alone process for instance for micro-drilling. Industrial application of these processes requires increasingly efficient and accurate development tools to predict the performance of the ultrasonic device: the so-called sonotrode and the piezo-transducer. This electromechanical system consists of a structural part and of a piezo-electrical part (actuator). In this paper, we show how to combine two simulation softwares - for stuctures and electromechanical devices - to perform a complete design analysis and optimization of a sonotrode for ultrasonic drilling applications.