In the present study, the modal properties of an ultrasonic stack are investigated. The ultrasonic stack comprises a wide horn. The horn of the ultrasonic stack is designed with the genetic algorithm. The objectives of the problem are: the main longitudinal mode shape frequency should be similar to the frequency of the transducer-booster, and this mode has adequate frequency separation from other modes. The finite element simulation is used to calculate the natural frequencies and mode shapes. An experimental modal analysis using the roving hammer method is utilized to detect real natural frequencies, and mode shapes and verify the simulation results. Based on the simulation results and due to the complex structure of the ultrasonic stack, three different setups are utilized for the experimental modal analysis. The results show that the experimental test identifies all detected modes from the finite element simulation. Also, the frequency difference between the simulation and experimental results is less than 1% in most cases. The average frequency difference between the simulation and experimental results is 1.42%. The simulation frequency of the main longitudinal mode is 14 Hz (0.07%) lower than the experimental result.
