Laboratory for Dynamics of Machines and Structures 
Development of an automatic modal hammer

Diploma thesis, LADISK, Faculty of Mech Eng, Univ of Ljubljana, August 2019
From the early beginnings of the experimental modal analysis, one of the research focus is oriented towards the development of reliable and efficient ways of dynamic excitation. Usually the excitation is performed using an impact hammer, which proves to be efficient, however the accuracy and the impact location are highly subjected to the user experience. To improve on the realization of ideal impulse force, the human effect had to be excluded and isolated from the force generation with incorporation of an electrical power source to mechanical force transducer. A prototype of an automatic modal hammer with linear solenoid as force generator and 555IC timer as control chip was developed within this thesis. The excitation system is able to generate a reproducible, adjustable and short excitation impulse force, which enables the excitation of the structure in a broader frequency range. In this way it is possible to obtain more precise and reproducible measurement of modal characteristics, compared to a manual impact hammer.