Impact force excitation generated by an ISO tapping machine on wooden floors

Prediction of the impact sound insulation of wooden floors requires information of the excitation forces driving the structure. According to earlier research, it is evident, that the impact force generated by the ISO tapping machine on the wooden floors is different than on bare concrete floors. However, only a few measurement results of the force have been shown in the literature. The purpose of our study was to experimentally determine the impact force excitation with an instrumented ISO tapping machine on a large range of wooden floors. One of the hammers of the tapping machine was equipped with both force and acceleration sensors. The hammer itself was modified to fulfil the requirements for the tapping machine presented in the standards ISO 10140-5 and ISO 16283-2. Based on the measured force signals, force spectra and impulses exerted by the instrumented hammer were determined. According to the results, differences between the force spectra on the wooden floors were prominent in the frequencies above 500 Hz. In the low-frequency range, the variation of the driving force corresponded to a level difference of more than 3 dB. In addition, the results showed that the process of excitation was not transient for the structures studied. Thus, the vibration of the measured wooden floors did not seem to influence the impact force. The findings of this paper are of very high importance for those developing mathematical calculation tools to predict the impact sound insulation of wooden floors. (C) 2020 The Authors. Published by Elsevier Ltd.