220 J. Berntsen and A. Brandt Table 21.1 Difference between operation and impact tests. Operational excitation frequencies are more stable than for the impact tests for all sensors Natural frequency [Hz] Mode [-] Operation Impact (DUT) Hexapod Impact (DUT) concrete Impact (No DUT) Hexapod Impact (No DUT) concrete 1 1.5 − − − − 2 3.9 3.9 3.9 3.9 3.9 3 9.8 −∗ 10 8 10 4 13.7 13.7 13.7 − 13.7 * The FRF does not show peaks but some variation can be seen for 8 and 10 Hz References 1. Brandt, A.: ABRAVIBE – A MATLAB toolbox for noise and vibration analysis and teaching, Department of Technology and Innovation, University of Southern Denmark. http://www.abravibe.com (2018) 2. Brandt, A.: Noise and Vibration Analysis. Wiley, Chichester (2011) Jesper Berntsen Background as a mechanical engineer. Worked at year at an engineering consultancy before taking a master’s degree in construction at the University of Southern Denmark. Started as an industrial PhD student in March, shortly after finishing the master’s degree.
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