Impact Hammer Testing
Each part in a vehicle goes through tremendous stress through their life cycle. All these parts have to be tested individually to ensure they are fit for use. To understand modal analysis, I picked vehicle disc rotors to perform Impact Hammer Testing. I used this test to understand the kind of hammer tips to use in such tests and also analyzed for bending and torsional vibrations.
Modal Accelerometers were placed along 72 points on the disc rotor. Impact hammer with force transducers was used to create an impact force along these points. The data was recorded and post processed using Siemens DAC and Siemens TestLab.
Natural frequencies associated with the modes of vibration was calculated analytically and then an experimental modal survey was performed on the structure. The experimentally determined frequencies were compared to the calculations.
The concepts of modal frequencies, mode shapes and the utilization of the frequency response function matrix to analyze the modal parameters was demonstrated. The significance of choosing the right tip for the impact hammer and the concepts of drive point measurement and reciprocity were learnt.