Experimental Characterization of a Steel Spring Mount using Virtual Point Transformation

The application of virtual point transformation for determining the transfer dynamic stiffness of a steel spring mount is demonstrated in this experimental study. Rigid fixtures are attached to both ends of the spring, and frequency response functions are measured using impact hammer excitation. These measured frequency response functions are transformed to the virtual points, analogous to nodes in finite element analysis, with six degrees of freedom. This allows for high-quality frequency response functions to be obtained through specialized post-processing techniques. The six degrees of freedom transfer dynamic stiffness is then extracted using the inverse sub-structuring method, which eliminates the influence of the fixture dynamics. The results are validated by a direct measurement approach. Additionally, the study investigates the effects of liquid sprayed damping material coatings on the spring's transfer dynamic stiffness, revealing that certain damping materials significantly reduce vibration amplitudes at the surge frequencies, indicating effective damping properties.