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 helical coil spring 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 excitations. These frequency response functions are transformed into virtual points, analogous to a node in finite element analysis, with six degrees of freedom. The six degrees of freedom transfer dynamic stiffness is then extracted using the inverse substructuring method, which eliminates the need to account for fixture dynamics. The results are validated by a direct measurement approach. Additionally, the study investigates the effect of liquid applied sprayed damping coatings on the spring's transfer dynamic stiffness, revealing that the coating significantly reduces vibration amplitudes at the surge frequencies. This suggest that the springs effective damping properties are enhanced.