Development and Validation of an In-Situ Utility Pole Simulation Model for Virtual Modal Testing

Modal testing is being investigated as a non-destructive test (NDT) method for wood poles. Modal properties of the pole must be extracted from sensor data containing frequency content associated with the interaction of the pole with its conductors. A dynamic model of a utility pole with attached conductors has been developed and validated through experimentation. The model will allow controlled, repeatable simulations of modal hammer hits for preliminary verification of pole property identification methods. The cable is modeled as a series of point masses connected by translational springs. The pole is represented by a modal expansion based on separation of variables. To facilitate creating and connecting the pole and cable models, scaling the model to represent longer pole lines, and introducing modal hammer inputs; the bond graph formalism was employed. To validate the model, an instrumented reduced-scale pole and cable system was built and tested in the laboratory. Time series measurements of cable tension and transverse motion, along with frequency-domain accelerometer data, show that the simulation model has sufficient fidelity to predict the effect of conductors on a pole’s response spectrum over the frequency range of interest.