Load Case Characterization and Modal Coordinate Estimates from Damper Displacements

This paper evaluates estimations of modal coordinates from chassis damper displacements on heavy vehicles. The objective is to study to what extent relative displacements are sufficient as control input for semi active damping systems. The possibility to combine passive damping requirements at different driving conditions is furthermore investigated by studying damper displacements in the phase plane. For both objectives, vehicle simulations with a 3D - tractor semi trailer model are utilized.

Results show that modal coordinate estimates based solely on relative damper displacements, during impact for transient load cases show significant discrepancies to actual motion. For subsequent free oscillations, modal coordinates may however be estimated this way.

Phase plane plots are finally shown to be useful tools to illustrate conflicting demands on passive damping characteristic and to rate expected benefits from different damper techniques.