A MODAL INTERACTION INDICATOR FOR QUALIFYING Cs AS AN INDICATOR OF STRENGTH OF COUPLING BETWEEN SEA SUBSYSTEMS

In two previous papers [1, 2], a technique for the indication of strength of coupling between SEA subsystems was proposed. However, an apparent limitation to the use of the coupling strength indicatorCS was revealed by computational simulation. Whereas a value for CSgreater than 0·07 clearly indicates weak coupling, a smaller value only confirms strong coupling between subsystems when the uncoupled resonance frequencies of each subsystem are sufficiently proximate. In order to overcome this major difficulty in the interpretation of small values for CS, an indicator of modal interactionMp is proposed. In the case of weak coupling, modal interaction is directly related to the proximity between uncoupled resonance frequencies. The definition of Mprelies upon both a deterministic analysis of the coupling between two oscillators and a statistical model of interaction between uncoupled resonant modes.Mp can be assessed on assembled structures and improves the reliability ofCS as an indicator of strength of coupling between SEA subsystems.