SPRING-MASS VIBRATION ISOLATION MODULES FOR TOWED LINE SONAR ARRAYS. MODELLING AND SEA TRIALS RESULTS

摘要

In this paper, a simulation of a new vibration isolation module (VIM) design, which is a periodical cells series, delimited by internal objects coupled with the module hosewall, is developed. The mechanical transfer function (TF) of the VIM, weighted at its downstream extremity by the acoustic modules which are modelled as a rigid body and taken into account by an impedance term, is calculated with validated assumptions. The influence of geometry, material properties including hosewall loss factor, towing speed, is studied. The calculated TF are compared to experimental ones, measured at sea for a set of different kinds of VIMs. If comparisons of the TF magnitudes are not always very good, likely because some experimental parameters couldn't be taken into account in the simulation, trends are very consistent. Moreover, the TF phases are in agreement with calculated ones, and the propagation wave speeds assessed from these phase curves, are close ones to the others over different frequency bands.