UACE: Target echo strength of layered media with an active surface

• Session: 17. Target Echo Strength – Measurements and Modelling
  Organised by: David Nunn 
• Lecture: Target echo strength of layered media with an active surface
  Paper ID: 2195
  Author(s): Kevin Hostombe, Delf Sachau
  Presenter: Kevin Hostombe
  Abstract: Layered media, in form of both fluid layers and solid structures, play an important role in underwater acoustics. Typical applications are acoustic windows for sonar systems or absorption layers for submarines. However, the either desired total absorption, total reflection or total transmission is not achieved in practice. The vibro-acoustic behaviour of an object plays a particularly important role in the resulting target echo strength. Active surfaces, for example made of piezo-ceramics, increase the possibilities of influencing the target echo strength beyond the geometry, material properties and material composition of the layer.\nThis study compares the target strength behaviour of different layered media including active surfaces for underwater applications. An analytical model is first used to estimate the reflection and transmission behaviour. A multiphysics-simulation of the layered media is then used to investigate the vibro-acoustic behaviour of the solid structures, the influence of the active surface and the resulting reflection and transmission behaviour. When the reflection of a surface is minimized by an active coating, the transmission increases significantly. This is a particular problem in layered media, as the transmitted sound waves can cause subsequent layers and structures to vibrate and thus increase the total target echo strength. Various countermeasures are being investigated to prevent this.\n
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• Corresponding author: Mr Kevin Hostombe
  Affiliation: Helmut-Schmidt-University, Hamburg
  Country: Germany