Acoustic digital twin for passive structural health monitoring.

This study presents simulation results on passive structural health monitoring of a vibrating elastic structure for defect localization. The object considered in this study consists of a shell equipped with vibration sensors surrounding a vibrating structure such that they are coupled at a finite number of points. An acoustic digital twin (ADT) is used to model the non-defective state of the external shell.

Inferring the characteristics of marine sediments from the acoustic response of a known, partially buried object.

We investigate the feasibility of using a known elastic target located near the seabed for the purpose of inferring characteristics of marine sediment. In the problem considered the object position and its burial depth are not known with precision. First, the admittance matrix of the elastic object is determined (numerically or experimentally) over a wide frequency range in the structural acoustic regime.

Bistatic scattering of an elastic object using the structural admittance and noise-based holographic measurements.

This paper presents a method to calculate the bistatic response of an elastic object immersed in a fluid using its structural Green's function (in vacuo structural admittance matrix), calculated by placing the object in a spatially random noise field in air. The field separation technique and equivalent source method are used to reconstruct pressure and velocity fields at the object's surface from pressure measurements recorded on two conformal holographic surfaces surrounding the object. Accurate reconstruction of the surface velocity requires subtraction of the rigid body response computed using a finite element approach.

Broadband transmission losses and time dispersion maps from time-domain numerical simulations in ocean acoustics.

In this letter, a procedure for the calculation of transmission loss maps from numerical simulations in the time domain is presented. It can be generalized to arbitrary time sequences and to elastic media and provides an insight into how energy spreads into a complex configuration. In addition, time dispersion maps can be generated.

An axisymmetric time-domain spectral-element method for full-wave simulations: Application to ocean acoustics.

The numerical simulation of acoustic waves in complex three-dimensional (3D) media is a key topic in many branches of science, from exploration geophysics to non-destructive testing and medical imaging. With the drastic increase in computing capabilities this field has dramatically grown in the last 20 years. However many 3D computations, especially at high frequency and/or long range, are still far beyond current reach and force researchers to resort to approximations, for example, by working in two dimensions (plane strain) or by using a paraxial approximation.