Abstract:The governing system of differential equations for the linear problem of the transient interaction of plane acoustic waves and a submerged elastic cylindrical shell is transformed into a system of Volterra integral equations of the second kind. The integral equations are solved by a step-by-step integration scheme and numerical results to the problem are obtained exactly within the limit of series solution imposed by the Gibb’s phenomenon and within the limit of numerical truncation and roundoff errors. Detail… Show more
“…10 with the 8-term finite series analytical solution found by Huang (1970). Again, very good agreement between the finite element and analytical solutions is seen.…”
Section: Infinite Cylinder Subjected To a Plane Acousticsupporting
confidence: 64%
“…These analyses examined the elastic response of a spherical shell and an infinite cylinder to loading from a plane acoustic step wave propagating through an acoustic fluid media. Huang (1969Huang ( , 1970) solved these problems analytically, using a direct inverse Laplace transform of a finite number of terms of the infinite series expansion of the equations for the respective shells. For our finite element analyses, the same material properties, parameters, and nondimen- Spherical Shell Subjected to a Plane Acoustic Step Wave Figure 3 shows the geometry of the spherical shell subjected to a plane acoustic step wave problem.…”
Section: Coupled Analysis Of Classical Problemsmentioning
The application of coupled Lagrangian-Eulerian analysis to various types of underwater shock problems was investigated, with the verification and validation of this analysis approach in mind. Analyses were conducted for a simple TNT detonation problem and for the classical problems of an infinite cylindrical shell and a spherical shell loaded by a plane acoustic step wave. The advantages, disadvantages, and limitations of this approach are identified and discussed.
“…10 with the 8-term finite series analytical solution found by Huang (1970). Again, very good agreement between the finite element and analytical solutions is seen.…”
Section: Infinite Cylinder Subjected To a Plane Acousticsupporting
confidence: 64%
“…These analyses examined the elastic response of a spherical shell and an infinite cylinder to loading from a plane acoustic step wave propagating through an acoustic fluid media. Huang (1969Huang ( , 1970) solved these problems analytically, using a direct inverse Laplace transform of a finite number of terms of the infinite series expansion of the equations for the respective shells. For our finite element analyses, the same material properties, parameters, and nondimen- Spherical Shell Subjected to a Plane Acoustic Step Wave Figure 3 shows the geometry of the spherical shell subjected to a plane acoustic step wave problem.…”
Section: Coupled Analysis Of Classical Problemsmentioning
The application of coupled Lagrangian-Eulerian analysis to various types of underwater shock problems was investigated, with the verification and validation of this analysis approach in mind. Analyses were conducted for a simple TNT detonation problem and for the classical problems of an infinite cylindrical shell and a spherical shell loaded by a plane acoustic step wave. The advantages, disadvantages, and limitations of this approach are identified and discussed.
“…(21) and (22) give the late time shell deflections long after the incident wave has engulfed the outer shell and they can also be This procedure has been demonstrated to be quite effective in previous studies of the single cylindrical shell problem [ 4,5].…”
Section: Solution S In the Laplace Transform Domainmentioning
confidence: 99%
“…[4] and plotted in solid lines for the case wherein the outer shell is absent. (22) and (24) respectively.…”
Section: S (T) -A~( T ) -~~( T) + R'( T) + R C ( T )mentioning
confidence: 99%
“…in order to juxtapose solutions to those for a single shell previously obtained in Ref. [4], the version of shell equations of motion used therein is also used here . In the Laplace transform domain , they are…”
The transient response of a system of two initially concentric circular cylindrical elastic shells coupled by an ideal fluid and impinged upon by an incident plane pressure pulse is studied. The classical techniques of separation of variable and Laplace transforms are employed for simultaneously solving the wave equations governing the fluid motions and the shell equations of motion. The transformed solutions are arranged in such a manner that their inverse transforms can be accurately calculated by solving a set of Volterra integral equations in the time domain. A sample calculation of shell responses was performed and results are compared to the case in which the outer shell is absent. It is found that the primary effects of a thin outer shell could be estimated by simple asymptotic formulas.
SUMMARYSuperposition principle is used to separate the incident acoustic wave from the scattered and radiated waves in a displacement-based finite element model. An absorbing boundary condition is applied to the perturbation part of the displacement. Linear constitutive equation allows for inhomogeneous, anisotropic materials, both fluids and solids. Displacement-based finite elements are used for all materials in the computational volume. Robust performance for materials with limited compressibility is achieved using assumed-strain nodally integrated simplex elements or incompatible-mode brick elements. A centereddifference time-stepping algorithm is formulated to handle general damping accurately and efficiently. Verification problems (response of empty steel cylinder immersed in water to a step plane wave, and scattering of harmonic plane waves from an elastic sphere) are discussed for assumed-strain simplex and for voxel-based brick finite element models. A voxel-based modeling scheme for complex biological geometries is described, and two illustrative results are presented from the bioacoustics application domain: reception of sound by the human ear and simulation of biosonar in beaked whales.
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