Product: ABAQUS/Explicit
When an underwater explosion occurs, a compressive wave is generated. This wave can have a substantial effect on a submerged structure. Simulating the response of submerged structures of simple geometric shapes to simple explosion wavefront types constitutes an important part of the validation of any fluid-structure interaction code. In this example the ability of ABAQUS/Explicit to model the interaction between an air-backed elastic plate and a planar exponentially decaying wave is illustrated. The results obtained using ABAQUS/Explicit are compared with those obtained independently using the Doubly Asymptotic Approximation (Geers (1978), ABAQUS/USA Version 6.1). This problem has been solved analytically by Taylor (1950).
This problem models the interaction between an air-backed elastic plate and a weak planar exponentially decaying shock wave with a maximum pressure of 15.4 MPa and a decay time of 0.433 ms. In contrast to Taylor's solution, engineering material parameters for the fluid and solid media are used. The plate is a square of side 1 m and has a thickness of 0.00635 m. The plate is made of steel with a density of 7850 kg/m3, a Young's modulus of 210.0 GPa, and a Poisson's ratio of 0.3. The fluid is water with a density of 1000 kg/m3, in which the speed of sound is 1461 m/s. The plate is represented by a single S4R element, and the surrounding fluid is represented by a fluid region that extends from the plate to a distance of 5.5 m away from the plate in the direction of the incoming shock wave. The fluid region is modeled by a single stack of 400 AC3D8R elements. A planar nonreflective boundary condition is imposed on the exterior surface of the fluid region furthest from the plate using the *SIMPEDANCE option. The fluid response is coupled to that of the structure using the *TIE option on the fluid surface nearest to the plate and the plate itself. The fluid-solid system is excited by a planar exponentially decaying wave applied at the fluid-solid interface through the use of the *INCIDENT WAVE option. In addition, the plate motion is constrained by the use of four springs attached to the nodes of the plate, each possessing a spring constant of 4.919 MN/m. A linear bulk viscosity parameter of 0.25 and a quadratic bulk viscosity parameter of 10.0 are used.
The results from ABAQUS/Explicit show good qualitative comparison with those in the referenced literature. We also compare the translational velocity imparted to the plate obtained using ABAQUS/Explicit with that obtained using ABAQUS/USA (Version 6.1). As shown in Figure 1.13.5–1, the results agree closely.
Geers, T., “Doubly Asymptotic Approximations for Transient Motions of Submerged Structures,” Journal of the Acoustical Society of America, vol. 64, pp. 1500–1508, 1978.
Taylor, G. I., “The Pressure and Impulse of Submarine Explosion Waves on Plates,” Underwater Explosion Research, Office of Naval Research, vol. 1, pp. 1155–1173, 1950.
