Sloshing phenomenon consists in the movement of liquids inside partially filled tanks, which generates dynamic loads on the tank structure. Resulting impact pressures are of great importance in assessing structural strength, and their correct evaluation still represents a challenge for the designer due to the high nonlinearities involved, with complex free surface deformations, violent impact phenomena and influence of air trapping. In the present paper a set of two-dimensional cases for which experimental results are available are considered to assess merits and shortcomings of different numerical methods for sloshing evaluation, namely two commercial RANS solvers (FLOW-3D and LS-DYNA), and two own developed methods (Smoothed Particle Hydrodynamics and RANS). Impact pressures at different critical locations and global moment induced by water motion for a partially filled tank with rectangular section having a rolling motion have been evaluated and results are compared with experiments.
The aim of this contribution is to present a theoretical and numerical model applied to the ®nite deformations of elastoviscoplastic metallic materials at room temperature. The constitutive equations are integrated numerically in the context of a ®nite element formulation and numerical examples are given to demonstrate the effectiveness of the model and the numerical algorithms. The model is then compared to experimental results obtained from shear tests of a mild steel for various strain rates. Model predictions show a general agreement with experimental data for monotonic and cyclic conditions on this particular material and reproduce correctly the fast plastic loadings and unloadings in the large deformation ®eld. IntroductionThe prediction of the strength of structures subjected to fast mechanical loadings requires an accurate modelling of the real behavior of the material. Moreover when the loadings include cyclic or large deformations, it is necessary to take into account, not only the monotonic and cyclic hardening effects but also the strain rate dependence, even at room temperature.In the case of mild steels, while a great number of experiments have been performed on the cyclic dynamical behavior in tension or in compression (Favier et al., 1989b), it appears that the behavior concerning other simple mechanical tests in the large deformation ®eld is not as well-known. In this case, shear tests appear to have several advantages. Firstly, both shear and tensile samples can be machined from the same plate material form. Secondly, shear tests enable cyclic or reversed deformations to be carried out. Finally, the deformation can be considered as homogeneous throughout the shear gauge section; actually near the free ends of the sample, boundary effects disturb the strain homogeneity, but it has been shown that these effects may be neglected by using a long and thin shear zone (Rauch and G'Sell, 1989).In general, the theory of viscoplasticity takes into consideration the rate-dependent material behavior with equilibrium hysteresis and incorporates all macroscopically observable phenomena. At this time, several models have been developed and applied for viscoplastic materials, which can be divided in three main approaches. The ®rst approach is based on the classical decomposition of the inelastic strain into a plastic strain and a viscoplastic strain (Perzyna, 1966). The second approach, which corresponds to a uni®ed theory, uses only one inelastic strain (Bodner and Partom, 1975;Chaboche, 1989), is built on the framework of thermodynamics with internal variables (Sidoroff, 1975). This approach is based on the superposition of elementary hardening rules (Nouailhas, 1989) and the superposition of isotropic and nonlinear kinematic rules constitutes its basic formulation (Lush et al., 1989). Additional effects such as plastic strain range memory or recovery, justi®ed on the basis of experimental results and microstructural considerations, are introduced by using new variables or modifying the basic ones. Finally, ...
Impact pressures, due to slamming, are of particular importance in assessing local and global structural strength. Knowledge of pressure distribution and slamming forces, experimental or numerical, in the forefoot and aftbody of a ship can be used in the evaluation of global wave-induced loads, for example, whipping bending moment. Impact pressures and slamming forces for a bow section, impacting upright and at two angles of heel are presented in this article. The relevant impact loads are predicted using a range of two-dimensional potential and viscous flow methods and compared with available experimental measurements
Sloshing phenomenon consists in the movement of liquids inside partially filled tanks, which generates dynamic loads on the tank structure. Resulting impact pressures are of great importance in assessing structural strength, and their correct evaluation still represents a challenge for the designer due to the high nonlinearities involved, with complex free surface deformations, violent impact phenomena and influence of air trapping. In the present paper a set of two-dimensional cases for which experimental results are available are considered to assess merits and shortcomings of different numerical methods for sloshing evaluation, namely two commercial RANS solvers (FLOW-3D and LS-DYNA), and two own developed methods (Smoothed Particle Hydrodynamics and RANS). Impact pressures at different critical locations and global moment induced by water motion for a partially filled tank with rectangular section having a rolling motion have been evaluated and results are compared with experiments.
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