Hydrostatic equilibrium

About: Hydrostatic equilibrium is a research topic. Over the lifetime, 2451 publications have been published within this topic receiving 62172 citations.

An accurate and stable alternating directional moving particle semi-implicit method for incompressible flow simulation

Abstract: As a Lagrangian mesh free method, Moving Particle Semi-implicit (MPS) method can easily handle complex incompressible flow with free surface. However, some deficiencies of MPS method such as inaccurate results, unphysical pressure oscillation and particle thrust near free surface still required to be further resolved. In this paper, an improved MPS method based on Crank-Nicolson time scheme, named Alternating Direction Moving Particle Semi-implicit (ADMPS) method, is proposed. In addition, a time integral source term (TIS) is developed to suppress unphysical pressure oscillation and a free-surface revise (FR) technique is proposed to avoid particle thrust near free surface. Enhancement of accuracy and stability by these improvements is proved by hydrostatic and dam breaking benchmarks, and the numerical results of the ADMPS-FR-TIS model show good agreement with the hydrostatic analytical solution and the dam breaking experiment data.

Statistical approach to description of stressed state of syntactic foam microstructure

Abstract: Object and purpose of research. The object of research is a composite material of the syntactic foam type (SF), which forms a heterogeneous medium consisting of a polymer matrix filled with spherical inclusions- micro spheres. The paper suggests that distribution of micro spheres in SF should be used as a qualitative measure for estimation procedures. Comparison of such distribution for various models can be used for explaining the SF efficiency estimations. Materials and methods. The initial data inputs for the study were the composition and structure of syntactic foam and characteristics of its components: polymer matrix and glass micro spheres. Numerical studies were carried out using the earlier developed structural model of SF deformation and damage. The structural model assesses the stressed-strained state of large micro sphere assemblies (models with a number of spheres about 105 are used in the study). Results obtained by the model let us use statistical methods of processing the stress raisers and identify patterns of distributions for predicting the SF strength. The results are verified by comparison with estimations by finite element models. Main results. The structural model of deformation and damage is highly effective in calculation of the stressed-strained state of micro structures with a number of micro spheres of about 105 and more. Conclusion. The structural model developed for SF makes it possible to accurately assess the stresses of its components under external hydrostatic pressure considering a large number of micro spheres. The results show excellent convergence of the stressed-strained state estimates with detailed estimations by FE models. With accurate data on the stressed-strained state of micro structure one can predict how the damage would develop and calculate the process to failure and full loss of buoyance.

A reduced order model for FSI of tank walls subject to wave impacts during sloshing

Abstract: Loads due to wave impacts are a limiting factor in the design of liquefied natural gas (LNG) tankers and their insulation. The current methodology considers the load independent from the response of the tank. Better tanks can be designed by knowing the effect of the interaction between the wave loads and the response, however predicting these effects is computationally expensive. In this paper a new application of the non-hydrostatic shallow water equations are presented, namely as a reduced order model (ROM) for fluid structure interaction for wave impacts. Our ROM is compared to a high fidelity model. The proposed ROM is fast and accurately predicts the total impulse and added mass, and therefore the general behaviour of the structure during the free vibration phase. It does however not always accurately predict the maximum force. It is therefore considered an appropriate tool for a first screening of the loads for which fluid-structure interaction is important, after which a more accurate method can be used to evaluate the most interesting cases. A sensitivity study is performed for various impact angles and velocities, showing that the importance of fluid structure interaction depends highly on the specific situation.

The dependence of the deformation behavior of fiberglass pipes on the initial disorientation of reinforcement subjected to repeated-static internal hydrostatic pressure and axial tension

Abstract: The problems of influence of the technological reinforcement disorientation on the deformation behavior of composite tubular elements subjected to repeated-static internal hydrostatic pressure and axial tension, as well as the resistance to fracture of these elements subjected to the above-mentioned loading are discussed. The experimental part of research is carried out applying thin-walled tubular elements manufactured from the fiberglass fabric prepreg based on the modified epoxy resin. It is established that a possible deviation of the reinforcement angle from 60 to 80 taking place during the processing of material into goods has little effect on the fracture resistance both subjected to the internal hydrostatic pressure and axial tension of fiberglass pipes manufactured so that the directions of reinforcing fiberglass fabric warp and ones axis are coincided. Meanwhile, the following was stated that the accompanied shearing deformations are arising besides the basic cyclic deformations (noted in the direction of force application) for initially disorientation fiberglass pipes in difference from non-disoriented ones at the condition of pulsating (irregular) loading by the above-mentioned load-bearing factors. Calculations are proved that the reinforcement disorientation direction in the above-underlined limits is brought to the significant decrease of the energy dissipation coefficient of fiberglass pipes. The statement aiming the constructional solution of the problem is formulated in a sense of negative influence of the technological reinforcement disorientation on the composite tubular elements functioning at the conditions of cyclic axial tension and internal hydrostatic pressure.