State Key Laboratory of Structure Analysis for Industrial Equipment

Dalian, China

State Key Laboratory of Structure Analysis for Industrial Equipment

Dalian, China
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Li L.,Shanghai JiaoTong University | Hu Z.,Shanghai JiaoTong University | Hu Z.,State Key Laboratory of Structure Analysis for Industrial Equipment | Jiang Z.,China National Offshore Oil Corporation
Mathematical Problems in Engineering | Year: 2013

This paper deals with ship-jacket platform collisions. An examination on NORSOK N-004 rule is carried out. Furthermore, elastic and plastic response of jacket platform is studied. This paper also conducts a sensitivity analysis, focusing on collision points. Simulation models of a ductile and a rigid supply vessel were developed, as well as models of two typical jacket platforms. Data such as collision force, kinetic energy, and deformation energy have been obtained. Several conclusions have been drawn: NORSOK rule underestimates the resistance for certain indention, due to inaccurate description of column deformation mode. Elastic response is extremely important in dynamic analysis of ship-platform impacts, by contributing to reducing impact loads and local energy dissipation. Struck members are therefore subjected to impacts to a low extent, which can be regarded as result of a buffering effect. Before a buffering effect works, a time delay exists. This is caused because the topside has to take up adequate kinetic energy. Striking position has an effect on dynamic behavior of platform. High local strength is in favor of buffering an effect. Elastic response is more significant in a flexible platform than in a sticky one. © 2013 Liang Li et al.


Chen Z.,National University of Singapore | Zong Z.,State Key Laboratory of Structure Analysis for Industrial Equipment | Zong Z.,Dalian University of Technology | Liu M.B.,Peking University | And 5 more authors.
Journal of Computational Physics | Year: 2015

In this paper, an improved SPH model for multiphase flows with complex interfaces and large density differences is developed. The multiphase SPH model is based on the assumption of pressure continuity over the interfaces and avoids directly using the information of neighboring particles' densities or masses in solving governing equations. In order to improve computational accuracy and to obtain smooth pressure fields, a corrected density re-initialization is applied. A coupled dynamic solid boundary treatment (SBT) is implemented both to reduce numerical oscillations and to prevent unphysical particle penetration in the boundary area. The density correction and coupled dynamics SBT algorithms are modified to adapt to the density discontinuity on fluid interfaces in multiphase simulation. A cut-off value of the particle density is set to avoid negative pressure, which can lead to severe numerical difficulties and may even terminate the simulations. Three representative numerical examples, including a Rayleigh-Taylor instability test, a non-Boussinesq problem and a dam breaking simulation, are presented and compared with analytical results or experimental data. It is demonstrated that the present SPH model is capable of modeling complex multiphase flows with large interfacial deformations and density ratios. © 2014 Elsevier Inc.


Liu G.R.,National University of Singapore | Wang Z.,National University of Singapore | Wang Z.,Dalian University of Technology | Zhang G.Y.,National University of Singapore | And 3 more authors.
Mechanics of Advanced Materials and Structures | Year: 2012

In this work, the edge-based smoothed point interpolation method (ES-PIM) is extended to treat material discontinuity problems. The PIM shape functions used in the ES-PIM possess the Delta function property, which allows straightforward imposition of point essential boundary conditions and, hence, no additional treatment needs to be applied along the interface to meet the interface condition. By performing the generalized strain smoothing operation within the edge-based smoothing domains, the ES-PIM models possess a number of good features compared with the standard FEM using the same set of linear triangular elements, such as better accuracy, higher convergence rate, and efficiency. Three typical numerical examples, including the benchmark sandwiches cantilever beam, a hollow cylinder with two different materials and an automotive part of complicated shape, have been studied using the present ES-PIM. Analytical solutions for the first two problems have also been derived and presented. Very good agreement between the numerical results and the given analytical reference solutions demonstrate the effectiveness of the present ES-PIM method. © 2012 Copyright Taylor and Francis Group, LLC.


Yu Z.,Shanghai JiaoTong University | Hu Z.,Shanghai JiaoTong University | Hu Z.,State Key Laboratory of Structure Analysis for Industrial Equipment | Wang G.,ABS Greater China Division
Analysis and Design of Marine Structures - Proceedings of the 4th International Conference on Marine Structures, MARSTRUCT 2013 | Year: 2013

A theoretical model is introduced in this paper for structural performances of the stiffeners on the double bottom floor plating in a shoal grounding accidental scenario. It is based on a study of the progressive deformation process of numerical simulation results and the plastic analytical methods. Special emphasis is laid on establishing the characteristic deformation mechanism and identifying the major energy dissipation pattern. When calculating the structural performances of ship bottom during ship grounding accident, a prevailing method is to smear the stiffeners into the plating thickness for simplicity. Thus, the corresponding structural responses of the stiffeners are involved in the smeared plating. However, this method may not provide an accurate prediction of the structural performance characteristics of the stiffeners, and the deformation process of the stiffeners cannot be mastered. Therefore, a theoretical model is proposed in this paper to provide a deep insight into the deformation patterns with reasonable predictive accuracy. Using the plastic analytical method, the expressions of distortion energy composed of the crushing, bending, and membrane stretching effect of stiffeners on the floor plating are formulated, and the formulae of subsequent grounding resistances are obtained. The numerical simulation software LS-DYNA is employed to verify the proposed method. It covers a wide range of slope angles and indentations of shoal grounding scenarios. The results of the proposed simplified analytical method compare favorably with those of the numerical simulations and good predictive accuracy is acquired. Furthermore, the theoretical model proposed can conveniently lend itself for quick assessments of the performances of ship double bottom structures during shoal sliding grounding scenario, and it will benefit the application of accidental limit state design concept in the ship design stage. © 2013 Taylor & Francis Group.


Cao H.,Harbin Institute of Technology | Chu Y.,Harbin Institute of Technology | Wang E.,Harbin Institute of Technology | Cao Y.,Harbin Institute of Technology | And 3 more authors.
Journal of Propulsion and Power | Year: 2015

The barrel erosion, one type of accelerator grid erosion in an ion thruster, is important and needs more detailed studies. In this paper, a three-dimensional numerical simulation code is developed using a hybrid immersed-finiteelement particle-in-cell method and Monte Carlo collisions method; the dynamics of a neutral atom is modeled using a direct simulation Monte Carlo method; and a numerical simulation study is run to investigate the mechanism of aperture barrel erosion of an ion thruster accelerator grid. Simulation results indicate that the aperture barrel erosion of ion thruster accelerator grid is entirely caused by the charge-exchange ions under nominal operating condition, and the incident charge-exchange ions in four regions, namely the upstream region, the extraction (center) region, the extraction (edge) region, and downstream of the accelerator grid, are the causes of aperture barrel erosion. Highenergy charge-exchange ions originated from upstream region are not well focused and play an important role in the erosion of the aperture barrel. Charge-exchange ions originated from the extraction (center) region, which play an important role in the whole incident charge-exchange ions, also cause significant erosion on the aperture barrel. It is therefore believed that these findings would facilitate the prediction of aperture barrel erosion of an ion thruster accelerator grid. © 2015 by the American Institute of Aeronautics and Astronautics, Inc. All rights reserved.


Jiang S.,State Key Laboratory of Structure Analysis for Industrial Equipment | Jiang S.,University of Missouri | Zhang H.,State Key Laboratory of Structure Analysis for Industrial Equipment | Zheng Y.,State Key Laboratory of Structure Analysis for Industrial Equipment | And 2 more authors.
Journal of Physics D: Applied Physics | Year: 2010

The effect of loading path on the mechanical behaviour of single crystalline copper nanowires is investigated with molecular dynamics simulations. Different loading conditions including pre-tensile torsion and pre-torsional tension at different temperatures are taken into consideration. It is found that elastic pre-loading conditions can induce a distinct weakening on the resistance against plastic deformation under later applied loads. Meanwhile, coupled thermal and pre-loading effect can also facilitate the transformation from elasticity to plasticity. Formations of fivefold twins are observed in copper nanowires subjected to the loading path with tension after pre-torsion. These fivefold twins all form at the necking stage before fracture, and are found to be pre-torsion- and size-dependent but insensitive to the change in temperature and cross-sectional shape. The results reported here indicate that the loading path effect on the mechanical behaviour plays an important role in the formation of some special microstructures such as multiple twins in metallic nanowires. © 2010 IOP Publishing Ltd.


Zou L.,Dalian University of Technology | Zou L.,State Key Laboratory of Structure Analysis for Industrial Equipment | Zong Z.,State Key Laboratory of Structure Analysis for Industrial Equipment | Zong Z.,Dalian University of Technology | And 2 more authors.
Physics Letters, Section A: General, Atomic and Solid State Physics | Year: 2010

In this Letter, the differential transform method is developed to solve solitary waves governed by Camassa-Holm equation. Purely analytic solutions are given for solitons with and without continuity at crest. A Padé technique is also combined with DTM. This provides us a new analytic approach to solve soliton with discontinuity. © 2010 Elsevier B.V.


Zhou P.,State Key Laboratory of Structure Analysis for Industrial Equipment | Wu C.W.,State Key Laboratory of Structure Analysis for Industrial Equipment
Journal of Power Sources | Year: 2010

We developed an equivalent capillary model of a microscale fiber-fence structure to study the microscale evolution and transport of liquid in a porous media and to reveal the basic principles of water transport in gas diffusion layer (GDL). Analytical solutions using the model show that a positive hydraulic pressure is needed to drive the liquid water to penetrate through the porous GDL even consisting of the hydrophilic fibers. Several possible contributions for the water configuration, such as capillary pressure, gravity, vapor condensation, wettability and microstructures of the GDL, are discussed using the lattice Boltzmann method (LBM). It is found that the distribution manners of the fibers and the spatial mixed-wettability in the GDL also play an important role in the transport of liquid water. © 2009 Elsevier B.V. All rights reserved.


Chen Z.,State Key Laboratory of Structure Analysis for Industrial Equipment | Chen Z.,Dalian University of Technology | Zong Z.,State Key Laboratory of Structure Analysis for Industrial Equipment | Zong Z.,Dalian University of Technology | And 4 more authors.
Ocean Engineering | Year: 2013

In this paper, the pressure on solid boundaries in 2D sloshing problem for forced rolling motion is numerically investigated using smoothed particle hydrodynamics (SPH) method. The improved SPH model applied in this paper combines some advanced correction algorithms. The Moving Least Squares (MLS) method is used in the density reinitialization to obtain smoother and more stable pressure field in numerical simulation. An improved coupled dynamic solid boundary treatment (SBT) algorithm is implemented, and great improvement in the pressure field near solid boundaries is achieved. To analyze the pressure of specified points on solid walls, a special pressure measurement method on solid walls based on the coupled dynamic SBT method is given. In this method, both the physical pressure of the boundary particle and a correction term based on the repulsive forces are taken into account. Numerical results obtained show good agreement with the experimental ones in the analysis of both the pattern of the flow field and the pressure on the solid boundary. Further conclusions based on these results are discussed. © 2012 Elsevier Ltd.


Chen Z.,State Key Laboratory of Structure Analysis for Industrial Equipment | Chen Z.,Dalian University of Technology | Zong Z.,State Key Laboratory of Structure Analysis for Industrial Equipment | Zong Z.,Dalian University of Technology | And 3 more authors.
International Journal for Numerical Methods in Fluids | Year: 2013

In this paper, the performance of the incompressible SPH (ISPH) method and an improved weakly compressible SPH (IWCSPH) method for free surface incompressible flows are compared and analyzed. In both methods, the Navier-Stokes equations are solved, and no artificial viscosity is used. The ISPH algorithm in this paper is based on the classical SPH projection method with common treatments on solid boundaries and free surfaces. The IWCSPH model includes some advanced corrective algorithms in density approximation and solid boundary treatment (SBT). In density approximation, the moving least squares (MLS) approach is applied to re-initialize density every several steps to obtain smoother and more stable pressure fields. An improved coupled dynamic SBT algorithm is implemented to obtain stable pressure values near solid wall areas and, thus, to minimize possible numerical oscillations brought in by the solid boundaries. Three representative numerical examples, including a benchmark test for hydrostatic pressure, a dam breaking problem and a liquid sloshing problem, are comparatively analyzed with ISPH and IWCSPH. It is demonstrated that the present IWCSPH is more attractive than ISPH in modeling free surface incompressible flows as it is more accurate and more stable with comparable or even less computational efforts. © 2013 John Wiley & Sons, Ltd.

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