scholarly journals Improvements of Beam Structural Modelling in Hydroelasticity of Ultra Large Container Ships

2011 ◽  
Author(s):  
Ivo Senjanovic´ ◽  
Nikola Vladimir ◽  
Sˇime Malenica ◽  
Marko Tomic´
Keyword(s):  
Structural Model ◽  
Numerical Procedure ◽  
Effective Stiffness ◽  
Design Stage ◽  
3D Fem ◽  
Fem Model ◽  
Engine Room ◽  
Hydroelastic Analysis ◽  
Large Container

Increase in global ship transport induces building of Ultra Large Container Ships (ULCS), which have a capacity up to 14000 TEU with length up to 400 m, without changes of the operational requirements (speed around 27 knots). Natural frequencies of such ships can fall into the range of encounter frequencies in an ordinary sea spectrum. Present Classification Rules for ship design and construction don’t cover such conditions completely and hydroelastic analysis of ULCS seems to be the appropriate solution for analysis of their response in waves. This paper deals with numerical procedure for ship hydroelastic analysis with particular emphasis on improvements of the present beam structural model. The structural model represents a constitutive part of hydroelastic mathematical model and generally it can be formulated either as 1D FEM or 3D FEM model. For the preliminary design stage hydroelastic model derived by coupling 1D FEM structural model and 3D BEM hydrodynamic one seems to be an appropriate choice. Within the paper the importance of hydroelastic approach and methodology of hydroelastic analysis are elaborated. Further on, structural model based on advanced beam theory is described in details. The improvements include taking into account shear influence on torsion, contribution of bulkheads to hull stiffness as well as determination of effective stiffness of engine room structure. Along with that, hydrodynamic and hydrostatic models are presented in a condensed form. Numerical example, which includes complete hydroelastic analysis of a large container ship, is also added. In this case, validation of 1D FEM model is checked by correlation analysis with the vibration response of the fine 3D FEM model. The procedure related to determination of engine room effective stiffness is checked by 3D FEM analysis of ship-like pontoon which has been made according to the considered ship characteristics.

scholarly journals Global hydroelastic analysis of ultra large container ships by improved beam structural model

2014 ◽  
Vol 6 (4) ◽  
pp. 1041-1063 ◽  
Author(s):  
Ivo Senjanović ◽  
Nikola Vladimir ◽  
Marko Tomić ◽  
Neven Hadžić ◽  
Šime Malenica
Keyword(s):  
Structural Model ◽  
Hydroelastic Analysis ◽  
Large Container

Validation of Hydro-Structure Analysis Using Partial Structural Model

2016 ◽  
Author(s):  
George Jagite ◽  
Xiang-Dong Xu ◽  
Xiao-Bo Chen ◽  
Sime Malenica
Keyword(s):  
Structure Analysis ◽  
Structural Model ◽  
Structural Integrity ◽  
Structural Response ◽  
Offshore Structures ◽  
3D Fem ◽  
Fem Model ◽  
Ship Model ◽  
Partial Model ◽  
Analysis Methodology

Nowadays direct Finite Element Method (FEM) calculation using partial or full length model is necessary for checking the structural integrity of ship and offshore structures under given environmental conditions. The main advantage of using hydro-structure analysis on partial model is to obtain better accuracy than usual computation based on rule loads and also a consistent decrease of the time necessary to build a complete ship model. The comparison of different three cargo hold models with the complete ship model and the improvement of our partial FEM models are the main objectives of the work. Unlike the classical partial FEM models approach, our hydro-structure analysis is based on creating an equivalent full FEM model from the partial model. The equivalent full FEM model is built by adding to the partial model two concentrated masses in the center of gravity of missing aft and fore parts. The mass and inertia properties of the equivalent full FEM model are the same as full ship FEM model. By using an equivalent full FEM model the problem of balancing the partial model transforms into the same problem for the corresponding full model. Instead of using the traditional method for interpolating the pressure from hydrodynamic mesh to structural mesh, the pressure components are recalculated over structural mesh. The inertial loads are then determined by motion equations integrating all pressure loads. In this way, the structural model is fully balanced. The balancing of the 3D FEM structural models represents one important issue to avoid unphysical structural response induced by an unbalanced structural model. This paper is focused on the validation of hydro-structure analysis methodology by comparing the results on a FSO unit using an equivalent full FEM model and a complete ship model.

Experimental and Numerical Modal Analysis of Gearbox Casing in a Polishing Machinery

2009 ◽  
Vol 69-70 ◽  
pp. 560-564
Author(s):  
Yang Yu Wang ◽  
Shi Ming Ji ◽  
Dong Hui Wen ◽  
Xian Zhang
Keyword(s):  
Modal Analysis ◽  
Natural Frequencies ◽  
Test System ◽  
Structural Vibration ◽  
Mode Shapes ◽  
Modal Parameters ◽  
Vibration Test ◽  
3D Fem ◽  
Fem Model

Vibrations in polishing machinery may affect the manual or automatic controls and reduce the efficiency of the operations to be carried out. In this article, an experimental and numerical analysis on the dynamic characteristic of a gearbox casing in polishing machinery have been carried out. The numerical investigation was achieved with NASTRAN based on a 3D FEM model and the experimental modal analysis for the determination of the natural frequencies and the associated eigenmodes of the gearbox casing with LMS structural vibration test system was performed. The fundamental modal parameters including the first 10-order natural frequencies, damping ratios and mode shapes were estimated and identified. Analytical and experimental results have been compared and discussed. Agreement between measurements and calculations is satisfactory and the results can be used as reliable reference for improving the dynamic behavior of the gearbox casing.

scholarly journals Structural Design Of Ultra Large Ships Based On Direct Calculation Approach

2016 ◽  
Vol Special edition (1) ◽  
pp. 53-79
Author(s):  
Nikola Vladimir ◽  
Ivo Senjanović ◽  
Šime Malenica ◽  
Jérôme De Lauzon ◽  
Hongil Im ◽  
...  
Keyword(s):  
Structural Design ◽  
Numerical Procedure ◽  
Structural Response ◽  
Direct Calculation ◽  
Theoretical Models ◽  
3D Fem ◽  
South Korean ◽  
Bulk Carriers ◽  
Numerical Tools ◽  
Large Container

The trend in modern sea transportation is building of ever larger ships, which require application of different direct calculation methodologies and numerical tools to achieve their reliable structural design. This is particularly emphasized in case of ultra large container ships (ULCS), but also other ship types like bulk carriers or large LNG ships belong to this category. In this context some classification societies have developed guidelines for performing direct calculations and for that purpose there are several hydro-structure tools available around the world, mainly relying on the same theoretical assumptions, but having incorporated different numerical procedures. Such tools are mostly based on the application of the 3D potential flow theoretical models coupled with the 3D FEM structural models. This paper illustrates application of general hydro-structure tool HOMER (BV) in the assessment of ship structural response in waves. An outline of the numerical procedure based on the modal approach is given together with basic software description. Application case is 19000 TEU ULCS built in South Korean shipyard Hyundai Heavy Industries. Extensive hydroelastic analyses of the ship are performed, and here some representative results for fatigue response with linear springing influence are listed.

scholarly journals A critical review of FEM models to simulate the nano-impact test on PVD coatings

2018 ◽  
Vol 188 ◽  
pp. 04017
Author(s):  
Georgios Skordaris ◽  
Konstantinos Bouzakis ◽  
Paschalis Charalampous
Keyword(s):  
Finite Element ◽  
Impact Test ◽  
Fem Simulation ◽  
Numerical Procedure ◽  
Analytical Description ◽  
Computational Time ◽  
Pvd Coatings ◽  
3D Fem ◽  
Fem Model ◽  
Element Discretization

Nano-impact test is a reliable method for assessing the brittleness of PVD coatings with mono- or multi-layer structures. For the analytical description of this test, a 3D-FEM Finite Element Method (FEM) model and an axis-symmetrical one were developed using the ANSYS LS-DYNA software. The axis-symmetrical FEM simulation of the nano-impact test can lead to a significantly reduced computational time compared to a 3D-FEM model and increased result's accuracy due to the denser finite element discretization network. In order to create an axissymmetrical model, it was necessary to replace the cube corner indenter by an equivalent conical one with axis-symmetrical geometry. Results obtained by the developed FEM models simulating the nano-impact test on PVD coatings with various structures were compared with experimental ones. Taking into account the sufficient convergence between them as well as the reduced calculation time only in the case of an axis-symmetrical model, the latter introduced numerical procedure can be effectively employed to monitor the effect of various coating structures on their brittleness.

Numerical evaluation of hydrodynamic characteristics of planing hulls by using a hybrid method

2021 ◽  
pp. 147509022199024
Author(s):  
Emre Kahramanoglu ◽  
Silvia Pennino ◽  
Huseyin Yilmaz
Keyword(s):  
Experimental Data ◽  
Hybrid Method ◽  
Design Stage ◽  
Hydrodynamic Characteristics ◽  
Calm Water ◽  
Preliminary Design Stage ◽  
Reduction Function ◽  
Hull Forms ◽  
Good Agreement

The hydrodynamic characteristics of the planing hulls in particular at the planing regime are completely different from the conventional hull forms and the determination of these characteristics is more complicated. In the present study, calm water hydrodynamic characteristics of planing hulls are investigated using a hybrid method. The hybrid method combines the dynamic trim and sinkage from the Zarnick approach with the Savitsky method in order to calculate the total resistance of the planing hull. Since the obtained dynamic trim and sinkage values by using the original Zarnick approach are not in good agreement with experimental data, an improvement is applied to the hybrid method using a reduction function proposed by Garme. The numerical results obtained by the hybrid and improved hybrid method are compared with each other and available experimental data. The results indicate that the improved hybrid method gives better results compared to the hybrid method, especially for the dynamic trim and resistance. Although the results have some discrepancies with experimental data in terms of resistance, trim and sinkage, the improved hybrid method becomes appealing particularly for the preliminary design stage of the planing hulls.

3D FEM model to simulate Brownian motion inside trabecular tissue from human femoral head

2021 ◽  
pp. 1-8
Author(s):  
Fabiano Bini ◽  
Andrada Pica ◽  
Simone Novelli ◽  
Raffaella Pecci ◽  
Rossella Bedini ◽  
...  
Keyword(s):  
Brownian Motion ◽  
Femoral Head ◽  
3D Fem ◽  
Fem Model

scholarly journals Macro-Modelling of Laser Micro-Joints for Understanding Joint Strength in Electric Vehicle Battery Interconnects

Materials ◽  
2021 ◽  
Vol 14 (13) ◽  
pp. 3552
Author(s):  
Abhishek Das ◽  
Richard Beaumont ◽  
Iain Masters ◽  
Paul Haney
Keyword(s):  
Joint Strength ◽  
Structural Model ◽  
Design Stage ◽  
Structural Modelling ◽  
Laser Weld ◽  
Computationally Efficient ◽  
Early Design Stage ◽  
Lap Shear ◽  
Battery Module ◽  
Modelling Approach

Laser micro-welding is increasingly being used to produce electrically conductive joints within a battery module of an automotive battery pack. To understand the joint strength of these laser welds at an early design stage, micro-joints are required to be modelled. Additionally, structural modelling of the battery module along with the electrical interconnects is important for understanding the crash safety of electric vehicles. Fusion zone based micro-modelling of laser welding is not a suitable approach for structural modelling due to the computational inefficiency and the difficulty of integrating with the module model. Instead, a macro-model which computationally efficient and easy to integrate with the structural model can be useful to replicate the behaviour of the laser weld. A macro-modelling approach was adopted in this paper to model the mechanical behaviour of laser micro-weld. The simulations were based on 5 mm diameter circular laser weld and developed from the experimental data for both the lap shear and T-peel tests. This modelling approach was extended to obtain the joint strengths for 3 mm diameter circular seams, 5 mm and 10 mm linear seams. The predicted load–displacement curves showed a close agreement with the test data.

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