Long-Term Structural Analysis of 3-D Ship Structures Using a New Stiffened Plate Element

2000 ◽  
Vol 123 (1) ◽  
pp. 29-37 ◽  
Author(s):  
Y. V. Satish Kumar ◽  
Madhujit Mukhopadhyay ◽  
Tanmay Sarkar
Keyword(s):  
Finite Element ◽  
Structural Analysis ◽  
Coastal Waters ◽  
Degrees Of Freedom ◽  
Element Model ◽  
Computational Effort ◽  
Plate Element ◽  
Stiffened Plate ◽  
Principal Stresses

The paper presents the development of a technique for long-term 3-D structural analysis of the complete ship using a new stiffened plate element. The 3-D analysis involves the 3-D finite element modeling of the vessel and evaluation of hydrodynamic pressures using the 3-D linear diffraction theory. The elegance of the present stiffened plate element is that it can accommodate any number of arbitrarily oriented stiffeners within the plate element. Thus, the formulation obviates the use of mesh lines strictly along the longitudinals and transverses of the ship, which minimizes the required number of degrees of freedom of the finite element model of the complete vessel and reduces the computational effort considerably. The long-term prediction for the worst hydrodynamic pressures in the lifetime of the ship is carried out using the ISSC spectrum and scatter tables of Indian coastal waters. As an example problem, long-term structural analysis of a mini-bulk carrier in Indian coastal waters is presented in the paper. The long-term pressures are estimated with a probability of exceedence of 10−4 and principal stresses are calculated. It is shown that the present method provides a new, elegant, and economic technique for long-term 3-D structural analysis of the complete ship.

scholarly journals Analysis of stiffened laminated composite plates by finite element based on higher-order displacement theory

2008 ◽  
Vol 30 (2) ◽  
pp. 112-121 ◽  
Author(s):  
Tran Ich Thinh ◽  
Tran Huu Quoc
Keyword(s):  
Finite Element ◽  
Degrees Of Freedom ◽  
Plate Theory ◽  
Laminated Composite ◽  
Composite Plates ◽  
Element Model ◽  
Higher Order ◽  
Plate Element ◽  
Laminated Composite Plates ◽  
Element Free

In this paper, authors use a finite element model based on higher-order displacement plate theory for analysis of stiffened laminated composite plates. Transverse shear deformation is included in the formulation making the model applicable for both moderately thick and thin composite plates. The plate element used is a nine-noded isoparametric one with nine degrees of freedom at each node. The stiffness of stiffener is reflected at all nine nodes of plate element in which it is placed. Accordingly, the stiffeners can be positioned anywhere within the place element. Free vibration and deflection of stiffened laminated composite plates are carried out, and results are compared with existing analytical and other solutions.

scholarly journals MODELLING FROM THE PAST: THE LEANING SOUTWEST TOWER OF CAERPHILLY CASTLE 1539-2015

2017 ◽  
Vol IV-2/W2 ◽  
pp. 221-227 ◽  
Author(s):  
O. E. C. Prizeman ◽  
V. Sarhosis ◽  
A. M. D’Alri ◽  
C. J. Whitman ◽  
G. Muratore
Keyword(s):  
Finite Element ◽  
Structural Analysis ◽  
Finite Element Model ◽  
Three Dimensional ◽  
Element Model ◽  
Present Condition ◽  
Long Term Stability ◽  
Dimensional Finite Element ◽  
The Uk ◽  
Three Dimensional Finite Element

Caerphilly Castle (1268-70) is the first concentric castle in Britain and the second largest in the UK. The dramatic inclination of its ruinous south west tower has been noted since 1539. Comparing data from historical surveys and a terrestrial laser scan undertaken in 2015, this paper seeks to review evidence for the long-term stability of the tower. Digital documentation and archival research by architects is collated to provide data for structural analysis by engineers. A terrestrial laser scan was used to create a detailed three dimensional finite element model to enable structural analysis of the current shape of the tower made by tetrahedral elements. An automated strategy has been implemented for the transformation of the complex three dimensional point cloud into a three dimensional finite element model. Numerical analysis has been carried out aiming at understanding the main structural weaknesses of the tower in its present condition. Comparisons of four sets of data: 1539, 1830, 1870 and 2015 enabled us to determine change albeit between very different methods of measurement.

A Parallel Solution Strategy for Finite Element Models

1996 ◽  
Author(s):  
Jordan J. Cox ◽  
Jeffrey A. Talbert ◽  
Eric Mulkay
Keyword(s):  
Finite Element ◽  
Degrees Of Freedom ◽  
Element Model ◽  
Decomposition Methods ◽  
Finite Element Models ◽  
Unique Contribution ◽  
Matrix Equations ◽  
Parallel Solution ◽  
The Finite Element Model ◽  
Parallel Fashion

Abstract This paper presents a method for naturally decomposing finite element models into sub-models which can be solved in a parallel fashion. The unique contribution of this paper is that the decomposition strategy comes from the geometric features used to construct the solid model that the finite element model represents. Domain composition and domain decomposition methods are used to insure global compatibility. These techniques reduce the N2 behavior of traditional matrix solving techniques, where N is the number of degrees of freedom in the global set of matrix equations, to a sum of m matrices with n2 behavior, where n represents the number of degrees of freedom in the smaller sub-model matrix equations.

Finite Element Model of the Human Knee Joint to Study Tibio-Femoral Contact Mechanics

2000 ◽  
Author(s):  
Tammy Haut Donahue ◽  
Maury L. Hull ◽  
Mark M. Rashid ◽  
Christopher R. Jacobs
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Degrees Of Freedom ◽  
Soft Tissues ◽  
Element Model ◽  
Human Knee ◽  
Human Knee Joint ◽  
Solid Models ◽  
Flexion Extension ◽  
A New Technique

Abstract A finite element model of the tibio-femoral joint in the human knee was created using a new technique for developing accurate solid models of soft tissues (i.e. cartilage and menisci). The model was used to demonstrate that constraining rotational degrees of freedom other than flexion/extension when the joint is loaded in compression markedly affects the load distribution between the medial and lateral sides of the joint. The model also was used to validate the assumption that the bones can be treated as rigid.

The effects of well damage and completion designs on geo-electrical responses in mature wellbore environments

Geophysics ◽  
2021 ◽  
pp. 1-50
Author(s):  
Gungor D. Beskardes ◽  
Chester J. Weiss ◽  
Evan Um ◽  
Michael Wilt ◽  
Kris MacLennan
Keyword(s):  
Finite Element ◽  
Electrical Potential ◽  
Real Life ◽  
Element Model ◽  
Computational Effort ◽  
Real Surface ◽  
Well Completion ◽  
Geologic Storage ◽  
Well Damage ◽  
Electrical Responses

Well integrity is one of the major concerns in long-term geologic storage sites due to its potential risk for well leakage and groundwater contamination. Evaluating changes in electrical responses due to energized steel-cased wells has the potential to quantify and predict possible wellbore failures as any kind of breakage or corrosion along highly-conductive well casings will have an impact on the distribution of subsurface electrical potential. However, realistic wellbore-geoelectrical models that can fully capture fine scale details of well completion design and state of well damage at the field scale require extensive computational effort or can even be intractable to simulate. To overcome this computational burden while still keeping the model realistic, we utilize the Hierarchical Finite Element Method which represents electrical conductivity at each dimensional component (1-D edges, 2-D planes and 3-D cells) of a tetrahedra mesh. This allows us to consider well completion designs with real-life geometric scales and well systems with realistic, detailed, progressive corrosion and damage in our models. Here, we present a comparison of possible discretization approaches of a multi-casing completion design in the finite element model. The impacts of the surface casing length and the coupling between concentric well casings, as well as the effects of the degree and the location of well damage on the electrical responses are also examined. Finally, we analyze real surface electric field data to detect the wellbore integrity failure associated with damage.

Comparison of femur strain under different loading scenarios: Experimental testing

2020 ◽  
Vol 235 (1) ◽  
pp. 17-27
Author(s):  
Ievgen Levadnyi ◽  
Jan Awrejcewicz ◽  
Yan Zhang ◽  
Yaodong Gu
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Strain Distribution ◽  
Element Model ◽  
Surface Strain ◽  
Image Correlation ◽  
Loading Conditions ◽  
Bone Implant ◽  
Bone Stiffness

Bone fracture, formation and adaptation are related to mechanical strains in bone. Assessing bone stiffness and strain distribution under different loading conditions may help predict diseases and improve surgical results by determining the best conditions for long-term functioning of bone-implant systems. In this study, an experimentally wide range of loading conditions (56) was used to cover the directional range spanned by the hip joint force. Loads for different stance configurations were applied to composite femurs and assessed in a material testing machine. The experimental analysis provides a better understanding of the influence of the bone inclination angle in the frontal and sagittal planes on strain distribution and stiffness. The results show that the surface strain magnitude and stiffness vary significantly under different loading conditions. For the axial compression, maximal bending is observed at the mid-shaft, and bone stiffness is also maximal. The increased inclination leads to decreased stiffness and increased magnitude of maximum strain at the distal end of the femur. For comparative analysis of results, a three-dimensional, finite element model of the femur was used. To validate the finite element model, strain gauges and digital image correlation system were employed. During validation of the model, regression analysis indicated robust agreement between the measured and predicted strains, with high correlation coefficient and low root-mean-square error of the estimate. The results of stiffnesses obtained from multi-loading conditions experiments were qualitatively compared with results obtained from a finite element analysis of the validated model of femur with the same multi-loading conditions. When the obtained numerical results are qualitatively compared with experimental ones, similarities can be noted. The developed finite element model of femur may be used as a promising tool to estimate proximal femur strength and identify the best conditions for long-term functioning of the bone-implant system in future study.

Effect of cracks and pitting defects on gear meshing

2012 ◽  
Vol 226 (11) ◽  
pp. 2805-2815 ◽  
Author(s):  
Alfonso Fernandez del Rincon ◽  
Fernando Viadero ◽  
Miguel Iglesias ◽  
Ana de-Juan ◽  
Pablo Garcia ◽  
...  
Keyword(s):  
Finite Element ◽  
Computational Models ◽  
Inequality Constraints ◽  
Variable Stiffness ◽  
Element Model ◽  
Equation System ◽  
Transmission Error ◽  
Computational Effort ◽  
Gear Mesh ◽  
Non Linear

The development of vibration-based condition monitoring techniques, especially those focused on prognosis, requires the development of better computational models that enable the simulation of the vibratory behaviour of mechanical systems. Gear transmission vibrations are governed by the so-called gear mesh frequency and its harmonics, due to the variable stiffness of the meshing process. The fundamental frequency will be modulated by the appearance of defects which modify the meshing features. This study introduces an advanced model to assess the consequences of defects such as cracks and pitting on the meshing stiffness and other related parameters such as load transmission error or load sharing ratio. Meshing forces are computed by imposing the compatibility and complementarity conditions, leading to a non-linear equation system with inequality constraints. The calculation of deformations is subdivided into a global and a local type. The former is approached by a finite element model and the latter via a non-linear Herztian-based formulation. This procedure enables a reduced computational effort, in contrast to conventional finite element models with contact elements. The formulation used to include these defects is described in detail and their consequences are assessed by a quasi-static analysis of a transmission example.

Load application method for shell finite element model of wind turbine blade

2018 ◽  
Vol 42 (5) ◽  
pp. 467-482 ◽  
Author(s):  
Damien Caous ◽  
Nicolas Lavauzelle ◽  
Julien Valette ◽  
Jean-Christophe Wahl
Keyword(s):  
Finite Element ◽  
Structural Analysis ◽  
Finite Element Model ◽  
Wind Turbine ◽  
Turbine Blade ◽  
Element Model ◽  
Wind Turbine Blade ◽  
Detailed Structural Analysis ◽  
Body Load ◽  
Shell Finite Element

It is common to dissociate load computation from structural analysis when carrying out a numerical assessment of a wind turbine blade. Loads are usually computed using a multiphysics and multibody beam finite element model of the whole turbine, whereas detailed structural analysis is managed using shell finite element models. This raises the issue of the application of the loads extracted from the beam finite element model at one node for each section and transposed into the shell finite element model. After presenting the methods found in the literature, a new method is proposed. This takes into account the physical consistency of loads: aerodynamic loads are applied as pressure on the blade surface, and inertial loads are applied as body loads. Corrections imposed by pressure and body load computation in order to match loads from the beam finite element model are proposed and a comparison with two other methods is discussed.

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