scholarly journals Plate Finite Element with Physical Shape Functions: Correctness of the Formulation

2017 ◽  
Vol 63 (3) ◽  
pp. 19-37
Author(s):  
W. Gilewski ◽  
M. Sitek
Keyword(s):  
Finite Element ◽  
Good Choice ◽  
Test Case ◽  
Element Formulation ◽  
Structural Elements ◽  
Shape Functions ◽  
Solution Convergence ◽  
Wide Range ◽  
Physical Shape ◽  
Moderately Thick Plates

Abstract The formulation of a plate finite element with so called ‘physical’ shape functions is revisited. The derivation of the ‘physical’ shape functions is based on Hencky-Bolle theory of moderately thick plates. The considered finite element was assessed in the past, and the tests showed that the solution convergence was achieved in a wide range of thickness to in-plane dimensions ratios. In this paper a holistic correctness assessment is presented, which covers three criteria: the ellipticity, the consistency and the inf-sup conditions. Fulfilment of these criteria assures the existence of a unique solution, and a stable and optimal convergence to the correct solution. The algorithms of the numerical tests for each test case are presented and the tests are performed for the considered formulation. In result it is concluded that the finite element formulation passes every test and therefore is a good choice for modeling plate structural elements regardless of their thickness.

B-Spline Finite Element Formulation for Laminated Composite Shells

2008 ◽  
Author(s):  
Antonio Carminelli ◽  
Giuseppe Catania
Keyword(s):  
Finite Element ◽  
Tensor Product ◽  
Shear Deformation ◽  
Laminated Composite ◽  
Finite Element Formulation ◽  
Spline Functions ◽  
Element Formulation ◽  
Shape Functions ◽  
Composite Shells ◽  
B Spline

This paper presents a finite element formulation for the dynamical analysis of general double curvature laminated composite shell components, commonly used in many engineering applications. The Equivalent Single Layer theory (ESL) was successfully used to predict the dynamical response of composite laminate plates and shells. It is well known that the classic shell theory may not be effective to predict the deformational behavior with sufficient accuracy when dealing with composite shells. The effect of transverse shear deformation should be taken into account. In this paper a first order shear deformation ESL laminated shell model, adopting B-spline functions as approximation functions, is proposed and discussed. The geometry of the shell is described by means of the tensor product of B-spline functions. The displacement field is described by means of tensor product of B-spline shape functions with a different order and number of degrees of freedom with respect to the same formulation used in geometry description, resulting in a non-isoparametric formulation. A solution refinement method, making it possible to increase the order of the displacement shape functions without using the well known B-spline “degree elevation” algorithm, is also proposed. The locking effect was reduced by employing a low-order integration technique. To test the performance of the approach, the static solution of a single curvature shell and the eigensolutions of composite plates were obtained by numerical simulation and are then compared with known solutions. Discussion follows.

Finite Element Analysis Over Tangled Meshes

2012 ◽  
Author(s):  
Josh Danczyk ◽  
Krishnan Suresh
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Functional Space ◽  
Mesh Optimization ◽  
Element Formulation ◽  
Shape Functions ◽  
Element Analysis ◽  
Patch Tests ◽  
Galerkin Formulation ◽  
Element Shape

In finite element analysis (FEA), tasks such as mesh optimization and mesh morphing can lead to overlapping elements, i.e., to a tangled mesh. Such meshes are considered ‘unacceptable’ today, and are therefore untangled using specialized procedures. Here it is shown that FEA can be easily extended to handle tangled meshes. Specifically, by defining the nodal functional space as an oriented linear combination of the element shape functions, it is shown that the classic Galerkin formulation leads to a valid finite element formulation over such meshes. Patch tests and numerical examples illustrate the correctness of the proposed methodology.

Nonlinear Finite Element Formulation for the Large Displacement Analysis of Plates

1990 ◽  
Vol 57 (3) ◽  
pp. 707-718 ◽  
Author(s):  
Bilin Chang ◽  
A. A. Shabana
Keyword(s):  
Finite Element ◽  
Rigid Body ◽  
Coordinate System ◽  
Deformable Body ◽  
Finite Element Formulation ◽  
Deformation Analysis ◽  
Element Formulation ◽  
Rectangular Plates ◽  
Shape Functions ◽  
Intermediate Element

In this investigation a nonlinear total Lagrangian finite element formulation is developed for the dynamic analysis of plates that undergo large rigid body displacements. In this formulation shape functions are required to include rigid body modes that describe only large translational displacements. This does not represent any limitation on the technique presented in this study, since most of commonly used shape functions satisfy this requirement. For each finite plate element an intermediate element coordinate system, whose axes are initially parallel to the axes of the element coordinate system, is introduced. This intermediate element coordinate system, which has an origin which is rigidly attached to the origin of the deformable body, is used for the convenience of describing the configuration of the element with respect to the deformable body coordinate system in the undeformed state. The nonlinear dynamic equations developed in this investigation for the large rigid body displacement and small elastic deformation analysis of the rectangular plates are expressed in terms of a unique set of time invariant element matrices that depend on the assumed displacement field. The invariants of motion of the deformable body discretized using the plate elements are obtained by assembling the invariants of its elements using a standard finite element procedure.

Fundamentals and Applications of the Finite-Element Method in Analyzing Structural and Nonstructural Marine Problems

1982 ◽  
Vol 19 (03) ◽  
pp. 272-292
Author(s):  
Donald Liu ◽  
Yung-Kuang Chen
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Boundary Integral ◽  
Boundary Integral Method ◽  
Element Formulation ◽  
The Finite Element Method ◽  
Static And Dynamic Analysis ◽  
Marine Industry ◽  
Wide Range ◽  
Element Method

The finite-element method has become a popular and effective tool not only for structural analysis, but also for a wide range of physical problems which are of particular interest to the marine industry. A brief review of the finite-element formulation for structural and nonstructural problems is presented. Applications to marine structures, including static and dynamic analysis and fracture mechanics, are given. Nonstructural applications to heat transfer and ship hydrodynamic problems are also demonstrated. Recent developments in the coupled fluid-structural interaction problem using the boundary integral method, which is considered as an extension of the finite-element method, are also described.

A three‐dimensional strain concentration equation for countersunk holes

2008 ◽  
Vol 43 (2) ◽  
pp. 75-85 ◽  
Author(s):  
A Bhargava ◽  
K N Shivakumar
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Concentration Factor ◽  
Three Dimensional ◽  
Structural Elements ◽  
Element Analysis ◽  
Strain Concentration ◽  
Wide Range ◽  
Dimensional Equation ◽  
Concentration Equation

Countersunk rivets are used to join components to achieve aerodynamic or hydrodynamic surfaces. At countersunk holes, three‐dimensional stress and strain concentrations occur. Previously, the present authors developed a three‐dimensional equation for the stress concentration factor Kt through a detailed finite element analysis. This paper extends the study to include an equation for three‐dimensional strain concentration factor Ktε using a similar approach. The resulting equation was verified by finite element analysis for a wide range of countersunk hole configurations and plate sizes. Results showed that the maximum strain concentration is at the countersunk edge. The developed equation is within 5 per cent of the finite element results for all practical cases. It was also found that the Ktε and Kt expressions are similar and Ktε≥ Kt. The maximum difference between the two is 8 per cent (for = 0.3) or 2 for straight‐shank holes and about 2/2 for countersunk holes. The proposed equation is a valuable tool for strain‐based design of structural elements.

US-FE-LSPIM TRI3 Element for Free Vibration Analysis

2012 ◽  
Vol 246-247 ◽  
pp. 1278-1282 ◽  
Author(s):  
Hui Hui Chen ◽  
Cheng Jia
Keyword(s):  
Finite Element ◽  
Free Vibration ◽  
Vibration Analysis ◽  
Free Vibration Analysis ◽  
Element Model ◽  
Benchmark Problems ◽  
Element Formulation ◽  
Shape Functions ◽  
The Individual ◽  
Element Shape

For the purpose of construction an effective element model, the US- FE-LSPIM TRI3 element formulation, which is based on the concept of unsymmetric finite element formulation, is established. Classical linear triangle shape functions and FE-LSPIM TRI3 element shape functions are used as test and trial functions respectively. Classical linear triangle shape functions fulfill the requirements of continuity in displacement field for test functions. The FE-LSPIM TRI3 element shape functions synthesize the individual strengths of meshfree and finite element methods so they are more proper for trial functions. The element is applied in free vibration analysis of two dimension solids. Typical benchmark problems are solved. The results show that this element is more accurate and capable of good performances under both regular and irregular meshes.

scholarly journals Strength Analysis Modelling of Flexible Umbilical Members for Marine Structures

2012 ◽  
Vol 2012 ◽  
pp. 1-18 ◽  
Author(s):  
S. Sævik ◽  
J. K. Ø. Gjøsteen
Keyword(s):  
Finite Element ◽  
Cross Sections ◽  
External Pressure ◽  
Strength Analysis ◽  
Element Formulation ◽  
Structural Elements ◽  
3 Dimensional ◽  
Numerical Studies ◽  
Dimensional Finite Element ◽  
Slender Beams

This paper presents a 3-dimensional finite element formulation for predicting the behaviour of complex umbilical cross-sections exposed to loading from tension, torque, internal and external pressure including bending. Helically wound armours and tubes are treated as thin and slender beams formulated within the framework of small strains but large displacements, applying the principle of virtual displacements to obtain finite element equations. Interaction between structural elements is handled by 2- and 3-noded contact elements based on a penalty parameter formulation. The model takes into account a number of features, such as material nonlinearity, gap and friction between individual bodies, and contact with external structures and with a full 3-dimensional description. Numerical studies are presented to validate the model against another model as well as test data.

Effect of porosity and skew edges on transient response of functionally graded sandwich plates

2021 ◽  
pp. 030932472110626
Author(s):  
Abhilash Karakoti ◽  
Mahesh Podishetty ◽  
Shashank Pandey ◽  
Vishesh Ranjan Kar
Keyword(s):  
Finite Element ◽  
Transient Response ◽  
Volume Fraction ◽  
Pure Metal ◽  
Functionally Graded ◽  
Finite Element Formulation ◽  
Element Formulation ◽  
Sandwich Plates ◽  
Skew Angle ◽  
Wide Range

This work for the first time presents the effect of porosity and skew edges on the transient response of functionally graded material (FGM) sandwich plates using a layerwise finite element formulation. Two configurations of FGM sandwich plates are considered. In the first configuration, the top and the bottom layers are made of the FGM and the core is made of pure metal, whereas in the second configuration, the bottom, core and the top layers are made of pure metal, FGM and pure ceramic, respectively. Four micromechanics models based on the rule of mixture are used to model porosity for these two configurations of FGM sandwich plates. A layerwise theory based on a first-order shear deformation theory for each layer that maintains the displacement continuity at the layer interface is used for the present investigation. An eight-noded isoparametric element with nine degrees of freedom per node is used to develop the finite element model (FEM). The governing equations for the present investigation are derived using Hamilton’s principle. A wide range of comparison studies are presented to establish the accuracy of the present FEM formulation. It has been shown here that the parameters like skew angle, porosity coefficient, volume fraction index, core to facesheet thickness ratio and boundary conditions have a significant effect on the transient response of FGM sandwich plates. Also, the present finite element formulation is simple and accurate.

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