Nonlinear Dynamic Analysis of Flexible Riser Structures

2008 ◽  
Author(s):  
S. A. Hosseini Kordkheili ◽  
H. Bahai
Keyword(s):  
Finite Element ◽  
Dynamic Analysis ◽  
Three Dimensional ◽  
Nonlinear Dynamic Analysis ◽  
Linearization Method ◽  
Element Formulation ◽  
Large Rotation ◽  
Pipe Elbow ◽  
Lagrangian Finite Element ◽  
Updated Lagrangian

An updated Lagrangian finite element formulation of a three-dimensional pipe elbow element is presented for large displacement and large rotation dynamic analysis. In this formulation a particular linearization method is used to avoid inaccuracies normally associated with the linearization schemes. The formulation has been implemented in a nonlinear finite element code and the results are verified. It is shown that the proposed formulation generates improved results over those previously reported in the literature.

Lagrangian Finite Element Formulation to Axisymmetric Liquid Sloshing

2011 ◽  
Author(s):  
Shoichi Yoshida ◽  
Kazuyoshi Sekine ◽  
Tomohiko Tsuchida ◽  
Katsuki Iwata
Keyword(s):  
Finite Element ◽  
Axisymmetric Problem ◽  
Time Integration ◽  
Three Dimensional ◽  
Computer Code ◽  
Element Formulation ◽  
Liquid Storage ◽  
Analysis Technique ◽  
Lagrangian Finite Element ◽  
Spurious Modes

The sloshing analysis of liquid storage tanks by the finite element method is basically categorized into two approaches, Lagrangian approach and Eulerian approach. In the Lagragian approach, the behavior of the fluid is expressed in terms of the displacements at nodal points. The advantage of the Lagragian method is that the computer code can be easily developed to modify an existing structural analysis code. The disadvantage is that some spurious modes are included in the vibration modes. The Lagrangian method is widely used in two- and three-dimensional problems. On the other hand, it has not been reported its applicability to the axisymmetric problem. This paper presents the applicability of the Lagragian method to the axisymmetric sloshing problem. The eigenvalue of an elemental stiffness matrix is analyzed in order to investigate the characteristics of the rotational stiffness to the compressibility of the fluid. As a result, this method is found to be difficult to apply to the axisymmetric problem if the equation of motion is directly solved using time integration. However, it gives the highly precise response solutions if the only sloshing modes are taken out and the modal analysis technique is used.

The Cosserat Point Element as an Accurate and Robust Finite Element Formulation for Implicit Dynamic Simulations

2019 ◽  
Vol 17 (01) ◽  
pp. 1844006
Author(s):  
Mahmood Jabareen ◽  
Yehonatan Pestes
Keyword(s):  
Finite Element ◽  
Energy Function ◽  
Strain Energy ◽  
Three Dimensional ◽  
Nonlinear Dynamic Analysis ◽  
Strain Energy Function ◽  
Finite Element Formulation ◽  
Element Formulation ◽  
Dynamic Simulations ◽  
Cosserat Point

The reliability of numerical simulations manifested the need for an accurate and robust finite element formulation. Therefore, in the present study, an eight node brick Cosserat point element ( CPE ) for the nonlinear dynamic analysis of three-dimensional (3D) solids including both thick and thin structures is developed. Within the present finite element formulation, a strain energy function is proposed and additively decoupled into two parts. One part is characterized by any 3D strain energy function, while the other part controls the response to inhomogeneous deformations. Several example problems are presented, which demonstrate the accuracy and the robustness of the developed CPE in modeling the dynamic response of elastic structures.

Three-dimensional finite element nonlinear dynamic analysis of pile groups for lateral transient and seismic excitations

2004 ◽  
Vol 41 (1) ◽  
pp. 118-133 ◽  
Author(s):  
Bal Krishna Maheshwari ◽  
Kevin Z Truman ◽  
M Hesham El Naggar ◽  
Phillip L Gould
Keyword(s):  
Finite Element ◽  
Seismic Response ◽  
Radiation Effects ◽  
Seismic Analysis ◽  
Dynamic Stiffness ◽  
Three Dimensional ◽  
Nonlinear Dynamic Analysis ◽  
Element Formulation ◽  
Pile Groups ◽  
Pile Cap

The effects of material nonlinearity of soil and separation at the soil–pile interface on the dynamic behaviour of a single pile and pile groups are investigated. An advanced plasticity-based soil model, hierarchical single surface (HiSS), is incorporated in the finite element formulation. To simulate radiation effects, proper boundary conditions are used. The model and algorithm are verified with analytical results that are available for elastic and elastoplastic soil models. Analyses are performed for seismic excitation and for the load applied on the pile cap. For seismic analysis, both harmonic and transient excitations are considered. For loading on the pile cap, dynamic stiffness of the soil–pile system is derived and the effect of nonlinearity is investigated. The effects of spacing between piles are investigated, and it was found that the effect of soil nonlinearity on the seismic response is very much dependent on the frequency of excitation. For the loading on a pile cap, the nonlinearity increases the response for most of the frequencies of excitation while decreasing the dynamic stiffness of the soil–pile system.Key words: pile groups, plasticity, separation, dynamic stiffness, seismic response.

scholarly journals A new fluid structure coupling

2007 ◽  
pp. 521-536
Author(s):  
Nicolas Aquelet ◽  
Benjamin Tutt
Keyword(s):  
Finite Element ◽  
Flow Model ◽  
Air Flow ◽  
Coupling Method ◽  
Finite Element Formulation ◽  
Element Formulation ◽  
Interaction Forces ◽  
Porous Flow ◽  
Lagrangian Finite Element ◽  
Updated Lagrangian

The modelling of parachutes at Irvin Aerospace Inc. was based on the penalty Euler-Lagrange coupling method to compute the interaction between an Arbitrary Lagrange Euler formulation for the air flow and an updated Lagrangian finite element formulation for the canopy dynamics. This approach did not permit the effect of fabric porosity to be accounted for. In this paper, a new porosity Euler-Lagrange coupling models the fabric permeability by assessing the interaction forces based on the Ergun porous flow model. This paper provides validations for the technique when considering parachute applications and discusses the interest of this development to the parachute designer.

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