scholarly journals Dynamic Characters of Stiffened Composite Conoidal Shell Roofs with Cutouts: Design Aids and Selection Guidelines

2013 ◽  
Vol 2013 ◽  
pp. 1-18 ◽  
Author(s):  
Sarmila Sahoo
Keyword(s):  
Finite Element ◽  
Laminated Composite ◽  
Shell Element ◽  
Beam Element ◽  
Mode Shapes ◽  
Benchmark Problems ◽  
Curved Beam ◽  
Finite Element Code ◽  
Fundamental Frequencies ◽  
Curved Beam Element

Dynamic characteristics of stiffened composite conoidal shells with cutout are analyzed in terms of the natural frequency and mode shapes. A finite element code is developed for the purpose by combining an eight-noded curved shell element with a three-noded curved beam element. The code is validated by solving benchmark problems available in the literature and comparing the results. The size of the cutouts and their positions with respect to the shell centre are varied for different edge constraints of cross-ply and angle-ply laminated composite conoids. The effects of these parametric variations on the fundamental frequencies and mode shapes are considered in details. The results furnished here may be readily used by practicing engineers dealing with stiffened composite conoids with cutouts central or eccentric.

scholarly journals Performance Evaluation of Free Vibration of Laminated Composite Stiffened Hyperbolic Paraboloid Shell Panel with Cutout

2016 ◽  
Vol 7 ◽  
pp. 1-24 ◽  
Author(s):  
Sarmila Sahoo
Keyword(s):  
Free Vibration ◽  
Laminated Composite ◽  
Shell Element ◽  
Mode Shapes ◽  
Hyperbolic Paraboloid ◽  
Fundamental Frequencies ◽  
Curved Beam Element ◽  
Edge Conditions ◽  
Practical Engineering ◽  
Shell Panel

The paper considers free vibration characteristics of stiffened composite hyperbolic paraboloid shell panel with cutout in terms of natural frequency and mode shapes. A finite element code is developed for the purpose by combining an eight noded curved shell element with a three noded curved beam element. The size of the cutouts and their positions with respect to the shell centre are varied for different edge conditions of cross-ply and angle-ply laminated shells. The effects of these parametric variations on the fundamental frequencies and mode shapes are considered in details to conclude a set of inferences of practical engineering significance.

Laminated Composite Stiffened Cylindrical Shell Panels with Cutouts under Free Vibration

2015 ◽  
Vol 5 (3) ◽  
pp. 37-63 ◽  
Author(s):  
Sarmila Sahoo
Keyword(s):  
Cylindrical Shell ◽  
Free Vibration ◽  
Laminated Composite ◽  
Beam Element ◽  
Benchmark Problems ◽  
Finite Element Code ◽  
Optimum Size ◽  
Isoparametric Element ◽  
Stiffened Cylindrical Shell ◽  
Practical Constraints

The free vibration of laminated composite stiffened cylindrical shell panels in the presence of cutout is investigated. A finite element code is developed using eight-noded curved quadratic isoparametric element for shell with a three noded beam element for stiffener and the formulation is validated through solution of benchmark problems which were earlier solved by other researchers. Parametric study is carried out varying the size of the cutouts and their positions with respect to the shell centre for different edge constraints. The results are presented in the form of figures and tables. The results are further analyzed to suggest guidelines to select optimum size and position of the cutout with respect to shell centre considering the different practical constraints.

Locking Behavior of Isoparametric Curved Beam Finite Elements

1995 ◽  
Vol 48 (11S) ◽  
pp. S25-S29 ◽  
Author(s):  
Miguel Luiz Bucalem ◽  
Klaus-Ju¨rgen Bathe
Keyword(s):  
Shell Element ◽  
Beam Element ◽  
Curved Beam ◽  
Shear Locking ◽  
Shell Elements ◽  
One Dimensional ◽  
Curved Beam Element ◽  
The One ◽  
Insight Into ◽  
The Continuum

We present a study of the membrane and shear locking behavior in an isoparametric curved beam element. The objective is to gain insight into the locking phenomenon, specially membrane locking, of continuum based degenerated shell elements. This is possible since the isobeam element is the one-dimensional analogue of the continuum based shell element. In this context, reduced integration and mixed interpolation schemes are briefly examined. Such a study can be a valuable aid when developing new shell elements.

FiniteElement Vibration Characteristics of Composite Hypar Shallow Shells with Various Edge Supports

2005 ◽  
Vol 11 (10) ◽  
pp. 1291-1309 ◽  
Author(s):  
S. Sahoo ◽  
D. Chakravorty
Keyword(s):  
Boundary Conditions ◽  
Numerical Experiments ◽  
Laminated Composite ◽  
Shell Element ◽  
Vibration Characteristics ◽  
The Other ◽  
Mode Shapes ◽  
Review Of The Literature ◽  
Shallow Shells ◽  
Fundamental Frequencies

A review of the literature reveals that information regarding fundamental frequencies and mode shapes of shallow laminated composite hypar shells with practical civil engineering boundary conditions is not available. The present investigation aims to fill this gap by applying an eight-noded isoparametric shell element as the tool. Numerical experiments are carried out for different parametric variations including boundary conditions and stacking orders to obtain the fundamental frequencies and mode shapes. Some of the results are used for validating the correctness of the present approach by comparing with the existing benchmark, while the other results are studied meticulously to extract a set of meaningful conclusions regarding the free vibration characteristics of composite shallow hypar shells.

Free Vibration of Laminated Composite Beams and Plates Using ADINA Finite Element Code

1995 ◽  
Author(s):  
James Stolte
Keyword(s):  
Finite Element ◽  
Natural Frequency ◽  
Laminated Composite ◽  
Shell Element ◽  
Composite Beams ◽  
Advanced Technology ◽  
Finite Element Code ◽  
First Order ◽  
Natural Frequency Analysis ◽  
Laminated Composite Beams

Abstract Composite materials are being investigated in advanced technology test beds for use in future armored vehicles. We are particularly interested in the response to impulsive loading for which the knowledge of natural frequency behavior is important. In this paper, we investigate the natural frequency analysis capabilities of the multilayered shell element of the ADINA finite element code as applied to laminated composite beams and plates. Results are compared to those published in the literature or those derived from exact solutions. The ADINA shell element employs a first-order shear deformation theory, and the results are found to agree well with other first-order theories. Although ADINA does not allow for a direct method of incorporating a shear correction factor commonly used in first-order theories, it is demonstrated how this can be included by modifying the material properties.

A Three-Dimensional Curved Beam Element for Helical Components Modeling

2011 ◽  
Author(s):  
Rodrigo Provasi ◽  
Clo´vis de Arruda Martins
Keyword(s):  
Finite Element ◽  
Three Dimensional ◽  
Beam Element ◽  
Analytical Models ◽  
Cylindrical Layer ◽  
Curved Beam ◽  
Macro Elements ◽  
Curved Beam Element ◽  
Flexible Pipes ◽  
Custom Made

The offshore industry is in constant evolution due to the need of reaching new oil fields in increasingly water depths. In this scenario, not only new types of platforms are being designed, but also new types of flexible pipes and new umbilical cable configurations. The greatest difficulty to generate a new concept for a riser is to determine if it is viable or not. Flexible pipes and umbilical cables are complicated to model, due to the interactions between their layers and the large number of possible arrangements. To predict their behavior, adequate models are necessary. One can rely on finite element models, which show a great difficulty in mesh generation and convergence (especially due to the contact pairs). One can also rely on analytical models, which have many limitations due to simplifications (even though necessary ones). Another possible approach is to define macro elements, which represent a component, instead of classical finite elements (such as tetrahedral elements). Related to that approach, a numeric method using macro-elements is proposed. It consists in creating elements which has the desired characteristics of the problem in its formulation, leading to robust custom-made elements and to coarse meshes (since the complexity of the problem is within the element). Some elements are proposed in this model: a concentric one for cylindrical layer modeling; a three-dimensional curved beam for helices; a bridge element for node connection; and a contact element, for gap and friction treatment. The first two of them are already concluded and the later ones are being designed. This paper presents the three-dimensional curved beam element, which takes into account the effects of curvature and tortuosity. This is accomplished by using a strong coupling between displacements and assuming that the twist and shear strains varies linearly within the element. Using such hypothesis, the shear lock phenomenon is also avoided. This formulation is implemented and their results compared to those obtained by a classical finite element modeling tool, with good agreement.

A Three-Dimensional Curved Beam Element for Helical Components Modeling

2014 ◽  
Vol 136 (4) ◽  
Author(s):  
Rodrigo Provasi ◽  
Clóvis de Arruda Martins
Keyword(s):  
Finite Element ◽  
Three Dimensional ◽  
Beam Element ◽  
Structural Behavior ◽  
Curved Beam ◽  
Large Set ◽  
Flexible Pipe ◽  
Curved Beam Element ◽  
Macro Element ◽  
Umbilical Cable

The structural behavior of flexible pipes and umbilical cables is difficult to model due to their complex construction that includes components of different materials, shapes, and functions. Also, it is difficult to model due to the nonlinear interaction between those components, which includes contacts, gaps, and friction. To model a flexible pipe or umbilical cable, one can rely on analytical or numerical approaches. Analytical models need a large set of simplifying hypotheses. Numerical models, like classical finite elements models, require large meshes and have great difficulties to converge. But one can take profit of the particular characteristics of a specific component and develop a custom-made finite element that represents its structural behavior, a so-called finite macro-element. Adopting this approach, in a previous work, it was developed a cylindrical macro-element with orthotropic behavior, to model the plastic layers of a flexible pipe or umbilical cable. This paper presents a three-dimensional (3D) curved beam element, built to model a helical metallic component, which takes into account the effects of curvature and tortuosity of that kind of component. This is accomplished by using a strong coupling between displacements and assuming that the twist and shear strains vary linearly within the element, to avoid the shear lock phenomenon. The complete formulation of this element is presented. Results obtained with this formulation are also presented and compared to those obtained by a classical finite element modeling tool, with good agreement.

The curved beam element and its convergence rate

1989 ◽  
Vol 10 (6) ◽  
pp. 507-519 ◽  
Author(s):  
Lü He-xiang ◽  
Tang Li-min ◽  
Liu Xiu-lan
Keyword(s):  
Convergence Rate ◽  
Beam Element ◽  
Curved Beam ◽  
Curved Beam Element
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