Dynamic Stability Analysis of Stiffened Shell Panels With Cutouts

2009 ◽  
Vol 76 (4) ◽  
Author(s):  
S. N. Patel ◽  
P. K. Datta ◽  
A. H. Sheikh
Keyword(s):  
Degrees Of Freedom ◽  
Dynamic Instability ◽  
Torsional Rigidity ◽  
Shell Element ◽  
Beam Element ◽  
Radius Of Curvature ◽  
Efficient Manner ◽  
Instability Analysis ◽  
Stiffened Shell ◽  
Degenerated Shell Element

A finite element dynamic instability analysis of stiffened shell panels with cutout subjected to uniform in-plane harmonic edge loading along the two opposite edges is presented in this paper. The eight-noded isoparametric degenerated shell element and a compatible three-noded curved beam element are used to model the shell panels and the stiffeners, respectively. As the usual formulation of degenerated beam element is found to overestimate the torsional rigidity, an attempt has been made to reformulate it in an efficient manner. Moreover the new formulation for the beam element requires five degrees of freedom per node as that of shell element. Bolotin method is applied to analyze the dynamic instability regions. Numerical results of convergence studies are presented and comparison is made with the published results from literature. The effects of various parameters such as shell geometry, radius of curvature, cutout size, stiffening scheme, and dynamic load factors are considered in dynamic instability analysis of stiffened shell panels with cutout. The free vibration and static stability (buckling) results are also presented. With the consideration of radius of curvatures the panels reduce from deep shell case to shallow shell case and finally become flat plate.

An Efficient Finite Element Modeling of Composite Stiffened Shells

2014 ◽  
Vol 553 ◽  
pp. 673-678
Author(s):  
Hamid Sheikh ◽  
Liang Huang
Keyword(s):  
Finite Element ◽  
Finite Element Modeling ◽  
Degrees Of Freedom ◽  
Torsional Rigidity ◽  
Shell Element ◽  
Beam Element ◽  
Shell Elements ◽  
Element Modeling ◽  
Stiffened Shells ◽  
Element Technique

This paper presents an efficient finite element modeling technique for stiffened composite shells having different stiffening arrangements. The laminated shell skin is modeled with a triangular degenerated curved shell element having 3 corner nodes and 3 mid-side nodes. An efficient curved beam element compatible with the shell element is developed for the modeling of stiffeners which may have different lamination schemes. The formulation of the 3 nod degenerated beam element may be considered as one of the major contributions. The deformation of the beam element is completely defined in terms of the degrees of freedom of shell elements and it does not require any additional degrees of freedom. As the usual formulation of degenerated beam elements overestimates their torsional rigidity, a torsion correction factor is introduced for different lamination schemes. Numerical examples are solved by the proposed finite element technique to assess its performance.

EFFECT OF HARMONIC IN-PLANE EDGE LOADING ON DYNAMIC STABILITY OF STIFFENED SHELL PANELS WITH CUTOUTS

2010 ◽  
Vol 02 (04) ◽  
pp. 759-785 ◽  
Author(s):  
S. N. PATEL ◽  
P. K. DATTA ◽  
A. H. SHEIKH
Keyword(s):  
Dynamic Instability ◽  
Shell Element ◽  
Stiffened Panels ◽  
Stiffened Shell ◽  
Curved Beam Element ◽  
Load Factors ◽  
Edge Loading ◽  
Instability Regions ◽  
Degenerated Shell Element ◽  
Shell Geometry

The effect of non-uniform in-plane pulsating edge loading on dynamic instability behavior of perforated stiffened shell panels is presented in this paper using finite element method. The eight-noded isoparametric degenerated shell element and a compatible three-noded curved beam element are used to model the shell panels and the stiffeners, respectively. Bolotin method is applied to analyze the dynamic instability regions. Numerical results of convergence studies are presented and comparison is made with the published results from the literature. The effects of various parameters like shell geometry, loading type, cutout size and dynamic load factors are considered in dynamic instability analysis of stiffened shell panels with cutout. The buckling results of the cutout stiffened panels are also presented.

Dynamic Stability of Woven Fiber Laminated Composite Shallow Shells in Hygrothermal Environment

2017 ◽  
Vol 17 (08) ◽  
pp. 1750084 ◽  
Author(s):  
M. Biswal ◽  
S. K. Sahu ◽  
A. V. Asha
Keyword(s):  
Dynamic Stability ◽  
Degrees Of Freedom ◽  
Dynamic Instability ◽  
Shear Deformation Theory ◽  
Shell Element ◽  
Load Factor ◽  
Element Formulation ◽  
Shallow Shells ◽  
Instability Regions ◽  
Hygrothermal Environment

The dynamic stability of bidirectional woven fiber laminated glass/epoxy composite shallow shells subjected to harmonic in-plane loading in hygrothermal environment is considered. An eight-noded isoparametric shell element with five degrees of freedom is used in the analysis. In the present finite element formulation, a composite doubly curved shell model based on first-order shear deformation theory (FSDT) is used for the dynamic stability analysis of shell panels subjected to hygrothermal loading. A program is developed using MATLAB for the parametric study on the dynamic stability of shell panels under the hygrothermal field. The effects of various parameters like static load factor, curvature, shallowness, temperature, moisture, stacking sequence and boundary conditions on the dynamic instability regions of woven fiber glass/epoxy shell panels are investigated. The location of dynamic instability regions is shown to affect significantly due to presence of the hygrothermal field.

Buckling and dynamic instability analysis of stiffened shell panels

2006 ◽  
Vol 44 (3) ◽  
pp. 321-333 ◽  
Author(s):  
S.N. Patel ◽  
P.K. Datta ◽  
A.H. Sheikh
Keyword(s):  
Dynamic Instability ◽  
Instability Analysis ◽  
Stiffened Shell

Dynamic instability analysis of general shells reinforced with polymeric matrix and carbon fibers using a coupled IG-SFSM formulation

2021 ◽  
Vol 263 ◽  
pp. 113720
Author(s):  
Mohammad Amin Shahmohammadi ◽  
Mojtaba Azhari ◽  
Mohammad Mehdi Saadatpour ◽  
Hamzeh Salehipour ◽  
Ömer Civalek
Keyword(s):  
Carbon Fibers ◽  
Dynamic Instability ◽  
Polymeric Matrix ◽  
Instability Analysis

Improved Bilinear Degenerated Shell Element

2015 ◽  
Vol 12 (02) ◽  
pp. 1550004 ◽  
Author(s):  
N. V. Swamy Naidu ◽  
B. Sateesh
Keyword(s):  
Shell Element ◽  
Shell Structures ◽  
Thin Plates ◽  
Element Formulation ◽  
Rigid Body Modes ◽  
Test Requirements ◽  
Degenerated Shell Element ◽  
Deformation Modes ◽  
Torsional Rotation ◽  
Transverse Shear Strains

The development of a new four node 24 degree of freedom bilinear degenerated shell element is presented for the analysis of shell structures. The present finite element formulation considers the assumed covariant transverse shear strains to avoid the shear locking problem and the assumed covariant membrane strains, which are separated from covariant in-plane strains, to overcome the membrane locking problem. The formulation also includes the deviation of the normal torsional rotation of the mid surface in the governing equation. This element is free from serious shear and membrane locking problems and undesirable spurious kinematic deformation modes. The element is tested for rigid body modes and distorted edges to meet the patch test requirements. The versatility and accuracy of this new degenerated shell element is demonstrated by solving several numerical examples for thick and thin plates.

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