scholarly journals Influence of initial geometric imperfections on the 1:1:1:1 internal resonances and nonlinear vibrations of thin-walled cylindrical shells

2020 ◽  
Vol 151 ◽  
pp. 106730 ◽  
Author(s):  
Lara Rodrigues ◽  
Frederico M.A. Silva ◽  
Paulo B. Gonçalves
Keyword(s):  
Nonlinear Vibrations ◽  
Cylindrical Shells ◽  
Internal Resonances ◽  
Geometric Imperfections ◽  
Initial Geometric Imperfections ◽  
Thin Walled

Comparison for Different Circumferential Weld-Induced Imperfections on Steel Silos

2011 ◽  
Vol 250-253 ◽  
pp. 3734-3737
Author(s):  
Xiang Rong Chen ◽  
Yuan Yuan Jiang ◽  
Zhi Yun Zhao
Keyword(s):  
Practical Significance ◽  
Shape Functions ◽  
Element Analysis ◽  
Geometric Imperfections ◽  
The Finite Element Analysis ◽  
Practical Engineering ◽  
Initial Geometric Imperfections ◽  
Thin Walled ◽  
Steel Silos ◽  
Common Defect

As the thin-walled structure,the buckling of steel silos is very sensitive to the initial geometric imperfections. However, these imperfections are uncertain to the shape and amplitude, so the studies of the initial geometric imperfections have important practical significance. Over the years, the circumferential imperfections have been known to result in the most important influence on the buckling of steel silos, which is also the most common defect in practical engineering. Using the existing research results, this paper analyzes three different imperfection shape functions and compare to the result of experiment in order to identify a function for the finite element analysis.

The Influence of Modal Geometrical Imperfections on the Nonlinear Vibrations of a Thin-Walled Circular Cylindrical Shell

2016 ◽  
Author(s):  
Lara Rodrigues ◽  
Paulo B. Gonçalves ◽  
Frederico M. A. Silva
Keyword(s):  
Nonlinear Vibrations ◽  
Circular Cylindrical Shell ◽  
Cylindrical Shells ◽  
Nonlinear Behavior ◽  
Geometric Imperfections ◽  
Modal Expansion ◽  
Simply Supported ◽  
Transversal Displacement ◽  
Geometrical Imperfections ◽  
Standard Galerkin Method

This work investigates the influence of several modal geometric imperfections on the nonlinear vibration of simply-supported transversally excited cylindrical shells. The Donnell nonlinear shallow shell theory is used to study the nonlinear vibrations of the shell. A general expression for the transversal displacement is obtained by a perturbation procedure which identifies all modes that couple with the linear modes through the quadratic and cubic nonlinearities. The imperfection shape is described by the same modal expansion. So, a particular solution is selected which ensures the convergence of the response up to very large deflections. Substituting the obtained modal expansions into the equations of motions and applying the standard Galerkin method, a discrete system in time domain is obtained. Several numerical strategies are used to study the nonlinear behavior of the imperfect shell. Special attention is given to the influence of the form of the initial geometric imperfections on the natural frequencies, frequency-amplitude relation, resonance curves and bifurcations of simply-supported transversally excited cylindrical shells.

A New Design Method for Axially Loaded Thin-Walled Cylindrical Shells Based on Elasto-Plastic Buckling Analysis

2019 ◽  
Author(s):  
Peng Jiao ◽  
Zhiping Chen ◽  
He Ma
Keyword(s):  
Design Method ◽  
Cylindrical Shells ◽  
Load Carrying Capacity ◽  
Test Results ◽  
Geometric Imperfections ◽  
Compression Load ◽  
Load Carrying ◽  
Weight Design ◽  
Thin Walled ◽  
Improved Design

Abstract In engineering, thin-walled cylindrical shells subjected to axial compression load are very sensitive to geometric imperfections and are prone to buckling. However, how to reasonably take into account the influence of geometric imperfections on the load carrying capacity of thin-walled cylindrical shells is always the bottleneck of light-weight design of these structures. In this paper, four perturbation load approach (4PLA) is adopted to consider the influence of geometric imperfections. By judging the potential buckling status of cylindrical shells, a new improved design method based on 4PLA for thin-walled cylindrical shells is proposed, in which the influence of radius-to-thickness ratio, length-to-radius ratio, Young’s modulus and material yield strength are systematically considered. Correspondingly, the buckling tests for two steel cylindrical shells with the same geometric and material parameters are conducted. Compared with the experimental results and other test results in open literatures, the superiority and safety of proposed method for the preliminary design of thin-walled cylindrical shells are validated.

Influence of Geometric Imperfections and In-Plane Constraints on Nonlinear Vibrations of Simply Supported Cylindrical Panels

1984 ◽  
Vol 51 (2) ◽  
pp. 383-390 ◽  
Author(s):  
David Hui
Keyword(s):  
Shell Thickness ◽  
Nonlinear Vibrations ◽  
Vibration Mode ◽  
Vibration Frequencies ◽  
Linear Vibration ◽  
Geometric Imperfections ◽  
Simply Supported ◽  
Cylindrical Panels ◽  
Initial Geometric Imperfections ◽  
Large Amplitude Vibrations

This papers deals with the effects of initial geometric imperfections on large-amplitude vibrations of cylindrical panels simply supported along all four edges. In-plane movable and in-plane immovable boundary conditions are considered for each pair of parallel edges. Depending on whether the number of axial and circumferential half waves are odd or even, the presence of geometric imperfections (taken to be of the same shape as the vibration mode) of the order of the shell thickness may significantly raise or lower the linear vibration frequencies. In general, an increase (decrease) in the linear vibration frequency corresponds to a more pronounced soft-spring (hard-spring) behavior in nonlinear vibration.

Evaluation of stiffened shell characteristics from imperfection measurements

1987 ◽  
Vol 22 (1) ◽  
pp. 17-23 ◽  
Author(s):  
H Abramovich ◽  
R Yaffe ◽  
J Singer
Keyword(s):  
Cylindrical Shells ◽  
Data Bank ◽  
Laboratory Scale ◽  
Experimental Results ◽  
Geometric Imperfections ◽  
Buckling Loads ◽  
Stiffened Shell ◽  
Initial Geometric Imperfections ◽  
Stiffened Cylindrical Shells

The measurement of initial geometric imperfections of stringer-stiffened cylindrical shells on a laboratory scale is reviewed and recent results are presented. Buckling loads are predicted by the multimode analysis and are compared with experimental results. The concept and purpose of an international imperfection data bank is outlined and the activity of the Technion branch is described. An evaluation of the characteristics of shells from their measured imperfection record is attempted.

scholarly journals Applicability of thin-walled structures for energy-savings in steel construction

2019 ◽  
Vol 91 ◽  
pp. 02042
Author(s):  
Natalia D. Korsun ◽  
Daria A. Prostakishina
Keyword(s):  
Cross Section ◽  
Energy Savings ◽  
Effective Characteristics ◽  
Geometric Imperfections ◽  
Thin Walled Structures ◽  
Steel Construction ◽  
Full Cross Section ◽  
Initial Geometric Imperfections ◽  
Thin Walled ◽  
The Cross

The paper discusses the use of lightweight thin-walled structures which make it possible to save resources in steel construction. The highlighted challenges that this industry face in the Russian Federation involve insufficient development of the domestic standards. A thin-walled sigma-profile element with 300 mm in a section height has been studied. The element, its design diagram and loading have been chosen taking into account the structural performance of the columns and girders involved in CFS frameworks. The paper presents analysis technique for a thin-walled profile which performs under axial compression and axial bending compression. The structures have been calculated taking into account their main feature - the initial geometric imperfections. The analysis of the changed effective characteristics and stresses in the cross-section has revealed the significant influence of the initial geometric imperfections of the profiles and location of the extra eccentricity against the element’s initial curvatures. The elastic-plastic behaviour of material occurs when the stresses in the full cross-section achieve 0.71 Ryignoring the initial geometric imperfections, and 0.58 Ry– with regard to them. The paper substantiates the need to consider unevenness of the mechanical properties of steel distributed over the cross-section of the profile. Based on the experimental data obtained, conclusions have been drawn on the necessary adaptation of the indirect method for evaluating the strength characteristics of thin-walled samples.

Sign in / Sign up

Export Citation Format

Share Document