Remarks on the Static and Dynamic Imperfection-Sensitivity of Nonsymmetric Structures

1980 ◽  
Vol 47 (1) ◽  
pp. 111-115 ◽  
Author(s):  
Isaac Elishakoff
Keyword(s):  
Dynamic Buckling ◽  
Buckling Load ◽  
Imperfection Sensitivity ◽  
Nonlinear Spring ◽  
Asymmetric Structures ◽  
Rod System ◽  
Rigid Rod

The simple static and dynamic buckling model (the three-hinge rigid-rod system, constrained laterally by a nonlinear spring) originally proposed by Budiansky and Hutchinson, is modified so that the force of the spring includes both quadratic and cubic terms. Expressions are given for the buckling load of the imperfect structure as function of the imperfection. These formulas generalize the classical expressions for the static buckling load (due to Koiter), and for the dynamic buckling load (due to Budiansky and Hutchinson) for symmetric or asymmetric structures, to nonsymmetric ones.

scholarly journals Influence of Uncertainties on the Dynamic Buckling Loads of Structures Liable to Asymmetric Postbuckling Behavior

2008 ◽  
Vol 2008 ◽  
pp. 1-24 ◽  
Author(s):  
Paulo B. Gonçalves ◽  
Donald Mark Santee
Keyword(s):  
Static Load ◽  
Basin Of Attraction ◽  
Dynamic Buckling ◽  
Buckling Load ◽  
Postbuckling Behavior ◽  
Imperfection Sensitivity ◽  
Buckling Loads ◽  
Melnikov Criterion ◽  
Linear Buckling ◽  
The Stability

Structural systems liable to asymmetric bifurcation usually become unstable at static load levels lower than the linear buckling load of the perfect structure. This is mainly due to the imperfections present in real structures. The imperfection sensitivity of structures under static loading is well studied in literature, but little is know on the sensitivity of these structures under dynamic loads. The aim of the present work is to study the behavior of an archetypal model of a harmonically forced structure, which exhibits, under increasing static load, asymmetric bifurcation. First, the integrity of the system under static load is investigated in terms of the evolution of the safe basin of attraction. Then, the stability boundaries of the harmonically excited structure are obtained, considering different loading processes. The bifurcations connected with these boundaries are identified and their influence on the evolution of safe basins is investigated. Then, a parametric analysis is conducted to investigate the influence of uncertainties in system parameters and random perturbations of the forcing on the dynamic buckling load. Finally, a safe lower bound for the buckling load, obtained by the application of the Melnikov criterion, is proposed which compare well with the scatter of buckling loads obtained numerically.

Dynamic Buckling of Externally Pressurized Imperfect Cylindrical Shells

1975 ◽  
Vol 42 (2) ◽  
pp. 316-320 ◽  
Author(s):  
D. Lockhart ◽  
J. C. Amazigo
Keyword(s):  
Asymptotic Expression ◽  
Cylindrical Shells ◽  
Simple Relation ◽  
Dynamic Buckling ◽  
Fourier Component ◽  
Buckling Load ◽  
Buckling Mode ◽  
Geometric Imperfections ◽  
Circular Cylindrical Shells ◽  
Step Loading

The dynamic buckling of imperfect finite circular cylindrical shells subjected to suddenly applied and subsequently maintained lateral or hydrostatic pressure is studied using a perturbation method. The geometric imperfections are assumed small but arbitrary. A simple asymptotic expression is obtained for the dynamic buckling load in terms of the amplitude of the Fourier component of the imperfection in the shape of the classical buckling mode. Consequently, for small imperfection, there is a simple relation between the dynamic buckling load under step-loading and the static buckling load. This relation is independent of the shape of the imperfection.

Buckling Load Estimation of Two-way Grid Domes Stiffened by Diagonal Braces Under Vertical Load

2021 ◽  
Vol 62 (1) ◽  
pp. 7-23
Author(s):  
Shiro Kato ◽  
Shoji Nakazawa ◽  
Yoichi Mukaiyama ◽  
Takayuki Iwamoto
Keyword(s):  
Slenderness Ratio ◽  
Fem Analysis ◽  
Buckling Load ◽  
Vertical Load ◽  
Imperfection Sensitivity ◽  
Plastic Buckling ◽  
Elastic Plastic ◽  
Alternative Formula ◽  
Efficient Scheme ◽  
Estimation Scheme

The present study proposes an efficient scheme to estimate elastic-plastic buckling load of a shallow grid dome stiffened by diagonal braces. The dome is circular in plan. It is assumed to be subject to a uniform vertical load and to be supported by a substructure composed of columns and anti-earthquake braces. Based on FEM parametric studies considering various configurations and degrees of local imperfections, a set of formulations are presented to estimate the elastic-plastic buckling load. In the scheme, the linear buckling load, elastic buckling load, and imperfection sensitivity are first presented in terms of related parameters, and the elasticplastic buckling load is then estimated by a semi-empirical formula in terms of generalized slenderness ratio using a corresponding plastic load. For the plastic load, the present scheme adopts a procedure that it is calculated by a linear elastic FEM analysis, while an alternative formula for the plastic load is also proposed based on a shell membrane theory. The validity of the estimation scheme is finally confirmed through comparison with the results based on FEM nonlinear analysis. The formulations are so efficient and simple that the estimation may be conducted for preliminary design purposes almost with a calculator. .

scholarly journals Perturbation Approach in the Dynamic Buckling of a Model Structure with a Cubic-quintic Nonlinearity Subjected to an Explicitly Time Dependent Slowly Varying Load

2019 ◽  
pp. 1-19
Author(s):  
A. M. Ette ◽  
I. U. Udo-Akpan ◽  
J. U. Chukwuchekwa ◽  
A. C. Osuji ◽  
M. F. Noah
Keyword(s):  
Perturbation Technique ◽  
Dynamic Buckling ◽  
Buckling Load ◽  
Time Dependent ◽  
Initial Time ◽  
Perturbation Approach ◽  
Elastic Model ◽  
Model Structure ◽  
Regular Perturbation ◽  
Long Run

This investigation is concerned with analytically determining the dynamic buckling load of an imperfect cubic-quintic nonlinear elastic model structure struck by an explicitly time-dependent but slowly varying load that is continuously decreasing in magnitude. A multi-timing regular perturbation technique in asymptotic procedures is utilized to analyze the problem. The result shows that the dynamic buckling load depends, among other things, on the first derivative of the load function evaluated at the initial time. In the long run, the dynamic buckling load is related to its static equivalent, and that relationship is independent of the imperfection parameter. Thus, once any of the two buckling loads is known, then the other can easily be evaluated using this relationship.

Two-year follow-up results of the Isobar TTL Semi-Rigid Rod System for the treatment of lumbar degenerative disease

2013 ◽  
Vol 20 (3) ◽  
pp. 394-399 ◽  
Author(s):  
Zhonghai Li ◽  
Fengning Li ◽  
Shunzhi Yu ◽  
Hui Ma ◽  
Zhaohui Chen ◽  
...  
Keyword(s):  
Degenerative Disease ◽  
Lumbar Degenerative Disease ◽  
Rod System ◽  
Rigid Rod

Static and Dynamic Buckling of a Fiber Embedded in a Matrix With Interface Debonding

1993 ◽  
Vol 115 (3) ◽  
pp. 297-301
Author(s):  
Y. W. Kwon ◽  
M. Serttunc
Keyword(s):  
Dynamic Instability ◽  
Interfacial Debonding ◽  
Dynamic Buckling ◽  
Buckling Load ◽  
Interface Debonding ◽  
Buckling Mode ◽  
Simply Supported ◽  
Surrounding Matrix ◽  
Foundation Model ◽  
Dynamic Instability Domain

Analyses were performed for static and dynamic buckling of a continuous fiber embedded in a matrix in order to determine effects of interfacial debonding on the critical buckling load and the domain of instability. A beam on elastic foundation model was used for the study. The study showed that a local interfacial debonding between a fiber and a surrounding matrix resulted in an increase of the wavelength of the buckling mode. An increase of the wavelength yielded a decrease of the static buckling load and lowered the dynamic instability domain. In general, the effect of a partial or complete interfacial debonding on the domain of dynamic instability was more significant than its effect on the static buckling load. For dynamic buckling of a fiber, a local debonding of size 10 to 20 percent of the fiber length had the most important influence on the domains of dynamic instability regardless of the location of debonding and the boundary conditions of the fiber. For static buckling, the location of a local debonding was critical to a free, simply supported fiber, but not to a fiber with both ends simply supported.

An Estimation of the Dynamic Buckling Load for the Spacer Grid of Pressurized Water Reactor Fuel Assembly

2006 ◽  
Vol 326-328 ◽  
pp. 1603-1606 ◽  
Author(s):  
Sang Youn Jeon ◽  
Young Shin Lee
Keyword(s):  
Fuel Assembly ◽  
Dynamic Buckling ◽  
Buckling Load ◽  
Estimation Methods ◽  
Pressurized Water Reactor ◽  
Spacer Grid ◽  
Pressurized Water ◽  
Water Reactor ◽  
Spacer Grids ◽  
The Impact

This study contains an estimation of the dynamic buckling load for the spacer grid of fuel assembly in pressurized water reactor. Three different estimation methods were proposed for the calculation of the dynamic buckling loads of spacer grid. The dynamic impact tests and analyses were performed to evaluate the impact characteristics of the spacer grids and to predict the dynamic buckling load of the full size spacer grid. The estimation results were compared with the test results for the verification of the estimation methods.

Shell Stability

1983 ◽  
Vol 50 (4b) ◽  
pp. 935-940 ◽  
Author(s):  
C. D. Babcock
Keyword(s):  
Dynamic Buckling ◽  
Recent History ◽  
Postbuckling Behavior ◽  
Imperfection Sensitivity ◽  
Plastic Buckling ◽  
Shell Stability ◽  
Current Trends ◽  
Shell Buckling ◽  
History Of ◽  
Subject Areas

Recent advances in shell buckling research are reviewed. Five separate subject areas are covered: elastic postbuckling behavior and imperfection sensitivity, plastic buckling, dynamic buckling, experiments and computations. Recent history of the research is presented emphasizing important advances in understanding. Areas of needed research and current trends are pointed out.

Initial Postbuckling Behavior of Imperfect, Antisymmetric Cross-Ply Cylindrical Shells Under Torsion

1987 ◽  
Vol 54 (1) ◽  
pp. 174-180 ◽  
Author(s):  
David Hui ◽  
I. H. Y. Du
Keyword(s):  
Cylindrical Shells ◽  
Elastic Stability ◽  
Buckling Load ◽  
Postbuckling Behavior ◽  
Imperfection Sensitivity ◽  
Torsional Buckling ◽  
Buckling Mode ◽  
Young’S Moduli ◽  
Coupling Behavior ◽  
Parameter Variations

This paper deals with the initial postbuckling of antisymmetric cross-ply closed cylindrical shells under torsion. Under the assumptions employed in Koiter’s theory of elastic stability, the structure is imperfection-sensitive in certain intermediate ranges of the reduced-Batdorf parameter (approx. 4 ≤ ZH ≤ 20.0). Due to different material bending-stretching coupling behavior, the (0 deg inside, 90 deg outside) two-layer clamped cylinder is less imperfection sensitive than the (90 deg inside, 0 deg outside) configuration. The increase in torsional buckling load due to a higher value of Young’s moduli ratio is not necessarily accompanied by a higher degree of imperfection-sensitivity. The paper is the first to consider imperfection shape to be identical to the torsional buckling mode and presents concise parameter variations involving the reduced-Batdorf paramter and Young’s moduli ratio.

Sign in / Sign up

Export Citation Format

Share Document