Influence of initial geometric imperfection on static and free vibration analyses of porous FG nanoplate using an isogeometric approach

2021 ◽  
Vol 43 (4) ◽  
Author(s):  
Heidar Fazeli ◽  
Armen Adamian ◽  
Ahmad Hosseini-Sianaki
Keyword(s):  
Free Vibration ◽  
Geometric Imperfection ◽  
Initial Geometric Imperfection

Determination of collapse moment of different angled pipe bends with initial geometric imperfection subjected to in-plane bending moments

2021 ◽  
pp. 095440622199640
Author(s):  
Manish Kumar ◽  
Pronab Roy ◽  
Kallol Khan
Keyword(s):  
Finite Element ◽  
Cross Section ◽  
Circular Cross Section ◽  
Initial Imperfection ◽  
Bend Angle ◽  
Bending Moments ◽  
Element Analysis ◽  
Geometric Imperfection ◽  
Initial Geometric Imperfection

From the recent literature, it is revealed that pipe bend geometry deviates from the circular cross-section due to pipe bending process for any bend angle, and this deviation in the cross-section is defined as the initial geometric imperfection. This paper focuses on the determination of collapse moment of different angled pipe bends incorporated with initial geometric imperfection subjected to in-plane closing and opening bending moments. The three-dimensional finite element analysis is accounted for geometric as well as material nonlinearities. Python scripting is implemented for modeling the pipe bends with initial geometry imperfection. The twice-elastic-slope method is adopted to determine the collapse moments. From the results, it is observed that initial imperfection has significant impact on the collapse moment of pipe bends. It can be concluded that the effect of initial imperfection decreases with the decrease in bend angle from 150∘ to 45∘. Based on the finite element results, a simple collapse moment equation is proposed to predict the collapse moment for more accurate cross-section of the different angled pipe bends.

Analysis of Nonlinear Buckling of a Long-Span Elliptic Paraboloid Suspended Dome Structure

2013 ◽  
Vol 639-640 ◽  
pp. 191-197 ◽  
Author(s):  
Zheng Rong Jiang ◽  
Kai Rong Shi ◽  
Xiao Nan Gao ◽  
Qing Jun Chen
Keyword(s):  
Single Layer ◽  
Buckling Mode ◽  
Nonlinear Buckling ◽  
Elliptic Paraboloid ◽  
Geometric Imperfection ◽  
Long Span ◽  
Initial Geometric Imperfection ◽  
Dome Structure ◽  
Unsymmetrical Loading ◽  
The Stability

The suspended dome structure, which is a new kind of hybrid spatial one composed of the upper single layer latticed shell and the lower cable-strut system, generally has smaller rise-to-span ratio, thus the overall stability is one of the key factors to the design of the structure. The nonlinear buckling behavior of an elliptic paraboloid suspended dome structure of span 110m80m is investigated by introducing geometric nonlinearity, initial geometric imperfection, material elastic-plasticity and half-span distribution of live loads. The study shows that the coefficient of stable bearing capacity usually is not minimal when the initial geometric imperfection configuration is taken as the first order buckling mode. The unsymmetrical loading distribution and the material nonlinearity might have significant effects on the coefficient. The structure is sensitive to the changes of initial geometric imperfection, and the consistent mode imperfection method is not fully applicable to the stability analysis of suspended dome structure.

Behavior and Design of Web-Slotted Cold-Formed Channels Experiencing Local-Distortional-Global Interactive Buckling

2013 ◽  
Vol 351-352 ◽  
pp. 747-752
Author(s):  
Shuai Liu ◽  
Qi Jie Ma ◽  
Pei Jun Wang
Keyword(s):  
Effective Width ◽  
The Finite Element Method ◽  
Distortional Buckling ◽  
Buckling Mode ◽  
Geometric Imperfection ◽  
Interactive Behavior ◽  
Buckling Behavior ◽  
Initial Geometric Imperfection ◽  
Interactive Buckling ◽  
Shed Light

This article aims to shed light on the nonlinear local-distortional-global interactive behavior of web-slotted channel columns by use of the finite element method. The effects of three kinds of initial geometric imperfection based on different distortional buckling mode were evaluated. It indicates that different distortional buckling mode does little difference on the nonlinear interactive buckling behavior of web-slotted channels. Based on the extensive parametric study, some modifications were made to the traditional Effective Width Method for the practical design of web-slotted channel columns undergoing local-distortional-global interactive buckling.

Application of Fuzzy Set Theory to the Serviceability Limit State of a Steel Beam under Bending

2015 ◽  
Vol 769 ◽  
pp. 91-96
Author(s):  
Jan Vales ◽  
Zdenek Kala ◽  
Jindrich Melcher
Keyword(s):  
Limit State ◽  
Major Axis ◽  
Steel Beam ◽  
Maximum Deflection ◽  
Geometric Imperfection ◽  
Serviceability Limit State ◽  
Limit Value ◽  
Initial Geometric Imperfection ◽  
Slender Beams ◽  
Limiting Condition

Deformations of an I-section steel beam under equal end moments are studied in this article. Initial geometric imperfection of the beam axis was introduced according to the Eurocode standard. Numerical studies have shown that the lateral deflection of slender beams under major axis bending can be relatively high. The acceptability of high values of lateral deflections within the framework of the serviceability limit state is discussed. In the next part of the paper, the limit value of maximum deflection was introduced as a fuzzy number. Fuzzy analysis of the maximum moment, which causes maximum deflection, was performed. The slenderness values of beams for which the serviceability limit state is the limiting condition for design were identified.

Buckling mechanism of cable-stiffened lattice shells with bolted connections

2019 ◽  
Vol 22 (15) ◽  
pp. 3234-3248
Author(s):  
Xi Wang ◽  
Ruo-qiang Feng ◽  
Gui-rong Yan ◽  
Bao-chen Zhu ◽  
Feng-cheng Liu
Keyword(s):  
Bolted Joints ◽  
Bolted Connections ◽  
Elliptic Paraboloid ◽  
Buckling Loads ◽  
Geometric Imperfection ◽  
Initial Geometric Imperfection ◽  
In Series ◽  
Lattice Shell ◽  
Rigid Joints ◽  
Lattice Shells

The cable-stiffened lattice shell is a new structural system for its translucence and lighting. This article discusses the effect of the connections’ behavior and geometric imperfection on the structural stability and reveals the buckling mechanism of the cable-stiffened lattice shell. The spring stiffness for bolted connections of cable-stiffened lattice shells is deduced from the spring in series model. The buckling mechanism of cable-stiffened lattice shells with three types of joints have been studied based on the prototypical static experiments of bolted connections. The decrease of bolted connections’ stiffness would lead to the change in the displacement distribution for the lattice shell under its ultimate load. The buckling loads and initial structural stiffness of cable-stiffened lattice shells with shim-strengthened bolted joints are approximately 80% of those for cable-stiffened lattice shells with rigid joints. The result indicates that the buckling loads of cable-stiffened lattice shells with bolted connections decrease much more slowly than the decrease of bolted connections’ stiffness. The cable-stiffened lattice shell with SBP connections is more sensitive to the initial geometric imperfection. Finally, a formula has been proposed for estimating buckling loads of elliptic paraboloid cable-stiffened lattice shells with bolted connections.

Effects of Geometric Imperfections on Vibrations of Biaxially Compressed Rectangular Flat Plates

1983 ◽  
Vol 50 (4a) ◽  
pp. 750-756 ◽  
Author(s):  
David Hui ◽  
A. W. Leissa
Keyword(s):  
Plate Thickness ◽  
Biaxial Compression ◽  
Vibration Frequencies ◽  
Finite Deflections ◽  
Flat Plates ◽  
Geometric Imperfections ◽  
Geometric Imperfection ◽  
Simply Supported ◽  
Initial Geometric Imperfection

This paper deals with the effects of geometric imperfections on the vibration frequencies of simply supported flat plates under in-plane uniaxial or biaxial compression. The analysis is based on a solution of the nonlinear von Ka´rma´n equations for finite deflections, incorporating the influence of an initial geometric imperfection. It is found that significant increase in the vibration frequencies may occur for imperfection amplitude of the order of a fraction of the plate thickness, even in the absence of in-plane forces.

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