scholarly journals A Simplified Analysis of the Post-buckling Behavior of a Compressed Reinforcing Bar

10.14311/650 ◽  
2004 ◽  
Vol 44 (5-6) ◽  
Author(s):  
P. Kabele
Keyword(s):  
Plastic Material ◽  
Axial Loading ◽  
Central Line ◽  
Material Behavior ◽  
Multiscale Approach ◽  
Rigid Plastic ◽  
Element Analysis ◽  
Reinforcing Bar ◽  
Buckling Behavior ◽  
Post Buckling

Recently, a computational methodology based on a sequential multiscale approach, which facilitates numerical simulation of an R/C building demolition has been developed. In this type of analysis, it is necessary to capture the behavior of compressed reinforcement bars until complete rupture, which occurs due to extensive bending in the post-buckling regime. To this end, a simplified analytical model of the post-buckling behavior of a compressed bar is proposed. The simplification consists namely in considering rigid-plastic material behavior, neglecting axial contraction of the central line, and approximating the shape of the deformed central line in the plastic hinges by a circular arch. Consequently, the axial loading force, bar end displacement, and extreme strain can be expressed in relatively simple closed forms. The results obtained with the proposed model show very close agreement with those obtained by a detailed and realistic finite element analysis, which justifies the use of the simplifying assumptions. 

Elastic and elastic-plastic finite element analysis of hollow tubes with axisymmetric internal projections under combined axial and pressure loading

2001 ◽  
Vol 36 (4) ◽  
pp. 373-390 ◽  
Author(s):  
S. J Hardy ◽  
M. K Pipelzadeh ◽  
A. R Gowhari-Anaraki
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Internal Pressure ◽  
Plastic Material ◽  
Axial Loading ◽  
Material Model ◽  
Pressure Loading ◽  
Element Analysis ◽  
Elastic Plastic ◽  
Applied Loading

This paper discusses the behaviour of hollow tubes with axisymmetric internal projections subjected to combined axial and internal pressure loading. Predictions from an extensive elastic and elastic-plastic finite element analysis are presented for a typical geometry and a range of loading combinations, using a simplified bilinear elastic-perfectly plastic material model. The axial loading case, previously analysed, is extended to cover the additional effect of internal pressure. All the predicted stress and strain data are found to depend on the applied loading conditions. The results are normalized with respect to material properties and can therefore be applied to geometrically similar components made from other materials, which can be represented by the same material models.

Effect of Core Plasticity on the Post-Buckling Behavior of Debonded Sandwich Beams

2000 ◽  
Author(s):  
Bhavani V. Sankar ◽  
Manickam Narayanan ◽  
Abhinav Sharma
Keyword(s):  
Plastic Material ◽  
Maximum Load ◽  
Face Sheet ◽  
Compression Tests ◽  
Element Analysis ◽  
The Core ◽  
Perfectly Plastic ◽  
The Face ◽  
Post Buckling ◽  
Elastic Perfectly Plastic

Abstract Nonlinear finite element analysis was used to simulate compression tests on sandwich composites containing debonded face sheets. The core was modeled as an elastic-perfectly-plastic material, and the face-sheet as elastic isotropic. The effects of core plasticity, face-sheet and core thickness, and debond length on the maximum load the beam can carry were studied. The results indicate that the core plasticity is an important factor that determines the maximum load.

Effect of Matching Buckling Loads on Post-Buckling Behavior in Compliant Mechanisms

2021 ◽  
Author(s):  
A. Numić ◽  
T. W. A. Blad ◽  
F. van Keulen
Keyword(s):  
Compliant Mechanisms ◽  
Relative Length ◽  
Optimal Designs ◽  
Element Analysis ◽  
Buckling Loads ◽  
Actuation Force ◽  
Stepped Beam ◽  
Buckling Behavior ◽  
Post Buckling ◽  
Novel Method

Abstract In this paper, a novel method for stiffness compensation in compliant mechanisms is investigated. This method involves tuning the ratio between the first two critical buckling loads. To this end, the relative length and width of flexures in two architectures, a stepped beam and parallel guidance, are adjusted. Using finite element analysis, it is shown that by maximizing this ratio, the actuation force for transversal deflection in post-buckling is reduced. These results were validated experimentally by identifying the optimal designs in a given space and capturing the force-deflection characteristics of these mechanisms.

Delamination Suppression in Sandwich Beams Using Translaminar Reinforcements

1999 ◽  
Author(s):  
Brian T. Wallace ◽  
Bhavani V. Sankar ◽  
Peter G. Ifju
Keyword(s):  
Axial Compression ◽  
Sandwich Beam ◽  
Sandwich Beams ◽  
Thickness Direction ◽  
Compression Tests ◽  
Honeycomb Core ◽  
Element Analysis ◽  
Buckling Loads ◽  
Buckling Behavior ◽  
Post Buckling

Abstract The present study is concerned with translaminar reinforcement in a sandwich beam for preventing buckling of a delaminated face-sheet under axial compression. Graphite/epoxy pins are used as reinforcement in the thickness direction of sandwich beams consisting of graphite/epoxy face-sheets and a Aramid honeycomb core. Compression tests are performed to understand the effects of the diameter of the reinforcing pins and reinforcement spacing on the ultimate compressive strength of the delaminated beams. A finite element analysis is performed to understand the effects of translaminar reinforcement on the critical buckling loads and post-buckling behavior of the sandwich beam under axial compression.

On the Post-Buckling Behavior of Reinforced Composite Shells

1990 ◽  
Vol 34 (03) ◽  
pp. 207-211
Author(s):  
Victor Birman
Keyword(s):  
Sufficient Conditions ◽  
Axial Loading ◽  
Dynamic Buckling ◽  
General Analysis ◽  
Composite Shells ◽  
Stiffened Shells ◽  
Reinforced Composite ◽  
Buckling Behavior ◽  
Axisymmetric Buckling ◽  
Post Buckling

The problem of post-buckling behavior of composite cylindrical shells reinforced in the axial and circumferential directions and subject to axial loading is considered. The equations of equilibrium of an imperfect shell are formulated in terms of displacements. Then the sufficient conditions of imperfection in sensitivity for both static and dynamic buckling problems are formulated. This general analysis is applied to a particular case of axisymmetric buckling of ring-stiffened shells which appear to be practically imperfection-insensitive.

Simplified Equations for Predicting Secondary Stress Around Pipe’s Circumference

2013 ◽  
Author(s):  
Junkan Wang ◽  
Rajil Saraswat ◽  
Ali Mirzaee-Sisan
Keyword(s):  
Residual Stress ◽  
Plastic Material ◽  
Axial Strain ◽  
Quadratic Equation ◽  
Material Behavior ◽  
Global Maximum ◽  
Isotropic Hardening ◽  
Element Analysis ◽  
Hardening Material ◽  
Maximum Residual Stress

This paper examines the magnitude and location of the maximum residual stress induced in pipes after the process of bending, reverse-bending and straightening. Dimensional analysis is used to establish generalized equations relating the maximum residual stress magnitude and location to the pipe geometry, maximum bending curvature and pipe material’s yield stress. 64 design cases based on an analytical solution assuming elastic-perfectly-plastic material behavior have been conducted. Regression analysis has revealed that the magnitude of the maximum residual stress can be conservatively approximated by a simplified quadratic equation involving the maximum axial bending strain, whereas the location of the maximum residual stress can be approximated by a linear function based on the same. Both equations are expected to be valid and conservative for X65 and X70 grade steel pipes under global maximum axial strain between 1% and 3%. Non-linear finite element analysis based on a realistic design example with isotropic hardening material is used to validate the prediction results based on the simplified equations.

Elastic—plastic finite element analysis of short flat bars with projections part 2: Axial loading

1996 ◽  
Vol 31 (1) ◽  
pp. 25-33 ◽  
Author(s):  
S J Hardy ◽  
M K Pipelzadeh
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Plastic Material ◽  
Axial Loading ◽  
Material Model ◽  
Shear Loading ◽  
Element Analysis ◽  
Elastic Plastic ◽  
Elastic Plastic Material ◽  
Stress Concentration Factors

This paper describes the results of a study of the elastic–plastic behaviour of short flat bars with projections subjected to monotonic and cyclic axial loading using finite element analysis. The results are complementary to similar results for (a) shear loading and (b) combined axial and shear loading. Six geometries are considered and elastic–plastic stress and strain data for both local and remote restraints are presented. These geometries and associated restraints result in elastic stress concentration factors in the range 1.69–4.96. A simple bilinear elastic–plastic material model is assumed and the results are normalized with respect to material properties so that they can be applied to geometrically similar components made from other materials which can be represented by the same material models.

Comparative Study of Post-Buckling Load Redistribution in Stiffened Aircraft Panel With and Without Material Nonlinearity

2018 ◽  
Author(s):  
Enes Aydin ◽  
Altan Kayran
Keyword(s):  
Finite Element ◽  
Material Nonlinearity ◽  
Stiffened Panel ◽  
Effective Width ◽  
Element Analysis ◽  
Buckling Behavior ◽  
The Finite Element Analysis ◽  
Post Buckling ◽  
Buckling Coefficient ◽  
Clamped Edge

In this article, a comparative study is presented on the post-buckling load redistribution in stiffened aircraft panels modeled with and without material nonlinearity. In the first part of the study, a baseline stiffened panel is generated for further investigation of the material nonlinearity on the post-buckling behavior and on the effective width of the stiffened panel. In this respect, a stiffener section which provides classical clamped edge condition is designed by matching the compression buckling coefficient determined by the finite element analysis closely with the analytically determined buckling coefficient of the clamped edge panel. Post-buckling analysis of the stiffened panel is then performed utilizing linear and nonlinear material models in the finite element analysis and the effect of material plasticity on the post-buckling behavior of the panel is ascertained. The load distribution in the stiffened panel is investigated just before the buckling of the panel and before the collapse of the panel in the post-buckled stage. The effective widths of the panel are calculated before the collapse of the panel using the load distributions determined by the finite element analyses of the panel models with and without material nonlinearity and comparisons are made with the effective width calculated by the classical effective width formulation. It is shown that material nonlinearity accounts for higher effective width and in general the classical empirical approach gives the smallest effective width.

AXIAL CRUSHING OF TRIANGULAR TUBES

2013 ◽  
Vol 05 (01) ◽  
pp. 1350008 ◽  
Author(s):  
Z. FAN ◽  
G. LU ◽  
T. X. YU ◽  
K. LIU
Keyword(s):  
Plastic Material ◽  
Progressive Collapse ◽  
Material Model ◽  
Acute Angle ◽  
Rigid Plastic ◽  
Element Analysis ◽  
Axial Crushing ◽  
Rigid Plastic Material ◽  
Theoretical Predictions ◽  
New Type

In the present paper, the mechanical behavior of large deformation of a regular equilateral triangular tube under quasi-static axial crushing is reported, which is a polygon with an acute angle and odd number of sides. Based on the results from nonlinear finite element analysis (FEA), a new type of inextensional basic plastic collapse folding element is proposed to describe the plastic progressive collapse. The progressive folding around the stationary horizontal hinges and inclined traveling hinges are involved to develop the new basic folding element. Two types of inextensible deformation modes are discovered, i.e., diamond mode and rotational symmetrical mode. The average crushing load for each mode is predicted from the super-folding element theory, which was proposed from the previous investigation on the axial crushing of square columns. A rigid-plastic material model and a kinematically admissible model are involved in this theory. The results are further validated against experiments. The approximate quasi-static theoretical predictions for the mean crushing loads of triangular tubes provide reasonable agreement with the corresponding experimental results.

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