Buckling and Post-Buckling of Thin Elastoplastic Cylindrical Shells With Finite Rotations

2000 ◽  
Author(s):  
Philippe Le Grognec ◽  
Anh Le Van
Keyword(s):  
Yield Criterion ◽  
Kinematic Hardening ◽  
Three Dimensional ◽  
Thin Shells ◽  
Elastoplastic Material ◽  
Plane Stress Condition ◽  
Buckling Mode ◽  
Non Linear ◽  
Post Buckling ◽  
Non Linear System

Abstract An elastoplastic thin shell model is presented in this work in order to compute the buckling and post-buckling behavior of cylindrical shell-type structures. Standard assumptions in the shell kinematics allow us to develop a large deformation and finite rotation model for thin shells from the three-dimensional continuum. An elastoplastic constitutive model for thin shells is derived from the three-dimensional framework, assuming the plane stress condition. The von Mises yield criterion is adopted including non-linear isotropic and linear kinematic hardening. The resulting non-linear system is solved by a Newton-Raphson solution procedure, including the consistent linearization of the shell kinematics and the elastoplastic material model. The high non-linearities due to the buckling-type instabilities, especially those occuring in the neighbourhood of critical points, necessitate the use of an appropriate step-length control. An arc-length method has been successfully implemented for passing through limit points (load or displacement peaks) where pure load or displacement controls fail. The proposed method is effective in handling both sharp snap-throughs and snap-backs. Two numerical examples are presented in view of the assessment of the proposed approach and a particular attention is devoted to the post-buckling of hollow cylinders under axial compression. We identify several types of buckling mode for these structures, among which the axisymmetric mode, the “diamond” mode and the “elephant foot” mode, depending on geometry and boundary conditions.

Towards imperfection insensitive buckling response of shell structures-shells with plate-like post-buckled responses

2016 ◽  
Vol 120 (1224) ◽  
pp. 233-253 ◽  
Author(s):  
S. C. White ◽  
P. M. Weaver
Keyword(s):  
Variable Stiffness ◽  
Axial Stiffness ◽  
Asymptotic Model ◽  
Imperfection Sensitivity ◽  
Asymptotic Results ◽  
Buckling Mode ◽  
Design Variables ◽  
Non Linear ◽  
Buckling Stability ◽  
Post Buckling

ABSTRACTThe imperfection sensitivity of cylindrical panels under compression loading is shown to be not only reduced but effectively eliminated using stiffness tailoring techniques. Shells are designed with variable angle-tow (VAT) laminae, giving their laminates variable-stiffness properties over the surface co-ordinates. By employing an asymptotic model of the non-linear shell behaviour and a genetic algorithm, the post-buckling stability was maximised with respect to the VAT design variables. Results for optimised straight-fibre and VAT shells are presented in comparison with quasi-isotropic designs. In the straight-fibre case, small improvements in the post-buckling stability are shown to be possible but at the expense of the buckling load. In the VAT case, on the other hand, considerable improvements in the post-buckling stability are obtained and drops in axial stiffness and load associated with buckling are reduced to negligible levels. The improvements are shown to be a result of a benign membrane stress distribution prior to buckling and a localisation of the buckling mode. The asymptotic results are compared with non-linear finite-element analyses and are found to be in good agreement. Potential future multi-objective optimisation studies are discussed.

Analysis of Residual Stress in the Rotational Autofrettage of Thick-Walled Disks

2018 ◽  
Vol 140 (6) ◽  
Author(s):  
S. M. Kamal
Keyword(s):  
Plastic Deformation ◽  
Residual Stresses ◽  
Yield Criterion ◽  
Three Dimensional ◽  
Circular Disk ◽  
Flow Rule ◽  
Plane Stress Condition ◽  
Radial Temperature ◽  
Fem Validation ◽  
Compressive Residual Stresses

Autofrettage is a means of generating compressive residual stresses at the inner side of a thick-walled cylinder or hollow disk by causing nonhomogeneous plastic deformation of the material at the inner side. The presence of residual compressive stresses at the inner region of the cylinder/disk enhance the pressure withstanding capacity, fatigue life and the resistance to stress corrosion cracking of the component. Despite the hydraulic and swage autofrettage are the widely practiced processes in industries, there are certain disadvantages associated with these processes. In view of this, in the recent years, researchers have proposed new methods of achieving autofrettage. Rotational autofrettage is such a recently proposed autofrettage method for achieving the beneficial compressive residual stresses in the cylinders. In the present work, the rotational autofrettage is studied for a thick-walled hollow circular disk. A theoretical analysis of the residual stresses produced in the disk after unloading are obtained assuming plane stress condition, Tresca yield criterion and its associated flow rule. The analysis takes into account the effect of strain hardening during plastic deformation. Further, the effect of residual stresses in the typical SS304 and aluminum disk is studied by subjecting them into three different types of loads viz., internal pressure, radial temperature difference, and rotational speed individually. A three-dimensional (3D) finite element method (FEM) validation of the theoretical stresses during rotational autofrettage of a disk is also presented.

A Numerical Elastoplastic Model for Rough Contact

1995 ◽  
Vol 117 (3) ◽  
pp. 422-429 ◽  
Author(s):  
C. Mayeur ◽  
P. Sainsot ◽  
L. Flamand
Keyword(s):  
Yield Criterion ◽  
Kinematic Hardening ◽  
Three Dimensional ◽  
Surface Shape ◽  
Real Surface ◽  
Pressure Distributions ◽  
Surface Displacements ◽  
Elastic Shakedown ◽  
Von Mises

Pressure distributions due to surface roughness in contact induce high stresses just beneath the surface. These stresses can bring on crack initiation and micro-pitting. A purely elastic contact model to account for these effects is restrictive because stress fields often exceed the yield strength of the material. Plastic flow occurs and modifies the surface shape and material properties (work hardening). This paper presents a numerical model for elastoplastic rough contact. It allows the determination of real pressures and permanent surface displacements (flattening of asperities) as well as residual stress and plastic strains useful in fatigue analysis). The material is assumed to obey the Von-Mises yield criterion with linear kinematic hardening. Real surface profiles obtained from a measurement can be considered. In addition, simplified methods have been used to treat cyclic loading. Thus the ability of a rough surface to reach an elastic shakedown state can be investigated, even for a three-dimensional contact found, for instance, in roller bearings.

scholarly journals A Chaotic Three Dimensional Non-Linear Autonomous System Beyond Lorenz Type Systems

2012 ◽  
Vol 36 (2) ◽  
pp. 159-170
Author(s):  
Md Shariful Islam Khan ◽  
Md Shahidul Islam
Keyword(s):  
Autonomous System ◽  
Three Dimensional ◽  
Type Systems ◽  
Control Parameters ◽  
Fundamental Properties ◽  
Non Linear ◽  
Linear Autonomous System ◽  
Non Linear System ◽  
Academy Of Sciences ◽  
The Relationship

Some fundamental properties of a chaotic three-dimensional non-linear system of the Lorenz type systems were studied. The invariance, dissipation, bifurcation and the strange attractors were investigated and analyzed one 1-scroll, two 2-scroll and two 4-scroll attractors by adding control   parameters to this system. The relationship and connecting function for the 2-scroll attractor of this system were also explored. DOI: http://dx.doi.org/10.3329/jbas.v36i2.12959 Journal of Bangladesh Academy of Sciences, Vol. 36, No. 2, 159-170, 2012  

scholarly journals A nonlinear viscoelastic–viscoplastic constitutive model for adhesives under creep

2021 ◽  
Author(s):  
Yi Chen ◽  
Lloyd V. Smith
Keyword(s):  
Yield Criterion ◽  
Kinematic Hardening ◽  
Viscoelastic Model ◽  
Three Dimensional ◽  
Creep Recovery ◽  
Element Analysis ◽  
Viscoplastic Model ◽  
Nonlinear Viscoelastic ◽  
Residual Strains ◽  
Scarf Joints

AbstractIn this study, we consider the nonlinear viscoelastic–viscoplastic behavior of adhesive films in scarf joints. We develop a three-dimensional nonlinear model, which combines a nonlinear viscoelastic model with a viscoplastic model using the von Mises yield criterion and nonlinear kinematic hardening. We implement an iterative scheme for the viscoplastic solution and a numerical algorithm with stress correction for the combined viscoelastic–viscoplastic model into finite element analysis. The viscoelastic component of the model is calibrated using creep-recovery data from adhesive films in scarf joints. The viscoplastic parameters are calibrated from the residual strains of recovered creep tests with varying load durations. A two-dimensional form of the model shows good agreement with the three-dimensional model for the scarf joint considered in this work and is compared with experiment. The numerical results show favorable agreement with the experimental creep and recovery responses of two epoxy adhesive systems. We also discuss the contribution of nonlinear viscoelasticity and viscoplasticity to the stress/strain distribution along the adhesive center lines. Viscoplasticity tends to lower the stress concentration.

Finite Element Analysis of Vacant Tubular Members under Static Loading Considering the Tip Shapes of Load

2014 ◽  
Vol 575 ◽  
pp. 497-500
Author(s):  
Mahmud Kori Effendi ◽  
Shuhei Zaitsu ◽  
Hiromitsu Kawaguchi ◽  
Akihiko Kawano ◽  
Shintaro Matsuo ◽  
...  
Keyword(s):  
Static Loading ◽  
Isotropic Material ◽  
Yield Criterion ◽  
Kinematic Hardening ◽  
Deformable Body ◽  
Three Dimensional ◽  
Fem Analysis ◽  
Element Analysis ◽  
Fem Model ◽  
Von Mises

FEM analysis of MSC. Marc program is used to simulate the models. Three-dimensional FEM model with contact analysis between deformable body of specimens and rigid body of load are studied. The isotropic material and The Von Mises yield criterion are used and kinematic hardening is used as a flow plasticity model. The effect of various shapes of loading tips is investigated. The load-displacement were established. The results of these works are expected to be a useful reference for analyzing structures under various shapes of loading tips either static or dynamic loading.

Soil/Tire Interaction Analysis Using FEM and FVM

2005 ◽  
Vol 33 (1) ◽  
pp. 38-62 ◽  
Author(s):  
S. Oida ◽  
E. Seta ◽  
H. Heguri ◽  
K. Kato
Keyword(s):  
Large Scale ◽  
Interaction Analysis ◽  
Yield Criterion ◽  
Surrounding Medium ◽  
Flow Analysis ◽  
Measurement Data ◽  
Traction Force ◽  
Elastoplastic Material ◽  
The Road ◽  
Soil Flow

Abstract Vehicles, such as an agricultural tractor, construction vehicle, mobile machinery, and 4-wheel drive vehicle, are often operated on unpaved ground. In many cases, the ground is deformable; therefore, the deformation should be taken into consideration in order to assess the off-the-road performance of a tire. Recent progress in computational mechanics enabled us to simulate the large scale coupling problem, in which the deformation of tire structure and of surrounding medium can be interactively considered. Using this technology, hydroplaning phenomena and tire traction on snow have been predicted. In this paper, the simulation methodology of tire/soil coupling problems is developed for pneumatic tires of arbitrary tread patterns. The Finite Element Method (FEM) and the Finite Volume Method (FVM) are used for structural and for soil-flow analysis, respectively. The soil is modeled as an elastoplastic material with a specified yield criterion and a nonlinear elasticity. The material constants are referred to measurement data, so that the cone penetration resistance and the shear resistance are represented. Finally, the traction force of the tire in a cultivated field is predicted, and a good correlation with experiments is obtained.

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