Plastic Deformation of Anisotropic Tubes in Hydraulic Bulging

1978 ◽  
Vol 100 (4) ◽  
pp. 421-425 ◽  
Author(s):  
D. M. Woo ◽  
A. C. Lua
Keyword(s):  
Strain Distribution ◽  
Circumferential Strain ◽  
Plastic Anisotropy ◽  
Strain Ratio ◽  
Stress Strain ◽  
Thickness Strain ◽  
Process Comparison ◽  
Tension Tests ◽  
Anisotropy Effect ◽  
Hydraulic Bulging

The anisotropy of tubular material is assessed from the values of the width/thickness strain ratio determined in the tension tests. Applying Hill’s theory of plastic anisotropy, these values are incorporated in the expressions for determining the stress/strain characteristics for anisotropic material in the tension and bulge tests, and also in the theoretical analysis of the hydraulic bulging of anisotropic tubes. Experiments have been carried out on copper tubes. Taking into account the anisotropy effect, the stress/strain curves determined in the tension and bulge tests agree closely except at the low strain region. In the analysis of the bulging process, comparison is made between the theoretical and the experimental circumferential strain distribution. The results appear satisfactory.

Routes towards Novel Active Pressure Sensors in SOI Technology

2011 ◽  
Vol 276 ◽  
pp. 145-155
Author(s):  
Benoit Olbrechts ◽  
Bertrand Rue ◽  
Thomas Pardoen ◽  
Denis Flandre ◽  
Jean Pierre Raskin
Keyword(s):  
Finite Elements ◽  
Strain Distribution ◽  
Pressure Sensors ◽  
High Sensitivity ◽  
Stress Strain ◽  
Pressure Transducers ◽  
Active Devices ◽  
Active Pressure ◽  
Soi Technology

In this paper, novel pressure sensors approach is proposed and described. Active devices and oscillating circuits are directly integrated on very thin dielectric membranes as pressure transducers. Involved patterning of the membrane is supposed to cause a drop of mechanical robustness. Finite elements simulations are performed in order to better understand stress/strain distribution and as an attempt to explain the early burst of patterned membranes. Smart circuit designs are reported as solutions with high sensitivity and reduced footprint on membranes.

Characterization of Hyperelastic (Rubber) Material Using Uniaxial and Biaxial Tension Tests

2012 ◽  
Vol 570 ◽  
pp. 1-7
Author(s):  
Yawar Jamil Adeel ◽  
Ahsan Irshad Muhammad ◽  
Azmat Zeeshan
Keyword(s):  
Shear Test ◽  
Biaxial Tension ◽  
Constitutive Models ◽  
Hyperelastic Material ◽  
Strain Response ◽  
Stress Strain ◽  
Rubber Material ◽  
Tension Tests ◽  
Planar Shear

Hyperelastic material simulation is necessary for proper testing of products functionality in cases where prototype testing is expensive or not possible. Hyperelastic material is nonlinear and more than one stress-strain response of the material is required for its characterization. The study was focused on prediction of hyperelastic behavior of rubber neglecting the viscoelastic and creep effects in rubber. To obtain the stress strain response of rubber, uniaxial and biaxial tension tests were performed. The data obtained from these tests was utilized to find the coefficients of Mooney-Rivlin, Odgen and Arruda Boyce models. Verification of the behavior as predicted by the fitted models was carried out by comparing the experimental data of a planar shear test with its simulation using the same constitutive models.

Research on Hydraulic Conductivity of Coarse Sandstone under Triaxial Compression

2011 ◽  
Vol 94-96 ◽  
pp. 1146-1151 ◽  
Author(s):  
Guan Rong ◽  
Xiao Jiang Wang
Keyword(s):  
Hydraulic Conductivity ◽  
Circumferential Strain ◽  
Triaxial Compression ◽  
Confining Pressure ◽  
Test Results ◽  
Stress Strain ◽  
Deformation And Failure ◽  
Maximum Value ◽  
Strain Process ◽  
Peak Value

Permeability test for complete stress-strain process of coarse sandstone were carried out in triaxial test instrument. On the basis of test results, the influence of confining pressure and strain on the hydraulic conductivity was discussed. It is shown that in the complete stress-strain process, hydraulic conductivity changes in the law that presents the same character with the curve of stress-strain. The hydraulic conductivity reduces slightly with the increase of deviatoric stress in the stage of micro fracture compressing and elastic; In the elastoplastic stage, along with the expansion of new fractures, the hydraulic conductivity increases slowly at first and then reaches sharply to the maximum value after peak point; In the post-peak stage, the fracture which controls the hydraulic conductivity of coarse sandstone is compressed because of the confining pressure and the hydraulic conductivity decreases. During the process of deformation and failure, the hydraulic conductivity is more sensitive to the change of circumferential strain. With the increase of confining pressure, the increased value from initial to peak value and the decreased value from peak to residual value decreases.

Plastic Instability of Thin Shells Deformed by Rigid Punches and by Hydraulic Pressure

1973 ◽  
Vol 95 (1) ◽  
pp. 36-40 ◽  
Author(s):  
Bilgin Kaftanog˘lu
Keyword(s):  
Large Deformations ◽  
Initial Conditions ◽  
Plastic Anisotropy ◽  
Plastic Instability ◽  
Strain History ◽  
Thin Shells ◽  
Hydraulic Pressure ◽  
Varying Thickness ◽  
New Criterion ◽  
Hydraulic Bulging

A theory has been developed to provide a solution for axisymmetrical shells in the plastic range for large deformations up to fracture. It includes the effects of strain history, nonlinear strain-hardening characteristics of materials, plastic anisotropy in the thickness direction, prestrain, through-thickness stress, and boundary tractions. It is also possible to use nonuniform initial conditions such as varying thickness and varying prestrain. A numerical solution has been developed especially suitable for stretch forming by a rigid punch and for hydraulic bulging of shells or diaphragms. It can easily be modified for the deep-drawing problem. Different instability criteria have been studied. It was found that the conventional criteria would not yield satisfactory results. A new criterion called the “strain propagation” criterion gave satisfactory results in the prediction of the onset of fracture. It could expalin the fracture taking place at increasing or decreasing pressures in the hydraulic bulging problem.

Effect of Material Frame Rotation on the Hardening of an Anisotropic Material in Simple Shear Tests

2018 ◽  
Vol 85 (12) ◽  
Author(s):  
Kelin Chen ◽  
Stelios Kyriakides ◽  
Martin Scales
Keyword(s):  
Simple Shear ◽  
Plastic Anisotropy ◽  
Yield Function ◽  
Strain Response ◽  
Shear Tests ◽  
Stress Strain ◽  
Anisotropic Yield Function ◽  
Torsion Experiment ◽  
Thin Walled Tube ◽  
Material Frame

The shear stress–strain response of an aluminum alloy is measured to a shear strain of the order of one using a pure torsion experiment on a thin-walled tube. The material exhibits plastic anisotropy that is established through a separate set of biaxial experiments on the same tube stock. The results are used to calibrate Hill's quadratic anisotropic yield function. It is shown that because in simple shear the material axes rotate during deformation, this anisotropy progressively reduces the material tangent modulus. A parametric study demonstrates that the stress–strain response extracted from a simple shear test can be influenced significantly by the anisotropy parameters. It is thus concluded that the material axes rotation inherent to simple shear tests must be included in the analysis of such experiments when the material exhibits anisotropy.

Stress and Strain Distribution in the Upsetting Process

2021 ◽  
pp. 288-301
Author(s):  
Japheth Obiko ◽  
Fredrick Madaraka Mwema
Keyword(s):  
Finite Element ◽  
Strain Distribution ◽  
Metal Flow ◽  
Stress Strain ◽  
Element Analysis ◽  
The Finite Element Analysis ◽  
Contact Surfaces ◽  
Stress Behaviour ◽  
Stress And Strain Distribution ◽  
Forging Load

Numerical simulation of metal flow behaviour was studied using DeformTM3D software. The simulation process was done on X20 steel taken from the software database at 1073-1273K temperature, 10mm/s die speed, and 67% height reduction. From the simulation results, forging load, damage, and stress/strain distributions were obtained. The results show that the forging load increased with a decrease in temperature or decreased with an increase in temperature. The maximum damage values increased as the temperature increased. The obtained maximum damage values were 0.42 (1073K), 0.43 (1173K), and 0.45 (1273K). The damage distribution was inhomogeneous in the deformed cylinder. The stress/strain distributions were inhomogeneous in the deformed cylinder. The location of the maximum strain was at the centre of the deformed cylinder while the maximum stress occurred at the die-cylinder contact surfaces. The study showed that flow stress behaviour can be predicted using finite element method. This shows the feasibility of applying the finite element analysis to analyse the forging process.

scholarly journals Quantifying the Contribution of Crystallographic Texture and Grain Morphology on the Elastic and Plastic Anisotropy of bcc Steel

Metals ◽  
2019 ◽  
Vol 9 (12) ◽  
pp. 1252 ◽  
Author(s):  
Martin Diehl ◽  
Jörn Niehuesbernd ◽  
Enrico Bruder
Keyword(s):  
Young’S Modulus ◽  
Crystallographic Texture ◽  
Young's Modulus ◽  
Hsla Steel ◽  
Geometric Mean ◽  
Plastic Anisotropy ◽  
Grain Morphology ◽  
Strain Partitioning ◽  
Stress Strain ◽  
Full Field

The influence of grain shape and crystallographic orientation on the global and local elastic and plastic behaviour of strongly textured materials is investigated with the help of full-field simulations based on texture data from electron backscatter diffraction (EBSD) measurements. To this end, eight different microstructures are generated from experimental data of a high-strength low-alloy (HSLA) steel processed by linear flow splitting. It is shown that the most significant factor on the global elastic stress–strain response (i.e., Young’s modulus) is the crystallographic texture. Therefore, simple texture-based models and an analytic expression based on the geometric mean to determine the orientation dependent Young’s modulus are able to give accurate predictions. In contrast, with regards to the plastic anisotropy (i.e., yield stress), simple analytic approaches based on the calculation of the Taylor factor, yield different results than full-field microstructure simulations. Moreover, in the case of full-field models, the selected microstructure representation influences the outcome of the simulations. In addition, the full-field simulations, allow to investigate the micro-mechanical fields, which are not readily available from the analytic expressions. As the stress–strain partitioning visible from these fields is the underlying reason for the observed macroscopic behaviour, studying them makes it possible to evaluate the microstructure representations with respect to their capabilities of reproducing experimental results.

scholarly journals Calculation of composite elements of slabs in buildings, structures and fragments of spans of bridges

2018 ◽  
Vol 230 ◽  
pp. 02007 ◽  
Author(s):  
Stanislav Fomin ◽  
Yuriy Izbash ◽  
Serhii Butenko ◽  
Maryna Iakymenko ◽  
Karina Spirande
Keyword(s):  
Bearing Capacity ◽  
High Temperatures ◽  
Composite Structures ◽  
Strain Ratio ◽  
Strain Diagram ◽  
Stress Strain ◽  
Maximum Deformation ◽  
Definition Of ◽  
Two Stages ◽  
The Mathematical Model

The calculation consists of two stages. The first one begins with the definition of their class, bearing capacity at temperature of 20 °C, according to EN 1992-1-1. At the second stage, the calculation at high temperatures shall be carried out in accordance with Eurocode 4 part 1-2. Comparison of the “stress-strain” diagram of concrete of class 30 under compression and temperature of 20 °C in two formulas showed their difference. That is, the designers do not have the opportunity to continue the calculation of diagrams at different heating temperatures. There was a need to improve the mathematical model of the “stress-strain” ratio of concrete high temperatures, clarification of the criteria of the bearing capacity of concrete in calculation of the fire resistance of composite structures in EN 1994-1-2:2005. In this paper, the method of determination of εcu1,θ developed has allowed, based on the energy approach, to formulate the corrected dependence of the limit deformation on temperature, dependence of the maximum deformation on temperature, and the value of the parameters of the “stress-strain” diagram. According to these data, using the formulas of the first stage, the “stress-strain” diagrams of the concrete of class 30 are calculated at the compression and heating according to EN 1992-1-2:2004.

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