Procedure for the Determination of True Stress-Strain Curves From Tensile Tests With Rectangular Cross-Section Specimens

2004 ◽  
Vol 126 (1) ◽  
pp. 70-76 ◽  
Author(s):  
I. Scheider ◽  
W. Brocks ◽  
A. Cornec
Keyword(s):  
Finite Element ◽  
Rectangular Cross Section ◽  
Three Dimensional ◽  
Strain Curve ◽  
Tensile Tests ◽  
Tensile Specimen ◽  
True Stress ◽  
Image Correlation ◽  
Stress Strain ◽  
Three Dimensional Finite Element

The problem of determining true stress-strain curves from flat tensile specimens beyond the onset of necking has been investigated based on finite element analyses under consideration of experimental accessible data using digital image correlation (DIC). The displacement field on the specimen surface is determined by in-situ deformation field measurement. A three-dimensional finite element study with different stress-strain-curves has been carried out to develop a formula, with which it is possible to calculate the true stress subject to the strain in the necking region. The method has been used to evaluate the true stress-strain curve with a so-called micro flat tensile specimen, which is normally used to determine the material properties in the material gradient around thin weldments.

Estimation of transverse tensile behavior of Zircaloy pressure tubes using ring-tensile test and finite element analysis

2012 ◽  
Vol 227 (6) ◽  
pp. 1177-1186 ◽  
Author(s):  
MK Samal ◽  
KS Balakrishnan ◽  
J Parashar ◽  
GP Tiwari ◽  
S Anantharaman
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Tensile Tests ◽  
Tensile Specimen ◽  
Displacement Curve ◽  
Stress Strain ◽  
Element Analysis ◽  
Transverse Tensile ◽  
Pressure Tubes ◽  
Load Displacement

Determination of transverse mechanical properties from the ring type of specimens directly machined from the nuclear reactor pressure tubes is not straightforward. It is due to the presence of combined membrane as well as bending stresses arising in the loaded condition because of the curvature of the specimen. These tubes are manufactured through a complicated process of pilgering and heat treatment and hence, the transverse properties need to be determined in the as-manufactured condition. It may not also be possible to machine small miniaturized specimen in the circumferential direction especially in the irradiated condition. In this work, we have performed ring-tensile tests on the un-irradiated ring tensile specimen using two split semi-cylindrical mandrels as the loading device. A three-dimensional finite element analysis was performed in order to determine the material true stress–strain curve by comparing experimental load–displacement data with those predicted by finite element analysis. In order to validate the methodology, miniaturized tensile specimens were machined from these tubes and tested. It was observed that the stress–strain data as obtained from ring tensile specimen could describe the load–displacement curve of the miniaturized flat tensile specimen very well. However, it was noted that the engineering stress–strain as directly obtained from the experimental load–displacement curves of the ring tensile tests were very different from that of the miniaturized specimen. This important aspect has been resolved in this work through the use of an innovative type of 3-piece loading mandrel.

Three-Dimensional Finite Element Analysis of Qingyi River Aqueduct during Operation Period

2014 ◽  
Vol 556-562 ◽  
pp. 679-682
Author(s):  
Yan Yan Zhang ◽  
Cai Ying Chen
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Rectangular Cross Section ◽  
Three Dimensional ◽  
Engineering Practice ◽  
Good Precision ◽  
Operation Condition ◽  
Element Analysis ◽  
Dimensional Finite Element ◽  
Three Dimensional Finite Element

In this paper, finite element model of the Qingyi River rectangular section reinforced concrete aqueduct is set up by using three-dimensional finite element analysis software ANSYS. Considering the conventional static load, the seismic loads which use quasi-static method, and considering five combinations of operation condition of aqueduct in operation process, the structure stress and displacement rules of aqueduct are obtained in the different conditions. The results show that the rectangular cross-section aqueduct in the water level under the action of the full tank, the vertical displacement of the aqueduct body structure is nearly doubled than the empty slot, indicating the water load have a significant impact on the aqueduct. The calculated results has a good precision, can meet the needs of practical engineering, can provide a reference basis for the design of thin-walled rectangular aqueduct and the theoretical basis for engineering practice and guidance recommendations.

ANALYSIS OF THE STRESS-STRAIN STATE OF A RIVET JOINT USING THE ABAQUS CAE SYSTEM

2020 ◽  
Vol 6 ◽  
pp. 51-57
Author(s):  
V.V. LEONTYEV
Keyword(s):  
Finite Element ◽  
Strain State ◽  
Three Dimensional ◽  
Element Model ◽  
Stress Strain ◽  
Stress Strain State ◽  
Riveted Joints ◽  
Dimensional Finite Element ◽  
Three Dimensional Finite Element ◽  
Cae System

The method for analyzing of stress-strain state characteristics of unloaded riveted joints performed with OST 1 11781-74 rivets has been developed using Coupled Euler-Lagrange finite element approach implemented in the CAD / CAE system Abaqus. A comparative analysis of the stress-strain state characteristics of the examined riveted joint’s finite element models using the Lagrangian and the Coupled Lagrangian-Eulerian finite element approaches has been conducted. A three- dimensional finite element model based on the CLE method has been proposed for further study of fatigue strength and durability of the loaded riveted joints.

Constitutive modelling of the mechanical response of a polycaprolactone based polyurethane elastomer: Finite element analysis and experimental validation through a bulge test

2020 ◽  
pp. 030932472095833
Author(s):  
Nahuel Rull ◽  
Asanka Basnayake ◽  
Michael Heitzmann ◽  
Patricia M. Frontini
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Mechanical Response ◽  
Strain Curve ◽  
Image Correlation ◽  
Bulge Test ◽  
Polyurethane Elastomer ◽  
Stress Strain ◽  
Element Analysis ◽  
Nonlinear Stress

The mechanical behaviour of a high performance polycaprolactone based polyurethane elastomer (PCL) up to large strain levels, cyclic loading and equibiaxial stress has been assessed. The PCL can be categorised as a rubber-like material, thus, showing nonlinear stress-strain behaviour. The materials elastic network is based on a high molecular weight PCL polyol which gives the material its elastomeric behaviour similar to polyurethanes. In this work, mechanical testing capturing the major features of the stress-strain curve under different loading conditions is performed. Both, uni-axial loading-unloading curves and bulge test are thoroughly studied through the addition of digital image correlation (DIC) to measure the strain field. Results show the presence of hysteresis and loading configuration dependence. Then, two well-known hyperelastic constitutive models, the Arruda-Boyce eight-chain and Bergström-Boyce, were fitted to the uni-axial monotonic and cyclic test data and compared to the bulge test experimental results through finite element analysis (FEA) in Abaqus.

Comparative Study of Predictive Finite Element Methods for Mechanical Properties in 2D Woven Carbon/Carbon Composites

2008 ◽  
Vol 59 ◽  
pp. 116-119
Author(s):  
Joshim Ali ◽  
Derek Buckthorpe ◽  
Allister Cheyne ◽  
Johar Farooqi ◽  
Paul M. Mummery
Keyword(s):  
Finite Element ◽  
Three Dimensional ◽  
Tensile Tests ◽  
Unit Cell ◽  
Carbon Composites ◽  
Fe Model ◽  
Dimensional Finite Element ◽  
Composite Microstructure ◽  
Tomographic Data ◽  
Three Dimensional Finite Element

Three-dimensional finite element (FE) methods are used to predict the Young’s modulus of two types of 2D woven carbon/carbon composites. Tensile tests are performed to validate the predictions. The results indicate that a novel image-based route in generating FE meshes gave strong agreement with experimental data, while a comparative unit cell FE model of the structure was found to be poorer. The differences between the image-based and unit cell methodologies were the consideration of the finer architectures of the composites and their porosity. The image-based approach highlighted true porosity in the structure due to meshes forming directly from X-ray tomographic data. However, the finer fibre architectures of the composites were compromised because of limitations in the pixel resolutions employed during the initial scanning process. In comparison, the unit cell models were based solely on idealisations of the composite microstructure, in which porosity was neglected.

Numerical and Experimental Study on Ultimate Strength of Stiffened Column Under Axial Compression

2020 ◽  
Author(s):  
Hongyuan Mei ◽  
Deyu Wang ◽  
Qi Wan
Keyword(s):  
Ultimate Strength ◽  
Axial Compression ◽  
Strain Curve ◽  
High Strength ◽  
Tensile Tests ◽  
True Stress ◽  
Stress Strain ◽  
Test Fixture ◽  
Perfectly Plastic ◽  
Elastic Perfectly Plastic

Abstract Six specimens with one Tee-bar stiffener and its attached plating were tested under axial compression to investigate the ultimate strength. The specimens have one longitudinal span and the simply supported boundary conditions at the end edge of loading were produced based on a horizontal test fixture. The initial geometrical imperfections were measured and tensile tests of high tensile steel used in the specimens with different thickness were conducted. The results calculated by FE analysis with true stress-strain curves, average measured thickness and measured initial geometrical deformation could reach a good agreement with experimental results. The ultimate strength calculated with elastic/perfectly plastic curve is approximately 10% larger than that with true stress-strain curve. The reason is that the proportional limit stress of material is significantly lower than 0.2% proof stress for the high strength steel used in specimens. And the occurrence of buckling is earlier than the time that the material enters into plastic stage. As a result, the ultimate strength assessed with elastic/perfectly plastic curve doesn’t always the lowest result and it should be adopted carefully.

Determination of constitutive relation from miniature tensile test with digital image correlation

2020 ◽  
Vol 55 (3-4) ◽  
pp. 99-108 ◽  
Author(s):  
Yunlu Zhang ◽  
Sreekar Karnati ◽  
Tan Pan ◽  
Frank Liou
Keyword(s):  
Digital Image Correlation ◽  
Tensile Test ◽  
Constitutive Relation ◽  
Digital Image ◽  
Strain Curve ◽  
True Stress ◽  
Image Correlation ◽  
Stress Strain Curve ◽  
Stress Strain

The determination of constitutive relation from the miniature tensile test is of high interest in multiple areas. Here, a convenient experimental method is proposed to determine the true stress–strain curve from the miniature tensile test. The instantaneous cross-sectional area is estimated by only one camera in aid of digital image correlation technique. This method was applied on commercial pure titanium and aluminum 6061 alloys, and the results indicate that the extracted true stress–strain curves are not scale-dependent. The derived mechanical properties from miniature specimens match well with the results of standard specimens. The correctness of the true stress–strain curve was evaluated by the finite element analysis method. The results suggest that the derived true stress–strain curve is capable to represent the constitutive behavior of the tested materials.

Layered fracture prediction of QStE700 medium-thickness steel plate under tensile loading

2020 ◽  
pp. 095440542097803
Author(s):  
Chuanmin Zhu ◽  
Peng Gu ◽  
Yiqing Yu ◽  
Zhan Tao ◽  
Heng Zhang
Keyword(s):  
Steel Plate ◽  
Strain Curve ◽  
Tensile Loading ◽  
Equivalent Strain ◽  
True Stress ◽  
Image Correlation ◽  
Correlation Technique ◽  
Stress Strain Curve ◽  
Stress Strain ◽  
Medium Thickness

Layered fracture frequently occurs in the deforming process of QStE700 medium-thickness steel plates under tensile loading. In this study, the morphology of a layered fracture was observed via scanning electron microscopy, and the mechanism of the layered fracture was also analyzed. Based on the three-dimensional digital image correlation technique, a section analysis method was adopted for determining the true stress–strain curve including the necking process. A modified Bridgeman’s equation was adopted to transform the true stress–strain curve into the equivalent stress–strain curve. At the time of layered fracture occurrence, the equivalent strain and stress triaxiality of differently shaped specimens were obtained and fitted to a linear exponential relationship equation. The equation was the layered fracture criterion function and combined with the finite element method (FEM) simulations for determining the damage criterion of the layered fracture of a certain specimen. The FEM-simulated equivalent strain was consistent with the experimental equivalent strain of the layered fracture. Summarizing, the proposed method to predict the layered fracture of a QStE700 medium-thickness steel plate is effective and can be adopted in the study and control of layered fracture.

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