Ductile Fracture Property of Structural Steels With a Surface Flaw Under Large Deformation

2002 ◽  
Author(s):  
Satoshi Igi ◽  
Hiroyuki Sumi ◽  
Masayoshi Kurihara
Keyword(s):  
Ductile Fracture ◽  
Large Deformation ◽  
Deformation Behavior ◽  
Shape Change ◽  
Three Dimensional ◽  
Tensile Tests ◽  
Surface Flaw ◽  
Stress Strain ◽  
Crack Shape ◽  
Critical Flaw

Tensile tests using plate specimens with a surface flaw were conducted in order to study the large deformation behavior of steels with a flaw. Steels prepared for examination had tensile strengths of 470–490MPa with different stress-strain relationships. The strain distribution during loading and the maximum strain at fracture were measured in order to investigate the influence of stress-strain properties on ductile fracture. The crack shape changes during ductile crack growth were also examined and compared with empirical formulae for estimating fatigue crack shape change. In order to assess test results, three dimensional elastoplastic finite element analyses were carried out which included detailed analysis of the influence of stress-strain properties on deformation behavior. In addition, a simplified analytical model to estimate fracture strain and critical flaw size was proposed using the stress-strain relationship of Swift’s equation. The results from the model show fairly good agreement with experimental results.

Ductile Fracture Evaluation of Welded Joints With a Surface Flaw Under Large Deformation

2005 ◽  
Author(s):  
Satoshi Igi ◽  
Takahiro Kubo ◽  
Masayoshi Kurihara
Keyword(s):  
Ductile Fracture ◽  
Large Deformation ◽  
Analytical Model ◽  
Welded Joint ◽  
Three Dimensional ◽  
Base Material ◽  
Tensile Tests ◽  
Surface Flaw ◽  
Stress Strain ◽  
Joint Specimen

Tensile tests using welded joint specimens with a surface flaw were conducted in order to study the large deformation behavior and ductile fracture of welded structural component with a flaw. Two types of 490MPa class steel plates with different yield strength are prepared for this study. The surface flaw was introduced at the center of welded metal of welded joint specimen. Strain distribution during loading and the maximum strain at ductile fracture of specimen were measured in order to investigate the influence of stress-strain properties on ductile fracture behavior of the welded joint. Three dimensional elastoplastic finite element analyses were also carried out by using the welded joint specimen models in order to calculate the detailed stress and strain distributions around notch tip. In addition, a simplified analytical model to estimate fracture strain and critical flaw size of the welded joint was proposed using the stress-strain relationship combination between base material and welded metal by Swift’s equation. The results from the analytical model show fairly good agreement with experimental results.

Influence of Processing Route on the Work-Hardening and Ductile Fracture of an AA6060 Aluminium Alloy

2014 ◽  
Vol 794-796 ◽  
pp. 284-289 ◽  
Author(s):  
Odd Sture Hopperstad ◽  
Ida Westermann ◽  
Ketill Olav Pedersen ◽  
Trond Furu ◽  
Tore Børvik
Keyword(s):  
Ductile Fracture ◽  
Aluminium Alloy ◽  
Work Hardening ◽  
Large Strain ◽  
Tensile Tests ◽  
Grain Structure ◽  
Processing Route ◽  
Stress Strain ◽  
Minimum Cross Section ◽  
Processing Step

Tensile tests on smooth and notched axisymmetric specimens were carried out to determine the large strain work-hardening curves and the ductile fracture characteristics of an AA6060 aluminium alloy for three different processing routes. The alloy was processed in three subsequent steps: 1) casting and homogenization, 2) extrusion, and 3) cold rolling and heat treatment to obtain a recrystallized grain structure. After each processing step, the material was tested after natural ageing for more than one week. A laser-based extensometer was used to continuously measure the average true strains to failure in the minimum cross-section of the specimens and the true stress-strain curves were calculated. Since these curves are influenced by necking, they do not represent the correct work-hardening of the material. Accordingly, finite element (FE) simulations of the tensile tests on the smooth axisymmetric specimens were conducted to determine the work-hardening curves to failure, using an optimization tool that interfaced with the nonlinear FE code and the experimental stress-strain curves as objectives. The microstructure of the alloy was characterized after the three processing steps by optical and scanning electron microscopy, and fractography was used to investigate the failure mechanisms.

scholarly journals ELEMENT-FREE MULTISCALE MODELING OF LARGE DEFORMATION BEHAVIOR OF RED BLOOD CELL MEMBRANE WITH MALARIA INFECTION

2017 ◽  
Author(s):  
A.S. Ademiloye ◽  
L.W. Zhang ◽  
K.M. Liew
Keyword(s):  
Red Blood Cells ◽  
Large Deformation ◽  
Optical Tweezers ◽  
Blood Cells ◽  
Deformation Behavior ◽  
Malaria Infection ◽  
Three Dimensional ◽  
Meshfree Method ◽  
Pass Through ◽  
Element Free

SUMMARYIn normal physiological and healthy conditions, red blood cells (RBCs) deform readily as they pass through the microcapillaries and the spleen. In this paper, we examine the effects of Plasmodium falciparum infection and maturation on the large deformation behavior of malaria-infected red blood cells (iRBCs) by means of a three-dimensional (3D) multiscale meshfree method. We numerically simulated the optical tweezers experiment and observed the force-displacement response of the iRBC membrane as malaria infection progresses. Our simulation results agree well with experimental data and confirm that the deformability of malaria-infected cells decreases significantly as malaria infection progresses.

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.

Room Temperature Deformation Behavior of Inconel718

2005 ◽  
Vol 475-479 ◽  
pp. 677-680 ◽  
Author(s):  
Fang Bian ◽  
Guoyue Su ◽  
Fan Ya Kong ◽  
Ke Yang
Keyword(s):  
Grain Size ◽  
Deformation Behavior ◽  
Room Temperature ◽  
Tensile Tests ◽  
True Stress ◽  
Temperature Deformation ◽  
Stress Strain ◽  
Limit Value ◽  
Heat Treated ◽  
Work Hardening Rate

The deformation behavior of Inconel718 at room temperature was studied by tensile tests. Three kinds of specimens were tested, including cold rolled, heat treated with grain size ASTM5 and heat treated with grain size ASTM7. The true stress-strain curves were obtained based on the tensile test records. The true stress-strain relation can express the room temperature deformation behavior, which can be described by equations similar to the Voce equation. The limit value of the work-hardening rate θ0 is very sensitive to the microstructure of the alloy.

Investigation of the Static Behavior and Failure Mechanisms of a 3D Printed Bio-Based Sandwich with Auxetic Core

2020 ◽  
Vol 12 (05) ◽  
pp. 2050051
Author(s):  
Khawla Essassi ◽  
Jean-Luc Rebiere ◽  
Abderrahim El Mahi ◽  
Mohamed Amine Ben Souf ◽  
Anas Bouguecha ◽  
...  
Keyword(s):  
Failure Mechanisms ◽  
Three Dimensional ◽  
Acoustic Emissions ◽  
Shear Stiffness ◽  
Tensile Tests ◽  
Sandwich Composite ◽  
Static Behavior ◽  
Flax Fibers ◽  
Data Points ◽  
3D Printed

In this research contribution, the static behavior and failure mechanisms are developed for a three-dimensional (3D) printed dogbone, auxetic structure and sandwich composite using acoustic emissions (AEs). The skins, core and whole sandwich are manufactured using the same bio-based material which is polylactic acid reinforced with micro-flax fibers. Tensile tests are conducted on the skins and the core while bending tests are conducted on the sandwich composite. Those tests are carried out on four different auxetic densities in order to investigate their effect on the mechanical and damage properties of the materials. To monitor the invisible damage and damage propagation, a highly sensitive AE testing method is used. It is found that the sandwich with high core density displays advanced mechanical properties in terms of bending stiffness, shear stiffness, facing bending stress and core shear stress. In addition, the AE data points during testing present an amplitude range of 40–85[Formula: see text]dB that characterizes visible and invisible damage up to failure.

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