Anisotropic Damage Evolution for Perforated Sheet under Tensile Deformation

2016 ◽  
Vol 725 ◽  
pp. 489-494
Author(s):  
Shigeru Nagaki ◽  
Daigo Saboi ◽  
Kenta Muroi ◽  
Makoto Iizuka ◽  
Kenichi Oshita
Keyword(s):  
Plastic Deformation ◽  
Void Growth ◽  
Damage Evolution ◽  
Tensile Deformation ◽  
Yield Function ◽  
Uniaxial Tensile ◽  
Uniaxial Tensile Test ◽  
Thermodynamic Consideration ◽  
Perforated Sheets ◽  
Growth Of Voids

It is important to formulate a constitutive equation which represents the growth of voids during plastic deformation in order to predict ductile fracture of metallic materials. For this purpose, we proposed an anisotropic Gurson’s yield function with the damage tensor, which represents the anisotropy due to the void distribution and the damage evolution was assumed isotropic for simplicity. Then we also proposed an anisotropic void growth law derived from the anisotropic Gurson’s yield function based on thermodynamic consideration. In this study we carried out the uniaxial tensile test of perforated sheets of stainless steel and aluminum alloy as the ideal two dimensional model of the damaged material and investigate the damage growth during plastic deformation. As a result, we obtained a good agreement between the experimental and the calculated void growth for both materials and it is also found that material parameters for damage evolutions are almost the same for both materials and are hardly affected by the work-hardening exponent.

scholarly journals Visualization of the damage evolution for Ti–3Al–2Mo–2Zr alloy during a uniaxial tensile process using a microvoids proliferation damage model

2021 ◽  
Vol 40 (1) ◽  
pp. 310-324
Author(s):  
Ying Tong ◽  
Jiang Zhao ◽  
Guo-zheng Quan
Keyword(s):  
Plastic Deformation ◽  
Damage Evolution ◽  
Volume Fraction ◽  
Tensile Deformation ◽  
Damage Model ◽  
Tensile Tests ◽  
Uniaxial Tensile ◽  
Strain Rates ◽  
Stress Strain ◽  
Gtn Damage Model

Abstract Understanding the damage evolution of alloys during a plastic deformation process is significant to the structural design of components and accident prevention. In order to visualize the damage evolution in the plastic deformation of Ti–3Al–2Mo–2Zr alloy, a series of uniaxial tensile experiments for this alloy were carried out under the strain rates of 0.1–10 s−1 at room temperature, and the stress–strain curves were achieved. On the other hand, the finite element (FE) models of these uniaxial tensile processes were established. A microvoids proliferation model, Gurson–Tvergaard–Needleman (GTN) damage model, was implanted into the uniaxial tensile models, and the simulated stress–strain curves corresponding to different GTN parameter combinations were obtained. Based on the simulated and experimental stress–strain curves, the GTN parameters of this alloy were solved by response surface methodology (RSM). The solved GTN parameters suggest that higher strain rate can enhance the proliferation and coalescence of microvoids. Furthermore, the uniaxial tensile tests over different strain rates were simulated using the solved GTN parameters. Then, the damage processes were visualized and evaluated. The result shows that the degradation speed of this alloy is slow at the initial stage of the tensile deformation and then accelerates once the voids volume fraction reaches a critical value.

Studies on Post-Yield Behavior of Cortical Bone

2012 ◽  
Vol 232 ◽  
pp. 157-161 ◽  
Author(s):  
N.K. Sharma ◽  
J. Nayak ◽  
D.K. Sehgal ◽  
R.K. Pandey
Keyword(s):  
Plastic Deformation ◽  
Cortical Bone ◽  
Uniaxial Tensile ◽  
Uniaxial Tensile Test ◽  
Yield Behavior ◽  
Plastic Properties ◽  
Joint Replacements ◽  
Hierarchical Assembly ◽  
Plastic Modulus ◽  
Stiffness Loss

Complex hierarchical assembly and presence of large amount of organics and water content are responsible for enough amount of plasticity in bone material. Plastic properties are not only important to assess the various changes and fracture risk in bone but also for the development of better bone implants and joint replacements. The present study is focused on the post-yield behavior of cortical bone. The plastic properties of goat femoral and tibiae cortical bone were assessed and compared in terms of plastic modulus (H), tangent modulus (Et), plastic work (Wp) and plastic strain (εp) using uniaxial tensile test. Both femoral and tibiae cortical bone were found to be having similar post-yield behavior and significant stiffness loss was observed in both the bones during plastic deformation. The value of plastic modulus for femoral cortical bone was found to be 1.2 times higher as compared to the corresponding value for tibiae cortical bone. This shows higher hardening rate for femoral cortical bone. It was also observed that femoral bone requires higher energy during plastic deformation until fracture as compared to tibiae cortical bone.

Synchrotron x-ray Study of Elastic Phase Strains in the Bulk of an Externally Loaded Cu/Mo Composite

1999 ◽  
Vol 590 ◽  
Author(s):  
A. Wanner ◽  
D.C. Dunand
Keyword(s):  
Plastic Deformation ◽  
Load Transfer ◽  
Tensile Deformation ◽  
Copper Matrix ◽  
High Energy ◽  
Uniaxial Tensile ◽  
X Rays ◽  
Synchrotron Source ◽  
Peak Broadening ◽  
The Matrix

ABSTRACTHigh-energy, high-flux x-rays from a third-generation synchrotron source were used to measure average elastic strains in the bulk of 1.5 mm thick composites consisting of a copper matrix reinforced with 7.5 vol.% molybdenum particles. From the evolution of lattice strains in both phases during uniaxial tensile deformation, the internal load transfer between phases and reinforcement damage were characterized during elastic and plastic deformation of the composite. The graininess of the diffraction rings, which is related to the Bragg peak broadening, was quantified as a function of applied stress and related to plastic deformation in the matrix.

Elasto-Plastic Analysis of a Miniature Circular Disk Bending Specimen

2006 ◽  
Author(s):  
Vishnu Verma ◽  
A. K. Ghosh ◽  
G. Behera ◽  
Kamal Sharma ◽  
R. K. Singh
Keyword(s):  
Plastic Deformation ◽  
Finite Element ◽  
Yield Stress ◽  
Material Properties ◽  
Stable Solution ◽  
Bending Test ◽  
Uniaxial Tensile ◽  
Uniaxial Tensile Test ◽  
Plastic Behavior ◽  
Element Analysis

Miniature disk bending test is used to evaluate the mechanical behavior of irradiated materials and its properties — mainly ductility loss due to irradiation in steel. In Miniature Disk Bending Machine the specimen is firmly held between the two horizontal jaws of punch, and an indentor with spherical ball travels vertically. Researchers have observed reasonable correlations between values of the yield stress, strain hardening and ultimate tensile strength estimated from this test and mechanical properties determined from the uniaxial tensile test. Some methods for the analysis of miniature disk bending, proposed by various authors have been discussed in the paper. It is difficult to distinguish between the regimes of elastic and plastic deformation since local plastic deformation occurs for very small values of load when the magnitude of spatially averaged stress will be well below the yield stress. Also, the analytical solution for large amplitude, plastic deformation becomes rather unwieldy. Hence a finite element analysis has been carried out. The finite element model, considers contact between the indentor and test specimen, friction between various pairs of surfaces and elastic plastic behavior. The load is increased in steps and converged solution has been obtained and analysis terminated at a load beyond which a stable solution cannot be obtained. A sensitivity study has been carried out by varying the various parameters defining the material properties by ±10% around the base values. This study has been carried out to generate a data base for the load-deflection characteristics of similar materials from which the material properties can be evaluated by an inverse calculation. It is seen that the deflection obtained by analytical elastic bending theory is significantly lower than that obtained by the elasto-plastic finite element solution at relatively small values of load. The FE solution and experimental results are in reasonably good agreement.

Modeling of Anisotropic Deformation in Superplastic Sheet Metal Stretching

2005 ◽  
Vol 127 (1) ◽  
pp. 159-164 ◽  
Author(s):  
Fadi K. Abu-Farha ◽  
Marwan K. Khraisheh
Keyword(s):  
Sheet Metal ◽  
Microstructural Evolution ◽  
Superplastic Deformation ◽  
Yield Function ◽  
Internal Variables ◽  
Uniaxial Tensile ◽  
Uniaxial Tensile Test ◽  
Initial State ◽  
Plane Stress Condition ◽  
Deformation And Failure

Currently available models describing superplastic deformation are mostly based on uniaxial tensile test data and assume isotropic behavior, thus leading to limited predictive capabilities of material deformation and failure. In this work we present a multi-axial microstructure-based constitutive model that describes the anisotropic superplastic deformation within the continuum theory of viscoplasticity with internal variables. The model accounts for microstructural evolution and employs a generalized anisotropic dynamic yield function. The anisotropic yield function can describe the evolution of the initial state of anisotropy through the evolution of unit vectors defining the direction of anisotropy during deformation. The generalized model is then reduced to the plane stress condition to simulate sheet metal stretching in superplastic blow forming using pressurized gas. Different ratios of biaxial stretching were investigated, including the case simulating the uniaxial loading condition, where the model successfully captured the uniaxial experimental data. The model is also used to develop a new forming pressure profile that accounts for anisotropy and microstructural evolution.

Anisotropic Deformation Behavior of Porous Polymeric Membranes Under Uni-Axial and Bi-Axial Loadings

2019 ◽  
Author(s):  
Kanako Emori ◽  
Akio Yonezu ◽  
Takumi Nagakura ◽  
Tatsuma Miura
Keyword(s):  
Deformation Behavior ◽  
Biaxial Loading ◽  
Tensile Deformation ◽  
Cell Structure ◽  
Plane Deformation ◽  
Uniaxial Tensile ◽  
Uniaxial Tensile Test ◽  
Displacement Curve ◽  
Out Of Plane ◽  
Anisotropic Deformation

Abstract This study systematically investigates the uniaxial and biaxial tensile deformation behavior of polytetrafluoroethylene (PTFE) membranes which are used for water purification. The present PTFE membrane has micron size pores with open cell structure, and the pore is anisotropic shape. During the uniaxial tensile test, the membranes undergo elastic deformation and plastic deformation with strain rate sensitivity (i.e. time-dependent deformation behavior). In addition, it strongly demonstrates anisotropic deformation, i.e. deformation behavior is different along longitudinal direction and transverse ones. To clarify the microscopic deformation mechanism, in-situ SEM observation is carried out during tensile loading. It is found that the anisotropic deformation behavior appears due to the inherent pore structure. Next, to investigate deformation behavior under biaxial loading condition, small punch test using a spherical indenter is carried out. The membrane undergoes elastic and plastic deformations. Finally, crack nucleates around the indenter contact and indenter completely penetrates through the membrane. It is also found that the membrane demonstrates anisotropic out-of-plane deformation behavior. To clarify these mechanisms, FEM computation is carried out, such that experimental results of force-displacement curve and out-of-plane deformation behavior are compared with the computational ones. The present FEM model enables the prediction of the membrane’s deformation behavior under biaxial loading.

Examination and modeling of void growth kinetics in modern high strength dual phase steels during uniaxial tensile deformation

2016 ◽  
Vol 172 ◽  
pp. 54-61 ◽  
Author(s):  
N. Saeidi ◽  
F. Ashrafizadeh ◽  
B. Niroumand ◽  
M.R. Forouzan ◽  
S. Mohseni mofidi ◽  
...  
Keyword(s):  
Growth Kinetics ◽  
Void Growth ◽  
Tensile Deformation ◽  
High Strength ◽  
Uniaxial Tensile ◽  
Dual Phase ◽  
Dual Phase Steels

Surface Roughening and Formability in Sheet Metal Forming of Polycrystalline Metal

2013 ◽  
Vol 535-536 ◽  
pp. 231-234 ◽  
Author(s):  
Takeji Abe
Keyword(s):  
Plastic Deformation ◽  
Sheet Metal ◽  
Uniaxial Tensile ◽  
Surface Irregularity ◽  
Surface Roughening ◽  
Uniaxial Tensile Test ◽  
Polycrystalline Metal ◽  
Biaxial Stretching ◽  
R Value ◽  
The Difference

The r–value is defined as the ratio of the width strain to the thickness strain under the uniaxial tensile test of the sheet metal. Based on r-value of grains, a model of plastic deformation of polycrystalline metal and surface roughening after plastic deformation was proposed in the previous paper. Meanwhile, Marciniak and Kuczynski proposed the so-called M-K model which give the analytical estimation of the formability of sheet metal under biaxial stretching considering a certain irregularity of the thickness of the sheet metal. Yamaguchi et al showed that the experimentally measured surface roughness may correspond to the surface irregularity suggested in the M-K model. In the present paper, the formability of sheet metal under biaxial stretching is analyzed based on the previous analysis of surface roughening caused by the difference of the r-value in the sheet metal.

scholarly journals Calculated Shoulder to Gauge Ratio of Fatigue Specimens in PWR Environment

Metals ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 376
Author(s):  
Igor Simonovski ◽  
Alec Mclennan ◽  
Kevin Mottershead ◽  
Peter Gill ◽  
Norman Platts ◽  
...  
Keyword(s):  
Plastic Deformation ◽  
Water Environment ◽  
Hysteresis Loops ◽  
Constitutive Law ◽  
Uniaxial Tensile ◽  
Uniaxial Tensile Test ◽  
Material Behaviour ◽  
Pressurized Water ◽  
Elastic Plastic ◽  
Gauge Section

A ratio of shoulder to gauge displacements (S2G) is calculated for three different fatigue specimens in a pressurized water environment. This ratio needs to be known beforehand to determine the applied shoulder displacements during the experiment that would result in the desired strain amplitude in the gauge section. Significant impact of both the applied constitutive law and specimen geometry on the S2G is observed. The calculation using the fully elastic constitutive law results in the highest S2G values and compares very well with the analytical values. However, this approach disregards the plastic deformation within the specimens that mostly develops in the gauge section. Using the constitutive laws derived from actual fatigue curves captures the material behaviour under cyclic loading better and results in lower S2G values compared to the ones obtained with the fully elastic constitutive law. Calculating S2G values using elastic–plastic constitutive law based on the monotonic uniaxial tensile test should be avoided as they are significantly lower compared to the ones computed with elastic–plastic laws derived from hysteresis loops at half-life.

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