scholarly journals Deformation Behavior of Press Formed Shell by Indentation and Its Numerical Simulation

2015 ◽  
Vol 2015 ◽  
pp. 1-11 ◽  
Author(s):  
Minoru Yamashita ◽  
Zubair Bin Khalil
Keyword(s):  
Deformation Behavior ◽  
Kinematic Hardening ◽  
Shell Height ◽  
Mutual Effect ◽  
Material Model ◽  
Shell Shape ◽  
Indentation Force ◽  
Hemispherical Shell ◽  
Deformation Behaviors ◽  
Energy Absorbing

Deformation behavior and energy absorbing performance of the press formed aluminum alloy A5052 shells were investigated to obtain the basic information regarding the mutual effect of the shell shape and the indentor. Flat top and hemispherical shells were indented by the flat- or hemispherical-headed indentor. Indentation force in the rising stage was sharper for both shell shapes when the flat indentor was used. Remarkable force increase due to high in-plane compressive stress arisen by the appropriate tool constraint was observed in the early indentation stage, where the hemispherical shell was deformed with the flat-headed indentor. This aspect is preferable for energy absorption performance per unit mass. Less fluctuation in indentation force was achieved in the combination of the hemispherical shell and similar shaped indentor. The consumed energy in the travel length of the indentor equal to the shell height was evaluated. The increase ratio of the energy is prominent when the hemispherical indentor is replaced by a flat-headed one in both shell shapes. Finite element simulation was also conducted. Deformation behaviors were successfully predicted when the kinematic hardening plasticity was introduced in the material model.

Numerical Modeling and Analytical Investigation of Autofrettage Process on the Fluid End Module of Fracture Pumps

2018 ◽  
Vol 140 (4) ◽  
Author(s):  
Mahdi Kiani ◽  
Roger Walker ◽  
Saman Babaeidarabad
Keyword(s):  
Residual Stresses ◽  
Kinematic Hardening ◽  
Analytical Formula ◽  
Strain Analysis ◽  
Material Model ◽  
Analytical Investigation ◽  
Stress Strain ◽  
Element Analysis ◽  
Hardening Material ◽  
Strain Evolution

One of the most important components in the hydraulic fracturing is a type of positive-displacement-reciprocating-pumps known as a fracture pump. The fluid end module of the pump is prone to failure due to unconventional drilling impacts of the fracking. The basis of the fluid end module can be attributed to cross bores. Stress concentration locations appear at the bores intersections and as a result of cyclic pressures failures occur. Autofrettage is one of the common technologies to enhance the fatigue resistance of the fluid end module through imposing the compressive residual stresses. However, evaluating the stress–strain evolution during the autofrettage and approximating the residual stresses are vital factors. Fluid end module geometry is complex and there is no straightforward analytical solution for prediction of the residual stresses induced by autofrettage. Finite element analysis (FEA) can be applied to simulate the autofrettage and investigate the stress–strain evolution and residual stress fields. Therefore, a nonlinear kinematic hardening material model was developed and calibrated to simulate the autofrettage process on a typical commercial triplex fluid end module. Moreover, the results were compared to a linear kinematic hardening model and a 6–12% difference between two models was observed for compressive residual hoop stress at different cross bore corners. However, implementing nonlinear FEA for solving the complicated problems is computationally expensive and time-consuming. Thus, the comparison between nonlinear FEA and a proposed analytical formula based on the notch strain analysis for a cross bore was performed and the accuracy of the analytical model was evaluated.

A geometric analysis of growth in gastropod shells, with particular reference to turbinate forms

1983 ◽  
Vol 63 (4) ◽  
pp. 777-797 ◽  
Author(s):  
S. U. K. Ekaratne ◽  
D. J. Crisp
Keyword(s):  
Conversion Factor ◽  
Shell Height ◽  
Geometric Analysis ◽  
Logarithmic Spiral ◽  
Maximum Growth ◽  
Relative Magnitude ◽  
Shell Shape ◽  
Growth Band ◽  
Apical Angle ◽  
Image Position

Nucella lapillus and Littorina littorea afford examples of turbinately coiled shells with no space between the columella and the inner face of the whorls. Three constants are sufficient to determine the form of such shells: λ, the ratio between diameters of successive whorls; β, the semi-apical angle and ρ, the ratio of aperture length and breadth in the apertural plane passing through the axis. The variation of these three constants with size was examined and shown to be relatively small and insignificant in Nucella, but in Littorina it was significant.For Nucella and Littorina these shell characteristics were used to relate for the nth whorl, the length along the shell spiral (ln) to the shell height (Hn), the latter being the measure usually employed in growth studies. This relation was derived mathematically and confirmed empirically aswhere α is the angle of the logarithmic spiral given by α = tan−1 2π sin β/loge λ. The increased resolution of the micro-growth band increments, which are measured along the shell spiral was directly related to the ln:Hn ratios.Since the formula for the ln/Hn ratio (= shell conversion factor) includes λ, β and ρ, the three constants necessary to determine shell form in turbinately coiled shells of the type described, the shell conversion factor may be a better index of shell shape than indices based on a single constant. In species where the shell grows isometrically this ratio will remain constant, whereas changes in shell shape with size will influence this ratio. Such changes in shell shape during growth can be quantified in terms of the shell constants and when included in calculating the shell conversion factor, will show the relative magnitude of shell shape changes brought about by growth. The shell conversion factor may also be used to study the effects of ecological variations on the geometry of the shell.The conical shell of the limpet, Patella vulgata, is geometrically a much simpler system in which direct shell measurements were used to relate length along the direction of maximum growth to the antero-posterior diameter of aperture.

scholarly journals Cutting Mechanism of Sulfrized Free-Machining Steel

2009 ◽  
Vol 407-408 ◽  
pp. 416-419 ◽  
Author(s):  
Junsuke Fujiwara ◽  
Tsubasa Kawazoe ◽  
Naoki Matsui
Keyword(s):  
Electron Microscope ◽  
Scanning Electron Microscope ◽  
Deformation Behavior ◽  
Environmental Problem ◽  
Orthogonal Cutting ◽  
Machining Performance ◽  
Cutting Mechanism ◽  
Deformation Behaviors ◽  
Production Industry ◽  
Scanning Electron

Leaded free-machining steel is used in production industry. However the use of the leaded free-machining steel is limited from an environmental problem. So sulfurized free-machining steel, not include lead, has been researched widely. In order to improve the machining performance of the sulfurized free-machining steel, it is necessary to find out the behavior of inclusion. The experiment was carried out to find out the mechanism of the surfurized inclusion on the machinability, using some kinds of materials which were changed the size of the inclusion. In orthogonal cutting, the deformation behaviors of the sulfurized inclusion in the work materials were observed in the vicinity of tool face. Cutting forces were also measured and finished surfaces were observed. Besides, low speed orthogonal cutting in Scanning Electron Microscope (SEM) which was mounted a small cutting device was carried out in order to observe the deformation behavior more microscopically. As a result, it is clear that some inclusions creates voids around them and some broke to several pieces depending on their conditions. Moreover, in order to investigate the formation and growth of BUE, a quick stop experiment was done during turning. As a result, it is clear that the larger inclusions can reduce the formation of BUE.

scholarly journals Modification of the Johnson–Cook Material Model for Improved Simulation of Hard Milling High-Performance Steel Components

2021 ◽  
Vol 2 (3) ◽  
pp. 571-580
Author(s):  
Andrey Vovk ◽  
Amin Pourkaveh Dehkordi ◽  
Rainer Glüge ◽  
Bernhard Karpuschewski ◽  
Jens Sölter
Keyword(s):  
High Performance ◽  
Kinematic Hardening ◽  
Material Model ◽  
Detailed Knowledge ◽  
Hard Milling ◽  
Bending Tests ◽  
Finite Element Software ◽  
Steel Material ◽  
Finish Cutting ◽  
Cutting Processes

Understanding the effect of thermomechanical loads during finish cutting processes, in our case hard milling, on the surface integrity of the workpiece is crucial for the creation of defined quality characteristics of high-performance components. Compared to computationally generated modifications by simulation, the measurement-based determination of material modifications can only be carried out selectively and on a point-by-point basis. In practice, however, detailed knowledge of the changes in material properties at arbitrary points of the high-performance component is of great interest. In this paper, a modification of the well-known Johnson–Cook material model using the finite element software Abaqus is presented. Special attention was paid to the kinematic hardening behavior of the used steel material. Cyclic loads are relevant for the chip formation simulation because, during milling, after each cut, the material under the surface is loaded plastically several times and not necessarily in the same direction. Therefore, in analogy, multiple bending was investigated on samples made of 42CrMo4. A pronounced Bauschinger effect was observed in the bending tests. An adaptation of the material model to the results of the bending tests was only possible to a limited extent without kinematic hardening, which is why the Johnson–Cook model was supplemented by the Armstrong–Frederick hardening approach. The modified Johnson–Cook–Armstrong–Frederick material model was developed for practical use as a VUMAT and verified by bending tests for simulation use.

Method and Verification for Material Calibration of the Chaboche Plasticity Model for Multiple Material Directions

2021 ◽  
Author(s):  
Charles R. Krouse ◽  
Grant O. Musgrove ◽  
Taewoan Kim ◽  
Seungmin Lee ◽  
Muhyoung Lee ◽  
...  
Keyword(s):  
Experimental Data ◽  
Kinematic Hardening ◽  
Material Model ◽  
Brute Force ◽  
Hardening Material ◽  
Material Constants ◽  
Automated Method ◽  
Chaboche Model ◽  
Multiple Material ◽  
Brute Force Approach

Abstract The Chaboche model is a well-validated non-linear kinematic hardening material model. This material model, like many models, depends on a set of material constants that must be calibrated for it to match the experimental data. Due to the challenge of calibrating these constants, the Chaboche model is often disregarded. The challenge with calibrating the Chaboche constants is that the most reliable method for doing the calibration is a brute force approach, which tests thousands of combinations of constants. Different sampling techniques and optimization schemes can be used to select different combinations of these constants, but ultimately, they all rely on iteratively selecting values and running simulations for each selected set. In the experience of the authors, such brute force methods require roughly 2,500 combinations to be evaluated in order to have confidence that a reasonable solution is found. This process is not efficient. It is time-intensive and labor-intensive. It requires long simulation times, and it requires significant effort to develop the accompanying scripts and algorithms that are used to iterate through combinations of constants and to calculate agreement. A better, more automated method exists for calibrating the Chaboche material constants. In this paper, the authors describe a more efficient, automated method for calibrating Chaboche constants. The method is validated by using it to calibrate Chaboche constants for an IN792 single-crystal material and a CM247 directionally-solidified material. The calibration results using the automated approach were compared to calibration results obtained using a brute force approach. It was determined that the automated method achieves agreeable results that are equivalent to, or supersede, results obtained using the conventional brute force method. After validating the method for cases that only consider a single material orientation, the automated method was extended to multiple off-axis calibrations. The Chaboche model that is available in commercial software, such as ANSYS, will only accept a single set of Chaboche constants for a given temperature. There is no published method for calibrating Chaboche constants that considers multiple material orientations. Therefore, the approach outlined in this paper was extended to include multiple material orientations in a single calibration scheme. The authors concluded that the automated approach can be used to successfully, accurately, and efficiently calibrate multiple material directions. The approach is especially well-suited when off-axis calibration must be considered concomitantly with longitudinal calibration. Overall, the automated Chaboche calibration method yielded results that agreed well with experimental data. Thus, the method can be used with confidence to efficiently and accurately calibrate the Chaboche non-linear kinematic hardening material model.

scholarly journals Hot Deformation Behavior of a New Al–Mn–Sc Alloy

Materials ◽  
2019 ◽  
Vol 13 (1) ◽  
pp. 22
Author(s):  
Weiqi Kang ◽  
Yi Yang ◽  
Sheng Cao ◽  
Lei Li ◽  
Shewei Xin ◽  
...  
Keyword(s):  
Flow Stress ◽  
Hot Deformation ◽  
Deformation Behavior ◽  
Material Model ◽  
Strain Rates ◽  
Hot Workability ◽  
Hot Deformation Behavior ◽  
Hollomon Parameter ◽  
Dynamic Material Model ◽  
Optimal Processing

The hot deformation behavior of a new Al–Mn–Sc alloy was investigated by hot compression conducted at temperatures from 330 to 490 °C and strain rates from 0.01 to 10 s−1. The hot deformation behavior and microstructure of the alloy were significantly affected by the deformation temperatures and strain rates. The peak flow stress decreased with increasing deformation temperatures and decreasing strain rates. According to the hot deformation behavior, the constitutive equation was established to describe the steady flow stress, and a hot processing map at 0.4 strain was obtained based on the dynamic material model and the Prasad instability standard, which can be used to evaluate the hot workability of the alloy. The developed hot processing diagram showed that the instability was more likely to occur in the higher Zener–Hollomon parameter region, and the optimal processing range was determined as 420–475 °C and 0.01–0.022 s−1, in which a stable flow and a higher power dissipation were achieved.

scholarly journals Stress-strain response in gears tooth root due to low cycle fatigue

2019 ◽  
Vol 287 ◽  
pp. 02002
Author(s):  
Marina Franulovic ◽  
Kristina Markovic ◽  
Zdravko Herceg
Keyword(s):  
Low Cycle Fatigue ◽  
Kinematic Hardening ◽  
Material Model ◽  
Strain Response ◽  
Tooth Root ◽  
Loading Conditions ◽  
Cycle Fatigue ◽  
Stress Strain ◽  
Main Research ◽  
Damage Initiation

Gears are mechanical components which experience high dynamic loading during their exploitation period. Therefore, their load carrying capacity together with life expectancy are often the main research interest in various studies. The research presented in this paper is focused on the materials response in spur gears tooth root, with the attention given to the repeated overloads during gears operation. In order to simulate low cycle fatigue by using numerical modeling of stress - strain relationship within material, the material model which takes into account isotropic and kinematic hardening is used here. Material response of specimens produced out of steel 42CrMo4 in different loading conditions is used for the calibration of material model, which is then applied to simulate damage initiation and materials stress - strain response in gears tooth root. The results show that materials response to the given loading conditions non-linearly change through the loading cycles.

Design of Energy Absorbing Structure Using Topology Optimization With a Multi-Material Model

2003 ◽  
Author(s):  
Daeyoon Jung ◽  
Hae Chang Gea
Keyword(s):  
Topology Optimization ◽  
Strain Energy ◽  
Effective Properties ◽  
Service Condition ◽  
Material Model ◽  
Three Phase ◽  
The Mean ◽  
Energy Absorbing ◽  
Dual Objectives ◽  
Mean Compliance

To accommodate the dual objectives of many engineering applications, one to minimize the mean compliance for the stiffest structure under normal service condition and the other to maximize the strain energy for energy absorption during excessive loadings, topology optimization with a multi-material model is applied to the design of energy absorbing structure in this paper. The effective properties of the three-phase material are derived using a spherical micro-inclusion model. The dual objectives are combined in a ratio formation. Numerical examples from the proposed method are presented and discussed.

Cyclic Deformation and Buckling Behavior of Pipe With Local Metal Loss Subjected to Seismic Ground Motion

2011 ◽  
Author(s):  
Masaki Mitsuya ◽  
Hiroshi Yatabe
Keyword(s):  
Finite Element ◽  
Cyclic Loading ◽  
Cyclic Deformation ◽  
Deformation Behavior ◽  
Low Cycle Fatigue ◽  
Kinematic Hardening ◽  
Earthquake Resistance ◽  
Metal Loss ◽  
Cycle Fatigue ◽  
Longitudinal Length

Buried pipelines may be deformed due to earthquakes and also corrode despite corrosion control measures such as protective coatings and cathodic protection. In such cases, it is necessary to ensure the integrity of the corroded pipelines against earthquakes. This study developed a method to evaluate the earthquake resistance of corroded pipelines subjected to seismic ground motions. Axial cyclic loading experiments were carried out on line pipes subjected to seismic motion to clarify the cyclic deformation behavior until buckling occurs. The test pipes were machined so that each one would have a different degree of local metal loss. As the cyclic loading progressed, displacement shifted to the compression side due to the formation of a bulge. The pipe buckled after several cycles. To evaluate the earthquake resistance of different pipelines, with varying degrees of local metal loss, a finite-element analysis method was developed that simulates the cyclic deformation behavior. A combination of kinematic and isotropic hardening components was used to model the material properties. These components were obtained from small specimen tests that consisted of a monotonic tensile test and a low cycle fatigue test under a specific strain amplitude. This method enabled the successful prediction of the cyclic deformation behavior, including the number of cycles required for the buckling of pipes with varying degrees of metal loss. In addition, the effect of each dimension (depth, longitudinal length and circumferential width) of local metal loss on the cyclic buckling was studied. Furthermore, the kinematic hardening component was investigated for the different materials by the low cycle fatigue tests. The kinematic hardening components could be regarded as the same for all the materials when using this component as the material property for the finite-element analyses simulating the cyclic deformation behavior. This indicates that the cyclic deformation behavior of various line pipes can be evaluated only based on their respective tensile properties and common kinematic hardening component.

On the Modeling of Evolving Elastic and Plastic Anisotropy in the Finite Strain Regime – Application to Deep Drawing Processes

2012 ◽  
Vol 504-506 ◽  
pp. 679-684 ◽  
Author(s):  
Ivaylo N. Vladimirov ◽  
Michael P. Pietryga ◽  
Vivian Tini ◽  
Stefanie Reese
Keyword(s):  
Deep Drawing ◽  
Evolution Equations ◽  
Finite Strain ◽  
Kinematic Hardening ◽  
Plastic Anisotropy ◽  
Material Model ◽  
Internal Variables ◽  
Time Step ◽  
Finite Element Software ◽  
Structure Tensors

In this work, we discuss a finite strain material model for evolving elastic and plastic anisotropy combining nonlinear isotropic and kinematic hardening. The evolution of elastic anisotropy is described by representing the Helmholtz free energy as a function of a family of evolving structure tensors. In addition, plastic anisotropy is modelled via the dependence of the yield surface on the same family of structure tensors. Exploiting the dissipation inequality leads to the interesting result that all tensor-valued internal variables are symmetric. Thus, the integration of the evolution equations can be efficiently performed by means of an algorithm that automatically retains the symmetry of the internal variables in every time step. The material model has been implemented as a user material subroutine UMAT into the commercial finite element software ABAQUS/Standard and has been used for the simulation of the phenomenon of earing during cylindrical deep drawing.

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