Comparing Two Selection Laws of Active Slip Systems in Finite Element Polycrystalline Model for Numerical Material Testing

2018 ◽  
Vol 920 ◽  
pp. 169-174
Author(s):  
Shin Onoshima ◽  
Tetsuo Oya
Keyword(s):  
Strain Rate ◽  
Crystal Orientation ◽  
Integration Method ◽  
Tensile Tests ◽  
Material Testing ◽  
Alloy Sheet ◽  
Material Models ◽  
Rate Dependent ◽  
Dependent Model ◽  
Polycrystalline Model

To meet the demand for high accuracy in metal forming simulation including difficult problems such as anisotropy, many material models have been developed. Since the recent material models usually possess many parameters and require cumbersome experiments, a reliable numerical material testing would be helpful to reduce the number of experiments. Therefore, we have engaged in development of a numerical material testing based on the finite element polycrystalline model in which the successive integration method is used for modeling slip systems. However, implementation based on the strain-rate dependent model, which is considered as the mainstream of such model, has not been rigorously considered in our research. In this study, two polycrystalline models were compared to establish better microstructural modeling for constructing a scheme of numerical material testing to predict material behavior that is not obtained by experiments. Numerical rolling, uniaxial tensile tests were conducted on aluminum alloy sheet with the strain-rate dependent model and the successive integration method. The crystal orientation calculated by the successive integration method exhibited close agreement with the experimental value of the rolled aluminum alloy sheet. On the other hand, the calculated crystal orientation by the strain-rate dependent model exhibited less close agreement with the experimental value of the same material than the successive integration method. To ascertain the characteristics of each model in terms of slip deformation quantitatively, the other tensile tests were conducted to calculate Lankford values caused by crystal orientation. Lankford values, calculated by the successive integration method, exhibited better agreement with experimental values than the strain-rate dependent model. These comparisons indicate that the successive integration method represented slip deformation more physically valid than the strain-rate dependent model and resulted in better calculation.

Constitutive Modeling of the Rate-Dependent Behavior of Ti-6Al-4V Using an Arrhenius-Type Law

2012 ◽  
Vol 591-593 ◽  
pp. 949-954
Author(s):  
Jun Jie Xiao ◽  
Dong Sheng Li ◽  
Xiao Qiang Li ◽  
Chao Hai Jin ◽  
Chao Zhang
Keyword(s):  
Flow Stress ◽  
Strain Rate ◽  
Tensile Tests ◽  
Alloy Sheet ◽  
Uniaxial Tensile ◽  
Thin Wall ◽  
Rate Dependent ◽  
Hot Environment ◽  
Dependent Behavior ◽  
Element Simulation

Uniaxial tensile tests were performed on a Ti-6Al-4V alloy sheet over the temperature range of 923K-1023K with the strain rates of 5×10-4s-1-5×10-2s-1 up to a 25% length elongation of the specimen. The true stress-strain curves reveal that the flow stress decreases with the increase of the temperature and the decrease of the strain rate. In the same process, the accompanying softening role increases. It is found that the Ti-6Al-4V shows the features of non-linearity, temperature sensitivity and strain rate dependence in hot environment. Finally, an Arrhenius-type law has been established to predict the experimental data and the prediction precision was verified by the plotting of parameter and flow stress, which revealed that the error of stress exponent was only 4.99%. This indicates the flow stress model has high precision and can be used for the process design and the finite element simulation of hot forming thin-wall Ti-6Al-4V alloy components.

A strain-rate dependent model for crack growth

1992 ◽  
pp. 109-119 ◽  
Author(s):  
G. E. Papakaliatakis ◽  
E. E. Gdoutos ◽  
E. Tzanaki
Keyword(s):  
Strain Rate ◽  
Crack Growth ◽  
Rate Dependent ◽  
Dependent Model

Effect of Fiber Orientation and Strain Rate on the Nonlinear Uniaxial Tensile Material Properties of Tendon

2003 ◽  
Vol 125 (5) ◽  
pp. 726-731 ◽  
Author(s):  
Heather Anne Lynch ◽  
Wade Johannessen ◽  
Jeffrey P. Wu ◽  
Andrew Jawa ◽  
Dawn M. Elliott
Keyword(s):  
Stress Relaxation ◽  
Strain Rate ◽  
Material Properties ◽  
Poisson’S Ratio ◽  
Constant Strain Rate ◽  
Tensile Tests ◽  
Poisson's Ratio ◽  
Fiber Direction ◽  
Linear Region ◽  
Rate Dependent

Tendons are exposed to complex loading scenarios that can only be quantified by mathematical models, requiring a full knowledge of tendon mechanical properties. This study measured the anisotropic, nonlinear, elastic material properties of tendon. Previous studies have primarily used constant strain-rate tensile tests to determine elastic modulus in the fiber direction. Data for Poisson’s ratio aligned with the fiber direction and all material properties transverse to the fiber direction are sparse. Additionally, it is not known whether quasi-static constant strain-rate tests represent equilibrium elastic tissue behavior. Incremental stress-relaxation and constant strain-rate tensile tests were performed on sheep flexor tendon samples aligned with the tendon fiber direction or transverse to the fiber direction to determine the anisotropic properties of toe-region modulus E0, linear-region modulus (E), and Poisson’s ratio (ν). Among the modulus values calculated, only fiber-aligned linear-region modulus E1 was found to be strain-rate dependent. The E1 calculated from the constant strain-rate tests were significantly greater than the value calculated from incremental stress-relaxation testing. Fiber-aligned toe-region modulus E10=10.5±4.7 MPa and linear-region modulus E1=34.0±15.5 MPa were consistently 2 orders of magnitude greater than transverse moduli (E20=0.055±0.044 MPa,E2=0.157±0.154 MPa). Poisson’s ratio values were not found to be rate-dependent in either the fiber-aligned (ν12=2.98±2.59, n=24) or transverse (ν21=0.488±0.653, n=22) directions, and average Poisson’s ratio values in the fiber-aligned direction were six times greater than in the transverse direction. The lack of strain-rate dependence of transverse properties demonstrates that slow constant strain-rate tests represent elastic properties in the transverse direction. However, the strain-rate dependence demonstrated by the fiber-aligned linear-region modulus suggests that incremental stress-relaxation tests are necessary to determine the equilibrium elastic properties of tendon, and may be more appropriate for determining the properties to be used in elastic mathematical models.

A Study on Rate Sensitivity of Impedance in TRIP Steel during Deformation at Various Strain Rate under Two Kinds of Deformation Mode

2014 ◽  
Vol 566 ◽  
pp. 140-145
Author(s):  
Daiki Inoshita ◽  
Takeshi Iwamoto
Keyword(s):  
Strain Rate ◽  
Strain Rate Sensitivity ◽  
Trip Steel ◽  
Testing Machine ◽  
Rate Sensitivity ◽  
Deformation Mode ◽  
Tensile Tests ◽  
Material Testing ◽  
Trip Steels ◽  
Material Testing Machine

TRIP steel possesses excellent mechanical properties dominated by strain-induced martensitic transformation (SIMT). For automotive industries, if TRIP steel can be applied to shock absorption members, it can be considered that the weight of automobile can be reduced. However, the strain rate sensitivity of TRIP steels has not been fully understood because the strain rate sensitivity and the deformation mode dependency of SIMT are still unclear. Therefore, it is important to reveal these sensitivity and dependency for confirming a reliability of TRIP steel. Therefore, in this study, it is attempted to estimate the amount of produced martensite in TRIP steel by measuring the inductance of TRIP steel. The specimen made of TRIP steel is used as a core of a prototype coil manufactured in this study. Then, the compressive and tensile tests are conducted by using a material testing machine and a drop weight testing machine using the specimen inside the coil. The inductance of the coil with the deformed specimen are measured continuously during the tests.

STRAIN RATE–DEPENDENT BEHAVIOR OF UNCURED RUBBER: EXPERIMENTAL INVESTIGATION AND CONSTITUTIVE MODELING

2022 ◽  
Author(s):  
Sanghyeub Kim ◽  
Thomas Berger ◽  
Michael Kaliske
Keyword(s):  
Strain Rate ◽  
Evolution Equations ◽  
Cyclic Creep ◽  
Tensile Tests ◽  
Internal Variables ◽  
Creep Tests ◽  
Rate Dependent ◽  
Nonlinear Viscosity ◽  
Dependent Behavior ◽  
Building Process

ABSTRACT The strain rate dependence of uncured rubber is investigated through a series of tensile tests (monotonic, multistep relaxation, cyclic creep tests) at different strain rates. In addition, loading/unloading tests in which the strain rate is varied every cycle are carried out to observe their dependence on the deformation history. A strain rate–dependent viscoelastic–viscoplastic constitutive model is proposed with the nonlinear viscosity and process-dependent recovery properties observed in the test results. Those properties are implemented by introducing evolution equations for additional internal variables. The identified material parameters capture the experiments qualitatively well. The proposed model is also evaluated by finite element simulations of the building process of a tire, followed by the in-molding.

The effect of minor element concentrations on the strain rate sensitivity and ductility of commercial purity aluminium sheet

1980 ◽  
Vol 295 (1413) ◽  
pp. 130-130
Keyword(s):  
Strain Rate ◽  
Strain Rate Sensitivity ◽  
Rate Sensitivity ◽  
Minor Element ◽  
Tensile Tests ◽  
Plastic Instability ◽  
Alloy Sheet ◽  
Second Phase ◽  
Commercial Purity ◽  
Aluminium Sheet

Minor element levels vary considerably in commercial purity ( ca .99.5 % Al) aluminium alloy sheet obtained from various sources. Minor elements may be present in solution or as second phase particles formed during solidification or subsequent processing. The present work is largely concerned with the effects of elements in solution on strain-rate sensitivity and ductility. Recent treatments of plastic instability in tensile tests incorporate the strain rate sensitivity and note its importance in determining the strain at which instability occurs (Ghosh 1977; Marciniak 1974). Tensile properties have been determined on a range of aluminium sheet samples. The results show that small increases in solute concentration can result in a change from positive (flow stress increasing with strain rate) to negative strain rate sensitivity. The rate sensitivity was found to be strain dependent and this had led to a reconsideration of the effect of strain rate sensitivity on ductility. The work suggests that it is not the absolute value of the rate sensitivity that determines its effect on the strain to plastic instability, but rather the sign of its variation with strain. If this is positive then the strain to instability exceeds that expected in the absence of rate sensitivity; if the slope is negative the opposite trend is observed.

Modeling and Testing Strain Rate-Dependent Tensile Strength of Carbon/Epoxy Composites

2007 ◽  
Vol 353-358 ◽  
pp. 1418-1421 ◽  
Author(s):  
Gui Ping Zhao ◽  
Zheng Hao Wang ◽  
Jian Xin Zhang ◽  
Qiao Ping Huang
Keyword(s):  
Tensile Strength ◽  
Strain Rate ◽  
Strain Rate Range ◽  
Split Hopkinson Tensile Bar ◽  
Rate Dependent ◽  
Dependent Behavior ◽  
Split Hopkinson ◽  
Rate Experiment ◽  
Epoxy Matrix Composite ◽  
Dependent Model

Tensile strength is an important material property and usually can be determined experimentally. The strain rate dependent behavior of T300 carbon/epoxy matrix composite was characterized over a wide strain rate range (10×10-5 s-1to10×104s-1). The low to moderate strain rate experiments were carried out on a MTS machine, while the high strain rate experiment was conducted with a split Hopkinson tensile bar. A rate dependent model was introduced to simulate the material response. Two kinds of stacking sequence of composite specimens [(45/-45)4]s and [(0/45/90/-45)2]s were tested at different strain rates, and the results were used to determine parameters of the model. The predictions of the model showed to agree fairly well with the experimental results. The tensile strength and initial elastic modulus of the composites increase when the strain rate increases.

Temperature and Strain-Rate Dependent Characteristics of AISI 300 Series of Austenitic Stainless Steel

2010 ◽  
Author(s):  
Woong-Sup Park ◽  
Chi-Seung Lee ◽  
Myung-Hyun Kim ◽  
Jae-Myung Lee
Keyword(s):  
Stainless Steel ◽  
Strain Rate ◽  
Material Properties ◽  
Austenitic Stainless Steels ◽  
Tensile Tests ◽  
Substantial Effect ◽  
Test Results ◽  
Aisi 304L ◽  
Rate Dependent ◽  
Cryogenic Conditions

AISI 300 series austenite stainless steel tensile tests under cryogenic conditions were performed to determine the effect of strain-rate and cryogenic temperature. Four types of commercial austenitic stainless steels widely used in LNG applications, AISI 304L, 316L, 321 and 347, were tested. To analyse strain-rate and temperature dependency, material properties were compared quantitatively. Temperatures ranging from 110K to 293K and strain-rates ranging from 1.6E−4/sec to 1.0E−2/sec have been studied as test conditions. From the test results, both strain-rate and temperature have substantial effect on material properties such as strength and elongation. The experimental results could be used to validate numerical techniques for tested materials as well as structures in cryogenic environment.

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