Parameters Identification of Johnson-Cook Constitutive Equation for Aluminum Brass

Aluminum brass HAL66-6-3-2 is abrasion-resistant alloy with high strength, hardness and wear resistance, corrosion resistance is also well, commonly used in the field of marine and ordnance industry. The quasi static and dynamic mechanical properties were tested through the use of electronic universal testing machine and Split Hopkinson Tension Bar (SHTB). Meanwhile, the material stress-strain curve at different temperatures and different strain rates is also obtained. Based on Johnson-Cook constitutive model, using the method of least squares fitting the experimental data to determine the model parameters, fitting and experimental results agree well.

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Stress-Strain Curves for Oxygen-Free High Conductivity Copper at Shear Strain Rates of up to 103s-1

Proceedings of the Institution of Mechanical Engineers ◽

10.1243/pime_proc_1970_185_125_02 ◽

1970 ◽

Vol 185 (1) ◽

pp. 1149-1158 ◽

Cited By ~ 2

Author(s):

K. Bitans ◽

P. W. Whitton

Keyword(s):

Shear Strain ◽

Testing Machine ◽

Shear Bands ◽

Strain Curve ◽

Strain Rates ◽

Adiabatic Shear Bands ◽

Stress Strain Curve ◽

Stress Strain ◽

The Given ◽

Tubular Specimens

Shear stress-shear strain curves for o.f.h.c. copper at room temperature have been obtained at constant shear strain rates in the range 1 to 103s-1, using thin walled tubular specimens in a flywheel type torsion testing machine. Results show that, for a given value of strain, the stress decreases when the rate of strain is increased. Moreover, the elastic portion of the stress-strain curve tends to disappear as the rate of strain is increased. It is postulated that these effects are due to the formation of adiabatic shear bands in the material when the given rate of strain is impressed rapidly enough. A special feature of the design of the testing machine used is the rapid application of the chosen strain rate.

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Transformation of Test Data for the Specification of a Viscoelastic Marlow Model

Solids ◽

10.3390/solids1010002 ◽

2020 ◽

Vol 1 (1) ◽

pp. 2-15

Author(s):

Olaf Hesebeck

Keyword(s):

Tensile Test ◽

Strain Rate ◽

Finite Strain ◽

Strain Curve ◽

Model Parameters ◽

Strain Rates ◽

Stress Strain Curve ◽

Stress Strain ◽

Material Response ◽

Rate Dependent

The combination of hyperelastic material models with viscoelasticity allows researchers to model the strain-rate-dependent large-strain response of elastomers. Model parameters can be identified using a uniaxial tensile test at a single strain rate and a relaxation test. They enable the prediction of the stress–strain behavior at different strain rates and other loadings like compression or shear. The Marlow model differs from most hyperelastic models by the concept not to use a small number of model parameters but a scalar function to define the mechanical properties. It can be defined conveniently by providing the stress–strain curve of a tensile test without need for parameter optimization. The uniaxial response of the model reproduces this curve exactly. The coupling of the Marlow model and viscoelasticity is an approach to create a strain-rate-dependent hyperelastic model which has good accuracy and is convenient to use. Unfortunately, in this combination, the Marlow model requires to specify the stress–strain curve for the instantaneous material response, while experimental data can be obtained only at finite strain rates. In this paper, a transformation of the finite strain rate data to the instantaneous material response is derived and numerically verified. Its implementation enables us to specify hyperelastic materials considering strain-rate dependence easily.

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The Rate (Time)-Dependent Behavior of Ti-7Al-2Cb-1Ta Titanium Alloy at Room Temperature Under Quasi-Static Monotonic and Cyclic Loading

Journal of Applied Mechanics ◽

10.1115/1.3157592 ◽

1981 ◽

Vol 48 (1) ◽

pp. 55-63 ◽

Cited By ~ 39

Author(s):

D. Kujawski ◽

E. Krempl

Keyword(s):

Titanium Alloy ◽

Strain Rate ◽

Testing Machine ◽

Strain Curve ◽

High Strength ◽

Prior History ◽

Strain Rates ◽

Inelastic Behavior ◽

Creep Tests ◽

Rate Dependent

Uniaxial tests using a servocontrolled testing machine and strain measurement at the gage length were performed on a high-strength, low-ductility Titanium alloy. Tests involved monotonic and cyclic loadings with strain rates between 2 × 10−8 to 10−3 s−1, stress rates from 10−1 to 102 MPa s−1, repeated changes in strain rates, and short-term relaxation and creep tests. The inelastic behavior is strongly rate-dependent. Ratchetting is shown to increase as the stress rate decreases. No strain-rate history effect was found. A unique stress-strain curve is ultimately reached for a given strain rate irrespective of prior history as long as only positive stresses are imposed. In the plastic range the relaxation drop in a given time period depends only on the strain rate preceding the test and is independent of the actual stress and strain.

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Experimental Research on Dynamic Mechanical Properties of 5083 Aluminum Alloy

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.535-536.497 ◽

2013 ◽

Vol 535-536 ◽

pp. 497-500 ◽

Cited By ~ 1

Author(s):

Zhi Wu Zhu ◽

Guo Zheng Kang ◽

Dong Ruan ◽

Yue Ma ◽

Guo Xing Lu

Keyword(s):

Aluminum Alloy ◽

Strain Rate ◽

Split Hopkinson Pressure Bar ◽

High Strength ◽

Dynamic Mechanical Properties ◽

Strain Rates ◽

Hopkinson Pressure Bar ◽

Split Hopkinson ◽

Pressure Bar ◽

5083 Aluminum Alloy

5083 aluminum alloy was investigated with respect to its uniaxial dynamic compressive properties over a range of strain rates using the split Hopkinson pressure bar (SHPB). The dynamic stress-strain curves of this alloy were obtained for strain rates from 1000 s-1 to 6000 s-1. Effects of strain rate, the samples size and anti-impact capability were analyzed. The experimental results show that under impaction loading, 5083 aluminum alloy has a remarkable strengthening response to strain rate and size; in particular, the responded stress increases with increasing strain rate, which implies that this alloy has high strength and high anti-impact capability.

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Experimental Study on Biaxial Dynamic Compressive Properties of ECC

Materials ◽

10.3390/ma14051257 ◽

2021 ◽

Vol 14 (5) ◽

pp. 1257

Author(s):

Shuling Gao ◽

Guanhua Hu

Keyword(s):

Strain Rate ◽

Lateral Pressure ◽

Deformation Modulus ◽

Strain Curve ◽

Peak Stress ◽

Pressure Level ◽

Strain Rates ◽

Peak Strain ◽

Stress Strain Curve ◽

Toughness Index

An improved hydraulic servo structure testing machine has been used to conduct biaxial dynamic compression tests on eight types of engineered cementitious composites (ECC) with lateral pressure levels of 0, 0.125, 0.25, 0.5, 0.7, 0.8, 0.9, 1.0 (the ratio of the compressive strength applied laterally to the static compressive strength of the specimen), and three strain rates of 10−4, 10−3 and 10−2 s−1. The failure mode, peak stress, peak strain, deformation modulus, stress-strain curve, and compressive toughness index of ECC under biaxial dynamic compressive stress state are obtained. The test results show that the lateral pressure affects the direction of ECC cracking, while the strain rate has little effect on the failure morphology of ECC. The growth of lateral pressure level and strain rate upgrades the limit failure strength and peak strain of ECC, and the small improvement is achieved in elastic modulus. A two-stage ECC biaxial failure strength standard was established, and the influence of the lateral pressure level and peak strain was quantitatively evaluated through the fitting curve of the peak stress, peak strain, and deformation modulus of ECC under various strain rates and lateral pressure levels. ECC’s compressive stress-strain curve can be divided into four stages, and a normalized biaxial dynamic ECC constitutive relationship is established. The toughness index of ECC can be increased with the increase of lateral pressure level, while the increase of strain rate can reduce the toughness index of ECC. Under the effect of biaxial dynamic load, the ultimate strength of ECC is increased higher than that of plain concrete.

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Hopkinson rod test results and constitutive description of TRIP780 steel resistance spot welding material

Open Physics ◽

10.1515/phys-2020-0206 ◽

2020 ◽

Vol 18 (1) ◽

pp. 961-967

Author(s):

Xiaomin Li ◽

Jianrong Zhang

Keyword(s):

Spot Welding ◽

Steel Strip ◽

Strain Curve ◽

Test Machine ◽

Strain Rates ◽

Test Results ◽

Welding Material ◽

Static Tensile ◽

Split Hopkinson ◽

Brittle Fractures

Abstract A quasi-static tensile test was performed on a 1.4 mm-thick TRIP780 steel strip with welding points. An MTS810 material test machine was used in the test, and a Split Hopkinson tension bar device was used in performing impact stretch loading at different strain rates. The dynamic tensile stress–strain curve of the spot welding material with different strain rates was obtained through the finely designed Hopkinson rod test, and the strain rate dependence of a TRIP780 steel spot welding material was discussed. According to the dynamic constitutive equation of the TRIP780 steel spot welding material, the test results were numerically simulated, the constitutive description and test curves were compared, and the simulation results and test results were discussed and analyzed. The fractures of the test recovery specimen were scanned with the scanning electron microscope, and the fracture mechanism of the TRIP780 steel spot welding material was explored by observing the fractures. The surfaces of the fractures surface showed obvious cleavage river patterns, and the evolution process of microcracks was determined and used in characterizing brittle fractures in specimen spot welding sample subjected to dynamic stretch loading.

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Dynamic Behaviour of Reinforcing Steel Bars in Tension

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.82.86 ◽

2011 ◽

Vol 82 ◽

pp. 86-91 ◽

Cited By ~ 8

Author(s):

Ezio Cadoni ◽

Matteo Dotta ◽

Daniele Forni ◽

Nicoletta Tesio

Keyword(s):

Testing Machine ◽

Maximum Load ◽

Gauge Length ◽

Strain Rates ◽

Reinforcing Bars ◽

Static Tests ◽

Split Hopkinson Tensile Bar ◽

Steel Bars ◽

Split Hopkinson ◽

Reinforced Steel

In this paper the preliminary results of the tensile behavior of reinforced steel in a large range of strain rates are presented. Tensile testing at several strain rates, using different experimental set-ups, was carried out. For the quasi-static tests a universal electromechanical testing machine with the maximum load-bearing capacity of 50 kN was used, while for the intermediate and high-strain rate regimes a hydro-pneumatic apparatus and a JRC-Split Hopkinson Tensile Bar respectively were used. The target strain rates were set at the following five levels: 10-3, 30, 250, 500, and 1000 1/s. The specimens used in this research were round samples having 3mm in diameter and 5mm of gauge length obtained from reinforcing bars. Finally, the material parameters for Cowper-Symonds and Johnson-Cook models were determined.

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Understanding Dynamic Recrystallization Behavior through a Delay Differential Equation Approach

Materials Science Forum ◽

10.4028/www.scientific.net/msf.558-559.441 ◽

2007 ◽

Vol 558-559 ◽

pp. 441-448 ◽

Cited By ~ 3

Author(s):

Jong K. Lee

Keyword(s):

Differential Equation ◽

Strain Rate ◽

Critical Strain ◽

Strain Curve ◽

Single Peak ◽

Strain Rates ◽

Stress Strain Curve ◽

Stress Strain ◽

Strain Behavior ◽

Delay Differential

During hot working, deformation of metals such as copper or austenitic steels involves features of both diffusional flow and dislocation motion. As such, the true stress-true strain relationship depends on the strain rate. At low strain rates (or high temperatures), the stress-strain curve displays an oscillatory behavior with multiple peaks. As the strain rate increases (or as the temperature is reduced), the number of peaks on the stress-strain curve decreases, and at high strain rates, the stress rises to a single peak before settling at a steady-state value. It is understood that dynamic recovery is responsible for the stress-strain behavior with zero or a single peak, whereas dynamic recrystallization causes the oscillatory nature. In the past, most predictive models are based on either modified Johnson-Mehl-Avrami kinetic equations or probabilistic approaches. In this work, a delay differential equation is utilized for modeling such a stress-strain behavior. The approach takes into account for a delay time due to diffusion, which is expressed as the critical strain for nucleation for recrystallization. The solution shows that the oscillatory nature depends on the ratio of the critical strain for nucleation to the critical strain for completion for recrystallization. As the strain ratio increases, the stress-strain curve changes from a monotonic rise to a single peak, then to a multiple peak behavior. The model also predicts transient flow curves resulting from strain rate changes.

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