Strain-Rate Sensitivity of Aluminum Alloys AA1200 and AA3103

2010 ◽  
Vol 132 (4) ◽  
Author(s):  
O.-G. Lademo ◽  
O. Engler ◽  
J. Aegerter ◽  
T. Berstad ◽  
A. Benallal ◽  
...  
Keyword(s):  
Aluminum Alloys ◽  
Constitutive Model ◽  
Strain Rate ◽  
Strain Hardening ◽  
Rate Sensitivity ◽  
Structural Parameter ◽  
Model Parameters ◽  
Good Representation ◽  
Nominal Strain Rate ◽  
Instantaneous Rate

Tensile tests are carried out for the aluminum alloys AA1200 and AA3103 at various strain-rates in the range from 10−4 s−1 to 1 s−1. Tests with constant nominal strain-rate and strain-rate jump tests are conducted, and the instantaneous rate sensitivity and the rate sensitivity of strain hardening are investigated. For both materials, the instantaneous rate sensitivity is found to be rather independent of strain, while the rate sensitivity of the strain hardening is important and the saturation stress increases with increasing strain-rate. A phenomenological constitutive model is described that comprises a kinetic equation governing the instantaneous rate sensitivity of the flow stress and a structural parameter that determines the mechanical state of the material. The evolution of the structure parameter is assumed to depend on strain-rate. The model parameters are determined for the two materials using the available experimental information. It is found that the constitutive model provides a good representation of the experimental results.

Deformation Behaviors and Constitutive Model of DP1000 under Different Strain Rates

2017 ◽  
Vol 898 ◽  
pp. 810-817 ◽  
Author(s):  
Ran Wei ◽  
Ren Bo Song ◽  
Long Jiang ◽  
Heng Jun Cai
Keyword(s):  
Constitutive Model ◽  
Strain Rate ◽  
Strain Hardening ◽  
Dual Phase Steel ◽  
Constitutive Models ◽  
Rate Sensitivity ◽  
Dual Phase ◽  
Strain Rates ◽  
Deformation Behaviors ◽  
Means Of Transmission

The DP1000 cold-rolled dual phase steel, the thickness of which is 1.2 mm, was required to do the tensile test under nine different strain rates from 10-4 s-1 to 1000 s-1. The mechanical properties and morphologies of the steel were obtained and analyzed. According to the C-J model, the plastic deformation characteristics of dual phase steel under different strain rates were studied. By means of transmission electron microscope (TEM), the morphologies of ferrite and martensite in the dynamic were observed. Finally, the constitutive models of quasi-static and high strain rate were established by using the modified Johnson-Cook model. The results reveal that DP1000 dual phase steel has obvious strain rate sensitivity, and it is a relatively pure ferrite and martensite dual phase structure. There are two stage strain hardenging characteristics in DP1000. In the first stage, the strain hardening ability of ferrite is higher, and the second stage is martensite deformation stage, the strain hardening ability is lower. The modified J-C constitutive model has high fitting effect, and the experimental results are matched with the fitting values.

Optimization of constitutive model parameters for simulation of polystyrene concrete subjected to impact

2017 ◽  
Vol 9 (2) ◽  
pp. 121-140 ◽  
Author(s):  
Tae Kwang Yoo ◽  
Tong Qiu
Keyword(s):  
Constitutive Model ◽  
Strain Rate ◽  
Rate Sensitivity ◽  
Material Model ◽  
Drop Impact ◽  
Model Parameters ◽  
Compression Tests ◽  
Static Compression ◽  
Impact Tests ◽  
Quasi Static Compression

This article presents the results of a series of experimental testing and numerical modeling studies to optimize the parameters of a constitutive material model to accurately simulate the behavior of polystyrene crushable concrete during impact loading using LS-DYNA. Quasi-static compression tests and confined drop impact tests were conducted. To model the quasi-static compression tests, the response surface methodology was used to optimize Poisson’s ratio and friction angle in the pseudo-tensor model in LS-DYNA. Using the optimized model parameters, the simulated compression stress versus strain relationship showed an excellent agreement with those from the compression tests. To model the confined drop impact tests, the strain rate sensitivity parameter in LS-DYNA was optimized by comparing the drop impact simulations at different strain rate sensitivity values with the drop impact tests. This study suggests that the pseudo-tensor material model is potentially suitable for modeling crushable concrete. Although the optimized constitutive model parameters are specific for the polystyrene concrete mix used in this study, similar approach can be used to optimize model parameters for other polystyrene concrete mixes.

Experimental and Numerical Study of Soft Tissue Surrogate Behavior Under Ballistic Loading

2012 ◽  
Author(s):  
Ericka K. Amborn ◽  
Karim H. Muci-Küchler ◽  
Brandon J. Hinz
Keyword(s):  
Soft Tissue ◽  
Constitutive Model ◽  
High Strain Rate ◽  
Strain Rate ◽  
High Strain ◽  
Split Hopkinson Pressure Bar ◽  
Numerical Study ◽  
Constitutive Models ◽  
Material Behavior ◽  
Good Representation

Studying the high strain rate behavior of soft tissues and soft tissue surrogates is of interest to improve the understanding of injury mechanisms during blast and impact events. Tests such as the split Hopkinson pressure bar have been successfully used to characterize material behavior at high strain rates under simple loading conditions. However, experiments involving more complex stress states are needed for the validation of constitutive models and numerical simulation techniques for fast transient events. In particular, for the case of ballistic injuries, controlled tests that can better reflect the effects induced by a penetrating projectile are of interest. This paper presents an experiment that tries to achieve that goal. The experimental setup involves a cylindrical test sample made of a translucent soft tissue surrogate that has a small pre-made cylindrical channel along its axis. A small caliber projectile is fired through the pre-made channel at representative speeds using an air rifle. High speed video is used in conjunction with specialized software to generate data for model validation. A Lagrangian Finite Element Method (FEM) model was prepared in ABAQUS/Explicit to simulate the experiments. Different hyperelastic constitutive models were explored to represent the behavior of the soft tissue surrogate and the required material properties were obtained from high strain rate test data reported in the open literature. The simulation results corresponding to each constitutive model considered were qualitatively compared against the experimental data for a single projectile speed. The constitutive model that provided the closest match was then used to perform an additional simulation at a different projectile velocity and quantitative comparisons between numerical and experimental results were made. The comparisons showed that the Marlow hyperelastic model available in ABAQUS/Explicit was able to produce a good representation of the soft tissue surrogate behavior observed experimentally at the two projectile speeds considered.

Finite Deflections of a Rigid-Viscoplastic Strain-Hardening Annular Plate Loaded Impulsively

1968 ◽  
Vol 35 (2) ◽  
pp. 349-356 ◽  
Author(s):  
Norman Jones
Keyword(s):  
Strain Rate ◽  
Strain Hardening ◽  
Strain Rate Sensitivity ◽  
Annular Plate ◽  
Dominant Role ◽  
Plate Thickness ◽  
Rate Sensitivity ◽  
Finite Deflections ◽  
Analytical Treatment ◽  
Rigid Plastic

A relatively simple analytical treatment of the behavior of a rigid-plastic annular plate subjected to an initial linear impulsive velocity profile is presented. The influence of finite deflections has been included in addition to strain-hardening and strain-rate sensitivity of the plate material. It is shown, for deflections up to the order of twice the plate thickness, that strain-hardening is unimportant, strain-rate sensitivity has somewhat more effect, while membrane forces play a dominant role in reducing the permanent deflections.

Strain rate sensitivity and strain hardening response of DP1000 dual phase steel

2018 ◽  
Vol 115 (5) ◽  
pp. 507
Author(s):  
Onur Çavusoglu ◽  
Hakan Gürün ◽  
Serkan Toros ◽  
Ahmet Güral
Keyword(s):  
Tensile Strength ◽  
Strain Rate ◽  
Strain Hardening ◽  
Strain Rate Sensitivity ◽  
Dual Phase Steel ◽  
Rate Sensitivity ◽  
Dual Phase ◽  
Significant Difference ◽  
Load Carrying ◽  
Hardening Coefficient

In this study, strain hardening and strain rate sensitivity behavior of commercial DP1000 dual phase steel have been examined in detail at temperatures of 25 °C, 100 °C, 200 °C and 300 °C, at strain rates of 0.0016 s−1 and 0.16 s−1. As the strain rate has increased, the yield strength has increased but no significant change in tensile strength and strain hardening coefficient has been observed. As the temperature has increased, the yield and tensile strength has decreased in between 25 and 200 °C but it has showed an increase at 300 °C. The strain hardening coefficient has increased in parallel with temperature increase. It has been seen that the strain rate sensitivity has not been affected by temperature. No significant difference in the hardening rate has appeared in between 25 and 200 °C, but the highest value has been calculated at 300 °C. It has been determined that the fracture behavior has occurred earlier and load carrying capacity on necking has reduced with the increase of strain rate and not significantly affected by temperature.

Sensitivity Analysis of the Material Flow Stress in Machining

Manufacturing ◽  
2003 ◽  
Author(s):  
Ning Fang
Keyword(s):  
Sensitivity Analysis ◽  
Flow Stress ◽  
Aluminum Alloys ◽  
Strain Rate ◽  
Strain Hardening ◽  
Material Flow ◽  
Chemical Compositions ◽  
Wide Range ◽  
Strain Rate Hardening ◽  
Factor Governing

Among the effects of strain hardening, strain-rate hardening, and temperature softening, it has long been argued about which effect is predominant in governing the material flow stress in machining. This paper compares four material constitutive models commonly employed, including Johnson-Cook’s model, Oxley’s model, Zerilli-Armstrong’s model, and Maekawa et al.’s model. A new quantitative sensitivity analysis of the material flow stress is performed based on Johnson-Cook’s model covering a wide range of engineering materials, including plain carbon steels with different carbon contents, alloyed steels, aluminum alloys with different chemical compositions and heat treatment conditions, copper and copper alloys, iron, nickel, tungsten alloys, etc. It is demonstrated that the first predominant factor governing the material flow stress is either strain hardening or thermal softening, depending on the specific work material employed and the varying range of temperatures. Strain-rate hardening is the least important factor governing the material flow stress, especially when machining aluminum alloys.

Strain rate sensitivity of a mild steel at room temperature and strain rates of up to 105s−1

1980 ◽  
Vol 15 (4) ◽  
pp. 201-207 ◽  
Author(s):  
M S J Hashmi
Keyword(s):  
Finite Difference ◽  
Mild Steel ◽  
Strain Rate ◽  
Strain Hardening ◽  
Strain Rate Sensitivity ◽  
Elastic Strain ◽  
Room Temperature ◽  
Numerical Technique ◽  
Rate Sensitivity ◽  
Strain Rates

Experimental results on a mild steel are reported from ballistics tests which gave rise to strain rates of up to 105 s−1. A finite-difference numerical technique which incorporates material inertia, elastic-strain hardening and strain-rate sensitivity is used to establish the strain-rate sensitivity constants p and D in the equation, σ4 = σ1 (1+(∊/D)1/ p). The rate sensitivity established in this study is compared with those reported by other researchers.

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