scholarly journals Influence of Deformation Conditions on the Critical Damage Factor of AZ31 Magnesium Alloy

2018 ◽  
Vol 2018 ◽  
pp. 1-8
Author(s):  
Li-juan Pang ◽  
Xin Shang ◽  
Xuefeng Zhang
Keyword(s):  
Magnesium Alloy ◽  
Constitutive Model ◽  
Strain Rate ◽  
Outer Edge ◽  
Az31 Magnesium Alloy ◽  
Damage Factor ◽  
Finite Element Program ◽  
Softening Behavior ◽  
Element Program ◽  
Critical Damage

The influence of deformation conditions on the critical damage factor of AZ31 magnesium alloy was analyzed in this paper. Physical experiments and numerical simulation were used to study the critical damage factor. Compression test was carried out using a Gleeble 1500 device at temperatures between 250°C and 400°C, as well as strain rates from 0.01 s−1 to 1 s−1. True stress-strain curves of samples were obtained. Based on experimental data, an Arrhenius constitutive model was constructed. Material performance parameters and constitutive model were inputted into the finite element program DEFORM. Simulation results show that the maximum damage appears on the outer edge of the upsetting drum, and damage softening behavior is more sensitive to strain rate. According to the concept of damage sensitive rate, its values were computed. The intersection of line fitted and horizontal axis was obtained in the fracture step, and its relative maximum damage value was as the critical damage factor. The distribution of the critical damage value shows that it is not a constant but fluctuates within the range of 0.1445–0.3759, and it is more sensitive to strain rate compared with temperature.

scholarly journals Study on critical damage factor and the constitutive model including dynamic recrystallization softening of AZ80 magnesium alloy

2013 ◽  
Vol 45 (2) ◽  
pp. 199-208 ◽  
Author(s):  
Y. Xue ◽  
Z.M. Zhang ◽  
Y.J. Wu
Keyword(s):  
Magnesium Alloy ◽  
Constitutive Model ◽  
Dynamic Recrystallization ◽  
Strain Rates ◽  
Damage Factor ◽  
Strain And Strain Rate ◽  
Az80 Magnesium Alloy ◽  
Az80 Alloy ◽  
Process Simulator ◽  
Critical Damage

Quantities AZ80 magnesium alloy billets were compressed with 60 % height reduction on hot process simulator at 473, 523, 573, 623, 673, 723 K under strain rates of 0.001, 0.01, 0.1, 1 and 10 s-1. In order to predict the occurrence of surface fracture, the critical damage factor based on the Cockcroft-Latham equation were obtained by analysing the results of the corresponding finite element calculation. The results show that the critical damage factor at 523, 573, 623, 673 K under strain rates of 0.001, 0.01, 0.1 and 1 s-1 is not a constant but varies in a range from 0.1397 to 0.4653. Meanwhile, a constitutive model with a few parameters is used to characterize the dynamic recrystallization strain softening of AZ80 alloy, which comprehensively reflect the effects of the deformation temperature, strain and strain rate on the flow stress.

Transferability of the Gurson Damage Model Parameters with Charpy and Tensile Tests with Different Constrain Level

2009 ◽  
Vol 65 ◽  
pp. 19-31
Author(s):  
Ruben Cuamatzi-Melendez ◽  
J.R. Yates
Keyword(s):  
Strain Rate ◽  
Damage Model ◽  
Rolling Direction ◽  
Fracture Initiation ◽  
Tensile Tests ◽  
Model Parameters ◽  
Gurson Model ◽  
Finite Element Program ◽  
Element Program ◽  
Gurson's Model

Little work has been published concerning the transferability of Gurson’s ductile damage model parameters in specimens tested at different strain rates and in the rolling direction of a Grade A ship plate steel. In order to investigate the transferability of the damage model parameters of Gurson’s model, tensile specimens with different constraint level and impact Charpy specimens were simulated to investigate the effect of the strain rate on the damage model parameters of Gurson model. The simulations were performed with the finite element program ABAQUS Explicit [1]. ABAQUS Explicit is ideally suited for the solution of complex nonlinear dynamic and quasi–static problems [2], especially those involving impact and other highly discontinuous events. ABAQUS Explicit supports not only stress–displacement analyses but also fully coupled transient dynamic temperature, displacement, acoustic and coupled acoustic–structural analyses. This makes the program very suitable for modelling fracture initiation and propagation. In ABAQUS Explicit, the element deletion technique is provided, so the damaged or dead elements are removed from the analysis once the failure criterion is locally reached. This simulates crack growth through the microstructure. It was found that the variation of the strain rate affects slightly the value of the damage model parameters of Gurson model.

Damage Mechanism Research of Yushu Airport Road Landslide No.3 Base on Elastoplastic Damage Constitutive Model

2015 ◽  
Vol 744-746 ◽  
pp. 464-469
Author(s):  
Hong Gang Wu ◽  
Tao Yang ◽  
Xiao Yun Chen ◽  
Hui Min Ma ◽  
Hong Li Zhang ◽  
...  
Keyword(s):  
Constitutive Model ◽  
Damage Mechanism ◽  
Earthquake Triggering ◽  
Triggering Mechanism ◽  
Finite Element Program ◽  
Plastic Damage ◽  
Mechanism Research ◽  
Element Program ◽  
Damage Constitutive Model ◽  
Stability Of Slope

Due to the earthquake of Yushu in April 14, 2010, Airport Road landslide No.3 deformed cracking, resulting in lower stability of slope, triggering landslides and other diseases. Selecting the section 2-2 (mileage K823 + 809) of Airport Road landslide No.3 as the calculation section, we use the ABAQUS finite element program to establish landslide numerical mode. The slip mass of landslide was simulated by the elastic-plastic damage constitutive model, and the bedrock was analyzed as Mohr - Coulomb constitutive model. Landslide No3 is analyzed for example, and showed that earthquake triggering mechanism elastplastic damage constitutive model can describe the landslide very well.

Research on Flow Stress of Magnesium Alloy Sheet under Warm and High Strain Rate Forming Condition

2011 ◽  
Vol 189-193 ◽  
pp. 2522-2525
Author(s):  
Zheng Hua Meng ◽  
Shang Yu Huang ◽  
Jian Hua Hu
Keyword(s):  
Flow Stress ◽  
Magnesium Alloy ◽  
High Strain Rate ◽  
Strain Rate ◽  
Process Simulation ◽  
High Strain ◽  
Alloy Sheet ◽  
Az31 Magnesium Alloy ◽  
Rate Condition ◽  
Magnesium Alloy Sheet

Process simulation is a powerful tool to predict material behaviors under specified deformation conditions, so as to optimize the processing parameters. The equation for flow stress is important to numerically analyze. However, the reported constitutive equations of magnesium alloy are only suitable for processing simulation with strain rate between 0.001-1s-1. In this paper, the strain-stress behavior of AZ31 under warm and high strain rate (>103s-1) condition has been investigated by split Hopkinson pressure bar experiments at elevated temperature. The results show that the influence of the temperature on flow stress is more obvious than that of strain rate; the flow stress decreases with the rise of temperature at a certain strain rate. Based on Johnson-Cook model, the constitutive equation of AZ31 magnesium alloy under warm and high strain rate condition has been given out by fitting the experimental data, which can be applied in process simulation of AZ31 magnesium alloy sheet forming.

Behavior of Concrete as a Barrier Material for Nuclear Waste Disposal

1989 ◽  
Vol 176 ◽  
Author(s):  
R. J. James ◽  
Y. R. Rashid
Keyword(s):  
Constitutive Model ◽  
Material Property ◽  
Nuclear Waste ◽  
Waste Disposal ◽  
Elevated Temperatures ◽  
Nuclear Waste Disposal ◽  
Functional Requirements ◽  
Barrier Material ◽  
Finite Element Program ◽  
Element Program

SummaryThe foundation necessary for a constitutive model to simulate the response of concrete at elevated temperature has been presented. A model including temperature dependent creep, material property degradation, and cracking is needed to evaluate the long term functional requirements of concrete as a barrier material for nuclear waste disposal. Since the stress due to thermal load is proportional to the modulus, the degradation of the modulus with time even at constant elevated temperatures requires continual redistribution of load. Furthermore, since this degradation is not recoverable, the response of the material at elevated temperatures exhibits a complex dependence not only on the temperature distribution, but on the prior thermal history of the structure.This constitutive model for the response of concrete at elevated temperatures has been implemented into an implicit, finite element program called ANACAP [8]. Because of the direct coupling with temperature, both through thermal loads and material property dependency, ANACAP also contains a heat transfer module that includes thermal effects due to fluid flow and moving material boundaries. This program has been applied to problems involving underground waste storage tanks and grout vaults at the DOE Hanford site in Richland, Washington.

Muscle and Tendon Tissues: Constitutive Modeling and Computational Issues

2011 ◽  
Vol 78 (4) ◽  
Author(s):  
L. A. Spyrou ◽  
N. Aravas
Keyword(s):  
Constitutive Model ◽  
Three Dimensional ◽  
General Purpose ◽  
Connective Tissues ◽  
Semitendinosus Muscle ◽  
Finite Element Program ◽  
Passive Behavior ◽  
Rate Dependent ◽  
Activation Level ◽  
Element Program

A three-dimensional constitutive model for muscle and tendon tissues is developed. Muscle and tendon are considered as composite materials that consist of fibers and the connective tissues and biofluids surrounding the fibers. The model is nonlinear, rate dependent, and anisotropic due to the presence of the fibers. Both the active and passive behaviors of the muscle are considered. The muscle fiber stress depends on the strain (length), strain-rate (velocity), and the activation level of the muscle, whereas the tendon fiber exhibits only passive behavior and the stress depends only on the strain. Multiple fiber directions are modeled via superposition. A methodology for the numerical implementation of the constitutive model in a general-purpose finite element program is developed. The current scheme is used for either static or dynamic analyses. The model is validated by studying the extension of a squid tentacle during a strike to catch prey. The behavior of parallel-fibered and pennate muscles, as well as the human semitendinosus muscle, is studied.

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