scholarly journals Strain Rate-Dependent Constitutive and Low Stress Triaxiality Fracture Behavior Investigation of 6005 Al Alloy

2018 ◽  
Vol 2018 ◽  
pp. 1-14 ◽  
Author(s):  
Yong Peng ◽  
Xuanzhen Chen ◽  
Shan Peng ◽  
Chao Chen ◽  
Jiahao Li ◽  
...  
Keyword(s):  
Flow Stress ◽  
Plastic Strain ◽  
Strain Rate ◽  
Fracture Behavior ◽  
Equivalent Plastic Strain ◽  
Stress Triaxiality ◽  
Tensile Tests ◽  
Uniaxial Tensile ◽  
Strain Rates ◽  
Stress States

In order to study the dynamic and fracture behavior of 6005 aluminum alloy at different strain rates and stress states, various tests (tensile tests at different strain rates and tensile shearing tests at five stress states) are conducted by Mechanical Testing and Simulation (MTS) and split-Hopkinson tension bar (SHTB). Numerical simulations based on the finite element method (FEM) are performed with ABAQUS/Standard to obtain the actual stress triaxialities and equivalent plastic strain to fracture. The results of tensile tests for 6005 Al show obvious rate dependence on strain rates. The results obtained from simulations indicate the feature of nonmonotonicity between the strain to fracture and stress triaxiality. The equivalent plastic strain reduces to a minimum value and then increases in the stress triaxiality range from 0.04 to 0.30. A simplified Johnson-Cook (JC) constitutive model is proposed to depict the relationship between the flow stress and strain rate. What is more, the strain-rate factor is modified using a quadratic polynomial regression model, in which it is considered to vary with the strain and strain rates. A fracture criterion is also proposed in a low stress triaxiality range from 0.04 to 0.369. Error analysis for the modified JC model indicates that the model exhibits higher accuracy than the original one in predicting the flow stress at different strain rates. The fractography analysis indicates that the material has a typical ductile fracture mechanism including the shear fracture under pure shear and the dimple fracture under uniaxial tensile.

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.

scholarly journals ADI 1050-6 Mechanical Behavior at Different Strain Rates and Temperatures

2018 ◽  
Vol 925 ◽  
pp. 196-202 ◽  
Author(s):  
Andrew Ruggiero ◽  
Gianluca Iannitti ◽  
Stefano Masaggia ◽  
Federico Vettore
Keyword(s):  
Strain Rate ◽  
Damage Mechanics ◽  
Damage Model ◽  
Stress Triaxiality ◽  
Continuum Damage Mechanics ◽  
Tensile Tests ◽  
Yield Function ◽  
Strain Rates ◽  
The Continuum

An experimental characterization of the austempered ductile iron ISO 17804/JS/1050-6/S was performed carrying out tensile tests under different strain rates, temperatures and stress triaxiality levels. Then, composing a yield function surface, a hardening relation, and a damage criterion, a constitutive model was developed to describe the salient features of the observed macroscopic response. In particular, the Mohr-Coulomb yield function was selected to account for the pressure effect observed on the yield surface. A new hardening relation was proposed in order to account for both strain rate and temperature effects. The Bonora’s damage model, developed in the framework of the continuum damage mechanics, was adopted to capture the failure condition under different stress triaxiality levels. The damage model was appropriately modified to account for the effect of strain rate and temperature on the failure strain.

Effects of Temperature and Strain Rate on Commercial Aluminum Alloy AA5083

2014 ◽  
Vol 660 ◽  
pp. 332-336 ◽  
Author(s):  
Mohd Khir Mohd Nor ◽  
Ibrahim Mohamad Suhaimi
Keyword(s):  
Aluminum Alloy ◽  
Flow Stress ◽  
Strain Rate ◽  
Deformation Behaviour ◽  
Model Development ◽  
Tensile Tests ◽  
Gauge Length ◽  
Uniaxial Tensile ◽  
Important Conclusion ◽  
Commercial Aluminum Alloy

Superplastic forming, SPF is a special metalworking process that allows sheets of metal alloys such as aluminum to be stretched to lengths over ten times. Nowdays, only a few aluminium alloys can meet the specific requirement of SPF manufacturing process and not much data available to represent their mechanical behaviour. In order to deal with this issue, this research project is conducted to investigate the characteristics of commercial aluminum alloy, AA5083 when tested at different strain rates and temperatures. These parameters play a crucial roles in the design and manufacturing processes of military, automotive and aerospace structures. Equally, the effects must be considered in the constitutive model development to accurately capture the deformation behaviour of such materials. The specimens were prepared according to 12.5mm gauge length standard. The Uniaxial Tensile Tests were carried out at various strain rate from 4.167 x10-1s-1to 4.167 x10-5s-1over a wide temperature range from ambient to 95°C. The experimental data shows that increasing strain rate increases flow stress, while increasing temperature decrease flow stress. This is leads to important conclusion that material AA5083 exhibits strain rate and temperature sensitivite, and suit with the SPF operating condition.

Fracture Behavior of X65 Q&T Seamless Pipeline Steel Under Different Strain Rates and Stress States

2020 ◽  
Author(s):  
Pratiwi Fudlailah ◽  
Marcelo Paredes
Keyword(s):  
Strain Rate ◽  
Dynamic Fracture ◽  
Wall Thickness ◽  
Fracture Behavior ◽  
Pipeline Steel ◽  
Economic Feasibility ◽  
Dynamic Crack ◽  
Strain Rates ◽  
Drop Weight ◽  
Stress States

Abstract Dynamic crack propagation in pressurized pipelines is usually investigated by means of lab-scale specimens due to its economic feasibility and material saving. More recently, new generation of pipeline steels have incredibly shown a combined fracture toughness and plastic strength capabilities with even more heavier wall thickness, for which current design standards and practice codes underpredict largely the actual material response under different strain rates. The Drop-Weight Tear Test (DWTT) is commonly used to characterize dynamic fracture behavior of pipeline steel and its numerical implementation with appropriate constitutive equations has become essential in the fundamental understanding of the interaction between fracture process and local stress-strain fields. In the present study, a X65 Q&T seamless pipeline steel is fully characterized under different strain rate levels and stress states for dynamic fracture initiation. A rate dependent phenomenological fracture criterion is proposed in the form of Modified Mohr-Coulomb (MMC) fracture model coupling with a multiplicative decomposition of the hardening law to describe strain rate effect on post-necking behavior. The model implementation is then validated through a drop-weight tearing analysis on standard and non-standard specimen configurations including different wall thickness.

scholarly journals Effects of Temperature and Strain Rate on the Fracture Behaviors of an Al-Zn-Mg-Cu Alloy

Materials ◽  
2018 ◽  
Vol 11 (7) ◽  
pp. 1233 ◽  
Author(s):  
Yue Guo ◽  
Mingxing Zhou ◽  
Xingdong Sun ◽  
Long Qian ◽  
Lijia Li ◽  
...  
Keyword(s):  
Flow Stress ◽  
Strain Rate ◽  
Peak Stress ◽  
Uniaxial Tensile ◽  
Strain Rates ◽  
Cu Alloy ◽  
Deformation State ◽  
Wide Range ◽  
Fracture Behaviors ◽  
Effects Of Temperature

Effects of temperature and strain rate on the fracture behaviors of an Al-Zn-Mg-Cu alloy are investigated by isothermal uniaxial tensile experiments at a wide range of temperatures and strain rates, from room temperature (RT) to 400 °C and from 10−4 s−1 to 10−1 s–1, respectively. Generally, the elevation of temperature leads to the increasing of elongation to fracture and the reduction of peak stress, while higher strain rate results in the decreasing of elongation to fracture and the increasing of peak stress. Interestingly, we found that the coefficient of strain rate sensitivity (m-value) considerably rises at 200 °C and work of fracture (Wf) fluctuates drastically with the increase of strain rate at RT and 100 °C, both of which signify a non-uniform and unstable deformation state below 200 °C. A competition of work hardening (WH) and dynamic recrystallization (DRX) exists at 200 °C, making it serve as a transitional temperature. Below 200 °C, WH is the main deformation mechanism of flow stress, and DRX dominates the flow stress above 200 °C. It has been found that from RT to 200 °C, the main feature of microstructure is the generation of dimples and microvoids. Above 200 °C, the coalescence of dimples and microvoids mainly leads to the failure of specimen, while the phenomenon of typically equiaxed dimples and nucleation appear at 400 °C. The observations of microstructure are perfectly consistent with the related macroscopic results. The present work is able to provide a comprehensive understanding of flow stress of an Al-Zn-Mg-Cu alloy at a wide range of temperatures and strain rates, which will offer valuable information to the optimization of the hot forming process and structural design of the studied alloy.

scholarly journals Full-Field Temperature Measurement of Stainless Steel Specimens Subjected to Uniaxial Tensile Loading at Various Strain Rates

Materials ◽  
2021 ◽  
Vol 14 (18) ◽  
pp. 5259
Author(s):  
Krzysztof Żaba ◽  
Tomasz Trzepieciński ◽  
Stanislav Rusz ◽  
Sandra Puchlerska ◽  
Maciej Balcerzak
Keyword(s):  
Stainless Steel ◽  
Strain Rate ◽  
Strain Hardening ◽  
Heat Generation ◽  
Tensile Tests ◽  
Uniaxial Tensile ◽  
Strain Hardening Exponent ◽  
Strain Rates ◽  
Full Field ◽  
Dog Bone

This article presents a study on the effect of strain rate, specimen orientation, and plastic strain on the value and distribution of the temperature of dog-bone 1 mm-thick specimens during their deformation in uniaxial tensile tests. Full-field image correlation and infrared thermography techniques were used. A titanium-stabilised austenitic 321 stainless steel was used as test materials. The dog-bone specimens used for uniaxial tensile tests were cut along the sheet metal rolling direction and three strain rates were considered: 4 × 10−3 s−1, 8 × 10−3 s−1 and 16 × 10−3 s−1. It was found that increasing the strain rate resulted in the intensification of heat generation. High-quality regression models (Ra > 0.9) developed for the austenitic 321 steel revealed that sample orientation does not play a significant role in the heat generation when the sample is plastically deformed. It was found that at the moment of formation of a necking at the highest strain rate, the maximum sample temperature increased more than four times compared to the initial temperature. A synergistic effect of the strain hardening exponent and yield stress revealed that heat is generated more rapidly towards small values of strain hardening exponent and yield stress.

Analyzing Fracture Behavior of Beam-Column Joints Using Micromechanical Fracture Models

2015 ◽  
Vol 744-746 ◽  
pp. 3-7
Author(s):  
Chen Zhang ◽  
Yu Ping Sun ◽  
Ju Tao Zhang ◽  
Yu Gu
Keyword(s):  
Finite Element ◽  
Plastic Strain ◽  
Fracture Behavior ◽  
Equivalent Plastic Strain ◽  
Stress Triaxiality ◽  
Bolted Connection ◽  
Finite Element Software ◽  
Maximum Value ◽  
Fracture Models ◽  
Welded Connection

The micromechanical fracture models were used to study the fracture behavior of the welded connection and welded-bolted connection joints. The Void Growth Model was implemented in commercial finite element software ABAQUS through the user-defined subroutines. The results predicted that cracks initiated at the edge of the welds and extended along the length and thickness of the welds. Comparing the effects of equivalent plastic strain and stress triaxiality for the fracture of the first failure element of both beam-to-column joints, we found that the equivalent plastic strain grew linearly as the loads increased and the weld of the lower flange generated cracks when the stress triaxiality increased at maximum value.

HIGH-RATE TENSILE BEHAVIOR OF SILICONE RUBBER AT VARIOUS TEMPERATURES

2020 ◽  
Vol 93 (1) ◽  
pp. 183-194 ◽  
Author(s):  
Lingmei Guo ◽  
Yang Wang
Keyword(s):  
Strain Rate ◽  
Silicone Rubber ◽  
Tensile Tests ◽  
Tensile Behavior ◽  
High Rate ◽  
Uniaxial Tensile ◽  
Strain Rates ◽  
Strain Behavior ◽  
Split Hopkinson ◽  
Increasing Temperature

ABSTRACT The effects of strain rate and temperature on the tensile behavior of silicone rubber were investigated. The quasi-static uniaxial tensile experiments were conducted using an electromechanical testing system, and the high-rate uniaxial tensile tests were performed employing a modified split Hopkinson tension bar technique for low-strength and low-impedance materials. The tensile responses were obtained at strain rates of 0.001–1400 s−1 and temperatures ranging from −50 to 50 °C. The experiments reveal that the tensile stress–strain behavior of silicone rubber is nonlinear and highly dependent on strain rate and temperature. The values of stiffness and nominal stress at a given elongation increase with increased strain rate and decrease with increasing temperature. It is appropriate to postulate that the tensile response at high strain rates arises from the combination of hyperelasticity and viscoelasticity. According to the incompressibility assumption, a phenomenologically inspired visco-hyperelastic model was proposed to describe the constitutive behavior of silicone rubber over wide ranges of strain rates and temperatures.

scholarly journals Damage Evolution Due to Extremely Low-Cycle Fatigue for Inconel 718 Alloy

Metals ◽  
2019 ◽  
Vol 9 (10) ◽  
pp. 1109 ◽  
Author(s):  
Mohammed Algarni ◽  
Yuanli Bai ◽  
Mohammed Zwawi ◽  
Sami Ghazali
Keyword(s):  
Cyclic Loading ◽  
Plastic Strain ◽  
Damage Evolution ◽  
Low Cycle Fatigue ◽  
Equivalent Plastic Strain ◽  
Stress Triaxiality ◽  
Cycle Fatigue ◽  
Inconel 718 Alloy ◽  
Stress States ◽  
Evolution Behavior

This paper evaluates the damage evolution process under extremely low-cycle fatigue (ELCF). The study explores the damage behavior under different stress states. The influence of the multiaxial state of stress on the metal’s life is determined. Two different stress states were examined: (a) axisymmetric and (b) plane-strain. The study is based on the modified Mohr–Coulomb (MMC) ductile fracture criterion that was extended to cover the ELCF regime in a previous research study. Four distinctive geometries are designed to study the effect of different stress states on ELCF life and damage evolution. The damage model is calibrated for life prediction to agree with the ELCF experimental results. The investigation of the damage evolution behavior is dependent on equivalent plastic strain, stress triaxiality, Lode angle, and cyclic loading effect. The damage evolution is extracted from Abaqus finite element simulations and plotted versus the equivalent plastic strain. The damage accumulation shows nonlinear evolution behavior under cyclic loading conditions. SEM images were taken to further study the microscopic failure mechanisms of ELCF.

scholarly journals Experimental study of the stress state and strain rate dependent mechanical behaviour of TRIP-assisted steels

2021 ◽  
Vol 250 ◽  
pp. 05003
Author(s):  
A. Pontillo ◽  
C. Lonardi ◽  
S. Chandran ◽  
F. Vercruysse ◽  
L. Corallo ◽  
...  
Keyword(s):  
Strain Rate ◽  
Plane Strain ◽  
Strain Rate Sensitivity ◽  
Rate Sensitivity ◽  
Tensile Tests ◽  
Image Correlation ◽  
Strain Rates ◽  
Plane Shear ◽  
Rate Dependent ◽  
Stress States

This paper presents an investigation into the effect of different stress states and strain rates on the austenite-to-martensite transformation during plastic straining of a Q&P steel. Different stress states are imposed to the steel using purposed-designed samples. The sample geometries, including in-plane shear, dogbone and plane strain samples, are optimised by finite element modelling. Tensile tests are performed at different strain rates of 0.001 s-1, 10 s-1 and 500 s-1. Digital image correlation is used to capture the strain fields during the entire deformation process. The mechanical results indicate a positive strain rate sensitivity for both the shear and plane strain specimens and a negative strain rate sensitivity for the dogbone sample. In addition, the influence of the strain rate on the strain level is more pronounced for the shear than for the plane strain specimens and for the dogbone samples.

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