Comparison of two uncoupled ductile damage initiation models applied to DP900 steel sheet under various loading paths

2020 ◽  
Vol 30 (1) ◽  
pp. 25-45
Author(s):  
Zhiyu Tuo ◽  
Zhenming Yue ◽  
Xincun Zhuang ◽  
Xinrui Min ◽  
Houssem Badreddine ◽  
...  
Keyword(s):  
Hot Spot ◽  
Material Model ◽  
Tensile Tests ◽  
Research Field ◽  
Forming Limit ◽  
Uniaxial Tensile ◽  
Uniaxial Tensile Test ◽  
Forming Process ◽  
Damage Initiation ◽  
Loading Paths

Accurate prediction of the fracture occurrence of high strength materials is always the hot spot in the research field of metal-forming process. Appropriate material model is the key issue which can accurately describe the mechanical forming behavior under different forming conditions. However, advanced fully coupled damage/behavior models are heavy to use by engineers and have a high cost in term of calculation consuming time. In this paper, a simple uncoupled damage approach, designed to be easy to use for engineers and accurate as well, is investigated. Two uncoupled damage models, which consider the effect of the Lode angle and the hydrostatic pressure, combing three typical hardening rules, are selected and applied to the damage prediction of DP900 dual-phase steel. The hardening properties and forming limit strains under different loading paths of DP900 are investigated and studied throughout a variety of mechanical experiments, including the uniaxial tensile test, the pre-notched tensile tests with three notched radii, and the butterfly tests. Finally, the prediction accuracy of the used models for DP900 is compared and discussed.

scholarly journals Forming limit diagram prediction of 6061 aluminum by GTN damage model

2018 ◽  
Vol 19 (2) ◽  
pp. 202 ◽  
Author(s):  
Rasoul Safdarian
Keyword(s):  
Damage Model ◽  
Forming Limit Diagram ◽  
Numerical Results ◽  
Experimental Results ◽  
Correct Selection ◽  
Forming Limit ◽  
Uniaxial Tensile ◽  
Uniaxial Tensile Test ◽  
Gtn Model ◽  
Gtn Damage Model

Forming limit diagram (FLD) is one of the formability criteria which is a plot of major strain versus minor strain. In the present study, Gurson-Tvergaard-Needleman (GTN) model is used for FLD prediction of aluminum alloy 6061. Whereas correct selection of GTN parameters’ is effective in the accuracy of this model, anti-inference method and numerical simulation of the uniaxial tensile test is used for identification of GTN parameters. Proper parameters of GTN model is imported to the finite element analysis of Nakazima test for FLD prediction. Whereas FLD is dependent on forming history and strain path, forming limit stress diagram (FLSD) based on the GTN damage model is also used for forming limit prediction in the numerical method. Numerical results for FLD, FLSD and punch’s load-displacement are compared with experimental results. Results show that there is a good agreement between the numerical and experimental results. The main drawback of numerical results for prediction of the right-hand side of FLD which was concluded in other researchers’ studies was solved in the present study by using GTN damage model.

Systematic Experimental Investigation of Dielectric Electroactive Polymers Using a Custom-Built Uniaxial Tensile Test Rig

2015 ◽  
Author(s):  
Micah Hodgins ◽  
Alexander York ◽  
Stefan Seelecke
Keyword(s):  
Pure Shear ◽  
Tensile Force ◽  
Tensile Tests ◽  
Uniaxial Tensile ◽  
Uniaxial Tensile Test ◽  
Specimen Preparation ◽  
Testing Device ◽  
Test Results ◽  
Test Rig ◽  
Geometry Test

This work presents the design, fabrication and testing of a comprehensive DEAP test station. The tester is designed to perform tensile tests of planar DEAPs while measuring quantities such as tensile force, stretch, film thickness and voltage/current. The work details the specimen preparation and how the specimen is placed in the clamps. While the assembly process is performed by hand features were built-in to the design of the specimen frame and clamps to enable reliable placement and specimen geometry. Test results of the pure-shear specimen demonstrated good performance of the testing device. Although the electrode surface was rough the thickness stretch was evident during the stretching/actuation of the DEAP actuator.

scholarly journals Numerical investigation on the forming behaviour of stainless/carbon steel bimetal composite

2018 ◽  
Vol 185 ◽  
pp. 00012
Author(s):  
Zhou Li ◽  
Jingwei Zhao ◽  
Qingfeng Zhang ◽  
Sihai Jiao ◽  
Zhengyi Jiang
Keyword(s):  
Carbon Steel ◽  
Circumferential Stress ◽  
Tensile Tests ◽  
Uniaxial Tensile ◽  
Composite Sheet ◽  
Forming Process ◽  
Thickness Strain ◽  
Forming Simulation ◽  
Bimetal Composite ◽  
Forming Behaviour

Bimetal composites have wide applications due to their excellent overall performance and relatively low comprehensive cost. The aim of this study is to investigate the forming behaviour of stainless/carbon steel bimetal composite during stamping by finite element method (FEM). In this work, the bonding interface of bimetal composite sheet was assumed to be perfect without delamination during the plastic forming process for simplicity. Uniaxial tensile tests on base metal (carbon steel) and compositing metal (stainless steel) were first carried out, respectively, in order to obtain the tensile properties of each of the component materials required in the forming simulation. Processing variables, including the layer stacking sequence, relative thickness ratios of two layers and friction were considered, and their effects on the distributions of circumferential stress and thickness strain were analysed. The bimetal composite sheet was set as the eight-node solid elements in the developed FEM model, which is effective for evaluating the distributions of circumferential stress and thickness strain, and predicting the high-risk region of necking during the stamping of bimetal composites. The simulation results can be used as an evaluation indicator of the capability of forming machine to ensure the bimetal composite can be safely formed.

Experimental Study on the Mechanical Property and Forming Limit of Magnesium Sheet at Elevated Temperatures

2009 ◽  
Author(s):  
Y. Huang ◽  
J. Huang ◽  
J. Cao
Keyword(s):  
Elevated Temperature ◽  
Room Temperature ◽  
Elevated Temperatures ◽  
Strain Curve ◽  
Tensile Tests ◽  
Alloy Sheet ◽  
Dome Height ◽  
Forming Limit ◽  
Uniaxial Tensile ◽  
Magnesium Sheet

Magnesium alloy sheet has received increasing attention in automotive and aerospace industries. It is widely recognized that magnesium sheet has a poor formability at room temperature. While at elevated temperature, its formability can be dramatically improved. Most of work in the field has been working with the magnesium sheet after annealed around 350°C. In this paper, the as-received commercial magnesium sheet (AZ31B-H24) with thickness of 2mm has been experimentally studied without any special heat treatment. Uniaxial tensile tests at room temperature and elevated temperature were first conducted to have a better understanding of the material properties of magnesium sheet (AZ31B-H24). Then, limit dome height (LDH) tests were conducted to capture forming limits of magnesium sheet (AZ31B-H24) at elevated temperatures. An optical method has been introduced to obtain the stress-strain curve at elevated temperatures. Experimental results of the LDH tests were presented.

scholarly journals Performance of Thermo-Mechanically Processed AA7075 Alloy at Elevated Temperatures—From Microstructure to Mechanical Properties

Metals ◽  
2020 ◽  
Vol 10 (7) ◽  
pp. 884 ◽  
Author(s):  
Seyed Vahid Sajadifar ◽  
Emad Scharifi ◽  
Ursula Weidig ◽  
Kurt Steinhoff ◽  
Thomas Niendorf
Keyword(s):  
Mechanical Properties ◽  
Elevated Temperatures ◽  
Tensile Tests ◽  
Uniaxial Tensile ◽  
Forming Process ◽  
Softening Mechanism ◽  
Rate Dependent ◽  
Heat Treated ◽  
Different Temperatures ◽  
Die Forming

This study focuses on the high temperature characteristics of thermo-mechanically processed AA7075 alloy. An integrated die forming process that combines solution heat treatment and hot forming at different temperatures was employed to process the AA7075 alloy. Low die temperature resulted in the fabrication of parts with higher strength, similar to that of T6 condition, while forming this alloy in the hot die led to the fabrication of more ductile parts. Isothermal uniaxial tensile tests in the temperature range of 200–400 °C and at strain rates ranging from 0.001–0.1 s−1 were performed on the as-received material, and on both the solution heat-treated and the thermo-mechanically processed parts to explore the impacts of deformation parameters on the mechanical behavior at elevated temperatures. Flow stress levels of AA7075 alloy in all processing states were shown to be strongly temperature- and strain-rate dependent. Results imply that thermo-mechanical parameters are very influential on the mechanical properties of the AA7075 alloy formed at elevated temperatures. Microstructural studies were conducted by utilizing optical microscopy and a scanning electron microscope to reveal the dominant softening mechanism and the level of grain growth at elevated temperatures.

scholarly journals Determination of the Plastic Strain by Spherical Indentation of Uniaxially Deformed Sheet Metals

2015 ◽  
Vol 651-653 ◽  
pp. 950-956 ◽  
Author(s):  
Mohamad Idriss ◽  
Olivier Bartier ◽  
Gérard Mauvoisin ◽  
Charbel Moussa ◽  
Eddie Gazo Hanna ◽  
...  
Keyword(s):  
Plastic Strain ◽  
Accurate Determination ◽  
Tensile Tests ◽  
Uniaxial Tensile ◽  
Spherical Indentation ◽  
Instrumented Indentation ◽  
Forming Process ◽  
Hardening Law ◽  
Indentation Tests

This work consists of determining the plastic strain value undergone by a material during a forming process using the instrumented indentation technique (IIT). A deep drawing steel DC01 is characterized using tensile, shear and indentation tests. The plastic strain value undergone by this steel during uniaxial tensile tests is determined by indentation. The results show that, the identification from IIT doesn’t lead to an accurate value of the plastic strain if the assumption that the hardening law follows Hollomon law is used. By using a F.E. method, it is shown that using a Voce hardening law improves significantly the identification of the hardening law of a pre-deformed material. Using this type of hardening law coupled to a methodology based on the IIT leads to an accurate determination of the hardening law of a pre-deformed material. Consequently, this will allow determining the plastic strain value and the springback elastic strain value of a material after a mechanical forming operation.

scholarly journals A New Electron Backscatter Diffraction-Based Method to Study the Role of Crystallographic Orientation in Ductile Damage Initiation

Metals ◽  
2020 ◽  
Vol 10 (1) ◽  
pp. 113
Author(s):  
Behnam Shakerifard ◽  
Jesus Galan Lopez ◽  
Leo A. I. Kestens
Keyword(s):  
Crystallographic Orientation ◽  
Electron Backscatter Diffraction ◽  
Uniaxial Tensile ◽  
Uniaxial Tensile Test ◽  
Second Phase ◽  
Post Mortem ◽  
Bainitic Steel ◽  
Damage Initiation ◽  
Electron Backscatter ◽  
Backscatter Diffraction

The third generation of advanced high strength steels shows promising properties for automotive applications. The macroscopic mechanical response of this generation can be further improved by a better understanding of failure mechanisms on the microstructural level and micro-mechanical behavior under various loading conditions. In the current study, the microstructure of a multiphase low silicon bainitic steel is characterized with a scanning electron microscope (SEM) equipped with an electron backscatter diffraction detector. A uniaxial tensile test is carried out on the bainitic steel with martensite and carbides as second phase constituents. An extensive image processing on SEM micrographs is conducted in order to quantify the void evolution during plastic deformation. Later, a new post-mortem electron backscatter diffraction-based method is introduced to address the correlation between crystallographic orientation and damage initiation. In this multiphase steel, particular crystallographic orientation components were observed to be highly susceptible to micro-void formation. It is shown that stress concentration around voids is rather relaxed by void growth than local plasticity. Therefore, this post-mortem method can be used as a validation tool together with a crystal plasticity-based hardening model in order to predict the susceptible crystallographic orientations to damage nucleation.

Evaluating the Mechanical Behavior of ARB Processed Aluminum Composites Using Shear Punch Testing

2020 ◽  
Vol 986 ◽  
pp. 86-92
Author(s):  
Dhyai Hassan Jawad ◽  
Ali Hosseinzadeh ◽  
Mustafa Misirli ◽  
Guney Guven Yapici
Keyword(s):  
Tensile Tests ◽  
Mechanical Analysis ◽  
Test Method ◽  
Uniaxial Tensile ◽  
Uniaxial Tensile Test ◽  
Punch Test ◽  
Processed Material ◽  
Shear Punch Test ◽  
Shear Punch ◽  
Shear Punch Testing

Multi-layered metal composites have received considerable attention due to their improved mechanical and physical properties. In this study, Al6061/Al2024 composite was processed by accumulative roll bonding (ARB) as a severe plastic deformation technique. Mechanical properties of processed material were evaluated using the uniaxial tensile test and shear punch test method (SPT). The correlation between the results of the tension experiments and shear strengths was calculated. Experimental results demonstrated that the shear strength enhanced with increased number of ARB passes. However, the elongation under shear manifested a reduction when the number of ARB passes increased. Inspection of the results of tensile tests and SPT revealed that they follow a similar trend for both strength and ductility. Therefore, it can be asserted that the shear punch test represents a useful and complementary tool in the mechanical analysis of the ARB sample.

Predicting Edge Cracks on Shear-Cut High-Strength Steels by Modified Uniaxial Tensile Tests

2016 ◽  
Vol 703 ◽  
pp. 49-55 ◽  
Author(s):  
Martin Feistle ◽  
Isabella Pätzold ◽  
Roland Golle ◽  
Wolfram Volk
Keyword(s):  
Tensile Test ◽  
Measurement Method ◽  
High Strength Steels ◽  
High Strength ◽  
Tensile Tests ◽  
Uniaxial Tensile ◽  
Forming Process ◽  
Contact Measurement ◽  
Edge Cracks ◽  
Near Future

During the forming of high-strength steels, edge cracks occur unexpectedly on sheared edges e.g. during collar forming. A non-contact measurement method based on the well-known tensile test was developed. It allows the investigation of the formation of edge cracks under tensile loads and determining general criteria to predict the formation of edge cracks during a specific forming process. The criteria are validated experimentally by means of the collar-forming test. In conjunction with the proposed line-fit-method these criteria can be implemented easily in FEM software in the near future for the prediction of edge cracks.

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