An Analytical and Numerical Investigation on Flange Wrinkling Behavior in Warm Forming Process of AA5754 Using Macro-Textured Tool Design

2016 ◽  
Vol 716 ◽  
pp. 586-594 ◽  
Author(s):  
Kai Lun Zheng ◽  
Lei Zhu ◽  
Denis J. Politis ◽  
Jian Guo Lin ◽  
Trevor A. Dean
Keyword(s):  
Aluminium Alloy ◽  
Draw Ratio ◽  
Elevated Temperatures ◽  
Material Model ◽  
Damage Mechanism ◽  
Alloy Sheet ◽  
Warm Forming ◽  
Forming Process ◽  
Flange Wrinkling ◽  
Forming Temperature

In this paper, an analytical buckling model is established to predict the flange wrinkling behavior of deep drawn cylindrical cups of aluminium alloy sheet in warm forming conditions using macro-textured blankholders for the first time. A continuum damage mechanism (CDM) based material model was utilized to reflect the visco-plastic feature of material at elevated temperatures. Forming speed and temperature effects were investigated, and texture ratio and draw ratio effects were also discussed. The developed analytical buckling model was validated by finite element simulations. The increase of forming temperature and forming speed is prone to cause wrinkling for AA5754, but the effects are not as significant as the texture geometry and draw ratio. The analytical model presented in this paper can be used as a design guide to determine tool texture geometry necessary to avoid wrinkling defects in the warm forming processes of aluminium alloy.

scholarly journals Experimental investigation of forming limit curves and deformation features in warm forming of an aluminium alloy

2016 ◽  
Vol 232 (3) ◽  
pp. 465-474 ◽  
Author(s):  
Zhutao Shao ◽  
Qian Bai ◽  
Nan Li ◽  
Jianguo Lin ◽  
Zhusheng Shi ◽  
...  
Keyword(s):  
Aluminium Alloy ◽  
Elevated Temperatures ◽  
Warm Forming ◽  
Dome Height ◽  
Forming Limit ◽  
Thickness Variation ◽  
Forming Process ◽  
Deformation Features ◽  
Forming Temperature ◽  
Forming Limit Curves

The determination of forming limit curves and deformation features of AA5754 aluminium alloy are studied in this article. The robust and repeatable experiments were conducted at a warm forming temperature range of 200 °C–300 °C and at a forming speed range of 20–300 mm/s. The forming limit curves of AA5754 at elevated temperatures with different high forming speeds have been obtained. The effects of forming speed and temperature on limiting dome height, thickness variation and fracture location are discussed. The results show that higher temperatures and lower forming speeds are beneficial to increasing forming limits of AA5754; however, lower temperatures and higher forming speeds contribute to enhancing the thickness uniformity of formed specimens. The decreasing forming speed and increasing temperature result in the locations of fracture to move away from the apexes of formed specimens. It is found that the analysis of deformation features can provide a guidance to understand warm forming process of aluminium alloys.

scholarly journals Determining the material model at elevated temperatures with different strain rates and simulating the warm forming process for Mg alloy AZ31B sheet

2015 ◽  
Vol 18 (2) ◽  
pp. 149-158
Author(s):  
Thien Tich Truong ◽  
Long Thanh Nguyen ◽  
Binh Nguyen Thanh Vu ◽  
Hien Thai Nguyen
Keyword(s):  
Magnesium Alloy ◽  
Constitutive Equations ◽  
Elevated Temperatures ◽  
Material Model ◽  
Alloy Sheet ◽  
Strain Rates ◽  
Functional Requirements ◽  
Temperature Dependent ◽  
Forming Process ◽  
Az31b Alloy

Magnesium alloy is one of lightweight alloys has been studied more extensively today. Because weight reduction while maintaining functional requirements is one of the major goals in industries in order to save materials, energy and costs, etc. Its density is about 2/3 of aluminum and 1/4 of steel.The material used in this study is commercial AZ31B magnesium alloy sheet which includes 3% Al and 1% Zn. However, due to HCP (Hexagonal Close Packed) crystal structure, magnesium alloy has limited ductility and poor formability at room temperature. But its ductility and formability will be improved clearly at elevated temperature. From the data of tensile testing, the constitutive equations of AZ31B was approximated using the Ramgberg-Osgood model with temperature dependent parameters to fit in the experiment results in tensile test. Yield locus are also drawn in plane stress σ1- σ2 with different yield criteria such as Hill48, Drucker Prager, Logan Hosford, Y. W. Yoon 2013 and particular Barlat 2000 criteria with temperature dependent parameters. Applying these constitutive equations were determined at various temperatures and different strain rates, the finite element simulation stamping process for AZ31B alloy sheet by software PAM- STAMP 2G 2012, to verify the model materials and the constitutive equations.

Investigation of EN AW 5754 Aluminum Alloy’s Formability at Elevated Temperatures

2017 ◽  
Vol 885 ◽  
pp. 98-103 ◽  
Author(s):  
Dávid Budai ◽  
Miklós Tisza ◽  
Péter Zoltán Kovács
Keyword(s):  
Elevated Temperatures ◽  
High Strength Steels ◽  
High Strength ◽  
Carbon Composite ◽  
Alloy Sheet ◽  
High Mass ◽  
Mass Reduction ◽  
Forming Process ◽  
Forming Temperature ◽  
Operating Distance

Nowadays, mass reduction is the most often used term in the automotive industry. Car manufacturers are continuously working on getting ever lighter models than the previous ones, because of the global competition and the rigorous emission rules. A light car has many advantages: lower consumption, better handling, longer operating distance, etc. The emission rules forced the car brands to start new researches to find new solutions for mass reduction. The formula is relatively simple, using lighter or less materials or both and the car will be lighter. In the recent solutions there are three different ways: application of high strength steels, aluminum alloys, and carbon-composite elements. Our investigations are focusing mainly on aluminum, because of its high mass reduction potential. The biggest problem with the aluminum is its low formability. The formability of aluminum is lower than the steel, and it causes problems for the manufacturers. To increase the formability of the aluminum is a hot topic in the research and development area. Forming at elevated temperatures is one of the best solutions to increase the formability of aluminum. The relation between the formability and the forming temperature is not linear, furthermore beyond the optimum forming temperature the formability decreases. We need dozens of investigations to describe the perfect relation, but sometimes a good approximation is enough to form sheet products safely. In our work we investigated the EN AW 5754 aluminum alloy sheet at room temperature, 130°C, 200°C and 260°C. From these tests we could obtain FLC curves of the alloy at different temperatures. Using these curves, the process engineers could find the optimum parameters of their forming process.

Gas Blow Forming in AA2017 Aluminium Alloy

2016 ◽  
Vol 878 ◽  
pp. 13-17
Author(s):  
Giuliano Gillo
Keyword(s):  
Aluminium Alloy ◽  
Constant Temperature ◽  
Constant Pressure ◽  
Reference Value ◽  
Alloy Sheet ◽  
Forming Process ◽  
Forming Temperature

In this paper the hot behaviour of AA2017 aluminium alloy sheet was analyzed through gas blow forming tests. The material, heated and kept at a constant temperature, was subjected to gas blow forming tests under a constant pressure. Specimens with a thickness of 1.00 mm and 0.55 mm were employed. The study defines a reference value for the forming temperature as well as the hardness of the finished component. In addition, the hardness was also measured following tests conducted in several steps of the forming process.

Study on the Formability of Aluminium Alloy Sheets at Room and Elevated Temperatures

2016 ◽  
Vol 877 ◽  
pp. 393-399
Author(s):  
Jia Zhou ◽  
Jun Ping Zhang ◽  
Ming Tu Ma
Keyword(s):  
Mechanical Properties ◽  
Aluminum Alloy ◽  
Elevated Temperature ◽  
Aluminium Alloy ◽  
Aluminium Alloys ◽  
Elevated Temperatures ◽  
Hot Stamping ◽  
Natural Aging ◽  
Alloy Sheet ◽  
Aluminum Alloy Sheet

This paper presents the main achievements of a research project aimed at investigating the applicability of the hot stamping technology to non heat treatable aluminium alloys of the 5052 H32 and heat treatable aluminium alloys of the 6016 T4P after six months natural aging. The formability and mechanical properties of 5052 H32 and 6016 T4P aluminum alloy sheets after six months natural aging under different temperature conditions were studied, the processing characteristics and potential of the two aluminium alloy at room and elevated temperature were investigated. The results indicated that the 6016 aluminum alloy sheet exhibit better mechanical properties at room temperature. 5052 H32 aluminum alloy sheet shows better formability at elevated temperature, and it has higher potential to increase formability by raising the temperature.

Flow Stress Experimental Determination for Warm-Forming Process

2011 ◽  
Author(s):  
Ting Fai Kong ◽  
Luen Chow Chan ◽  
Tai Chiu Lee
Keyword(s):  
Stainless Steel ◽  
Flow Stress ◽  
Room Temperature ◽  
Warm Forming ◽  
Recrystallization Temperature ◽  
Process Conditions ◽  
Compression Tests ◽  
Forming Process ◽  
Forming Temperature ◽  
Flow Stress Data

Warm forming is a manufacturing process in which a workpiece is formed into a desired shape at a temperature range between room temperature and material recrystallization temperature. Flow stress is expressed as a function of the strain, strain rate, and temperature. Based on such information, engineers can predict deformation behavior of material in the process. The majority of existing studies on flow stress mainly focus on the deformation and microstructure of alloys at temperature higher than their recrystallization temperatures or at room temperature. Not much works have been presented on flow stress at warm-forming temperatures. This study aimed to determine the flow stress of stainless steel AISI 316L and titanium TA2 using specially modified equipment. Comparing with the conventional method, the equipment developed for uniaxial compression tests has be verified to be an economical and feasible solution to accurately obtain flow stress data at warm-forming temperatures. With average strain rates of 0.01, 0.1, and 1 /s, the stainless steel was tested at degree 600, 650, 700, 750, and 800 °C and the titanium was tested at 500, 550, 600, 650, and 700 °C. Both materials softened at increasing temperatures. The overall flow stress of stainless steel was approximately 40 % more sensitive to the temperature compared to that of titanium. In order to increase the efficiency of forming process, it was suggested that the stainless steel should be formed at a higher warm-forming temperature, i.e. 800 °C. These findings are a practical reference that enables the industry to evaluate various process conditions in warm-forming without going through expensive and time consuming tests.

Study on Formability about ME20M Magnesium Alloy Sheet

2010 ◽  
Vol 136 ◽  
pp. 23-27
Author(s):  
Ting Fang Zhang ◽  
Shi Kun Xie
Keyword(s):  
Numerical Simulation ◽  
Magnesium Alloy ◽  
Deep Drawing ◽  
Material Model ◽  
Alloy Sheet ◽  
Simulation Software ◽  
Constitutive Relationship ◽  
Magnesium Alloy Sheet ◽  
Forming Temperature ◽  
Made In

Warm forming of magnesium alloy sheet has attracted more and more attention in recent years. Mechanics tension test has been made in this paper in order to study the constitutive relationship of ME20M magnesium alloy sheet at different temperatures and strain rates. And a constitutive relationship which includes a softening factor has been put forward. Warm deep drawing experiment and numerical simulation on ME20M magnesium alloy sheet have been made in which the attention was focused on the forming temperature. The results showed that the limit deep drawing height of ME20M magnesium alloy sheet can be dramatically improved as the temperature goes up, especially when the temperature was over about 250°C. Simultaneity, it is feasible and effective to add a material model into numerical simulation software by user subroutine.

Effects of Surface Strength and Temperature on Warm Forming of MG-AL-SUS Clad Sheet

2010 ◽  
Vol 443 ◽  
pp. 183-188
Author(s):  
Young Seon Lee ◽  
Taek Woo Jung ◽  
Dae Yong Kim ◽  
Young Hoon Moon
Keyword(s):  
Elevated Temperatures ◽  
Interface Strength ◽  
Alloy Sheet ◽  
Warm Forming ◽  
Mg Alloy ◽  
Uniaxial Tensile ◽  
Al Alloy ◽  
Essential Property ◽  
Drawing Ratio ◽  
Clad Sheet

Clad metal sheets are composed of one or more different materials joined by resistance seam welding, roll-bonding process, etc. Good formability is an essential property in order to deform a clad metal sheet to a part or component. Temperature is one of the major factors affected the interface strength and formability on warm forming of multilayered sheet metal. In this study, the mechanical properties and formability of a Mg-Al-SUS clad sheet are investigated. The clad sheet was deformed at elevated temperatures because of its poor formability at room temperature. Tensile tests were performed at various temperatures above 250°C and at various strain rates. The limit drawing ratio (LDR) was obtained using a deep drawing test to measure the formability of the clad sheet. Interface strength and fracture pattern were changed mainly by temperature. Uniaxial tensile strength represents entirely different type below and above 200°C at also different strain rate. Mg alloy sheet was fractured earlier more than SUS and Al alloy sheet below 250°C testing temperature. On the contrary, Mg alloy sheet was elongated much more than other metals above 250°C.

Finite Element Modeling and Analysis of Warm Forming of Aluminum Alloys—Validation Through Comparisons With Experiments and Determination of a Failure Criterion

2005 ◽  
Vol 128 (3) ◽  
pp. 613-621 ◽  
Author(s):  
Hong Seok Kim ◽  
Muammer Koç ◽  
Jun Ni ◽  
Amit Ghosh
Keyword(s):  
Finite Element ◽  
Elevated Temperatures ◽  
Maximum Load ◽  
Thickness Ratio ◽  
Warm Forming ◽  
Forming Limit ◽  
Minimum Thickness ◽  
Element Analysis ◽  
Forming Temperature ◽  
Accuracy And Repeatability

In this study, thermomechanically coupled finite element analysis (FEA) was performed for forming aluminum rectangular cups at elevated temperatures. In order to identify the onset of a failure during FEA, applicability, accuracy, and repeatability of three different failure criteria (maximum load, minimum thickness, and thickness ratio) were investigated. The thickness ratio criterion was selected since it resulted in accurate prediction of necking-type failure when compared with experimental measurements obtained under a variety of warm forming conditions. Predicted part depth values from FEA at various die-punch temperature combinations and blank holder pressures conditions were also compared with experiments, and showed good agreement. Forming limit diagrams were established at three different warm forming temperature levels (250°C, 300°C, and 350°C). An increasing limiting strain was observed with increasing forming temperature both in FEA and experiments. In addition, strain distributions on the formed part obtained under different die-punch temperature combinations were also compared to further validate the accuracy of FEA. A high temperature gradient between die and punch (Tdie>Tpunch) was found to result in increased formability; i.e., high part depths.

Consideration of Elastic Tool Deformation in Numerical Simulation of Hydroforming with Granular Material Used as a Medium

2011 ◽  
Vol 473 ◽  
pp. 707-714 ◽  
Author(s):  
Martin Grüner ◽  
Marion Merklein
Keyword(s):  
Numerical Simulation ◽  
Granular Material ◽  
Elevated Temperatures ◽  
High Strength Steels ◽  
High Strength ◽  
Appropriate Technology ◽  
The Body ◽  
Warm Forming ◽  
Forming Process ◽  
Blank Holder

The use of high and ultra high strength steels in modern bodies in white raises steadily since the 1980’s. This trend is caused by the consumers’ wish of low fuel consuming cars with an increased passenger’s safety. The processing of these steels brings new challenges e.g. high flow stresses and a low formability at room temperature or high tool loads. These challenges can be resolved by warm forming at temperatures up to 600 °C reducing the flow stresses and increasing formability. For the production of complex parts that can not be produced by deep drawing hydroforming is an appropriate technology which can also help to reduce the number of parts and thus the weight of the body in white. Nowadays typical fluids used for hydroforming are only temperature stable up to about 330 °C so that it is not possible to combine the benefits of warm forming and hydroforming. Media like gases and fluids tend to leakage during the process which can only be avoided by a sealing or high blank holder forces. A new approach is the use of ceramic beads as medium for hydroforming at elevated temperatures. Building up a heatable tool for hydroforming with granular material used as medium makes it necessary to consider thermal conductivity so that there is a need of thick insulation plates. These insulation plates show high elastic deformations affecting the blank holder forces during the forming process. Measurements of the compressibility of these plates and implementation in numerical simulation allow a significant increase of the prediction accuracy of the model. A comparison of real part geometry and numerical results from models with and without consideration of elastic deformation will be given.

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