Limit dome height and failure location of stainless steel tailor-welded blanks

2007 ◽  
Vol 221 (12) ◽  
pp. 1497-1506 ◽  
Author(s):  
M Jie ◽  
C H Cheng ◽  
C L Chow ◽  
L C Chan
Keyword(s):  
Numerical Simulation ◽  
Stainless Steel ◽  
Dome Height ◽  
Forming Limit ◽  
Forming Limits ◽  
Limit Dome Height ◽  
Localized Necking ◽  
Tailor Welded Blanks ◽  
Necking Criterion ◽  
Failure Location

Forming limits of stainless steel tailor-welded blanks (TWBs) are investigated through both testing and numerical simulation. Limit dome height (LDH) tests were performed for 1.2/1.0 mm TWBs with 0°, 90°, 45° weldment orientations and various blank widths. Numerical simulation of the LDH test was conducted with LSDYNA. Since TWB is, in reality, a structure, the forming limits of TWBs in terms of the LDH and failure location should be characterized rather than the conventional forming limit diagrams (FLDs). A localized necking criterion based on the vertex theory was employed to identify the failure sites of TWBs. The localized necking criterion was compiled into a computer program, which processed the output data from LSDYNA. The LDHs and failure locations were computed for various combinations of blank thickness and weldment orientation. The predicted LDH and failure locations were compared with the test results and found to be satisfactory.

Comparison of different welding methods on mechanical properties and formability behaviors of tailor welded blanks (TWB) made from AA6061 alloys

2020 ◽  
pp. 095440622095250
Author(s):  
Behrouz Bagheri ◽  
Mahmoud Abbasi ◽  
Reza Hamzeloo
Keyword(s):  
Mechanical Properties ◽  
Laser Welding ◽  
Co2 Laser ◽  
Forming Limit Diagram ◽  
Dome Height ◽  
Forming Limit ◽  
Welding Parameters ◽  
Friction Stir ◽  
Tailor Welded Blanks ◽  
Different Characteristics

A tailor welded blank (TWB) includes two or more blanks joined together in order to make a single blank. Different welding methods are used to join blanks with different characteristics and form TWBs. In this study, a comparison is made among the effects of three different welding methods namely CO2 laser welding, friction stir welding (FSW), and friction stir vibration welding (FSVW) on mechanical and formability properties of developed TWBs. AA6061 alloy sheets with different thicknesses (1.2 and 0.8 mm) are joined to get TWBs. The forming limit diagram (FLD) and limiting dome height (LDH) are applied to assess the formability. The Taguchi method is applied to find the optimum values of welding parameters. It is concluded that TWBs made by FSVW have higher mechanical properties and formability compared to TWBs made by FSW and CO2 laser welding. The results also indicate that FLD for TWBs made by FSW is higher than FLD for TWBs made by CO2 laser welding and FLD0, for TWBs made by FSVW, increases as vibration frequency increases.

Damage-coupled FLD of Sheet Metals for Warm Forming and Nonproportional Loading

2011 ◽  
Vol 20 (8) ◽  
pp. 1243-1262 ◽  
Author(s):  
M. Jie ◽  
C. L. Chow ◽  
X. Wu
Keyword(s):  
Evolution Equation ◽  
Damage Evolution ◽  
Strain Softening ◽  
Forming Limit ◽  
Sheet Metals ◽  
Nonproportional Loading ◽  
Damage Evolution Equation ◽  
Localized Necking ◽  
Loading Paths ◽  
Necking Criterion

A method of forming limit prediction for sheet metals at high temperatures and under nonproportional loading is presented. The method takes into account the strain-softening behaviors of the material at elevated temperatures. A localized necking criterion based on an isotropic damage-coupled acoustic tensor is developed and employed to determine the forming limits of strain-softening materials. The damage evolution equation is developed within the thermo-mechanical framework. A closed-form expression of the forming limit strains is derived by coupling the damage evolution equation into the localized necking criterion. A computer program, incorporating the incremental theory of plasticity, the damage evolution equation and the localized necking criterion, is developed to compute the forming limit strains under several nonproportional loading paths. A series of the uniaxial tensile tests is performed to measure the relevant mechanical properties of AA6061 at the elevated temperature of 450°C. The material damage variables are determined from the measured elastic modulii from a series of loading and unloading paths. The damage evolution equation of AA6061 at 450°C is formulated based on the test data. The computed limit strains are compared with the test results under various loading paths and a good agreement is observed. It is found that the critical damage value is independent on the stress states and loading paths. It may be concluded that the application of the material damage as a reliable criterion of localized necking including the nonproportional loading cases.

Analysis of Forming Limits Using the Hill 1993 Yield Criterion

1998 ◽  
Vol 120 (3) ◽  
pp. 236-241 ◽  
Author(s):  
Siguang Xu ◽  
Klaus J. Weinmann ◽  
Abhijit Chandra
Keyword(s):  
Bifurcation Analysis ◽  
Yield Criterion ◽  
Forming Limit Diagram ◽  
Anomalous Behavior ◽  
Forming Limit ◽  
Forming Limits ◽  
Material Parameters ◽  
Localized Necking ◽  
Wide Range ◽  
The Hill

Forming limits of thin sheets are investigated using a yield criterion recently proposed by Hill (1993). This criterion utilizes five independent material parameters, which can be determined from uniaxial and balanced biaxial experiments, to describe a wide range of material properties of sheet metals, including the anomalous behavior of aluminum. In the present work, a bifurcation analysis is pursued to predict the onset of localized necking in strain rate insensitive sheet materials. A detailed parametric study is then conducted to evaluate the effect of various material parameters on the positive minor strain side of the forming limit diagram. It is observed that limit strains are strongly dependent on the shape of the yield locus. Forming limits predicted using Hill’s 1993 yield criterion are compared with those predicted using Hill’s 1948 and 1979 criteria. Results from the bifurcation analysis are also compared with experimental observations, as well as the limit strain predicitons based on the M-K analysis.

Numerical Simulation Support for a Stress-Based Failure Criterion

2005 ◽  
Author(s):  
Sumit Moondra ◽  
Aaron Sakash ◽  
Brad Kinsey
Keyword(s):  
Numerical Simulation ◽  
Numerical Simulations ◽  
Sheet Metal ◽  
Failure Criterion ◽  
Path Dependence ◽  
Tube Hydroforming ◽  
Forming Limit Diagram ◽  
Dome Height ◽  
Forming Limit ◽  
Sheet Metal Parts

Determining tearing concerns in numerical simulations of sheet metal components is difficult since the traditional failure criterion is strain-based and exhibits strain path dependence. Recently, a stress-based, as opposed to a strain-based, failure criterion has been proposed and demonstrated both analytically for sheet materials (Arrieux, 1987 and Stoughton, 2001) and experimentally for tube hydroforming (Kuwabara et al., 2003). The next steps in this progression to acceptance of a stress-based forming limit diagram is to demonstrate how this failure criterion can be used to predict failure of sheet metal parts in numerical simulations. In this paper, numerical simulation results for dome height testing specimens are presented and compared to experimental data from Graf and Hosford (1993). Reasonable agreement was obtained comparing the failure predicted from numerical simulations and those found experimentally.

The Forming Limits Prediction Model for Tailor Welded Blank with Straight Seam

2010 ◽  
Vol 26-28 ◽  
pp. 493-497
Author(s):  
Hao Bin Tian ◽  
Xiao Hang Liu ◽  
Jian Ping Lin ◽  
Xian Ping Liu
Keyword(s):  
Prediction Model ◽  
Analytical Method ◽  
Deformation Characteristic ◽  
Forming Limit ◽  
Forming Limits ◽  
Tailor Welded Blanks ◽  
Base Materials ◽  
Tailor Welded Blank ◽  
Light Weighting ◽  
Simulation Results

The forming of tailor-welded blank is an important technology to body light weighting. While it is difficult to predict the forming limits of tailor welded blanks with different base materials or thickness. For the expanding experiments, an analytical method to predict forming limit height of tailor-welded blanks is established based on the deformation characteristic and plastic theory, and verified by simulation results. This method is not only provided a path to predict forming limit of tailor welded blanks but also provided references to the design of tailor weld parts.

Effects of Stress Relieving on Limit Dome Height of Titanium Tailor-Welded Blanks at Elevated Temperatures

2006 ◽  
Vol 532-533 ◽  
pp. 977-980 ◽  
Author(s):  
Chi Ping Lai ◽  
Luen Chow Chan ◽  
Chi Loong Chow
Keyword(s):  
Room Temperature ◽  
Elevated Temperatures ◽  
Heating System ◽  
Dome Height ◽  
Control Panel ◽  
Blank Holder ◽  
Limit Dome Height ◽  
Tailor Welded Blanks ◽  
Heat Treated ◽  
Stress Relieving

This paper aims to study the effect of stress relieving on Limit Dome Height (LDH) of Ti-TWBs at elevated temperatures. This is achieved by developing a newly constructed heating system. The elevated temperature of the system can be varied and monitored by a separately control panel. All Ti-TWBs were prepared and used to examine the LDHs under elevated temperatures. Selected specimens were heat-treated at 600°C within an hour before being formed by HILLE machine. Meanwhile, the temperature of tool heating system was also adjusted from room temperature to 550°C. Specified tests were carried out to examine the stress relieving effects of Ti-TWBs on the LDHs with the temperature control panel. In addition, investigations were carried out to ascertain whether the elevated temperatures of the critical tooling components, i.e. the die and the blank holder, could result in any significant effects on LDHs of Ti-TWBs. The findings show that LDHs of Ti-TWBs can be improved by stress relieving. The stress relieving condition can be obtained by nearly isothermal forming of specimens at a range of 550°C to 600°C.

scholarly journals Observation of Different Experimental Parameters Effect using Friction Stir Welding Through Simulation of Tailor Welded Blanks

2019 ◽  
Vol 8 (3) ◽  
pp. 3421-3423
Keyword(s):  
Friction Stir Welding ◽  
Welding Speed ◽  
Base Material ◽  
Maximum Size ◽  
Minimum Size ◽  
Dome Height ◽  
Forming Limit ◽  
Friction Stir ◽  
Tailor Welded Blanks ◽  
Strain Paths

In the present scenario, the industries of automobile are focusing in decrease in the weight of the automotive body by using which we can increase the efficiency of fuel orally. Many researchers are working keeping this as motto, many joining techniques and engineering materials are used to decrease the decrease in weight for increasing the fuel efficiency. By synchronizing this, there is a technique called tailor welded blanks (TWB) is recommended highly by many automobile industries and researchers have been chosen this technology. In the current work, the motto is the behavior of forming in the TWBs using the process of friction stir welding (FSW) in two welding speeds (90 mm/min and 100 mm/min). The simulations of forming were conducted using the test called limiting dome height (LDH). Eight strain paths were considered for the simulation with maximum size of 200×200 mm to minimum size of 25×200 mm. The base metal Forming limit diagrams, the sheets of FSW are plotted and compared. From the results of simulation, it has noted that base material has lesser formability than FSW sheets. At 100 mm/min welding speed, FSW sheet fabricated and has noted increasing the formability than the welding speed of FSW sheet at 90 mm/min.

Intrinsic diagram of sheet metal forming limits for arbitrary strain paths

2008 ◽  
Vol 222 (4) ◽  
pp. 223-229 ◽  
Author(s):  
H. Fatmaoui ◽  
R. Mesrar ◽  
J. Chaoufi
Keyword(s):  
Biaxial Tension ◽  
Effective Strain ◽  
Forming Limit ◽  
Forming Limits ◽  
Stress Criterion ◽  
Localized Necking ◽  
Strain Paths ◽  
Mk Analysis ◽  
Localization Approach ◽  
Intrinsic Character

Localized necking in sheets under biaxial tension is analysed by an Marciniak—Kuczynski localization approach (MK-analysis) along with a new plane-stress criterion. Analysis is developed for a rigid viscoplastic behaviour based on flow-theory of plasticity. The model is introduced in numerical calculations to determine forming limits to ductility under linear and non-linear strain paths. However, the results are presented in a new diagram that represent the effective strain as a function of the current strain-rate ratio. A comparison with classical forming limit diagrams shows the intrinsic character of the new diagram.

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