Predicting Forming Limit Curve Using a New Ductile Failure Criterion

2017 ◽  
Author(s):  
ZiQiang Sheng ◽  
Pankaj Mallick
Keyword(s):  
Failure Criterion ◽  
Ductile Failure ◽  
Forming Limit ◽  
Limit Curve ◽  
Forming Limit Curve ◽  
Ductile Failure Criterion

Predicting Sheet Forming Limit of Aluminum Alloys for Cold and Warm Forming by Developing a Ductile Failure Criterion

2017 ◽  
Vol 139 (11) ◽  
Author(s):  
Z. Q. Sheng ◽  
P. K. Mallick
Keyword(s):  
Failure Criterion ◽  
Sheet Thickness ◽  
Ductile Failure ◽  
Alloy Sheet ◽  
Warm Forming ◽  
Forming Limit ◽  
Hollomon Parameter ◽  
Effect Function ◽  
Sheet Materials ◽  
Ductile Failure Criterion

In this study, the forming limit of aluminum alloy sheet materials is predicted by developing a ductile failure criterion (DFC). In the DFC, the damage growth is defined by Mclintock formula, stretching failure is defined at localized necking (LN) or fracture without LN, while the critical damage is defined by a so-called effect function, which reflects the effect of strain path and initial sheet thickness. In the first part of this study, the DFC is used to predict forming limit curves (FLCs) of six different aluminum sheet materials at room temperature. Then, the DFC is further developed for elevated temperature conditions by introducing an improved Zener–Hollomon parameter (Z′), which is proposed to provide enhanced representation of the strain rate and temperature effect on limit strain. In warm forming condition, the improved DFC is used to predict the FLCs of Al5083-O and failure in a rectangular cup warm draw process on Al5182 + Mn. Comparison shows that all the predictions match quite well with the experimental measurements. Thanks to the proposal of effect function, the DFC needs calibration only in uniaxial tension, and thus, provides a promising potential to predict forming limit with reduced effort.

The Effect of Model Parameters on Predicted Stress Based Failure Criterion for Sheet Metal

2008 ◽  
Author(s):  
Matthew J. Derov ◽  
Brad L. Kinsey ◽  
Igor Tsukrov
Keyword(s):  
Sheet Metal ◽  
Failure Criterion ◽  
Strain Path ◽  
Path Dependence ◽  
Prediction Method ◽  
Forming Limit ◽  
Model Parameters ◽  
Analytical Prediction ◽  
Limit Curve ◽  
Forming Limit Curve

Tearing failure in sheet metal forming has traditionally been predicted based on the strain state of the material. However, a concern with this failure prediction method is that the strain based forming limit curve exhibits significant strain path dependence. A stress based failure criterion has been proposed and shown to be less sensitive to the strain path through numerical simulations and by analytically converting strain based data to stress space. However, a means to predict this stress based failure criterion without prior knowledge of the strain based forming limit curve for sheet metal is required. In this paper, an analytical prediction of the stress based forming limit curve is derived and compared to experimental and numerical results. The effects of model parameters are also investigated.

Predicting Sheet Forming Limit of Aluminum Alloys for Cold and Warm Forming by Developing a Ductile Failure Criterion

2017 ◽  
Author(s):  
Z. Q. Sheng ◽  
P. K. Mallick
Keyword(s):  
Failure Criterion ◽  
Sheet Thickness ◽  
Ductile Failure ◽  
Alloy Sheet ◽  
Warm Forming ◽  
Forming Limit ◽  
Hollomon Parameter ◽  
Effect Function ◽  
Sheet Materials ◽  
Ductile Failure Criterion

In this study, the forming limit of aluminum alloy sheet materials are predicted by developing a Ductile Failure Criterion (DFAC). In the DFAC, the damage growth is defined by Mclintock formula, stretching failure is defined at Localized Necking (LN) or Fracture without LN, while the critical damage is defined by a so-called effect function, which reflects the effect of strain path and initial sheet thickness. In the first part of this study, the DFAC is used to predict Forming Limit Curves of six different aluminum sheet materials at room temperature. Then, the DFAC is further developed for elevated temperature condition by introducing an improved Zener-Hollomon parameter (Z′), which is proposed to provide enhanced representation of the strain rate and temperature effect on limit strain. In warm forming condition, the improved DFAC is used to predict the FLCs of Al5083-O and failure in a rectangular cup warm draw process on Al5182+Mn. Comparison shows that all the prediction matches quite well with experimental measurement. Thanks to the proposal of effect function, the DFAC only needs a calibration at uniaxial tension and thus provides a promising potential to predict forming limit with reduced efforts.

A novel failure criterion based upon forming limit curve for thermoplastic composites

2020 ◽  
Vol 202 ◽  
pp. 108320 ◽  
Author(s):  
Zhen Wang ◽  
Wenwu Zhang ◽  
Quantian Luo ◽  
Gang Zheng ◽  
Qing Li ◽  
...  
Keyword(s):  
Failure Criterion ◽  
Thermoplastic Composites ◽  
Forming Limit ◽  
Limit Curve ◽  
Forming Limit Curve

Formability Analysis of AA6061 Sheet in T6 Condition

2015 ◽  
Vol 766-767 ◽  
pp. 416-421
Author(s):  
S. Vijayananth ◽  
V. Jayaseelan ◽  
G. Shivasubbramanian
Keyword(s):  
Experimental Method ◽  
Forming Limit Diagram ◽  
Forming Limit ◽  
Ansys Software ◽  
Limit Curve ◽  
High Corrosion Resistance ◽  
Forming Limit Curve ◽  
Drawing Test ◽  
Deep Drawing Test ◽  
Alloy 6061

Formability of a material is defined as its ability to deform into desired shape without being fracture. There will always be a need for formability tests, a larger number of tests have been used in an effort to measure the formability of sheet materials. Aluminium Alloy 6061 is a magnesium and silicon alloy of aluminium. It is also called as marine material as it has high corrosion resistance to seawater. In this paper Formability test of AA6061 sheet is done by Forming Limit Diagram (FLD) Analysis. FLD or Forming Limit Curve (FLC) for the forming processes of AA6061 sheets is obtained by Experimental method and FEM. Experimental method involves Deep drawing test of the sheet and ANSYS software is used for FEM.

Experimental and Numerical Analysis of Forming Limits in CNC Incremental Sheet Forming

2007 ◽  
Vol 344 ◽  
pp. 511-518 ◽  
Author(s):  
Markus Bambach ◽  
M. Todorova ◽  
Gerhard Hirt
Keyword(s):  
Sheet Metal ◽  
Sheet Forming ◽  
Incremental Sheet Forming ◽  
Negative Slope ◽  
Evaluation Procedure ◽  
Forming Limit ◽  
Limit Curve ◽  
Forming Limit Curve ◽  
Forming Limits ◽  
Straight Line

Asymmetric incremental sheet forming (AISF) is a relatively new manufacturing process for the production of low volumes of sheet metal parts. Forming is accomplished by the CNC controlled movements of a simple ball-headed tool that follows a 3D trajectory to gradually shape the sheet metal blank. Due to the local plastic deformation under the tool, there is almost no draw-in from the flange region to avoid thinning in the forming zone. As a consequence, sheet thinning limits the amount of bearable deformation, and thus the range of possible applications. Much attention has been given to the maximum strains that can be attained in AISF. Several authors have found that the forming limits are considerably higher than those obtained using a Nakazima test and that the forming limit curve is approximately a straight line (mostly having a slope of -1) in the stretching region of the FLD. Based on these findings they conclude that the “conventional” forming limit curves cannot be used for AISF and propose dedicated tests to record forming limit diagrams for AISF. Up to now, there is no standardised test and no evaluation procedure for the determination of FLCs for AISF. In the present paper, we start with an analysis of the range of strain states and strain paths that are covered by the various tests that can be found in the literature. This is accomplished by means of on-line deformation measurements using a stereovision system. From these measurements, necking and fracture limits are derived. It is found that the fracture limits can be described consistently by a straight line with negative slope. The necking limits seem to be highly dependent on the test shapes and forming parameters. It is concluded that standardisation in both testing conditions and the evaluation procedures is necessary, and that a forming limit curve does not seem to be an appropriate tool to predict the feasibility of a given part design.

Visual method for measuring forming limit curve of pliable composite film

2021 ◽  
Vol 0 (0) ◽  
pp. 1-12
Author(s):  
CHEN Ren-hong ◽  
◽  
◽  
LIANG Jin ◽  
YE Mei-tu ◽  
...  
Keyword(s):  
Composite Film ◽  
Forming Limit ◽  
Limit Curve ◽  
Forming Limit Curve ◽  
Visual Method

Experimental Investigation on Forming Limit Curve at Elevated Temperature Through Dome and Biaxial Test

2020 ◽  
Author(s):  
Chetan P. Nikhare ◽  
Evan Teculver ◽  
Faisal Aqlan
Keyword(s):  
Air Pollution ◽  
Fuel Consumption ◽  
Axial Stress ◽  
High Strength ◽  
Tension Test ◽  
Forming Limit ◽  
Biaxial Test ◽  
Limit Curve ◽  
Forming Limit Curve ◽  
Stress States

Abstract The characteristics of metal and materials are very important to design any component so that it should not fail in the life of the service. The properties of the materials are also an important consideration while setting the manufacturing parameters which deforms the raw material to give the design shape without providing any defect or fracture. For centuries the commonly used method to characterize the material is the traditional uniaxial tension test. The standard has been created for this test by American Standard for Testing Materials (ASTM) – E8. This specimen is traditionally been used to test the materials and extract the properties needed for designing and manufacturing. It should be noted that the uniaxial tension test uses one axis to test the material i.e., the material is pulled in one direction to extract the properties. The data acquired from this test found enough for manufacturing operations of simple forming where one axis stretching is dominant. Recently a sudden increase in the usage of automotive vehicles results in sudden increases in fuel consumption which results in an increase in air pollution. To cope up with this challenge federal government is implying the stricter environmental regulation to decrease air pollution. To save from the environmental regulation penalty vehicle industry is researching innovation which would reduce vehicle weight and decrease fuel consumption. Thus, the innovation related to light-weighting is not only an option anymore but became a mandatory necessity to decrease fuel consumption. To achieve this target, the industry has been looking at fabricating components from high strength to ultra-high strength steels or lightweight materials. This need is driven by the requirement of 54 miles per gallon by 2025. In addition, the complexity in design increased where multiple individual parts are eliminated. This integrated complex part needs the complex manufacturing forming operation as well as the process like warm or hot forming for maximum formability. The complex forming process will induce the multi-axial stress states in the part, which is found difficult to predict using conventional tools like tension test material characterization. In many pieces of literature limiting dome height and bulge tests were suggested analyzing these multi-axial stress states. However, these tests limit the possibilities of applying multi-axial loading and resulting stress patterns due to contact surfaces. Thus, a test machine called biaxial test is devised which would provide the capability to test the specimen in multi-axial stress states with varying load. In this paper, two processes, limiting dome test and biaxial test were experimented to plot the forming limit curve. The forming limit curve serves the tool for the design of die for manufacturing operation. For experiments, the cruciform test specimens were used in both limiting dome test and biaxial test and tested at elevated temperatures. The forming limit curve from both tests was plotted and compared. In addition, the strain path, forming, and formability was investigated and the difference between the tests was provided.

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