An Intelligent Tool to Predict Fracture in Sheet Metal Forming Operations

2007 ◽  
Vol 344 ◽  
pp. 841-846
Author(s):  
Rosanna Di Lorenzo ◽  
Giuseppe Ingarao ◽  
Fabrizio Micari
Keyword(s):  
Sheet Metal ◽  
Sheet Metal Forming ◽  
Metal Forming ◽  
Production Quality ◽  
Forming Limit ◽  
Fracture Criteria ◽  
Predictive Tool ◽  
Forming Limit Diagrams ◽  
Early Results

One of the main issues in sheet metal forming operations design is the determination of formability limits in order to prevent necking and fracture. In fact, the ability to predict fracture represents a powerful tool to improve the production quality in mechanical industry. Many researchers investigated the problem here addressed, mainly studying forming limit diagrams (FLD) or developing fracture criteria which are able to foresee fracture defects for different processes. In this paper, the author present some early results of a research project focused on the application of artificial intelligence (AI) for ductile fracture prediction in sheet metal forming operations. The main advantage of the application of AI tools and in particular, of artificial neural networks (ANN), is the possibility to obtain a predictive tool with a wide applicability. The prediction results obtained in this paper fully demonstrate the usefulness of the proposed approach.

Preliminary Studies on the Determination of FLD for Single Point Incremental Sheet Metal Forming

2012 ◽  
Vol 504-506 ◽  
pp. 863-868 ◽  
Author(s):  
Miklos Tisza ◽  
Péter Zoltán Kovács ◽  
Zsolt Lukács
Keyword(s):  
Sheet Metal ◽  
Sheet Metal Forming ◽  
Metal Forming ◽  
New Technologies ◽  
Single Point ◽  
Research Work ◽  
Dimensional Accuracy ◽  
Forming Limit ◽  
Incremental Sheet Metal Forming

Development of new technologies and processes for small batch and prototype production of sheet metal components has a very important role in the recent years. The reason is the quick and efficient response to the market demands. For this reasons new manufacturing concepts have to be developed in order to enable a fast and reliable production of complex components and parts without investing in special forming machines. The need for flexible forming processes has been accelerated during the last 15 years, and by these developments the technology reaches new extensions. Incremental sheet metal forming (ISMF) may be regarded as one of the promising developments for these purposes. A comprehensive research work is in progress at the University of Miskolc (Hungary) to study the effect of important process parameters with particular emphasis on the shape and dimensional accuracy of the products and particularly on the formability limitations of the process. In this paper, some results concerning the determination of forming limit diagrams for single point incremental sheet metal forming will be described.

Formability of High Strength Sheet Metals with Special Regard to the Effect of the Influential Factors on the Forming Limit Diagrams

2015 ◽  
Vol 812 ◽  
pp. 271-275 ◽  
Author(s):  
Miklós Tisza ◽  
Péter Zoltán Kovács ◽  
Zsolt Lukács ◽  
Antal Kiss ◽  
Gaszton Gál
Keyword(s):  
Sheet Metal ◽  
Sheet Metal Forming ◽  
Metal Forming ◽  
High Strength Steels ◽  
High Strength ◽  
Forming Limit ◽  
Experimental Investigations ◽  
Sheet Metals ◽  
Forming Limit Diagrams ◽  
Research Activities

Car manufacturing is one of the main target fields of sheet metal forming: thus sheet metal forming is exposed to the same challenges as the automotive industry. The continuously increasing demand on lower consumption and lower CO2 emission means the highest challenges on materials developments besides design and construction. As a general requirement, the weight reduction and light weight construction principles should be mentioned together with the increased safety prescriptions which require the application of high strength steels. However, the application of high strength steels often leads to formability problems. Forming Limit Diagrams (FLD) are the most appropriate tools to characterize the formability of sheet metals. Theoretical and experimental investigations of forming limit diagrams are in the forefront of todays’ research activities.

Determination of FLD for Ti-6Al-4V Titanium Alloy Sheet

2016 ◽  
Vol 687 ◽  
pp. 171-178
Author(s):  
Piotr Lacki
Keyword(s):  
Titanium Alloy ◽  
Numerical Simulations ◽  
Real Time ◽  
Sheet Metal ◽  
Sheet Metal Forming ◽  
Metal Forming ◽  
Forming Limit Diagram ◽  
Alloy Sheet ◽  
Forming Limit

Ti-6Al-4V is the most widely applied titanium alloy in technology and medicine due its good mechanical properties combined with low density and good corrosion resistance. However, poor technological and tribological properties make it very difficult to process, including the problems with sheet-metal forming. The best way to evaluate sheet drawability is to use Forming Limit Diagram (FLD), which represents a line at which failure occurs. FLD allows for determination of critical forming areas.The FLDs can be determined both theoretically and experimentally. Recently, special optical strain measurement systems have been used to determine FLDs.In this study, material deformation was measured with the Aramis system that allows for real-time observation of displacements of the stochastic points applied to the surface using a colour spray. The FLD was determined for Ti-6Al-4V titanium alloy sheet with thickness of 0.8 mm. In order to obtain a complete FLD, a set of 6 samples with different geometries underwent plastic deformation in stretch forming i.e. in the Erichsen cupping test until the appearance of fracture.The real-time results obtained from the ARAMIS software for multiple measurement positions from the test specimen surface were compared with numerical simulations of the cupping tests. The numerical simulations were performed using the PamStamp 2G v2012 software dedicated for analysis of sheet-metal forming processes. PamStamp 2G is based on the Finite Element method (FEM). The major and minor strains were analysed. The effect of friction conditions on strain distribution was also taken into consideration

Numerical and Experimental Study of Forming Limit Diagrams in Sheet Metal Forming and Seamed Tube Hydroforming

2013 ◽  
Vol 395-396 ◽  
pp. 914-919 ◽  
Author(s):  
Ren Tao Zhang ◽  
Xian Feng Chen ◽  
Hai Bo Su ◽  
Zhi Yong Chen
Keyword(s):  
Sheet Metal ◽  
Sheet Metal Forming ◽  
Metal Forming ◽  
Experimental Approach ◽  
Tube Hydroforming ◽  
Numerical Approach ◽  
Forming Limit ◽  
Forming Limit Diagrams ◽  
Localized Necking ◽  
Biaxial Stretching

The paper establishes the forming limit diagrams (FLDs) for QSTE340 seamed tube hydroforming and the mother sheet metal forming by numerical approach and experimental approach. A novel experimental approach is proposed to evaluate the formability for tube hydroforming under biaxial stretching through elliptical bulging.Then the Nakazima and three types of tube hydroforming tests are simulated with finite element (FE) program LS-DYNA. The failure criterion of thickness gradient criterion (TGC) is introduced. The FLDs for seamed tube hydroforming and the mother sheet metal forming are constructed. The comparison of results based on TGC with experimental data shows the TGC is an appropriate one to determine the onset of localized necking. Finally, the differences and relationships between the FLDs for the seamed tube hydroforming and the mother sheet metal forming are discussed.

A Complex Measuring and Evaluation System for Determination of Forming Limit Diagrams

2008 ◽  
Vol 589 ◽  
pp. 233-238 ◽  
Author(s):  
Péter Kovács ◽  
Miklós Tisza
Keyword(s):  
Numerical Simulations ◽  
Sheet Metal ◽  
Sheet Metal Forming ◽  
Metal Forming ◽  
Evaluation System ◽  
Measuring System ◽  
Forming Limit ◽  
Forming Limit Curves ◽  
Complex Measuring

Forming limit curves are very important for the prediction of failure during sheet metal forming both in practical forming operations and particularly in numerical simulations. The reliability of numerical simulations in sheet metal forming processes is strongly influenced by the reliability of forming limit curves. Therefore, both the theoretical aspects and the experimental determination of the forming limit curves are challenging problems for scientific researchers and industrial practitioners as well. There are various experimental techniques and mathematical models used to determine the forming limit curves. In spite of the standardization efforts made recently by several institutions world wide, there are still significant differences in determining the forming limit curves. Recently, a new, complex measuring system capable for the automatic determination of FLCs was installed at the Department of Manufacturing Engineering. In this paper, first a short overview will be given on the theoretical background of FLCs, then the application of the complex measuring system will be shown.

Investigation of Influence Parameters on Forming Limit Diagrams of Aluminum Alloy-AA2024

2011 ◽  
Vol 473 ◽  
pp. 382-389 ◽  
Author(s):  
Gokhan Celik ◽  
Bilgin Kaftanoğlu ◽  
Celalettin Karadogan
Keyword(s):  
Aluminum Alloy ◽  
Sheet Metal ◽  
Sheet Metal Forming ◽  
Metal Forming ◽  
Material Characterization ◽  
Forming Limit ◽  
Uniaxial Tensile ◽  
Sheet Metals ◽  
Forming Limit Diagrams ◽  
Punch Speed

Sheet metal forming technology is the keyword for many industries such as aerospace, aeronautics and automobile industries. Customer expectations, quality and safety requirements and market competitions require sheet metal forming operations to be well analyzed before the process to fulfill all these requirements. In this study, combination of FEA (finite element analysis) and mechanical material characterization were used in order to improve sheet metal forming operations while considering cost and quality. On the material characterization side of the studies, simple uniaxial tensile tests were conducted to obtain anisotropy parameters and yield points along different directions and hydraulic bulge test (HBT) was performed to obtain plastic behavior of the material up to 0.7 strains. Deformation measurements were conducted using optical measurement system GOM-ARAMIS while a 60-ton hydraulic press; Zwick/Roell BUP600 was used to deform the sheet part AA2024-0 aluminum alloy. Effects of process parameters, which are initial material thickness, lubrication and punch speed, on sheet metal formability and forming limit diagrams (FLDs) were investigated. On the study of thickness effects, sheet metals those having 0.81mm, 1.27mm and 1.60mm thickness were tested. Punch velocities of 250mm/min, 500mm/min and 750mm/min were used to investigate effect of punch speed on formability of sheet metals. Finally, PTFE (Polytetrafluoroethylene), paraffin lubricated and dry conditions were presented to obtain friction effects. FE analyses were performed to simulate experiments and to obtain friction coefficients of different lubricants. Good correlations were observed between numerical simulations and experimental results.

Surrogate POD models for building forming limit diagrams of parameterized sheet metal forming applications

2013 ◽  
Author(s):  
M. Hamdaoui ◽  
Guénhaël Le Quilliec ◽  
Piotr Breitkopf ◽  
Pierre Villon
Keyword(s):  
Sheet Metal ◽  
Sheet Metal Forming ◽  
Metal Forming ◽  
Forming Limit ◽  
Forming Limit Diagrams

A Predictive Tool for Delaying Wrinkling and Tearing Failures in Sheet Metal Forming

1997 ◽  
Vol 119 (4) ◽  
pp. 354-365 ◽  
Author(s):  
J. Cao ◽  
M. C. Boyce
Keyword(s):  
Sheet Metal ◽  
Sheet Metal Forming ◽  
Metal Forming ◽  
Failure Modes ◽  
Design Tool ◽  
Forming Limit ◽  
Postbuckling Behavior ◽  
Proportional Loading ◽  
Predictive Tool ◽  
Design And Optimization

In the sheet metal forming industry, there is increasing demand to lower manufacturing costs while also providing a decrease in product development turnaround period as well as lighter weight products. These demands have put increasing pressure on the development and use of predictive numerical simulations and in the design and optimization of new forming technologies. In this paper, two of the primary in-process failure modes of sheet metal, wrinkling and tearing, are examined followed by construction of an advanced forming technology—Variable Binder Force—using numerical tools. Specifically, a methodology of capturing the onset of wrinkling and postbuckling behavior proposed in Cao and Boyce (1997) is used to predict wrinkling failure in conical and square cup forming. The results obtained from simulations and experiments demonstrate that the proposed method is not only accurate, but also robust. A tearing criterion based on Forming Limit Diagrams of non-proportional loading paths is then developed and again shows excellent predictability. Finally, a Variable Binder Force (VBF) trajectory for conical cup forming is designed using simulations which incorporate feedback control to the binder based on the predictions of wrinkling and tearing of the sheet. Experiments using this predefined VBF trajectory show a 16 percent increase informing height over the best conventional forming method, that is, constant binder force. The uniqueness of this paper is that numerical simulation is no longer utilized only as a verification tool, but as a design tool for, advanced manufacturing process with the help of the predictive tools incorporated directly into the numerical model.

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