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.

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.

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.

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.

A Graphical Method to Estimate Forming Limit Curve of Sheet Metals

2019 ◽  
Vol 794 ◽  
pp. 55-62 ◽  
Author(s):  
Quoc Tuan Pham ◽  
Duc Toan Nguyen ◽  
Jin Jae Kim ◽  
Young Suk Kim
Keyword(s):  
Sheet Metal ◽  
Sheet Metal Forming ◽  
Metal Forming ◽  
Graphical Method ◽  
Forming Limit ◽  
Sheet Metals ◽  
Limit Curve ◽  
Forming Limit Curve ◽  
Force Criterion ◽  
Necking Criterion

Since its foundation, the concept of forming limit diagram has been widely accepted in sheet metal forming community as a powerful tool for studying formability. There are pyramid models that were developed to estimate the forming limit curve theoretically, for example, Swift's diffuse necking criterion, Hill's localized necking criterion, Marciniak and Kuczynski model, Modified Maximum Force Criterion, etc.. Implement of these models, however, is a laborious task. To simply the task, this study presents a graphical method to estimate forming limit curve of sheet metal. Some new insights into the Modified Maximum Force Criterion, the Hora method, are discussed. The insights pertain to the use of a graphic tool to estimate limit strains at three critical forming modes in sheet metal forming that are the uniaxial tension, plane strain, and equi-biaxial tension. Connecting three points by linear lines yields to a simple graph of forming limit curve. Method validation is supported by comparing the estimated forming limit curve with experimentally measured data for several automotive sheet metals.

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

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.

Surrogate POD Models for Parametrized Sheet Metal Forming Applications

2013 ◽  
Vol 554-557 ◽  
pp. 919-927 ◽  
Author(s):  
Hamdaoui Mohamed ◽  
Guénhaël Le Quilliec ◽  
Piotr Breitkopf ◽  
Pierre Villon
Keyword(s):  
Finite Element ◽  
Sheet Metal ◽  
Sheet Metal Forming ◽  
Metal Forming ◽  
Optimization Problems ◽  
Strain Tensor ◽  
Forming Limit ◽  
Work Piece ◽  
Displacement Fields ◽  
Lagrange Strain

The aim of this work is to present a POD (Proper Orthogonal Decomposition) based surrogate approach for sheet metal forming parametrized applications. The final displacement field for the stamped work-piece computed using a finite element approach is approximated using the method of snapshots for POD mode determination and kriging for POD coefficients interpolation. An error analysis, performed using a validation set, shows that the accuracy of the surrogate POD model is excellent for the representation of finite element displacement fields. A possible use of the surrogate to assess the quality of the stamped sheet is considered. The Green-Lagrange strain tensor is derived and forming limit diagrams are computed on the fly for any point of the design space. Furthermore, the minimization of a cost function based on the surrogate POD model is performed showing its potential for solving optimization problems.

Stress-Based Forming Limits in Sheet-Metal Forming

2000 ◽  
Vol 123 (4) ◽  
pp. 417-422 ◽  
Author(s):  
Thomas B. Stoughton
Keyword(s):  
Sheet Metal ◽  
Sheet Metal Forming ◽  
Metal Forming ◽  
Strain Path ◽  
Forming Limit ◽  
Stress Strain ◽  
Strain Relation ◽  
Stress Strain Relation ◽  
The Stability ◽  
Definition Of

A strain-based forming limit criterion is widely used throughout the sheet-metal forming industry to gauge the stability of the deformed material with respect to the development of a localized neck prior to fracture. This criterion is strictly valid only when the strain path is linear throughout the deformation process. There is significant data that shows a strong and complex dependence of the limit criterion on the strain path. Unfortunately, the strain path is never linear in secondary forming and hydro-forming processes. Furthermore, the path is often found to be nonlinear in localized critical areas in the first draw die. Therefore, the conventional practice of using a path-independent strain-based forming limit criterion often leads to erroneous assessments of forming severity. Recently it has been reported that a stress-based forming limit criterion appears to exhibit no strain-path dependencies. Subsequently, it has been suggested that this effect is not real, but is due to the saturation of the stress-strain relation. This paper will review and compare the strain-based and stress-based forming limit criteria, looking at a number of factors that are involved in the definition of the stress-based forming limit, including the role of the stress-strain relation.

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