APPLICATION OF FORMING LIMIT CRITERIA BASED ON PLASTIC INSTABILITY CONDITION TO METAL FORMING PROCESS

2008 ◽  
Vol 22 (31n32) ◽  
pp. 5680-5685
Author(s):  
SEONG-CHAN HEO ◽  
TAE-WAN KU ◽  
JEONG KIM ◽  
BEOM-SOO KANG ◽  
WOO-JIN SONG
Keyword(s):  
Sheet Metal ◽  
Sheet Metal Forming ◽  
Metal Forming ◽  
Thin Sheet ◽  
Plastic Instability ◽  
Theoretical Background ◽  
Forming Limit ◽  
Preliminary Evaluation ◽  
Forming Process ◽  
Element Analysis

Metal forming processes such as hydroforming and sheet metal forming using tubular material and thin sheet metal have been widely used in lots of industrial fields for manufacturing of various parts that could be equipped with mechanical products. However, it is not easy to design sequential processes properly because there are various design variables that affect formability of the parts. Therefore preliminary evaluation of formability for the given process should be carried out to minimize time consumption and development cost. With the advances in finite element analysis technique over the decades, the formability evaluation using numerical simulation has been conducted in view of strain distribution and final shape. In this paper, the application of forming limit criteria is carried out for the tube hydroforming and sheet metal forming processes using theoretical background based on plastic instability conditions. Consequently, it is confirmed that the local necking and diffuse necking criteria of sheet are suitable for formability evaluation of both hydroforming and sheet metal forming processes.

scholarly journals Experimental And Theoretical Determination Of Forming Limit Curve

2015 ◽  
Vol 60 (3) ◽  
pp. 1881-1886
Author(s):  
J. Adamus ◽  
K. Dyja ◽  
M. Motyka
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Sheet Metal ◽  
Sheet Metal Forming ◽  
Metal Forming ◽  
Fracture Initiation ◽  
Forming Limit ◽  
Forming Process ◽  
Element Analysis ◽  
Metal Forming Process

Abstract The paper presents a method for determining forming limit curves based on a combination of experiments with finite element analysis. In the experiment a set of 6 samples with different geometries underwent plastic deformation in stretch forming till the appearance of fracture. The heights of the stamped parts at fracture moment were measured. The sheet - metal forming process for each sample was numerically simulated using Finite Element Analysis (FEA). The values of the calculated plastic strains at the moment when the simulated cup reaches the height of the real cup at fracture initiation were marked on the FLC. FLCs for stainless steel sheets: ASM 5504, 5596 and 5599 have been determined. The resultant FLCs are then used in the numerical simulations of sheet - metal forming. A comparison between the strains in the numerically simulated drawn - parts and limit strains gives the information if the sheet - metal forming process was designed properly.

Experimental Study on Residual Formability of Single Point Incrementally Formed Part

2019 ◽  
Author(s):  
Chetan P. Nikhare
Keyword(s):  
Sheet Metal ◽  
Sheet Metal Forming ◽  
Metal Forming ◽  
Incremental Forming ◽  
Thickness Distribution ◽  
Single Point ◽  
Forming Limit ◽  
Single Point Incremental Forming ◽  
Forming Process ◽  
Conventional Process

Abstract A substantial increase in demand on the sheet metal part usage in aerospace and automotive industries is due to the increase in the sale of these products to ease the transportation. However, due to the increase in fuel prices and further environmental regulation had left no choice but to manufacture more fuel efficient and inexpensive vehicles. These heavy demands force researchers to think outside the box. Many innovative research projects came to replace the conventional sheet metal forming of which single point incremental forming is one of them. SPIF is the emerging die-less sheet metal forming process in which the single point tool incrementally forces any single point of sheet metal at any processing time to undergo plastic deformation. It has several advantages over the conventional process like high process flexibility, elimination of die, complex shape and better formability. Previous literature provides enormous research on formability of metal during this process, process with various metals and hybrid metals, the influence of various process parameter, but residual formability after this process is untouched. Thus, the aim of this paper is to investigate the residual formability of the formed parts using single point incremental forming and then restrike with a conventional tool. The common process parameters of single point incremental forming were varied, and residual formability was studied through the conventional process. The strain and thickness distribution were measured and analyzed. In addition, the forming limit of the part was plotted and compared.

On Applying Kriging Approximate Optimization to Sheet Metal Forming

2011 ◽  
Vol 63-64 ◽  
pp. 3-7
Author(s):  
Yan Min Xie
Keyword(s):  
Sheet Metal ◽  
Process Parameters ◽  
Sheet Metal Forming ◽  
Metal Forming ◽  
Nonlinear Function ◽  
Kriging Model ◽  
Engineering Problem ◽  
Forming Process ◽  
Element Analysis ◽  
Metal Forming Process

This paper presents a methodology to effectively determine the optimal process parameters using finite element analysis (FEA) and design of experiments (DOE) based on Metamodels. The idea is to establish an approximation function relationship between quality objectives and process parameters to alleviate the expensive computational expense in the optimization iterations for the sheet metal forming process. This paper investigated the Kriging metamodel approach. In order to prove accuracy and efficiency of Kriging method, the nonlinear function as test functions is implemented. At the same time, the practical nonlinear engineering problems such as square drawing are also optimized successfully by proposed method. The results prove Kriging model is an effective method for nonlinear engineering problem in practice.

New Method for Blank Expansion of Rectangular Box

2011 ◽  
Vol 308-310 ◽  
pp. 1004-1007
Author(s):  
Liu Ru Zhou ◽  
Hai Ming Wan
Keyword(s):  
Sheet Metal ◽  
Sheet Metal Forming ◽  
Metal Forming ◽  
Tool Path ◽  
Incremental Forming ◽  
Apex Angle ◽  
Forming Limit ◽  
Forming Process ◽  
Incremental Sheet Metal Forming ◽  
Planning Experiment

The principle of NC incremental sheet metal forming as well as the process planning, experiment of the square conical box forming are presented. Because the deformation of sheet metal only occurs around the tool head and the deformed region is subjected to stretch deformation and thins, and surface area increases. Sheet metal forming stepwise is to lead to the whole sheet metal deformation. The sine law indicates that the thickness of the square conical box wall is close to zero when the half-apex angle of the square conical box wall is close to zero. Therefore, we must know the forming limit half-apex angle to ensure that the forming can be carried out successfully, i.e., to ensure that the deformed region with a certain thickness will not fracture. It will succeed in square conical box incremental forming in a single tool-path if the forming is carried out with an angle which is larger than the forming limit half-apex angle. The fracture in the forming component can be avoided by these methods. A square conical box of uniform wall-thickness can be formed by NC incremental forming process. The thickness of deformation area is increased by increasing half-apex angle. The wrinkle in the forming component can be avoided by these methods.

Development and Application of the Finite Element Analysis Program of the Stress-Based Forming Limit Criterion for Sheet Metal Forming

2007 ◽  
Vol 561-565 ◽  
pp. 1995-1998
Author(s):  
Ming He Chen ◽  
J.H. Li ◽  
Lin Gao ◽  
Dun Wen Zuo ◽  
Min Wang
Keyword(s):  
Numerical Simulation ◽  
Finite Element Analysis ◽  
Finite Element ◽  
Sheet Metal ◽  
Sheet Metal Forming ◽  
Metal Forming ◽  
Forming Limit ◽  
Analysis Program ◽  
Element Analysis ◽  
The Finite Element Analysis

In order to solve the problem existed in the numerical simulation of sheet metal forming for its use the strain-based forming limit diagram as criterion, which has the flaw of dependence on the strain paths, this paper develops the finite element analysis program based on the stress forming limit criterion applicable to the blank plastic forming technique, which follows the stress-strain transformation relationship when the sheet metal is undergoing plastic deformation, chooses Hill’s quadratic normal anisotropic criterion as computational model and selects the commercial finite element code Dynaform as its development environment. Also it be analyzed the finite element numerical simulation results of two deep drawing parts by the developed program module and realizes the prediction of sheet metal forming limit adopting the FLSD as criterion. The stress-based forming limit criterion for the developed program provides a new means to analyze the forming limit for the multistage sheet metal forming.

Influence of the Adaptive Remeshing during Simulations of Sheet Metal Forming Processes

2011 ◽  
Vol 473 ◽  
pp. 691-698
Author(s):  
Laurence Giraud-Moreau ◽  
Abel Cherouat ◽  
Houman Borouchaki
Keyword(s):  
Sheet Metal ◽  
Sheet Metal Forming ◽  
Metal Forming ◽  
Forming Process ◽  
Mesh Distortion ◽  
Element Analysis ◽  
Physical Size ◽  
Adaptive Remeshing ◽  
The Finite Element Analysis ◽  
Metal Forming Process

In this work, an adaptive remeshing scheme is presented in order to simulate with accuracy sheet metal forming processes. During simulations of metal forming processes, large plastic deformations with ductile damage occur and severe mesh distortion takes place after a few incremental steps. Hence frequent remeshing of the part must be performed in order to carry out the finite element analysis. The necessary steps to remesh the damaged structure during the simulation of the sheet metal forming process are given. The adaptive remeshing based on refinement and coarsening techniques, is controlled by geometrical and physical size maps. This remeshing strategy has been coupled with a projection method in order to avoid problems of contact between the part and the rigid tools. The influence of the remeshing is studied on numerical examples which show the capacity of the proposed procedure.

Numerical Prediction of Forming Limit in Hemispherical Punch Bulging by Lemaitre's Ductile Damage Model

2011 ◽  
Vol 110-116 ◽  
pp. 1437-1441 ◽  
Author(s):  
Farhad Haji Aboutalebi ◽  
Mehdi Nasresfahani
Keyword(s):  
Sheet Metal ◽  
Sheet Metal Forming ◽  
Metal Forming ◽  
Damage Mechanics ◽  
Thin Sheet ◽  
Damage Model ◽  
Ductile Damage ◽  
Forming Limit ◽  
St14 Steel ◽  
Hemispherical Punch

Prediction of sheet metal forming limits or analysis of forming failures is a very sensitive problem for design engineers of sheet forming industries. In this paper, first, damage behaviour of St14 steel (DIN 1623) is studied in order to be used in complex forming conditions with the goal of reducing the number of costly trials. Mechanical properties and Lemaitre's ductile damage parameters of the material are determined by using standard tensile and Vickers micro-hardness tests. A fully coupled elastic-plastic-damage model is developed and implemented into an explicit code. Using this model, damage propagation and crack initiation, and ductile fracture behaviour of hemispherical punch bulging process are predicted. The model can quickly predict both deformation and damage behaviour of the part because of using plane stress algorithm, which is valid for thin sheet metals. Experiments are also carried out to validate the results. Comparison of the numerical and experimental results shows good adaptation. Hence, it is concluded that finite element analysis in conjunction with continuum damage mechanics can be used as a reliable tool to predict ductile damage and forming limit in sheet metal forming processes.

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