Analysis of Tube Hydroforming by Means of an Inverse Approach1

2003 ◽  
Vol 125 (2) ◽  
pp. 369-377 ◽  
Author(s):  
Ba Nghiep Nguyen ◽  
Kenneth I. Johnson ◽  
Mohammad A. Khaleel
Keyword(s):  
Tube Hydroforming ◽  
Forming Limit Diagram ◽  
Computational Time ◽  
Forming Limit ◽  
Hydraulic Pressure ◽  
Computational Tool ◽  
Incremental Method ◽  
Inverse Approach ◽  
Initial Geometry ◽  
Good Agreement

This paper presents a computational tool for the analysis of freely hydroformed tubes by means of an inverse approach. The formulation of the inverse method developed by Guo et al. [1] is adopted and extended to the tube hydroforming problems in which the initial geometry is a round tube submitted to hydraulic pressure and axial feed at the tube ends (end-feed). A simple criterion based on a forming limit diagram is used to predict the necking regions in the deformed workpiece. Although the developed computational tool is a stand-alone code, it has been linked to the Marc finite element code for meshing and visualization of results. The application of the inverse approach to tube hydroforming is illustrated through the analyses of the aluminum alloy AA6061-T4 seamless tubes under free hydroforming conditions. The results obtained are in good agreement with those issued from a direct incremental approach. However, the computational time in the inverse procedure is much less than that in the incremental method.

Optimization of Tube Hydroforming Process Using Probabilistic Constraints on Failure Modes

2011 ◽  
Vol 62 ◽  
pp. 21-35 ◽  
Author(s):  
Anis Ben Abdessalem ◽  
A. El Hami
Keyword(s):  
Failure Modes ◽  
High Reliability ◽  
Thickness Distribution ◽  
Tube Hydroforming ◽  
Forming Limit Diagram ◽  
Plastic Instability ◽  
Probabilistic Constraints ◽  
Forming Limit ◽  
Reliability Based Design ◽  
Hydroforming Process

In metal forming processes, different parameters (Material constants, geometric dimensions, loads …) exhibits unavoidable scatter that lead the process unreliable and unstable. In this paper, we interest particularly in tube hydroforming process (THP). This process consists to apply an inner pressure combined to an axial displacement to manufacture the part. During the manufacturing phase, inappropriate choice of the loading paths can lead to failure. Deterministic approaches are unable to optimize the process with taking into account to the uncertainty. In this work, we introduce the Reliability-Based Design Optimization (RBDO) to optimize the process under probabilistic considerations to ensure a high reliability level and stability during the manufacturing phase and avoid the occurrence of such plastic instability. Taking account of the uncertainty offer to the process a high stability associated with a low probability of failure. The definition of the objective function and the probabilistic constraints takes advantages from the Forming Limit Diagram (FLD) and the Forming Limit Stress Diagram (FLSD) used as a failure criterion to detect the occurrence of wrinkling, severe thinning, and necking. A THP is then introduced as an example to illustrate the proposed approach. The results show the robustness and efficiency of RBDO to improve thickness distribution and minimize the risk of potential failure modes.

Integrated Hydraulic Bulge and Forming Limit Testing Method and Apparatus for Sheet Metals

2014 ◽  
Vol 626 ◽  
pp. 171-177 ◽  
Author(s):  
Yan Yo Chen ◽  
Yu Chung Tsai ◽  
Ching Hua Huang
Keyword(s):  
Forming Limit Diagram ◽  
Close Correlation ◽  
Biaxial Stress ◽  
Forming Limit ◽  
Hydraulic Pressure ◽  
Sheet Metals ◽  
Stress Strain ◽  
Testing Method ◽  
Hydraulic Bulge ◽  
Strain Relationship

This paper proposes an integrated hydraulic bulge and forming limit testing method and apparatus for sheet metals. By placing a PU (Polyurethane) plate between molds and uniformly applying hydraulic pressure to sheet metals, a biaxial stress-strain relationship and forming limit diagram (FLD) displaying both left and right sides were acquired using the same apparatus. An uniaxial tension test and traditional drawing test were conducted to compare the results obtained from the proposed hydraulic bulge and forming limit testing methods, respectively. A close correlation between the results of the stress-strain relationship and FLD in both comparisons verified the feasibility and capability of this integrated hydraulic testing method and apparatus for use with sheet metals.

Reliability Analysis of the Tube Hydroforming Process Based on Forming Limit Diagram

2005 ◽  
Vol 128 (3) ◽  
pp. 402-407 ◽  
Author(s):  
Bing Li ◽  
Don R. Metzger ◽  
Tim J. Nye
Keyword(s):  
Automotive Industry ◽  
Metal Forming ◽  
Tube Hydroforming ◽  
Forming Limit Diagram ◽  
Probability Of Failure ◽  
Alternative Methods ◽  
Forming Limit ◽  
Forming Process ◽  
Hydroforming Process ◽  
Free Bulging

Tube hydroforming is an attractive manufacturing process in the automotive industry because it has several advantages over alternative methods. In order to determine the reliability of the process, a new method to assess the probability of failure is proposed in this paper. The method is based on the reliability theory and the forming limit diagram, which has been extensively used in metal forming as the criteria of formability. From the forming limit band in the forming limit diagram, the reliability of the forming process can be evaluated. A tube hydroforming process of free bulging is then introduced as an example to illustrate the approach. The results show this technique to be an innovative approach to avoid failure during tube hydroforming.

Describing tube formability during pulsating hydroforming using forming limit diagrams

2017 ◽  
Vol 52 (4) ◽  
pp. 249-257 ◽  
Author(s):  
Lianfa Yang ◽  
Daofu Tang ◽  
Yulin He
Keyword(s):  
Deformation Behaviour ◽  
Forming Limit Diagram ◽  
Forming Limit ◽  
Hydraulic Pressure ◽  
Minor Strain ◽  
Steel Tubes ◽  
Periodic Oscillations ◽  
Forming Limit Diagrams ◽  
Uniform Wall ◽  
Forming Limit Curves

Pulsating hydroforming is a novel forming technique that applies pulsating hydraulic pressure to deform tubular materials. Larger expansions and more uniform wall thicknesses in tubes have reportedly been achieved using this technique. However, periodic oscillations of hydraulic pressure acting on the tubes during pulsating hydroforming make the tube deformation behaviour and formability unpredictable. Forming limit diagrams, which consist of two forming limit curves in a major–minor strain coordinate system, are widely used to indicate the formability of sheet materials in plastic deformation. The comparable use of forming limit diagrams to indicate the formability of tubular materials under the pulsating action of hydroforming has not been previously established. In this study, pulsating and non-pulsating hydro-bulging experiments were performed on SS304 stainless steel tubes. Under distinct tension–compression and tension–tension strain states with and without active axial feeding, the forming limit curves for the deformed tubes were constructed based on the experimental data. The effects of various hydraulic pressure pulsating parameters, including pulsating amplitude and frequency, on the forming limit curves were analysed and compared. The experimental results showed that each of the forming limit curves under pulsating hydro-bulging was higher than the forming limit curves under non-pulsating hydro-bulging, thereby confirming the influence of the pulsating parameters. In general, the height of the forming limit curves increased as the pulsating amplitude and frequency increased, largely independent of the tension–compression and tension–tension states. Overall, the results showed that the proposed method for determining the forming limit curves (and the subsequent forming limit diagram) for tubes during pulsating hydro-bulging is feasible.

Constitutive Modelling of Anisotropy, Hardening and Failure of Sheet Metals

2011 ◽  
Vol 473 ◽  
pp. 631-636 ◽  
Author(s):  
Ivaylo N. Vladimirov ◽  
Yalin Kiliclar ◽  
Vivian Tini ◽  
Stefanie Reese
Keyword(s):  
Kinematic Hardening ◽  
Plastic Anisotropy ◽  
Forming Limit Diagram ◽  
Material Model ◽  
Constitutive Modelling ◽  
Forming Limit ◽  
Isotropic Hardening ◽  
Continuum Damage ◽  
Aluminium Sheets ◽  
Good Agreement

The paper discusses the application of a newly developed coupled material model of finite anisotropic multiplicative plasticity and continuum damage to the numerical prediction of the forming limit diagram at fracture (FLDF). The model incorporates Hill-type plastic anisotropy, nonlinear Armstrong-Frederick kinematic hardening and nonlinear isotropic hardening. The numerical examples investigate the simulation of forming limit diagrams at fracture by means of the so-called Nakajima stretching test. Comparisons with test data for aluminium sheets display a good agreement between the finite element results and the experimental data.

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.

An Analysis of Forming Limit in Micro Deep Drawing of the Square Cup for Anisotropic Foil

2011 ◽  
Vol 105-107 ◽  
pp. 344-347
Author(s):  
Fung Huei Yeh ◽  
Ching Lun Li ◽  
Kun Nan Tsay
Keyword(s):  
Deep Drawing ◽  
Thickness Distribution ◽  
Forming Limit Diagram ◽  
Experimental Results ◽  
Forming Limit ◽  
Drawing Ratio ◽  
Micro Deep Drawing ◽  
Alloy Foil ◽  
Explicit Dynamic ◽  
Good Agreement

This paper presents an explicit dynamic finite element method (FEM) in conjunction with the forming limit diagram (FLD) to analyze the forming limit for the SPCC foil in micro deep drawing of square cup. In the present study, the tensile, anisotropic and friction test are performed to obtain the material parameters of the alloy foil according to the ASTM standards. Importing these properties, the numerical analysis is conducted by the explicit dynamic FEM. The FLD in numerical simulation is used as the criterion of the forming limit in micro deep drawing of the square cup. The forming limit, punch load-stroke relationship, deformed shape and thickness distribution of square cup, are discussed and compared with the experimental results. It shows that a good agreement is achieved from comparison between simulated and experimental results. The limit drawing ratio in micro deep drawing of square cup is 2.08 in this paper. From this investigation, the results of this paper can be used as reference in the relative researches and applications of micro forming.

The development of a novel forming limit diagram under nonlinear loading paths in tube hydroforming

2020 ◽  
Vol 172 ◽  
pp. 105392 ◽  
Author(s):  
Haihui Zhu ◽  
Zhubin He ◽  
Yanli Lin ◽  
Kailun Zheng ◽  
Xiaobo Fan ◽  
...  
Keyword(s):  
Tube Hydroforming ◽  
Forming Limit Diagram ◽  
Forming Limit ◽  
Loading Paths
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