Forming limit diagram of aluminum/copper bi-layered tubes by bulge test

2017 ◽  
Vol 92 (5-8) ◽  
pp. 1539-1549 ◽  
Author(s):  
Mehran Mohammadi ◽  
Javad Shahbazi Karami ◽  
Seyed Jalal Hashemi
Keyword(s):  
Forming Limit Diagram ◽  
Forming Limit ◽  
Bulge Test

Fundamental Investigation for Tensile Test Using Conical Cupping Die

2014 ◽  
Vol 622-623 ◽  
pp. 292-299 ◽  
Author(s):  
Tomoyuki Ota ◽  
Takashi Iizuka
Keyword(s):  
Tensile Test ◽  
Testing Machine ◽  
Forming Limit Diagram ◽  
Forming Limit ◽  
Uniaxial Tensile ◽  
Bulge Test ◽  
Uniaxial Tensile Test ◽  
Biaxial Tensile ◽  
Specimen Shape ◽  
Specimen Edge

A number of researches have conducted in order to evaluate the ductile fracture occurrence by using forming limit diagram. However, specimen shape and testing machine for obtaining forming limit diagram of sheet metal have some problems. The problem about specimen shape is occurring at the specimen edge. In uniaxial tensile test, the specimen edge may cause a defused neck in width direction and may have influence on fracture occurrence. In biaxial tensile test by using a cruciform specimen, a uniform biaxial deformation is not obtained because uniaxial tensile stress occurs at the specimen edge. Tensile test by using a specimen which does not have such edges should carry out, for example, in bulge test and multi-axial tube expansion test, specimens without edge are used. However, these methods need special machines. Therefore, new biaxial tensile testing method is required. By this method, materials deform depending on biaxial strain state by using popular pressing machines.

Effects of Anisotropic Yield Functions on Prediction of Forming Limit Diagram for AHS Steel

2014 ◽  
Vol 622-623 ◽  
pp. 257-264
Author(s):  
Sansot Panich ◽  
Vitoon Uthaisangsuk
Keyword(s):  
Biaxial Tension ◽  
Yield Criterion ◽  
Forming Limit Diagram ◽  
High Strength ◽  
Forming Limit ◽  
Bulge Test ◽  
Yield Criteria ◽  
Hardening Law ◽  
Yield Functions ◽  
Work Hardening Coefficient

In this study, experimental and numerical analyses of Forming Limit Diagram (FLD) for Advanced High Strength (AHS) steel grade 980 were performed. Forming limit curve was first determined by means of the Nakazima stretch-forming test. Then, analytical calculations of the FLD based on the Marciniak-Kuczynski (M-K) model were carried out. Different yield criteria, namely, Hill’48 (r-value and stress-based), Yld89 (r-value and stress-based) and Barlat2000 (Yld2000-2d) were investigated. The strain hardening law according to Swift was applied. To identify parameters of each model, uniaxial tension, balanced bi-axial bulge test and in-plane biaxial tension test were performed. As a result, predicted plastic flow stresses and plastic anisotropies of the AHS steel by various directions were evaluated. In addition, effects of the anisotropic yield functions, strain rate sensitivities, imperfection values and work hardening coefficient on the predicted FLD were studied and discussed. It was found that the FLD based on the Yld2000-2d yield criterion was in better agreement with the experimental curve. Accuracy of the FLD predictions based on the M-K theory, especially in the biaxial state of stress, significantly depended on the applied yield criteria, for which yield stresses and r-values of different loading directions were required.

The Effect of Strain Rate on the Strain to Fracture of a Sheet Steel Under Biaxial Tensile Stress Conditions

1982 ◽  
Vol 104 (2) ◽  
pp. 102-106 ◽  
Author(s):  
P. Broomhead ◽  
R. J. Grieve
Keyword(s):  
Strain Rate ◽  
Sheet Steel ◽  
Low Carbon Steel ◽  
Forming Limit Diagram ◽  
Forming Limit ◽  
Bulge Test ◽  
Low Carbon ◽  
Forming Limit Curve ◽  
Biaxial Tensile Stress ◽  
Preliminary Study

The present investigation was undertaken as a preliminary study into the influence of strain rate on the forming limit diagram for low carbon steel. For a variation in strain rate from 10−3 s−1 to 70 s−1 experiments have shown that, in the positive quadrant of the forming limit diagram, the position of the forming limit curve is lowered with increasing strain rate. Further, it is suggested that a degree of correlation exists between strain rate and the work hardening exponent “n,” and as such the influence of strain rate on the forming limit diagram manifests itself through the change in n value. Slow speed forming was carried out under oil pressure using a bulge test with elliptical dies. To attain higher strain rate a water-hammer forming technique was employed together with the same die sets as those used for bulge forming.

Optimizing Material Parameters for Better Formability of DQ Steel Pipe

2019 ◽  
Author(s):  
Shabbir Memon ◽  
Obaidur Rahman Mohammed ◽  
D. V. Suresh Koppisetty ◽  
Hamid M. Lankarani
Keyword(s):  
Additive Model ◽  
Forming Limit Diagram ◽  
Strain Ratio ◽  
Forming Limit ◽  
Bulge Test ◽  
Optimum Process ◽  
Strain Hardening Exponent ◽  
Hydraulic Pressure ◽  
Plastic Strain Ratio ◽  
Material Parameters

Abstract As Pipelines are subjected to bursting failure, the prediction of the burst capacities of corroded pipelines is of significant relevance to the pipeline industry. The Single mode deformation processes, most commonly used in laboratory evaluations like tensile test, may not realistically predict formability performance. Therefore, limit strains tests that use multiple deformation stages would better simulate actual material performance hence bulge test is widely used in pipeline industry for analyzing formability. The tube bulge test is an advanced testing material in which the tube is placed in a die cavity and is sealed from both the ends, the water is injected from the hole inside the sealing punch and hydraulic pressure is increased and the tube gets deformed at the center. The objective of this work is to utilize Taguchi coupled finite element computational methodology to determine the optimum material parameters to attain better formability without necking-splitting failure. To evaluate the dependence of the slope of the forming limit diagram on the material parameters, the simulation under various combinations of strain-hardening exponent (n), plastic strain ratio (r) and thickness of tube (t) is carried out and using thickness gradient criterion, the occurrence of necking i. e. forming limit strains during tube bulging is examined. By observing the optimum condition obtained for maximum plain strain it is concluded that higher the n, r and t more the limit strains will be. It is also observed that among n, r and t, n is the most prominent factor contributing on limit strains followed by r and t. The verification of optimum process parameters obtained through Taguchi technique is carried out using additive model and it is found that the observed value is well in agreement with the predicted value, the extra validation simulation is carried out to validate the Taguchi results.

scholarly journals Influence of the Laser Heat Treatment on the AA5754-H32 strain path during hydraulic bulge tests

2021 ◽  
Author(s):  
Angela Cusanno ◽  
Shanmukha Moturu ◽  
David Carty ◽  
Gianfranco Palumbo
Keyword(s):  
Strain Path ◽  
Forming Limit Diagram ◽  
Local Heat ◽  
Forming Limit ◽  
Bulge Test ◽  
Forming Limit Curve ◽  
Hydraulic Bulge ◽  
Strain Paths ◽  
The Right

The hydraulic bulge test represents an effective experimental method to characterise sheet metals since the equivalent strains before failure are much larger than those measured during tensile testing and there is nearly no frictional effect on the results. Recently this test has been proposed not only for extracting data concerning the equi-biaxial strain condition, but to determine the forming limit diagram (FLD) in the range of positive minor strains. In the proposed methodology, different strain paths can be obtained by merely using a test blank having two holes with a suitable geometry and position to be tested, without the need of dies with elliptical apertures. However, a carrier sheet is necessary, thus implying results may be affected by friction effects. This paper proposes a new methodology for the determination of the right side of the Forming Limit Curve (FLC), based on the adoption of local heat treatments aimed at determining different strain paths on the blank to be tested while using the classical circular die for bulge tests. In particular, the formability of the alloy AA5754-H32 was investigated; 3D Finite Element simulations were conducted setting different laser strategies and monitoring the resulting strain path. Results revealed that the proposed methodology supports obtaining many additional points in the right side of the FLC, thus being effective and friction free.

Effects of Prestrain With Strain Gradient Present on Sheet Metal Formability

1985 ◽  
Vol 107 (4) ◽  
pp. 298-306 ◽  
Author(s):  
H. M. Shang ◽  
G. S. Tan ◽  
W. C. M. Tan
Keyword(s):  
Sheet Metal ◽  
Strain Gradient ◽  
Forming Limit Diagram ◽  
Diameter Ratio ◽  
Forming Limit ◽  
Bulge Test ◽  
Strain Gradients ◽  
Second Stage

In this investigation, two double-stage forming processes are used to study the effects of prestrain on sheet metal formability. The processes chosen are the bulge test and the plunger test using a die throat to punch diameter ratio of 2.42. It is seen that during the second stage of forming, deformation and shape of the deformed shell are influenced by the level of prestrain and strain gradients on the prestrained workpiece. An improved formability is observed when the workpiece for the plunger test is prestrained by hydroforming, but the formability is reduced when the prestraining process becomes the plunger test. The present results also imply that care should be taken in utilizing the forming limit diagram even if it is constructed from double-stage forming, in which strain gradient on the prestrained workpiece is generally absent.

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.

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.

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