The Maximum Drawing Ratio in Hydroforming Processes

1990 ◽  
Vol 112 (1) ◽  
pp. 47-56 ◽  
Author(s):  
S. Yossifon ◽  
J. Tirosh
Keyword(s):  
Failure Modes ◽  
Fluid Pressure ◽  
Radius Of Curvature ◽  
Strain Hardening Exponent ◽  
Drawing Ratio ◽  
Limit Drawing Ratio ◽  
Normal Anisotropy ◽  
Geometrical Properties ◽  
Buckling Instability ◽  
Hydroforming Process

The concept of Maximum Drawing Ratio (MDR), supplementary to the well-known Limit Drawing Ratio (LDR), is defined, examined, and illustrated by experiments. In essence the MDR is reached when the two basic failure modes, namely: rupture (due to tensile instability) and wrinkling (due to buckling instability) are delayed till they occur simultaneously. Thus the process is beneficially utilized for higher drawing ratio by postponing earlier interception of either one of the above failures alone. The ability to suppress (up to a certain extent) the appearance of these failure modes depends heavily on the fluid-pressure path which controls the hydroforming process. The effect of the material properties, like the strain hardening exponent, the normal anisotropy of the blank, etc., as well as the geometrical properties (i.e., the thickness of the blank, the radius of curvature at the lip, etc.) on the MDR, are considered here in some detail. The nature of the solutions by which MDR is reached is discussed.

A Simplified Approach to Estimate Limiting Drawing Ratio and Maximum Drawing Load in Cup Drawing

2004 ◽  
Vol 126 (1) ◽  
pp. 116-122 ◽  
Author(s):  
Daw-Kwei Leu ◽  
Jen-Yu Wu
Keyword(s):  
Friction Coefficient ◽  
Strain Hardening ◽  
Sheet Metal ◽  
Elementary Theory ◽  
Strain Hardening Exponent ◽  
Drawing Ratio ◽  
Normal Anisotropy ◽  
Limiting Drawing Ratio ◽  
Special Cases ◽  
Cup Drawing

A new and practically applicable equation, including the normal anisotropy R, the strain hardening exponent n, the friction coefficient μ, and the bending factor t0/rd for estimating the limiting drawing ratio LDR (a measure of drawability of sheet metal) in cup drawing of a cylindrical cup with a flat-nosed punch is derived by an elementary theory of plasticity in an explicit form. Whiteley’s and Leu’s equations for estimating the LDR, and Hill’s upper limit value of LDR, all are the special cases of the derived equation. The estimation of LDR agrees well with the experiment. It is shown that the most important parameters for LDR are the normal anisotropy R and friction coefficient μ, however the strain hardening exponent n has little effect on the LDR. On the other hand, a new and simple equation, incorporating the derived LDR and the critical drawing load Pc, for estimating the maximum drawing load Pd at a certain drawing ratio is derived. It also agrees well with the experiment. It is thereby possible to better understand and control the drawing limit of sheet metal in industry necessity.

Process analysis of hydrodynamic deep drawing of cone cups assisted by radial pressure

2015 ◽  
Vol 231 (10) ◽  
pp. 1793-1802 ◽  
Author(s):  
Alireza Jalil ◽  
Mohammad Hoseinpour Gollo ◽  
SM Hossein Seyedkashi
Keyword(s):  
Deep Drawing ◽  
Critical Pressure ◽  
Process Analysis ◽  
Fluid Pressure ◽  
Radial Pressure ◽  
Strain Hardening Exponent ◽  
Geometrical Parameters ◽  
Drawing Ratio ◽  
Hydrodynamic Deep Drawing ◽  
Rupture Pressure

Forming of flat sheets into shell conical parts is a complex manufacturing process. Hydrodynamic deep drawing process assisted by radial pressure is a new hydroforming technology in which fluid pressure is applied to the peripheral edge of the sheet in addition to the sheet surface. This technique results in higher drawing ratio and dimensional accuracy, better surface quality, and ability of forming more complex geometries. In this research, a new theoretical model is developed to predict the critical rupture pressure in production of cone cups. In this analysis, Barlat–Lian yield criterion is utilized and tensile instability is considered based on the maximum load applied on the sheet. The proposed model is then validated by a series of experiments. The theoretical predictions are in good agreement with the experimental results. The effects of geometrical parameters and material properties on critical rupture pressure are also studied. The critical pressure is increased with increase in the height ratio, strain hardening exponent, and anisotropy. Higher punch nose radius expands the safe zone. It is shown that the critical pressure decreases for drawing ratios higher than 4.

Theoretical, numerical and experimental investigation of hydro-mechanical deep drawing of steel/polymer/steel sandwich sheets

2018 ◽  
Vol 233 (5) ◽  
pp. 1529-1546 ◽  
Author(s):  
Majid Fazlollahi ◽  
Mohammad Reza Morovvati ◽  
Bijan Mollaei Dariani
Keyword(s):  
Deep Drawing ◽  
Fluid Pressure ◽  
Chamber Pressure ◽  
Drawing Ratio ◽  
Drawing Process ◽  
Forming Force ◽  
Limit Drawing Ratio ◽  
Deep Drawing Process ◽  
Sandwich Sheet ◽  
Sandwich Sheets

Fabricating flat sandwich sheets into components with a required shape and dimensions is a challenging job in the metal forming field. In this article, hydro-mechanical deep drawing was used for sandwich sheet forming. The aim of the work is to achieve higher drawing ratio of these sheets. Theoretical, numerical and experimental analysis of the hydro-mechanical deep drawing of sandwich sheets was carried out. Separated layers theory method is used for theoretical analysis of the process. Then, the numerical simulation of the process was developed by finite element method. The effect of core layer thickness on the forming force of the sandwich sheet and effective parameters of the process such as strain and forming force was investigated. Experimental works were conducted on the steel/polymer/steel sandwich sheets by a hydro-mechanical deep drawing die. A good agreement was observed between theoretical, numerical and experimental results. The safe zone of fluid pressure for achieving a part without rupture was obtained. It was shown that the limit drawing ratio is increased by increasing the pressure but after a particular point, the limit drawing ratio is decreased by increasing the chamber pressure. It was also observed that maximum drawing ratio for achieving a part without rupture in the hydro-mechanical deep drawing process is higher than conventional deep drawing process.

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.

A Critical Review of Tube and Sheet Metal Hydroforming Technology

1996 ◽  
Author(s):  
Jian An ◽  
A. H. Soni
Keyword(s):  
Sheet Metal ◽  
Thickness Distribution ◽  
Fluid Pressure ◽  
Point Of View ◽  
Parameter Design ◽  
Back Side ◽  
Part Quality ◽  
Element Simulation ◽  
Part Surface ◽  
Hydroforming Process

Abstract The hydroforming technology, which is rapidly gaining popularity in the sheet metal and tube forming industry is reviewed. The features and the characteristics of the hydroforming process are described. The uniformly distributed fluid pressure covers the back side of the sheet as a die generates many advantages in the technical point of view as improving the part surface quality, reducing the forming severity and smoothing the thickness distribution. The benefits of using hydroforming technology are examined and analyzed in a technical level. The better part quality, less cost of tooling, materials saving and part weight reduction can be achieved using the hydroforming technology. The design methodologies for the hydroforming process parameters are reviewed and discussed in a certain detail. Computer-aided-engineering such as finite element simulation is suggested for such process parameter design.

The limit drawing ratio and formability prediction of advanced high strength dual-phase steels

2011 ◽  
Vol 32 (6) ◽  
pp. 3320-3327 ◽  
Author(s):  
Wang Wu-rong ◽  
He Chang-wei ◽  
Zhao Zhong-hua ◽  
Wei Xi-cheng
Keyword(s):  
High Strength ◽  
Drawing Ratio ◽  
Dual Phase ◽  
Limit Drawing Ratio ◽  
Dual Phase Steels ◽  
Formability Prediction

Effect of Cu Content on the Formability and Portevin-Le Chatelier Effect of Al-Mg Alloys

2015 ◽  
Vol 817 ◽  
pp. 150-157
Author(s):  
Peng Cheng Ma ◽  
Di Zhang ◽  
Lin Zhong Zhuang ◽  
Ji Shan Zhang
Keyword(s):  
Plastic Strain ◽  
Stress Drop ◽  
Strain Ratio ◽  
Mg Alloys ◽  
Dynamic Strain ◽  
Strain Hardening Exponent ◽  
Drawing Ratio ◽  
Plastic Strain Ratio ◽  
Cu Content ◽  
Al Mg Alloys

Al-Mg alloys developed for auto body sheets with different Cu contents were fabricated in the laboratory scale. The effects of Cu content on the microstructures, formability and Portevin–Le Chatelier(PLC) effect of the alloys were investigated by polarizied optical microscopy and room temperature tensile testing. It has been found that with increasing Cu content, there was little change of the strain hardening exponent, but the plastic strain ratio and limiting drawing ratio increased firstly and then decreased. A quantitative statistical analysis of the characteristics of the PLC effect was made, including the stress drop and the reloading time, which follow a common linear relationship with plastic strain, and the increase rate of stress drop and reloading time was bigger with more Cu content. A detailed discussion of the corresponding mechanism of Cu and Cu-containing precipitates on the dynamic strain aging(DSA) was made.

Enhanced Formability of AZ31 Magnesium Alloy Sheet Processed by Equal Channel Angular Rolling and Annealing Treatment

2007 ◽  
Vol 26-28 ◽  
pp. 91-94
Author(s):  
Zhen Hua Chen ◽  
Yong Qi Cheng ◽  
Wei Jun Xia ◽  
Hong Ge Yan ◽  
Ding Chen
Keyword(s):  
Magnesium Alloy ◽  
Rolling Direction ◽  
Annealing Treatment ◽  
Alloy Sheet ◽  
Az31 Magnesium Alloy ◽  
Strain Hardening Exponent ◽  
Drawing Ratio ◽  
Magnesium Alloy Sheet ◽  
Optical Microstructure ◽  
Az31 Magnesium Alloy Sheet

In order to improve the formability of AZ31 magnesium alloy sheet at room temperature, a new process, so-called equal channel angular rolling (ECAR) and followed by annealing treatment was applied to process the sheet. The optical microstructure of the as-received sheet was similar with that of the ECARed one after annealing treatment, the Erichsen value and limiting drawing ratio of the ECARed sheet was about 6.26mm and 1.6, respectively, which was much larger than that of 4.18mm and 1.2 for the as-received sheet. These can be attributed to the low yield ratio and high strain hardening exponent due to the modified texture induced by the shear deformation during ECAR process, which is favor of the activations of basal slipping and twinning at ambient temperature, especially deforming at the rolling direction.

scholarly journals Anisotropy Study of Inconel 718 alloy at Sub-Zero temperatures

2020 ◽  
Vol 184 ◽  
pp. 01004
Author(s):  
L Jayahari ◽  
K Nagachary ◽  
Chandra Ch Sharath ◽  
SM Hussaini
Keyword(s):  
Mechanical Properties ◽  
Strain Hardening ◽  
Inconel 718 ◽  
Anisotropy Parameter ◽  
Tensile Tests ◽  
Strain Hardening Exponent ◽  
Inconel 718 Alloy ◽  
Normal Anisotropy ◽  
Axial Tensile ◽  
Forming Characteristics

There is an increase in demand for new alloys in aerospace, power generation and nuclear industries. Nickel Based super alloys are known for having distinctive properties which are best suitable for these industries. In this study Nickel based super alloy Inconel 718, is used. Over the many years of intense research and development, these alloys have seen considerable evolution in their properties and efficiency. Behaviour of materials and its forming characteristics can be precisely analysed by determining anisotropic behaviour and mechanical properties. In the present study, tried to analyse the mechanical properties of Inconel 718 like yield strength (Ys), ultimate tensile strength (UTS), strain hardening exponent (n) and strain hardening coefficient (k). Uni-axial tensile tests were conducted on specimens with various parameters such as orientations, temperature and Strain rate. Anisotropy of Inconel 718 alloy was measured based on measurable parameters. The normal anisotropy parameter (f) and planer anisotropy (Δr) were measured and observed that the anisotropy parametres are incresed with the decrease in temperature.

Comparison of Microstructure and Mechanical Behavior of the Ferritic Stainless Steels ASTM 430 Stabilized with Niobium and ASTM 439 Stabilized with Niobium and Titanium

2016 ◽  
Vol 879 ◽  
pp. 1651-1655 ◽  
Author(s):  
Leandro Paulo de Almeida Reis Tanure ◽  
Cláudio Moreira de Alcântara ◽  
Tarcísio Reis de Oliveira ◽  
Dagoberto Brandão Santos ◽  
Berenice Mendonça Gonzalez
Keyword(s):  
Stainless Steels ◽  
Lower Cost ◽  
Volume Fraction ◽  
Austenitic Stainless Steels ◽  
Total Elongation ◽  
Drawing Ratio ◽  
Limit Drawing Ratio ◽  
Soaking Time ◽  
Ferritic Stainless Steels ◽  
Cold Rolled

The use of Ferritic Stainless Steels has become indispensable due its lower cost and the possibility to replace austenitic stainless steels in many applications. In this study, cold rolled sheets of two stabilized ferritic stainless steels with 85% thickness reduction were annealed by applying a heating rate of 24 oC/s and a soaking time of 24 s. The niobium stabilized ferritic stainless steel type ASTM 430 (430Nb) was annealed at 880 oC while the niobium and titanium bi-stabilized steel ASTM 439 was annealed at 925 oC. The annealed samples were tensile tested and due to the smaller grain size, steel 430Nb, showed a higher yield stress and a higher total elongation. Concerning drawability the steel ASTM 439 presented a better performance with higher average R-value, lower planar anisotropy coefficient and a greater value for Limit Drawing Ratio (LDR). These results are explained in terms of the differences in size and volume fraction of precipitates between the two steels.

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