scholarly journals Stability analysis and finite element simulations of superplastic forming in the presence of hydrostatic pressure

2018 ◽  
Author(s):  
M. A. Nazzal
Keyword(s):  
Finite Element ◽  
Stability Analysis ◽  
Hydrostatic Pressure ◽  
Superplastic Forming ◽  
Finite Element Simulations

Finite Element Modeling of Superplastic Forming in the Presence of Back Pressure

2007 ◽  
Vol 551-552 ◽  
pp. 257-262 ◽  
Author(s):  
Mohammad Nazzal ◽  
Marwan K. Khraisheh
Keyword(s):  
Finite Element ◽  
Hydrostatic Pressure ◽  
Finite Element Modeling ◽  
Damage Evolution ◽  
Superplastic Forming ◽  
Back Pressure ◽  
Finite Element Simulations ◽  
Experimental Results ◽  
Formed Part ◽  
Copper Based Alloy

It is established that some superplastic materials undergo significant cavitation during deformation. Cavitation not only limits the superplastic ductility of the material, but also reduces the service properties and the fatigue performance of the formed parts. Experimental results have shown that an effective method to eliminate cavitation is the application of hydrostatic pressure during deformation. In this work, finite element simulations are carried out to study the effects of hydrostatic pressure on damage evolution during SPF. The analysis is conducted for the superplastic copper based alloy Coronze-638 at 550 °C. The results clearly demonstrate the effectiveness of the superimposition of hydrostatic pressure in reducing the amount of cavities generated during SPF and improving the integrity of the formed part.

scholarly journals Regimes of wrinkling in pressurized elastic shells

2017 ◽  
Vol 375 (2093) ◽  
pp. 20160330 ◽  
Author(s):  
Matteo Taffetani ◽  
Dominic Vella
Keyword(s):  
Finite Element ◽  
Stability Analysis ◽  
Detailed Analysis ◽  
Indentation Depth ◽  
Elastic Shell ◽  
Analytical Techniques ◽  
Finite Element Simulations ◽  
Media Theory ◽  
Threshold Analysis ◽  
Elastic Shells

We consider the point indentation of a pressurized elastic shell. It has previously been shown that such a shell is subject to a wrinkling instability as the indentation depth is quasi-statically increased. Here we present detailed analysis of this wrinkling instability using a combination of analytical techniques and finite-element simulations. In particular, we study how the number of wrinkles observed at the onset of instability grows with increasing pressurization. We also study how, for fixed pressurization, the number of wrinkles changes both spatially and with increasing indentation depth beyond onset. This ‘Far from threshold’ analysis exploits the largeness of the wrinkle wavenumber that is observed at high pressurization and leads to quantitative differences with the standard ‘Near threshold’ stability analysis. This article is part of the themed issue ‘Patterning through instabilities in complex media: theory and applications.’

scholarly journals Mechanical Modelling of the Plastic Flow Machining Process

Materials ◽  
2018 ◽  
Vol 11 (7) ◽  
pp. 1218 ◽  
Author(s):  
Viet Vu ◽  
Yan Beygelzimer ◽  
Roman Kulagin ◽  
Laszlo Toth
Keyword(s):  
Finite Element ◽  
Hydrostatic Pressure ◽  
Plastic Flow ◽  
Deformation Gradient ◽  
Back Pressure ◽  
Extrusion Ratio ◽  
Finite Element Simulations ◽  
Analytical Modelling ◽  
Lateral Extrusion ◽  
Lateral Channel

A new severe plastic deformation process, plastic flow machining (PFM), was introduced recently to produce sheet materials with ultrafine and gradient structures from bulk samples in one single deformation step. During the PFM process, a part of a rectangular sample is transformed into a thin sheet or fin under high hydrostatic pressure. The obtained fin is heavily deformed and presents a strain gradient across its thickness. The present paper aims to provide better understanding about this new process via analytical modelling accompanied by finite element simulations. PFM experiments were carried out on square commercially pure aluminum (CP Al) billets. Under pressing, the material flowed from the horizontal channel into a narrow 90° oriented lateral channel to form a fin sheet product, and the remaining part of the sample continued to move along the horizontal channel. At the opposite end of the bulk sample, a back-pressure was applied to increase the hydrostatic pressure in the material. The experiments were set at different width sizes of the lateral channel under two conditions; with or without applying back-pressure. A factor called the lateral extrusion ratio was defined as the ratio between the volume of the produced fin and the incoming volume. This ratio characterizes the efficiency of the PFM process. The experimental results showed that this ratio was greater when back-pressure was applied and further, it increased with the rise of the lateral channel width size. Finite element simulations were conducted in the same boundary conditions as the experiments using DEFORM-2D/3D software, V11.0. Two analytical models were also established. The first one used the variational principle to predict the lateral extrusion ratio belonging to the minimum total plastic power. The second one employed an upper-bound approach on a kinematically admissible velocity field to describe the deformation gradient in the fin. The numerical simulations and the analytical modelling successfully predicted the experimental tendencies, including the deformation gradient across the fin thickness.

Optimisation of the superplastic forming of a dental implant for bone augmentation using finite element simulations

2004 ◽  
Vol 20 (5) ◽  
pp. 409-418 ◽  
Author(s):  
Denis Garriga-Majo ◽  
Robin J Paterson ◽  
Richard V Curtis ◽  
Rajab Said ◽  
Richard D Wood ◽  
...  
Keyword(s):  
Finite Element ◽  
Dental Implant ◽  
Superplastic Forming ◽  
Finite Element Simulations ◽  
Bone Augmentation

Thermomechanical finite element simulations of ultrasonically assisted turning

2005 ◽  
Vol 32 (3-4) ◽  
pp. 463-471 ◽  
Author(s):  
A.V. Mitrofanov ◽  
V.I. Babitsky ◽  
V.V. Silberschmidt
Keyword(s):  
Finite Element ◽  
Finite Element Simulations
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