Damage mechanics based approach in failure predication of draw forming procecesses

In a cup draw forming operation, the desired shape results from the material hardening process under controlled plastic deformation and the springback phenomena. In this study, a mechanics-of-deformation approach is developed based on damage variables and large plastic deformation. The approach is t...

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Main Author:	Abu Shah, Ismail
Format:	Thesis
Language:	English
Published:	2017
Subjects:	TJ Mechanical engineering and machinery
Online Access:	http://eprints.utm.my/id/eprint/79126/1/IsmailAbuShahPFKM2017.pdf
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spelling	my-utm-ep.791262018-09-30T08:17:29Z Damage mechanics based approach in failure predication of draw forming procecesses 2017 Abu Shah, Ismail TJ Mechanical engineering and machinery In a cup draw forming operation, the desired shape results from the material hardening process under controlled plastic deformation and the springback phenomena. In this study, a mechanics-of-deformation approach is developed based on damage variables and large plastic deformation. The approach is then employed to estimate the onset of the material damage event and the location of fracture based on the mechanics response of the metal blank. Draw forming behavior of low carbon steel is examined as a case study. The loading rate is conducted at a slow loading response of the steels in the large deformation of the draw forming processes. Axisymmetric and 3D solid models are developed for finite element (FE) simulations to gain insight into the evolution of internal states and damage in the steel blanks during the draw forming process. In the FE simulation, Johnson-Cook constitutive model with isotropic hardening rule is employed. The Rice-Tracey ductile damage criterion is employed to indicate damage initiation event along with a linear energy-displacement relation for damage evolution rule. Results show that while the applied loading (tool displacement) is quasi-static corresponding to the strain rate of 0.001 sec-1, the maximum plastic strain rate at fracture could reach 100 times greater at the critical material flow region. Failure of the deforming steel blank is localized with excessive plastic deformation. While the onset of damage can be efficiently predicted using the axisymmetric FE model with damage-based model, the subsequent damage evolution of the localized ductile failure requires a 3D continuum FE model. The predicted tool load-displacement response is employed in validating the FE model. Effects of drawing parameters including drawing speed, blank holder force and die clearance on the resulting deformation of the drawn cup-shape part are established. Based on the response of the mechanics-of-deformation, the established failure prediction approach is proven more accurate and reliable. 2017 Thesis http://eprints.utm.my/id/eprint/79126/ http://eprints.utm.my/id/eprint/79126/1/IsmailAbuShahPFKM2017.pdf application/pdf en public phd doctoral Universiti Teknologi Malaysia, Faculty of Mechanical Engineering Faculty of Mechanical Engineering
institution	Universiti Teknologi Malaysia
collection	UTM Institutional Repository
language	English
topic	TJ Mechanical engineering and machinery
spellingShingle	TJ Mechanical engineering and machinery Abu Shah, Ismail Damage mechanics based approach in failure predication of draw forming procecesses
description	In a cup draw forming operation, the desired shape results from the material hardening process under controlled plastic deformation and the springback phenomena. In this study, a mechanics-of-deformation approach is developed based on damage variables and large plastic deformation. The approach is then employed to estimate the onset of the material damage event and the location of fracture based on the mechanics response of the metal blank. Draw forming behavior of low carbon steel is examined as a case study. The loading rate is conducted at a slow loading response of the steels in the large deformation of the draw forming processes. Axisymmetric and 3D solid models are developed for finite element (FE) simulations to gain insight into the evolution of internal states and damage in the steel blanks during the draw forming process. In the FE simulation, Johnson-Cook constitutive model with isotropic hardening rule is employed. The Rice-Tracey ductile damage criterion is employed to indicate damage initiation event along with a linear energy-displacement relation for damage evolution rule. Results show that while the applied loading (tool displacement) is quasi-static corresponding to the strain rate of 0.001 sec-1, the maximum plastic strain rate at fracture could reach 100 times greater at the critical material flow region. Failure of the deforming steel blank is localized with excessive plastic deformation. While the onset of damage can be efficiently predicted using the axisymmetric FE model with damage-based model, the subsequent damage evolution of the localized ductile failure requires a 3D continuum FE model. The predicted tool load-displacement response is employed in validating the FE model. Effects of drawing parameters including drawing speed, blank holder force and die clearance on the resulting deformation of the drawn cup-shape part are established. Based on the response of the mechanics-of-deformation, the established failure prediction approach is proven more accurate and reliable.
format	Thesis
qualification_name	Doctor of Philosophy (PhD.)
qualification_level	Doctorate
author	Abu Shah, Ismail
author_facet	Abu Shah, Ismail
author_sort	Abu Shah, Ismail
title	Damage mechanics based approach in failure predication of draw forming procecesses
title_short	Damage mechanics based approach in failure predication of draw forming procecesses
title_full	Damage mechanics based approach in failure predication of draw forming procecesses
title_fullStr	Damage mechanics based approach in failure predication of draw forming procecesses
title_full_unstemmed	Damage mechanics based approach in failure predication of draw forming procecesses
title_sort	damage mechanics based approach in failure predication of draw forming procecesses
granting_institution	Universiti Teknologi Malaysia, Faculty of Mechanical Engineering
granting_department	Faculty of Mechanical Engineering
publishDate	2017
url	http://eprints.utm.my/id/eprint/79126/1/IsmailAbuShahPFKM2017.pdf
_version_	1747818152923758592

Damage mechanics based approach in failure predication of draw forming procecesses

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