Effect of plastic deformation on elastic and plastic recovery in CP-Titanium

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Abstract

The springback associated with cold deep drawing of sheet metals leads to undesired dimensional changes in the final products. This is often due to the heterogeneous plastic deformation in different areas of the intended geometry that creates various stress states throughout the part. The major objective of this study is to understand the interconnection between springback, level of plastic deformation, degradation of elastic modulus and strain recovery in a CP-Ti material. The mechanical properties of the sheet material and the dependency of mechanical properties on directionality are investigated by examining samples from three orientations of parallel to the rolling direction (RD), at 45° to RD and perpendicular to RD. The degradation of elastic modulus as a function of level of plastic deformation was explored for 0° and 45° samples by conducting multi-step uniaxial loading-unloading in tension.
The experimental results showed that the mechanical properties vary for each direction, with the lowest elastic modulus along RD. A significant degradation was observed in elastic modulus (up to 50% reduction) with increased plastic deformation. This resulted in more strain relaxation compared to that associated with the initial elastic modulus. For stresses below 100MPa, a nonlinear (plastic) recovery was observed, resulting in additional relaxation in the total strain upon load removal in each step of the interrupted tests. This plastic recovery behaviour is observed to be dependent on sample orientation. It is concluded that accurate prediction of springback during sheet metal forming, requires a material model which takes into accounts the directional degradation of elastic modulus and the plastic recovery as a function of plastic deformation.

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Titanium
Plastic deformation
Elastic moduli
Plastics
Recovery
Degradation
Sheet metal
Mechanical properties
Strain relaxation
Deep drawing
Metal forming
Unloading
Loads (forces)
Direction compound
Geometry

Keywords

  • springback
  • CP-titanium
  • sheet forming
  • plastic deformation
  • sheet metal
  • dimensional changes
  • heterogenous plastic deformation
  • elastic modulus degradation
  • strain recovery
  • strain relaxation

Cite this

@article{965a1e2c7bae40c1a9b17f7d8b4c1392,
title = "Effect of plastic deformation on elastic and plastic recovery in CP-Titanium",
abstract = "The springback associated with cold deep drawing of sheet metals leads to undesired dimensional changes in the final products. This is often due to the heterogeneous plastic deformation in different areas of the intended geometry that creates various stress states throughout the part. The major objective of this study is to understand the interconnection between springback, level of plastic deformation, degradation of elastic modulus and strain recovery in a CP-Ti material. The mechanical properties of the sheet material and the dependency of mechanical properties on directionality are investigated by examining samples from three orientations of parallel to the rolling direction (RD), at 45° to RD and perpendicular to RD. The degradation of elastic modulus as a function of level of plastic deformation was explored for 0° and 45° samples by conducting multi-step uniaxial loading-unloading in tension.The experimental results showed that the mechanical properties vary for each direction, with the lowest elastic modulus along RD. A significant degradation was observed in elastic modulus (up to 50{\%} reduction) with increased plastic deformation. This resulted in more strain relaxation compared to that associated with the initial elastic modulus. For stresses below 100MPa, a nonlinear (plastic) recovery was observed, resulting in additional relaxation in the total strain upon load removal in each step of the interrupted tests. This plastic recovery behaviour is observed to be dependent on sample orientation. It is concluded that accurate prediction of springback during sheet metal forming, requires a material model which takes into accounts the directional degradation of elastic modulus and the plastic recovery as a function of plastic deformation.",
keywords = "springback, CP-titanium, sheet forming, plastic deformation, sheet metal, dimensional changes, heterogenous plastic deformation, elastic modulus degradation, strain recovery, strain relaxation",
author = "Saber Khayatzadeh and Salah Rahimi and Paul Blackwell",
year = "2016",
month = "10",
day = "17",
doi = "10.4028/www.scientific.net/KEM.716.891",
language = "English",
volume = "716",
pages = "891 -- 896",
journal = "Key Engineering Materials",
issn = "1013-9826",

}

TY - JOUR

T1 - Effect of plastic deformation on elastic and plastic recovery in CP-Titanium

AU - Khayatzadeh, Saber

AU - Rahimi, Salah

AU - Blackwell, Paul

PY - 2016/10/17

Y1 - 2016/10/17

N2 - The springback associated with cold deep drawing of sheet metals leads to undesired dimensional changes in the final products. This is often due to the heterogeneous plastic deformation in different areas of the intended geometry that creates various stress states throughout the part. The major objective of this study is to understand the interconnection between springback, level of plastic deformation, degradation of elastic modulus and strain recovery in a CP-Ti material. The mechanical properties of the sheet material and the dependency of mechanical properties on directionality are investigated by examining samples from three orientations of parallel to the rolling direction (RD), at 45° to RD and perpendicular to RD. The degradation of elastic modulus as a function of level of plastic deformation was explored for 0° and 45° samples by conducting multi-step uniaxial loading-unloading in tension.The experimental results showed that the mechanical properties vary for each direction, with the lowest elastic modulus along RD. A significant degradation was observed in elastic modulus (up to 50% reduction) with increased plastic deformation. This resulted in more strain relaxation compared to that associated with the initial elastic modulus. For stresses below 100MPa, a nonlinear (plastic) recovery was observed, resulting in additional relaxation in the total strain upon load removal in each step of the interrupted tests. This plastic recovery behaviour is observed to be dependent on sample orientation. It is concluded that accurate prediction of springback during sheet metal forming, requires a material model which takes into accounts the directional degradation of elastic modulus and the plastic recovery as a function of plastic deformation.

AB - The springback associated with cold deep drawing of sheet metals leads to undesired dimensional changes in the final products. This is often due to the heterogeneous plastic deformation in different areas of the intended geometry that creates various stress states throughout the part. The major objective of this study is to understand the interconnection between springback, level of plastic deformation, degradation of elastic modulus and strain recovery in a CP-Ti material. The mechanical properties of the sheet material and the dependency of mechanical properties on directionality are investigated by examining samples from three orientations of parallel to the rolling direction (RD), at 45° to RD and perpendicular to RD. The degradation of elastic modulus as a function of level of plastic deformation was explored for 0° and 45° samples by conducting multi-step uniaxial loading-unloading in tension.The experimental results showed that the mechanical properties vary for each direction, with the lowest elastic modulus along RD. A significant degradation was observed in elastic modulus (up to 50% reduction) with increased plastic deformation. This resulted in more strain relaxation compared to that associated with the initial elastic modulus. For stresses below 100MPa, a nonlinear (plastic) recovery was observed, resulting in additional relaxation in the total strain upon load removal in each step of the interrupted tests. This plastic recovery behaviour is observed to be dependent on sample orientation. It is concluded that accurate prediction of springback during sheet metal forming, requires a material model which takes into accounts the directional degradation of elastic modulus and the plastic recovery as a function of plastic deformation.

KW - springback

KW - CP-titanium

KW - sheet forming

KW - plastic deformation

KW - sheet metal

KW - dimensional changes

KW - heterogenous plastic deformation

KW - elastic modulus degradation

KW - strain recovery

KW - strain relaxation

UR - http://www.scientific.net/KEM

UR - http://metalforming2016.jordan.pl/

U2 - 10.4028/www.scientific.net/KEM.716.891

DO - 10.4028/www.scientific.net/KEM.716.891

M3 - Article

VL - 716

SP - 891

EP - 896

JO - Key Engineering Materials

T2 - Key Engineering Materials

JF - Key Engineering Materials

SN - 1013-9826

ER -