FLD and rolling direction

rzmehdipour

Hi all,

 

1- As sheet metal resistance to thinning is not the same in different directions (which is the subject of Lankford coefficients), how can we define FLD curve without considering rolling direction?

 

2- In Radioss one-step forming simulation in which we define r0, r45 and r90 during material definition, is there a pre-defined sheet rolling direction? Is it X axis or what?

 

Thanks in advance.

 

GAJENDRA KUMAR NHAICHANIYA

r0, r45 & r90 are lankford cofficient. Hope ur both questions answered by this.

rzmehdipour

Altair Forum User said:

r0, r45 & r90 are lankford cofficient. Hope ur both questions answered by this.

Thanks for your reply but my question is : As formability is not the same in different directions (relative to rolling one), how is it possible to predict the result without specifying rolling direction on raw material. Is there any default direction for rolling?

GAJENDRA KUMAR NHAICHANIYA

Hello,

See the average Lankford coefficient R is calculated by R0 R45 & R90 (to consider plastic anisotropy)

Here R0 R45 & R90 values are calculated by R = E_xy/E_z along 0,45 and 90 degree (assume any one direction as 0 degree for R0 and start calculating R45 & R90 )

E_xy = in plane plastic strain & E_z = strain along thickness

so no matter which direction u r choosing for calculation of R, because R value not calculated by axial strain. it calculated by share strain (E_xy).

 

For more u can go through link

https://en.wikipedia.org/wiki/Lankford_coefficient

rzmehdipour

Altair Forum User said:

Hello,

See the average Lankford coefficient R is calculated by R0 R45 & R90 (to consider plastic anisotropy)

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Here R0 R45 & R90 values are calculated by R = E_xy/E_z along 0,45 and 90 degree (assume any one direction as 0 degree for R0 and start calculating R45 & R90 )

E_xy = in plane plastic strain & E_z = strain along thickness

so no matter which direction u r choosing for calculation of R, because R value not calculated by axial strain. it calculated by share strain (E_xy).

 

For more u can go through link

https://en.wikipedia.org/wiki/Lankford_coefficient

 

Thanks again.

You're right. But physically material does not act according to average values, but real ones. I mean in real world material will behave differently in different directions. So how can we consider rolling direction in simulations? Sometimes considering rolling direction is quite necessary in first forming stage and forming the sheet in wrong direction will cause failure.

GAJENDRA KUMAR NHAICHANIYA

Hello,

The R0 is defined in X direction & R90 in Y direction.

Plz make sure your grain direction is along X axis. & draw direction should be Z.

 

 

 

rzmehdipour

Altair Forum User said:

Hello,

The R0 is defined in X direction & R90 in Y direction.

Plz make sure your grain direction is along X axis. & draw direction should be Z.

 

Thanks a lot

 

 

 

 

 

GAJENDRA KUMAR NHAICHANIYA

Most welcome.

Junta_20361

hi,
With incremental HyperForm, after you defined the forming process completely and 'create input', there will be some entities added into HF model >> check the model browser.

now, look at the property of the blank.

The rolling direction will be defined with Vx, Vy, Vz values.

By default, the Vx will be set as 1 >> indicate the rolling direction of the blank will be X-axis.
You can modify the values to change the rolling direction as you wished.

For the onestep analysis, i don't think the rolling direction will be defined.