Rolling - no increase in strip's length
Rolling - no increase in strip's length
(OP)
I have developed the rolling process in 2D.
The slab's geometry before the rolling was:
-length: 120 milimeters
-height: 2 milimeter

After the rolling process:
-length: 120 milimeters
-height: 0.9 milimeter

Relative displacement in 1 direction: 8.82149e-005 milimeters
Why there is no increase in strip's length? It is very weird. I do not understand it. Some of the material disappeared, or what?
The slab's geometry before the rolling was:
-length: 120 milimeters
-height: 2 milimeter

After the rolling process:
-length: 120 milimeters
-height: 0.9 milimeter

Relative displacement in 1 direction: 8.82149e-005 milimeters
Why there is no increase in strip's length? It is very weird. I do not understand it. Some of the material disappeared, or what?





RE: Rolling - no increase in strip's length
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RE: Rolling - no increase in strip's length
RE: Rolling - no increase in strip's length
I figured out where the problem is. The problem is with the slab speed application. This is the Temp-disp analysis, so the velocity can't be applicated in the predefined field. It has to be defined as a BC condition. Look at the figure:
That way of velocity application (to whole slab) constrained any other move in X-direction, that is why there was no increase in length.
What is the best way to applicate the velocity to the slab in rolling process?
RE: Rolling - no increase in strip's length
Look at some examples from the Example Problems Manual.
RE: Rolling - no increase in strip's length
RE: Rolling - no increase in strip's length
The friction and rotating velocity is defined. I cant define the initial velocity through the predefined field. I can define the velocity through the BC, but it won't be "initial".
corus,
I changed section to Generalized plane strain. I changed element type to Generalized plane strain.
I defined the reference point and I applied the velocity to the front face. See the figure below:
I do not know how can I fix the two out of plane rotations to zero.
Anyway, without that fixing, the simulation crashes after short time and the error is: "Too many attempts made for this increment".
The moment of simulation crash have been shown in figure below:
When I enter to the results module, the first what I see is the rotated image:
Is it due to lack of that fixation, which you were talking about?
I attach my input file, maybe it will be helpful.
RE: Rolling - no increase in strip's length
For this kind of analysis where you have contact and plasticity then it's better to use an explicit analysis rather than using standard as there are fewer constraints on achieving equilibrium everywhere. It should be possible to run it in standard though but it's a lot more trouble.
RE: Rolling - no increase in strip's length
I tried using symmetry and a finer mesh and running the job as a static, general model but didn't get the job to run much longer than you before it aborted due to too short a time step. An even finer mesh might help, but dynamic, explicit is probably the best option with the level of non-linearity in the model.
Here's a picture of the model I ran the just used half a slab and the top roll.
RE: Rolling - no increase in strip's length
It seems to me, that I have to use a coupled temperature displacement model, because:
1) I have temperature dependent properties
2) I have temperature variation due to plastic work. Material deforms, then its temperature increases (it is applied by inelastic heat fraction)
3) There should exist the heat exchange between material and rolls (rolls temperature is a room temperature), but it does not work with roll defined as an analitical rigid body. Should I create roll as a deformable body with very big young's modulus (to simulate rigid body) in order to make heat exchenge possible?
The reference point is required only for applying restrains to it? Freedom 6 probably can by applied in Boundary Condition Manager. At least, if I type the displacement/rotation option and check the UR3, then in KEYWORDS I can see:
*Boundary
ReferencePoint_slab, 6, 6
So, I will add the freedom 5 to it.
The job started to abort after applying the generalized plane strain.
RE: Rolling - no increase in strip's length
RE: Rolling - no increase in strip's length
My aim is to obtain the elongation of the material.
At the moment I run many of simulations with various parameters (different step, element type, speeds, etc.) to do that. There are also no coupled temperature displacement models. Additionaly in some cases I have turned off the material's speed BC and I positioned the material in such way, that it is in contact with the roll at the beginning. The roll should pull it.
Here is the screenshot from my excel sheet with my models description:
These simulations are running at the moment. The problem is that it takes a long time - a few hours in the best case.
I have noticed, that when initial thickness of the material was higher, the simulation takes minutes.
My material dimensions are as follow:
Length = 130 mm
Thickness = 2 mm (so it is 1 mm in model with Y-symmetry)
Roll diameter = 400 mm
Here is my assembly:
I have a mesh consisting of 8320 elements. There is no reduce in simulation time, when I cut the number of elements below 1000.
Is there a way to speed up the simulation with such material thickness?
RE: Rolling - no increase in strip's length
RE: Rolling - no increase in strip's length
After about 15 simulations with various parameters I realized, that only EXPLICIT with plane strain elements was succesful. I obtained the elongation. I think that if I do not apply the expansion coefficient to material, then I do not need the generalized plane strain elements (error appears when I apply them).
So, at the moment I will realize my target model and if some bugs appear, I will ask you for help.
Thanks, corus.