hollow cylinder torsion modelling in ABAQUS by rotational displacement
hollow cylinder torsion modelling in ABAQUS by rotational displacement
(OP)
Hi,
I am trying to solve a simple hollow cylinder torsion problem in ABAQUS 6.7. Instead of applying a moment I'd like to apply the angle of rotation as a boundary condition to the surface at one end and get the resultant stresses. I first defined a reference point and then a coupling constraint between the RF and the surface that I wanted to apply the torque and then applied a moment on the RP. It works good.
Actually I don't have any idea of the amount of torque but I know the angle of rotation. So, I have to define a "displacement/rotation" BC to solve the problem. I followed the same procedure as when I'm applying a moment but it's not working. I rotate the cylinder 1 degree and the stresses are in the order of e-10.
Can anyone help me with this? Thanks.
I am trying to solve a simple hollow cylinder torsion problem in ABAQUS 6.7. Instead of applying a moment I'd like to apply the angle of rotation as a boundary condition to the surface at one end and get the resultant stresses. I first defined a reference point and then a coupling constraint between the RF and the surface that I wanted to apply the torque and then applied a moment on the RP. It works good.
Actually I don't have any idea of the amount of torque but I know the angle of rotation. So, I have to define a "displacement/rotation" BC to solve the problem. I followed the same procedure as when I'm applying a moment but it's not working. I rotate the cylinder 1 degree and the stresses are in the order of e-10.
Can anyone help me with this? Thanks.





RE: hollow cylinder torsion modelling in ABAQUS by rotational displacement
Rob
Rob Stupplebeen
RE: hollow cylinder torsion modelling in ABAQUS by rotational displacement
What are the stresses when you apply a moment? For the case when you apply a moment, you can output the rotation and torque from the reference node to the history data by requesting TM and UR. I would then apply this rotation in your case that is rotation driven and see if the stress levels are the same. (which for a linear elastic material they will be)
RE: hollow cylinder torsion modelling in ABAQUS by rotational displacement
corus
RE: hollow cylinder torsion modelling in ABAQUS by rotational displacement
The unit of rotation in Abaqus is radians. So when I apply 1 degree of rotation I convert it to radian (0.0174) and then I enter it in ABAQUS. I do the coupling for all 6 degrees of freedom between the RF and the surface.
When I apply a moment(100 Nm) the Von Mises stress is around 800-900 MPa for the material that I'm using (EN25 Steel). I give ABAQUS both elastic and plastic data. For this amount of torque the rotation on the outer surface is around 4 degrees. So for 1 degree of rotation I should get a considerable amount of stress (not 1e-10).
I also checked the displaced shape. There is no change in the geometry. Deformed and Undeformed shapes are exactly the same (It should be because the stress is almost zero). I have encastered the cylinder on the other end.
Please let me know if you can think of any solution to this problem.
RE: hollow cylinder torsion modelling in ABAQUS by rotational displacement
RE: hollow cylinder torsion modelling in ABAQUS by rotational displacement
Rob Stupplebeen
RE: hollow cylinder torsion modelling in ABAQUS by rotational displacement
I've attached the file to this message. Please have a look and see if you can possibly help me.
RE: hollow cylinder torsion modelling in ABAQUS by rotational displacement
(Sorry, can't open tars on this computer)
RE: hollow cylinder torsion modelling in ABAQUS by rotational displacement
RE: hollow cylinder torsion modelling in ABAQUS by rotational displacement
RE: hollow cylinder torsion modelling in ABAQUS by rotational displacement
Also, you should apply a zero displacement boundary condition to your reference node in all the other DOFs (U1,U2,U3,UR1,UR2).
For your kinematic coupling, only constrain UR3 (remove constraint from UR1 and UR2).
RE: hollow cylinder torsion modelling in ABAQUS by rotational displacement
In my kinematic coupling constraint if I constraint all degrees of freedom, then it works very well, but when I just constrain UR3 (as you said), it doesn't work (it is for the case that I'm applying rotational displacement). On the other hand, to get my model with applying moment to work, If I just constrain UR3 it works and otherwise it doesn't. Why is it like that?
RE: hollow cylinder torsion modelling in ABAQUS by rotational displacement
You shouldn't have to change the BC's and Constraints when switching from Rotation to Moment control. How are you applying the moment? You should apply it to DOF 6 (which is rotation about axis 3). In the input file, it should look like:
*Cload
<node set>,6,<magnitude>
RE: hollow cylinder torsion modelling in ABAQUS by rotational displacement
This is what is shows in the input file:
*Cload
_PickedSet22, 5, 100000.
Why is it 5?
RE: hollow cylinder torsion modelling in ABAQUS by rotational displacement
this what it shows in the input file:
*Cload
_PickedSet18, 5, 0.
_PickedSet18, 6, 100000
RE: hollow cylinder torsion modelling in ABAQUS by rotational displacement