vyg29
Mechanical
- Nov 23, 2012
- 1
Hey everyone,
I'm a mechanical engineering grad student and for my research I'm working with ANSYS Classic (version 12.1). My research involves letting a structure of beams (a compliant mechanism) deform due to contact with another object. To get familiar with using contact elements in ANSYS I'm working on a small problem where I model just one straight beam with two contact points, and two target points on a circular arc. The beam is clamped in one end and has a point load applied to it on the other end.
After working on it for quite a while (weeks, unfortunately...) I was finally able to get it to converge and work perfectly, except that it takes far too long (>30 minutes for 1 run). I have to use this model for optimization, and right now it takes too long to do that. I need to have information (for example contact forces, deflections) over the entire range of motion, which is why I'm using a do/for loop.
So, my question is: could you perhaps take a look at the code, and see if there are things you'd recommend me to do differently? I feel that I'm missing something, but I just can't figure out what.
What I've tried so far:
- Use only solve instead of load steps (faster, but does not converge)
- Use solve but have NSUBST increase a bit each loop
- Change the contact stiffness and penetration tolerance (both higher and lower, no effect)
- Decrease the total number of load steps (by increasing P_step)
- Decrease NSUBST
Now I know that usually one comment is that when you're using contact elements you should not have a gap, as that leads to rigid body motion and that can give problems. However, I know of quite a few people who have used ANSYS in a similar method and that worked perfectly, so it should be doable.
I hope this is a clear explanation, if not please let me know! Thank you for your time!
Valerie
I'm a mechanical engineering grad student and for my research I'm working with ANSYS Classic (version 12.1). My research involves letting a structure of beams (a compliant mechanism) deform due to contact with another object. To get familiar with using contact elements in ANSYS I'm working on a small problem where I model just one straight beam with two contact points, and two target points on a circular arc. The beam is clamped in one end and has a point load applied to it on the other end.
After working on it for quite a while (weeks, unfortunately...) I was finally able to get it to converge and work perfectly, except that it takes far too long (>30 minutes for 1 run). I have to use this model for optimization, and right now it takes too long to do that. I need to have information (for example contact forces, deflections) over the entire range of motion, which is why I'm using a do/for loop.
So, my question is: could you perhaps take a look at the code, and see if there are things you'd recommend me to do differently? I feel that I'm missing something, but I just can't figure out what.
What I've tried so far:
- Use only solve instead of load steps (faster, but does not converge)
- Use solve but have NSUBST increase a bit each loop
- Change the contact stiffness and penetration tolerance (both higher and lower, no effect)
- Decrease the total number of load steps (by increasing P_step)
- Decrease NSUBST
Now I know that usually one comment is that when you're using contact elements you should not have a gap, as that leads to rigid body motion and that can give problems. However, I know of quite a few people who have used ANSYS in a similar method and that worked perfectly, so it should be doable.
I hope this is a clear explanation, if not please let me know! Thank you for your time!
Valerie