Mekanikal4
Mechanical
- Oct 12, 2013
- 1
Hi
I'm trying to get to grips with Abaqus. It is used at work by perhaps 2 people in the entire company and with possible contracts coming up I'm trying to get competent with the use of the software. So far I have analysed simple bar elements and a truss so far.
I've been working on the 'Plate with hole' example but there are several things I'm struggling to understand. It appears I've misunderstood some extremely fundamental concepts. The problem I'm having is finding information on any the bits I'm struggling with.
First of all, I've modelled a quarter of the plate (top RHS) and applied a load (3kN) in the 2 direction (vertical). I used element type CPS4 in this analysis. After generating results, I've made graphs of S11 and S22 along the 1 axis (horizontal). I had no reason to think there was anything wrong with what I saw until I read online something to do with that the Normal stress at the node at the edge of the hole and the node at the edge of the plate should be zero. Something to do with nodes in free space. I have absolutely no idea about this. What I had thought was that the stress would be at its highest right at the edge of the hole. How or why would it be zero? I would be extremely grateful for advice on this. Also, any links to further info on this topic.
I then ran the same problem using element type CPS8R. Again, I plotted Normal stress in 1 and 2 direction against distance from the edge of the hole. The graphs are different to the CPS4 run. The stress still doesn't reach zero at the edge of the hole or edge of the plate. However, it is closer than the CPS4 run. I understand that's because there are more nodes in this analysis and that the stress at each node is averaged. But how come there's such a drastic difference (e.g. between CPS4 S11 graph and CPS8R S11 graph, see attachment). If they shouldn't look like that, what should they look like? If I really wanted to get the nodes at either end to equal zero, how would I achieve this? Or is that impossible?
I have attached my graphs to demonstrate what I have produced.
I would greatly appreciate any advice. The whole zero stress at the end nodes and free space really confused me. I apologise if this comes across as extremely trivial, I'm learning...slowly.
Cheers.
I'm trying to get to grips with Abaqus. It is used at work by perhaps 2 people in the entire company and with possible contracts coming up I'm trying to get competent with the use of the software. So far I have analysed simple bar elements and a truss so far.
I've been working on the 'Plate with hole' example but there are several things I'm struggling to understand. It appears I've misunderstood some extremely fundamental concepts. The problem I'm having is finding information on any the bits I'm struggling with.
First of all, I've modelled a quarter of the plate (top RHS) and applied a load (3kN) in the 2 direction (vertical). I used element type CPS4 in this analysis. After generating results, I've made graphs of S11 and S22 along the 1 axis (horizontal). I had no reason to think there was anything wrong with what I saw until I read online something to do with that the Normal stress at the node at the edge of the hole and the node at the edge of the plate should be zero. Something to do with nodes in free space. I have absolutely no idea about this. What I had thought was that the stress would be at its highest right at the edge of the hole. How or why would it be zero? I would be extremely grateful for advice on this. Also, any links to further info on this topic.
I then ran the same problem using element type CPS8R. Again, I plotted Normal stress in 1 and 2 direction against distance from the edge of the hole. The graphs are different to the CPS4 run. The stress still doesn't reach zero at the edge of the hole or edge of the plate. However, it is closer than the CPS4 run. I understand that's because there are more nodes in this analysis and that the stress at each node is averaged. But how come there's such a drastic difference (e.g. between CPS4 S11 graph and CPS8R S11 graph, see attachment). If they shouldn't look like that, what should they look like? If I really wanted to get the nodes at either end to equal zero, how would I achieve this? Or is that impossible?
I have attached my graphs to demonstrate what I have produced.
I would greatly appreciate any advice. The whole zero stress at the end nodes and free space really confused me. I apologise if this comes across as extremely trivial, I'm learning...slowly.
Cheers.