Sawtooth patterned PEEQ-Time plots for nodes at contact. What can be the cause of this?

[husgutt]

Hello!

I'm modelling a ball that indents a plate. When I plot PEEQ / Time curves for the nodes at contact, some nodes have a sawtooth pattern.

It looks like this

| /\/\/\/\/\/\/\
P| /\/
E| /\/
E| /\/
Q| /\/
| /\/
|___/____________________________
TIME

I have displacement controlled general static analysis.

Anyone seen anything like this before?

Thank you for your input!

 

[husgutt]

I can't figure out how to edit my post:


'| ''''''''''''''''''/\/\/\/\/\/\/\/
P| '''''''''''''''/\/'''''''''''''''
E| ''''''''''''/\/''''''''''''''''''
E| '''''''''/\/'''''''''''''''''''''
Q| ''''''/\/''''''''''''''''''''''''
'| '''/\/'''''''''''''''''''''''''''
'|___/______________________________
''''''''''''''''TIME''''''''''''''''

 

[burningDiesel]

If I understand your ascii art correctly, you are plotting an element output (PEEQ) at nodal locations. This means you have 3, 4, 6 or 8 values at that node (1 for each element). If you plot the value at integration point level, you will only have 1 curve and no sawtooth pattern. If the jumps are big, your mesh is probably not refined enough.

 

[husgutt]

Ok, I will try this!

What is confusing me is that some nodes the same, and other regions, respond continuously.

Below is an updated attempt at med ascii art! ( )

(How does one edit posts?)

'''| '''''''''''''''''''''''''''''''''''/\/\/\/\/\/\/\/
'P| '''''''''''''''''''''''''''''/\/'''''''''''''''''''''''''''
'E| ''''''''''''''''''''''''/\/''''''''''''''''''''''''''''''''
'E| '''''''''''''''''''/\/'''''''''''''''''''''''''''''''''''''
Q| '''''''''''''''/\/''''''''''''''''''''''''''''''''''''''''''
'''| '''''''''/\/'''''''''''''''''''''''''''''''''''''''''''''''
'''|___/_____________________
''''''''''''''''TIME''''''''''''''''''''''''''''''''''''''''''


Thank your for your help!

 

[burningDiesel]

You can't edit posts, you can upload images though. The ones that are continuous probably aren't when you zoom in. It just means that there, your mesh is small enough to capture the stress gradient.