Problem in Solver

[Sri Harsha]

Hello,

I am using a Material 1.4404 in my analysis.
Along with the Youngs Modulus,density and poisson ratio, I am also defining Johnson Cook(also strain rate dependency) Plastic hardening parameters:

Following are the values used:

A = 514
B = 514
C = 0.042
n = 0.508
m = 0.533
strain rate = 0.001

After running the simulation,I am getting the following error:
1)THE STRAIN INCREMENT HAS EXCEEDED FIFTY TIMES THE STRAIN TO CAUSE FIRST YIELD AT 44 POINTS

I have been trying to analyse it, but could not find any solution till now.
Waiting for some update from anyone

Thanks in advance!

 

[Dave442]

Without any real info about your analysis I would suggest to check for consistent units.

 

[Sri Harsha]

Hi Dave,

I have tried to maintain all the units in mm
So,I am sure that all units are consistent

I am using the following material values:

Youngs Modulus: 193000 (in MPa)
Poissons ratio - 0.3
Density - 8e-9 (Tonne/mm3)

A = 514 [Mpa]
B = 514 [Mpa]
C = 0.042 [Dimensionless]
n = 0.508 [Dimensionless]
m = 0.533 [Dimensionless]
strain rate = 0.001 [Dimensionless]

I am also attaching my model with boundary conditions and load below.Would be really glad if you can help me in resolving this issue.
Please let me know if you need any other details to analyse the situation.
Thanks in advance!

 

[Dave442]

Its hard to tell much from your image. Some questions:

-Are you running this in standard or explicit?
-Does your analysis terminate? or is the error you mentioned just a warning message?
-Do you get any other warning/error messages?
-What does your mesh look like - can you verify the mesh to check for warnings or poor aspect ratio?
-the load you apply to your structure - have you used consistent units for that too?

 

[Sri Harsha]

Hi Dave,

Thanks for your reply again.

I have noticed the following errors:

1) 423 elements are distorted. Either the isoparametric angles are out of the suggested limits or the triangular or tetrahedral quality measure is bad. The elements have been identified in element set WarnElemDistorted.
2) The strain increment has exceeded fifty times the strain to cause first yield at 2275 points

I think,the first error will be resolved by proper fine meshing.
Also,my simulation is working fine for loads upto 100N. I am actually applying load/Node for my simulation.

Can you suggest some other mechanism for applying the load and fixing the other end? I just want to perform a tensile test.

Waiting for your reply

 

[Dave442]

It sounds like your mesh might be the problem. You can plot the element set "WarnElemDistorted" to investigate further and identify if/where your mesh needs to be refined. In terms of loading conditions - its hard to tell from your image. Have you fully constrained the nodes at the base of your structure? If so I would change that to something more realsitic. Also, if the loads at the opposite end of your model are symmetric you could exploit symmetry to reduce your model size significantly.

Have you done any testing? If so how was the structure loaded/constrained in the test?