Error message.

[MadEng]

I am new user of abaqus and need help.
I am modeling the unstable failure of a pillar under load control. i used abaqus explicit dynamic. I got this error message " the ratio of deformation speed to wave speed exceeds 1.0."

I checked the units several times, i believe no problem with the units.

Could you please help me.
Thanks

 

[Dave442]

Hi MadEng,

When an element deforms faster than a stress wave can propagate across it, the explicit solver will blow up and give you that error. If you are happy with your units you should check your mesh for excessively small or badly distorted elements. You should then check the definition of your material models to make sure that they have been set up correctly. In particular, make sure that the density of your materials has been specified correctly. Finally, you should check the definition of your loads and boundary conditions. Have you increased the rate of loading or applied an excessive amount of mass-scaling? You should also check out any warning messages you might have received before the solver blew up.

Good luck,
Dave

 

[MadEng]

Thank you Dave very much. I checked the mesh and it works.

I have another question for you.
I want to apply the total load on 3-steps, where in the first step 30% of the load will be applied, while in the second step 50% of the total load will be applied, and in the third step 20 % of the load will be applied.

When i did that ( apply the load on 3-steps) i got this error message : the elements contained in element set ErrelemExcessDistortion - step2 have distorted excessively. While when i apply the total load on [one step] i do not find any problem.

Do you know what might be the problem?

Thanks

 

[Dave442]

Hi MadEng,

Sorry, I don't really know anything about your model so its impossible to say why you get this error.

However, make sure you have applied your loads correctly. You could avoid using three separate load steps by incorporating the *AMPLITUDE function which is described pretty well in the manual. Also, even though your analysis was terminated, you should open the .odb database in ABAQUS/Viewer in order to see what the deformed structure looked like prior to termination. The solver even creates an element set called "ErrelemExcessDistortion" which you can plot in order to view the problematic elements. This should help you figure out your problem.

Good luck,
Dave

 

[MadEng]

Thank you so much for your answer.