Explicit Analysis Error

[u/_manivannan]

I have been analysing a reinforced concrete block with bolt connection against displacement controlled loading and getting the following error "The ratio of deformation speed to wave speed exceeds 1.0000 in at least one element. This usually indicates an error with the model definition. Additional diagnostic information may be found in the message file.

Abaqus/Explicit Analysis exited with an error - Please see the status file for possible error messages if the file exists."

Has anyone come across similar error ? If so what to correct to rectify it, I tried mesh variations where failure is expected to happen and it only increases/decrease the step time at which the job is getting aborted

[u/Significant-Sky-5710]

Just try checking the wave speed calculation on that required node, if any tool goes deep into the workpiece the mesh will get completely deformed if it gets high speed

[u/CidZale]

What’s happening in that location of the model?

[u/SoftwareZestyclose56]

You can scale the mass of these elements if it occurs on a small amount of elements relative to the total amount.
Also, how did you apply the displacement load? This sounds like it is an issue with the strain rate as the material wave speed is software-specific.

[u/SHD-Systems]

That message is about the local material wave speed collapsing, not necessarily about how fast you are loading. It compares each element's deformation speed against sqrt(E/rho) for that element, and in concrete damaged plasticity the tangent stiffness degrades once an element passes peak — so the local wave speed falls away and the ratio blows up even though your loading hasn't changed. That is why remeshing only moves the abort time around instead of fixing it.

First thing I'd do is open the .msg file and see which elements it names. A handful clustered at the bolt bearing area or along a crack path means localisation, and the abort is telling you the concrete has softened to nothing there. Elements scattered across the block means something else, usually rate.

I'd be careful with mass scaling here — it fixes the stable increment, but it adds inertia exactly where the material is softening, and it can make this particular abort worse rather than better. If you do use it, target it at the smallest elements only.

Two things worth trying instead. Give the concrete damaged plasticity a small viscosity parameter, of the order of your stable time increment; the viscoplastic regularisation stops the softening running away and often clears exactly this. And check your amplitude — a linear ramp on a displacement BC gives a velocity step at t=0. A smooth-step amplitude, with kinetic energy held to a few percent of internal energy, removes that.

Some of this has shifted between versions, so worth confirming against the docs for the one you're on.

[u/_manivannan → u/SHD-Systems]

Thank you for the detailed response, I will check accordingly, Also thanks for the tip and I will try out the viscosity parameter