Theoretical Study Case in Abaqus

[Batzo]

Hi, Before my study , I want to verify 2 different experiments of concrete slabs subjected to blast. Concrete behavior is dependent on strain rate.

I am using CDP, and i know I have to get the force-displacement curve for verification.
In each experiment I need to find it's strain rate - how do I do that? I just try different values of strain rates?

And then,
I have 2 different experiments so I have different strain rate for each experiment.
I'm asking which VALUE of strain rate should I go with in my study case? because mine is theoretical.

 

[FEA way]

In Abaqus you can define the dependence of material properties on strain-rate. But if you don’t know these values then you can only make an initial guess and adjust the data iteratively until the results from simulation are close enough to reference values. It might take some time but that’s probably the only way to calibrate the model without necessary data.

 

[Batzo]

Ok
But, if I get one strain rate and i want to verify the other experiment, the strain rate will be different. Right?

 

[FEA way]

It depends on the differences between these 2 experiments. If the same material is tested but subjected to different loading conditions then you can use both physical tests to calibrate the same model in Abaqus.

 

[Batzo]

Same material is concrete, not the same concrete strength and not the same loading conditions. It will work?

Second, how do I know which one of strain rates to choose in my theoretical study case?

 

[FEA way]

In such a case you will have to make two models and calibrate them separately based on these two experiments.

For clarity, let me explain the meaning of strain rate in Abaqus (and generally in simulations). What you have to define for the analyses is the dependece of various material constants on strain rate - you just fill tables where material properties are given for each value of strain rate. Then these properties will be used during the simulation depending on the rate of loading. You can plot current strain rate values for each frame as field output in Abaqus.

I recommend you to start from single element tests to fully understand these dependencies.