Dear Dr. Michael Okereke， Thank you for uploading this RVE. Still wish you would give a video on how to do 3D RVE periodic boundary conditions. My concern is if the displacement boundary condition is good enough to predict the strain strength curve, especially it is related to the multiscale approach. In other words is this enough to predict upper-scale modeling material properties?
Thanks for your query. I am not ready yet to start teaching and making videos on the 3D RVE. I need to find an easy way to teach this as the maths behind it can be quite challenging. I also want to get a software that can make this easy ready for public release before making the videos. This is what is holding me back. On your second question, the Dirichlet BC approach I used here is still suitable to predict homogenized (macroscale) properties. This falls in the area of computational homogenization. If you choose RVE right, apply appropriate boundary conditions, then homogenized properties extracted from the model will be representative of what you describe as upper-scale modelling material properties. So, you can use the strategy shown here with confidence.
@@MichaelOkereke Thank you for your reply. I have already seen that video, and in that video, you have only discussed elastic properties. Actually, I want to know about the ductile damage, fracture behavior, and hardening properties of metal matrix composite.
Dear Dr Okereke, Thanks you again for the great informative videos. I had a question; If I want to do damage and plasticity in the RVE using this Drichlet approach (if I don’t mistake like polynomial loads), is it possible to give the ductile damage properties and simulate the RVE? Thank you for your time and help.
Of course, you can undertake the RVE study with the Dirichlet approach. This is the most common way of running this sort of microscale simulations. What you need is to include the plasticity with a ductile damage polymer model (capturing the behaviour of the matrix). I typically use an elastoplastic material model, as it is quicker to use and the easiest to understand to the lay person who I tend to reach to with my videos. For more advanced users, polymers are typically modelled using the Drucker-Pragers yield criterion. This is because for such ductile materials that experiences yield, you need a criterion to instruct the simulation that damage (or more appropriately yielding) has commenced. If you search in literauture on say Google Scholar, you can find papers that give you parameters for the Drucker-Pragers yielding for an epoxy material. Here is one I found quickly: doi.org/10.1016/j.proeng.2015.12.622
I actually did not use PBC in this case. It is a simple Dirichlet Approach where I contrain a face to a reference point. I can see why someone might think it is PBC but no, it is not. If it were to be PBC, then you will have corresponding parallel and opposite faces having the same displacement. This is not what is done here.
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Dear Dr. Michael Okereke， Thank you for uploading this RVE. Still wish you would give a video on how to do 3D RVE periodic boundary conditions. My concern is if the displacement boundary condition is good enough to predict the strain strength curve, especially it is related to the multiscale approach. In other words is this enough to predict upper-scale modeling material properties?
Thanks for your query. I am not ready yet to start teaching and making videos on the 3D RVE. I need to find an easy way to teach this as the maths behind it can be quite challenging. I also want to get a software that can make this easy ready for public release before making the videos. This is what is holding me back.
On your second question, the Dirichlet BC approach I used here is still suitable to predict homogenized (macroscale) properties. This falls in the area of computational homogenization. If you choose RVE right, apply appropriate boundary conditions, then homogenized properties extracted from the model will be representative of what you describe as upper-scale modelling material properties. So, you can use the strategy shown here with confidence.
please make a video on particulate reinforced metal matrix hybrid composite with elastoplastic behavior to calculate the effective UTS of composite.
I did already in this video, not sure if you saw it:
ruclips.net/video/iNdFo5xwStI/видео.html
@@MichaelOkereke Thank you for your reply. I have already seen that video, and in that video, you have only discussed elastic properties. Actually, I want to know about the ductile damage, fracture behavior, and hardening properties of metal matrix composite.
Dear Dr Okereke,
Thanks you again for the great informative videos.
I had a question;
If I want to do damage and plasticity in the RVE using this Drichlet approach (if I don’t mistake like polynomial loads), is it possible to give the ductile damage properties and simulate the RVE?
Thank you for your time and help.
Of course, you can undertake the RVE study with the Dirichlet approach. This is the most common way of running this sort of microscale simulations. What you need is to include the plasticity with a ductile damage polymer model (capturing the behaviour of the matrix). I typically use an elastoplastic material model, as it is quicker to use and the easiest to understand to the lay person who I tend to reach to with my videos.
For more advanced users, polymers are typically modelled using the Drucker-Pragers yield criterion. This is because for such ductile materials that experiences yield, you need a criterion to instruct the simulation that damage (or more appropriately yielding) has commenced. If you search in literauture on say Google Scholar, you can find papers that give you parameters for the Drucker-Pragers yielding for an epoxy material. Here is one I found quickly: doi.org/10.1016/j.proeng.2015.12.622
What is the difference between with and without PBC
I actually did not use PBC in this case. It is a simple Dirichlet Approach where I contrain a face to a reference point. I can see why someone might think it is PBC but no, it is not. If it were to be PBC, then you will have corresponding parallel and opposite faces having the same displacement. This is not what is done here.
Thank you for your response
So in which case we need to use the PBC not the Dirichlet BC
If you have a mechanism for implementing 3D PBC, then you can use it. It would normally be for heterogeneous microscale RVE as here.