I am new to the Dusseldorf Advanced Material Simulation Kit (DAMASK). I want to carry out crystal plasticity simulation of a High Entropy Alloy (Predominantly FCC). I was thinking of checking the change in twinning fraction with respect to changes in strain rate. However, I am unsure whether the dislocation based crystal plasticity model is suitable for high strain rate. If it is not applicable, can any subroutine be written to incorporate a model suitable for the same? I will be grateful if someone can point me in the correct direction.
Dear Abhishek,
in general, the model is strainrate-dependent so you can investigate effects of higher strain rate.
The question is than what do you mean by 'high'? DAMASK simulations are usually quasi-static, so there are no inertia effects considered in the constitutive law and in the solution to the mechanical boundary value problem.
best regards,
Martin
Thank you Dr. Diehl. It makes things clearer. I was hoping to carry out simulation in a strain rate about of 1000 s-1. However, inertial effects in that range would be hard to ignore. What can be the maximum strain rate range below which micro-inertial effects are sufficiently small enough to ignore? Thank you again.
Dear Abhishek,
strain rates up to 1000 /s should not be too much of an issue regarding inertia (of course you might have to correct your experimental data for inertia effects, depending on how they were obtained). It also depends on how you are using the code: stand-alone or embedded in an FEA (in the latter, inertia effects would normally be included on the FEA level). I have myself had very good results with the Los Alamos VPSC code for strain rates up to 2000 /s without taking into account the inertia effects (to simulate the competition between slip and twinning in Ti6Al4V). DAMASK should be the same (or even better, as VPSC does not have an explicite way to take strain rate into account in most of its algorithms which DAMASK normally does).
Thank you Dr Coghe for your response. Your insights are very valuable. I have now a better idea about how to move forward.
Dear Abhishek,
In quasi-static and dynamic regimes (not shock regime), there are two main categories of strain rate dependence of the material response: 1) instantaneous strain rate dependence of the yield/flow stress (the viscous drag); and the other is 2) strain rate dependence of the strain hardening rate, which is due to non-zero strain rate sensitivity of various diffusion-controlled dislocation processes.
The first one is considered in the DAMASK's dislotwin constitutive model but the latter unfortunately not yet.
Since the overall strain rate dependence is affected by these two almost-independent rate sensitive responses, then one can argue that the model still requires some work with regard to its rate dependence features. Particularly, in case of TWIP steels where the diffusion-controlled dynamic strain aging (dislocation pinning process) associated with negative strain rate sensitivity of strain hardening rate, is dominant in room temperature.
Regards,
Amir
I have installed the DAMASK successfully with the help of the Internet. However, there is no specific tutorials about how to carry out a simulation. I have read all the Documentation from the website(https://damask.mpie.de/), but still do not know the complete and specific analysis procedures. If there is any step-by-step simulation tutorials, that will help me a lot. Thanks a lot!
Zhengwei Fan Hi. You can try running the example problem in the documentation first. That will give you an idea on how to proceed with similar problems. It takes a little time to get used to it.
You will also need Paraview to visualize your results.
Hi Abhishek ,glad to know someone working in the same area as mine ,i have developed an Abaqus UMAT for high strain rate upto 1000/s taking dislocation slips as the predominant mechanism and the experimental result on pure fcc alloy Al single crystal are matched well ,i have not taken inertia effects and nor do i used DAMASK package ,i am thinking to use it as well and work in high strain rate in HEAs ,can u tell me your gmail to connect further with you ?
Hey Harshdeep Sharma , thanks for reaching out. I have currently moved on from the DAMASK CP work to meso-scale modeling work. You can reach me at [email protected]. However, DAMASK is still one of the best CP open source code out there. You may also try to combine DAMASK with ABAQUS, if you are interested to do use FE solver instead of spectral solver, especially if your geometry and BCs are non-periodic. Spectral solvers are constrained to applications with simple geometries.
hello, i am also want to simualte the deformation for high strain rate up to 1000/s using DAMASK,but i don't know how to set the load file? thanks for anyone can help me to deal with this problem.