Thank you for the detail explanation. But, how can I incorporate nonlinear hardening instead of linear hardening? At 7:41, the derivative of function 'f' w.r.t 'Δp' would not be (-3G-H) for nonlinear hardening. For example: derivative of linear hardening (HΔp) is 'H' but for power hardening law [H(Δp)^n], its derivative would contain Δp itself. Should I replace 'H' with [n*H(Δp)^(n-1)] in 'dΔp' expression and solve accordingly? I am not sure if you got my point or not. I hope you would provide some help and suggestions. Thank you again. Waiting for the response...
Hey. I tried to implement it in a matlab code. I want to silmulate a uniaxial tensile Test. After the first plastic step i get a little stress in the 22 and 33 component of the stresstensor. this false components are then go into the new trial stress and over several loops add up to a very false result. what do you think i did wrong?
Hi, thank you very much for these explanations ! One question though, how come the deformation increment is an input to the algorithm, when it depends on the deformation at step k+1? And tell me if I'm wrong, but it seems to me that this algorithm is not compatible with an explicit approach, given the sub-iterations required to calculate the plastic deformation increment.
First about the implicit solver, in each increment several predictions and corrections for the final displacement happen, named as iteration. In each of these predicted displacements the UMAT is called and the stress is calculated. Please see this video to understand the implicit flowchart better. th-cam.com/video/GDGcNWRCG5M/w-d-xo.htmlsi=iudM-PHv31iCZx_8 The explicit is totally different and we will discuss its algorithm and differences of UMAT and VUMAT in future videos.
This is a sound informative vídeo, thank you for the effort. Could you explain how this algorithm changes if the flow stress is expressed as a function that depends on plastic strain, plastic strain rate and temperature, such as Johnson-Cook?
Dear David, writing the mentioned UMAT requires studying complicated relationships and numerical implementation of them which can not be explained in comments.
A correction at 1.49 .. the trace of plastic strain tensor is not zero.. however, the trace of plastic strain rate or incremental plastic strain tensor is zero.
thank you very much for this course, im a PhD student and you guys are helping me a lot during my work
Thank you for the detail explanation. But, how can I incorporate nonlinear hardening instead of linear hardening? At 7:41, the derivative of function 'f' w.r.t 'Δp' would not be (-3G-H) for nonlinear hardening. For example: derivative of linear hardening (HΔp) is 'H' but for power hardening law [H(Δp)^n], its derivative would contain Δp itself. Should I replace 'H' with [n*H(Δp)^(n-1)] in 'dΔp' expression and solve accordingly? I am not sure if you got my point or not. I hope you would provide some help and suggestions. Thank you again. Waiting for the response...
Thanks to Engineering Software team for really informative and helpful content.
If possible, plz produce content about fracture mechanics.
Hey. I tried to implement it in a matlab code. I want to silmulate a uniaxial tensile Test. After the first plastic step i get a little stress in the 22 and 33 component of the stresstensor. this false components are then go into the new trial stress and over several loops add up to a very false result. what do you think i did wrong?
Great explanation... Kudos to your presentation and explanation.
Hi, thank you very much for these explanations !
One question though, how come the deformation increment is an input to the algorithm, when it depends on the deformation at step k+1?
And tell me if I'm wrong, but it seems to me that this algorithm is not compatible with an explicit approach, given the sub-iterations required to calculate the plastic deformation increment.
First about the implicit solver, in each increment several predictions and corrections for the final displacement happen, named as iteration. In each of these predicted displacements the UMAT is called and the stress is calculated. Please see this video to understand the implicit flowchart better.
th-cam.com/video/GDGcNWRCG5M/w-d-xo.htmlsi=iudM-PHv31iCZx_8
The explicit is totally different and we will discuss its algorithm and differences of UMAT and VUMAT in future videos.
Thanks for your answers! Looking forward to the next videos ;)
Very good video, It helps me a lot. Thank you.
This is a sound informative vídeo, thank you for the effort. Could you explain how this algorithm changes if the flow stress is expressed as a function that depends on plastic strain, plastic strain rate and temperature, such as Johnson-Cook?
Dear David, writing the mentioned UMAT requires studying complicated relationships and numerical implementation of them which can not be explained in comments.
Hi David - Did you mange to get it sorted - if yes could you share as I also need similar kind of coding for Hensel spitel models please
thanks for this nice video
A correction at 1.49 .. the trace of plastic strain tensor is not zero.. however, the trace of plastic strain rate or incremental plastic strain tensor is zero.
Trace of 'Plastic Strain Tensor' and its rate or increment all are zero. That is the incompressibility rule of plastic deformation.