It helps a lot :)!!!

I will do try this!

Thank you very much for you help :D!

El viernes, 23 de octubre de 2015, 13:28:10 (UTC+2), Robert Cimrman escribió:

El viernes, 23 de octubre de 2015, 13:28:10 (UTC+2), Robert Cimrman escribió:

On 10/23/2015 12:39 PM, Patricia Garcia Cañadilla wrote:

> Dear Robert,

>

> Yes :), it would be nice if we could easily implement this in sfepy

> by modifying fibre_function i and creating a new term very similar to

> FibresActiveTLTerm. I am very new in this field, so could you give me some

> key starting points on how to do it?

Sure:

1. make a copy of FibresActiveTLTerm (-> FibresActive2TLTerm (better name?))

and fibre_function() (-> fibre_function2() (better name?)) in the same file.

2. modify the attributes of the new class:

- name (dw_tl_fib_a2?)

- arg_types, arg_shapes - add kappa

3. add the new material argument also to .get_fargs()

See also [1] but do no worry - here it is just the above.

[1] http://sfepy.org/doc-devel/developer_guide.html#how-to- implement-a-new-term

Then you would need to compute the rate of the fibre deformation eps. The fibre

deformation is computed in fibre_function(), line 16. It might be better to

compute that directly in .get_fargs(), and store the current eps as self.eps0

in the class, to be able to get the rate as deps = (eps - eps0) / dt.

Then having eps and deps, update the new fibre_function2() to compute the

active tension (fmode == 0), as well as its derivative w.r.t. eps (fmode == 1),

just like it is done in fibre_function()

> Another quick question, is, regarding the first term in the expression of

> active stress which is "viscosity coefficient*strain rate", is what you

> refer when you said "creating a new term", and then the exponential term

> should be introduced by modifying the term_fibers?

Above I am talking about adding the "exp{k min(0;de/dt}}" to the exponential

term. FibresActiveTLTerm in sfepy is exactly the exponential term without the

"exp{k min(0;de/dt}}" part. But you can add also "viscosity coefficient*strain

rate" in there, so that the new term computes the entire relation (9). If you

manage to add there the exponential part, adding this is trivial. :)

Does this help?

r.

> Thank you very much!

>

>

>

> El viernes, 23 de octubre de 2015, 11:33:27 (UTC+2), Robert Cimrman

> escribió:

>>

>> Dear Patricia,

>>

>> On 10/23/2015 10:39 AM, Patricia Garcia Cañadilla wrote:

>>> Dear Robert,

>>>

>>> I would like to the model the viscoelastic behavior of active fibers, as

>>> you done in the paper: "Modelling heart tissue using a composite muscle

>>> model with blood perfusion" or as here:

>>>

>> http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1. 488.5795&rep=rep1&type=pdf

>> and

>>> I was wondering if is easy to implemented in sfepy and/or if there is

>> some

>>> predefined term in Sfepy, since for example the term "dw_tl_fib_a"

>> doesn't

>>> include the "exp{k min(0;de/dt}}" that appears in the paper.

>>

>> The model from the "Modelling heart tissue using a composite muscle model

>> with

>> blood perfusion" paper would be pretty easy to add, yes. It would involve

>> modifying fibre_function() in sfepy/terms/terms_fibres.py and creating a

>> new

>> term very similar to FibresActiveTLTerm. Would you give it a shot? :)

>>

>> As for the cardiac model, it would certainly be possible to implement

>> those

>> fibres in sfepy, but not that easy - the model is quite complex. The

>> biggest

>> issue are the internal unknown variables (the contractile element

>> deformation

>> epsilon_c), that evolve in quadrature points - those are not supported

>> (yet).

>>

>> r.

>>

>