I'm opening this topic to share with you a simulation problem. I don't have access to the simulation modules yet and I'm trying to find out which ones to acquire to carry out the simulation I want as well as how to simulate all this (in broad strokes).
So there you have it.
I have a tubular mechanical element made of nitinol, so it is deformable and returns to its initial shape when you stop constraining it. The purpose of this element is to be deployed in a pipe to keep it open by exerting a radial force against the pipe. When the tube is pressed and then inserted into a pipe with a smaller cross-section, it will open and exert a radial force because the mechanical element will not yet have reached its unstressed form. Basically, he will exert a restoring force to try to regain his form which will depend on his current section. It should be noted that the mechanical element is not linear, the force exerted for the closing of the tube is not the same force exerted by the opening of the tube.
While doing some research, I haven't yet been able to figure out how to simulate the restoring force of the mechanical element . Anyone have an idea how to do this and which module I will need?
In order for us to be able to answer you within the framework of the rules of this forum: would you be so kind as to fill in your profile exhaustively.
Thank you for your message Zozo_mp, your message was very complete and allowed me to realize the potential difficulties.
The element in question is a stent inserted into a blood vessel. What interests me is the opening force of the stent which is different from the force of closing. It is therefore a very small element and exerts a force that is also small.
You would have to have a file with the stent deformed and then find a way to apply a radial force.
There are several types of Stent so !!! Do you have the part file of the stent In addition, it would be necessary to obtain the precise characteristics of the material to be able to create it in solidworks
In the library of materials, Nitinol is not included.
To answer your first question, it is possible to use a Nitinol material model in the SOLIDWORKS SIMULATION Premium package by performing nonlinear studies.
Nitinol is a model of materials apart with a particular law of behavior that does not require a good characterization of your material to carry out your study.
Putting this type of study into data can be tricky.
In your case, you will have to do a study that starts by crushing the stent in order to generate the internal constraints and then releasing it so that it partially returns to its "free form" in order to be able to solicit it to make it inflated.
In fact, Stent stents are not crushed, but stretched at each end. It is composed of a circular zigzag structure, repeated N times and zigzag element is connected with its neighbor by small Nitinol threads. So once the stent stretches naturally as the "auxetic structure" is naturally decreasing in diameter. Once in place, you release the pull at both ends and like a wave spring from Smalley (or Borrely ondufil) it returns to its original shape.
Since I am not asked for my opinion on a solution other than simulation with a "hypercherware simulation" and since you and I have answered the initial question , I consider that the subject can be closed. ;-) ;-)
Thank you for your answers. This gives me a better insight into what was possible with Solidwork.
To answer the question of Nitinol. I have all the mechanical parameters of the material thanks to a manufacturer's sheet. For the stent I have indeed the part modeled by me.
Just a quick additional question in response to your answers. If I summarize the idea, by applying a radial force I will deform the stent in my simulation. When I remove this force in question, the stent will return to its original strength and at that point, I could get the reopening forces with Solidwork simulation. Do you think this whole process is feasible and reliable with the Premium version?
I am sorry, but I do not share the way you want to proceed, or rather I do not follow you in your reasoning.
You say ( sums up the idea, by applying a radial force I will deform the stent in my simulation. When I remove this force in question, the stent will return to its original strength and at that point I could get the reopening forces with Solidwork simulation.)
If it's a Stent, as I said before, we don't work by a radial crush but by an axial stretch. The only thing you could measure relatively easily is the effort required to lengthen the stent. Using the traction points provided by the stent supplier. So if you need 20 grams of axial traction, you will know that this energy stored in a certain way will be restored.
I am not a specialist in stents and there may be several methods including "torsion traction" or "torsion only" to reduce the diameter of the stent.
In any case, what you won't know is the radial pressure exerted on the vein or other piping of a living being because not everyone has the same flexibility of the tubing.
If I had to solve this problem, I would first work in a workshop (sorry lab) and I would measure with a suitable tool the compressive strength of the stent when it is released and is supposed to rest entirely on the wall. So, if you are working with relatively small sections, you could, by knowing the full forces of the different sections, know the radial pressure exerted on a tube.
As for whether you can really use SOLIDWORKS SIMULATION Premium to do what you want, namely " " "get the reopening forces" " I leave it to @lmandon to answer because I don't have the software indicated, nor surely the training enough to use it in such conditions which may be sporty even on a reduced section.
Unfortunately, to come back to your suggestion of laboratory tests, they are not feasible, hence the desire to carry out a simulation.
However, it is possible for me to stretch my stent, with quantitative data to support it. I'm going to explore that idea. I'll leave this topic open for a few days if someone can give me some information about Solidworks' ability to provide reliable information in the way you stated.
Solidworks always provides reliable information: if there is an error, it always happens in the chair-keyboard interface.
I suggest you think backwards (which I've been quietly suggesting for a while).
I told you about the wave springs (CF the constant effort) because it's the closest thing to a Stent because nitinol is not everything. The form also plays its role (cf. auxetic structures). So thinking upside down means that the force to stretch it is equal to the force to return to the resting position. It must be considered that when the stent is in an expanded position, it does not have quite its maximum strength. But it is easy to measure progress by doing a simulation scenario. You can do let's say 10 successive studies by duplicating them and changing the axial force parameter each time (you can run the 10 or 20 studies at a time) Solidworks allows you to make a number of reports that should provide you with the information you are looking for.
I even think that it is possible to make phantom parts (quarter torus) of a few tenths thick and to put a radial force oriented towards the axis with the "spring" function as a counterforce. So you can know the forces exerted on the equivalent of the vein with the standard SW ratios. This method is the one that is closest to what you were originally looking for (and that I have already suggested to you ;-) ) it also allows you to do the equivalent of what would be possible to do in the workshop, a solution that you apparently cannot retain.
One last point not to lose sight of. Nitinol allows the surgeon to stretch the stent axially to the maximum to facilitate passage and placement. For this we use the "plateau phase deformation of plasticity" but as this is done almost at constant force this is of no use to know the force of separation of a vein for example. This is where the scenarios are interesting because you can get a glimpse of the beginning of the plateau phase by means of a precise axial tensile force and sequence. Only the beginning of the deformation curve has a therapeutic interest beyond that (from the beginning of the plateau phase) it serves the Chir but not the patient.