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I would appreciate help choosing a software for the Finite Elements Method (FEM).

I wish to model items like ropes, bull whips and fishing rods. (I intend to transfer the model into bio-mechanics, later.) E.g. I wish to study how the force/torque/movement applied to the handle of a fishing rod spreads to the end of the fishing rod.

I am not primarily interested in different methods of constructing e.g. fishing rods, like "should they be round or hexagonal, solid or hollow". I am interested in how they work, how the force at the handle is transmitted to the bait during a cast, and similar questions.

Many recommend Code_Aster with Salome-Meca for "FEM problems in general". It seems very advanced, highly developed and "hot". (Some more advanced docs only in French, though.)

I got the suggestion to use MBDyn. It does not have a graphical interface. But it seems adapted to my task. (It considers the movement of multiple bodies and elasticity.)

There are also many other software packages.

I have never used FEM. I know it is often used to analyze structural tension in solid objects, the flow of gases and fluids and electromagnetic fields. But those applications are a little different from my applications. My application is more focused on the movement of connected elastic objects. (I wish to model the fishing rod as connected elastic objects.) From what I have seen so far, FEM is more about "static" tension, triangulation of "uniform" matter. But I am just guessing from examples here. I do not have experience of FEM.

I thought I would start with Code_Aster, but first I would appreciate to hear what members familiar with FEM think.

The program should run on a Windows home PC. (If "absolutely needed" I can also set up Linux dual boot, but I just removed it due to storage limitations.)

So far, this is only a private project so the cost is of concern. I could consider spending up to maybe $1000 if I knew that I got something which definitely did the job better. But to me it seems open source and software free of charge are highly developed in this area.

What software is best suited for my task?

Thanks a lot

EDIT 22/6: To summarize the question: How does a fishing rod move when the fisherman casts his bait? (The fishing rod is modeled as a series of segments, the rigidity/elasticity and weight differs in each segment. A description in two dimensions will suffice.)

nicoguaro
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cvr
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  • What really matters is the goals of your analysis. What question about the fishing rod do you need to answer with a model? This will determine whether you need Dynamic vs. Static Analysis, Linear Elasticity vs. Plasticity, Eigenanalysis vs. Stress Analysis, etc. The goals of your analysis will determine the type of solver that you need. Only from this can you determine which software will meet your needs. Without extremely specific goals, it's impossible to give advice. – Paul Jun 22 '14 at 17:12
  • Thank you. I am not able to describe my goal in the terms you give. I describe my goal like this: You connect many short segments of a rod with plate springs. You then exert torque on the first segments. What forces will act and what movements will the connected segments show? Solving these kind of equations analytically is complicated for only two segments, already. How can it be simulated? (I do not need to know if a segment will break due to overload.) – cvr Jun 22 '14 at 17:31
  • Just intuitively I would say it is Dynamic and not Static, it is Elastic, not Plastic. it is not Stress analysis. -- Put very bluntly: How does the fishing rod move when the fisherman casts the bait? – cvr Jun 22 '14 at 17:32
  • What equations are you using to model the rod? E.g. Elastodynamic Equations? Dynamic Euler-Bernoulli Equations? Something else? – Paul Jun 22 '14 at 18:59
  • Most GUI-based FEM packages for Windows are going to be commercial (e.g., ANSYS, COMSOL, Abaqus), and most open source scientific packages are going to be easier to build and install in a Unix-like environment (Linux, for instance). Sometimes, it's possible to build software with a Unix-like compatibility layer (mingw, cygwin) and some effort. – Geoff Oxberry Jun 23 '14 at 00:25
  • This wiki page has good list of FEM programs, free and commercial http://en.wikipedia.org/wiki/List_of_finite_element_software_packages – Nasser Jun 23 '14 at 02:13
  • Thanks Paul. Elastodynamic Eq. and Dynamic Euler-Bernoulli Eq. are highly relevant but part of an analytical solution I deem too complex for me. I have duplicated the solution for the Lagrange (Euler-Lagrange) for the double pendulum and simulated it. This solution could probably be modified to a two segment fishing rod. (The potential energy of the Lagrange goes into plate springs.) Including more segments would be too complex for me, though. – cvr Jun 23 '14 at 03:02
  • ... Already 2 segments become complex. For me I deem it impossible to continue doing this for many segments. --- I have therefore turned to FEM. As I understand FEM will approximate these equations for me. I only wish to enter a series of segments joined by plate springs (or a series of elastic segments). The segments only vary by their elasticity/plate spring constant and weight. I wish to study how this series of elastic elements/plate springs react to torque/movement. – cvr Jun 23 '14 at 03:03
  • Thanks Geoff and Nasser. I am chekcking out, but still hard to be sure which program will, most easily, simulate a rod consisting of segments of variable elasticity (simulated as stiff rod segments, joined by plate springs) and how this rod reacts to movement. – cvr Jun 23 '14 at 03:03
  • There is 3 bob pendulum simulation here that you also run: http://goo.gl/ECzlI9 you would need to have the Mathematica CDF plugin installed in your browser (it is free plugin) to run the app. But I think a FEM solution is best for what you want. – Nasser Jun 23 '14 at 03:25
  • I just saw your edit, How does a fishing rod move when the fisherman casts his bait?. I would start with a simple model. Use a cantilever beam with point load at end? http://en.wikipedia.org/wiki/Deflection_%28engineering%29#End_loaded_cantilever_beams The fish is the point load. This has an analytical solution. You can make the point load be f(t) to model a fish vibrating trying to escape. Use a simple harmonic forcing function. – Nasser Jun 23 '14 at 03:58
  • Thanks Nasser. Cantilever beam also very relevant. I will look into it. But to study the dynamics when the beam (gradually thinner at one end) starts to move (rotate around the thicker end) I think i still need computer simulation (FEM) with as simple input parameters as possible. I think that would be a chain (rod) of joined plate springs, each with different spring constant and weight. – cvr Jun 23 '14 at 04:10
  • But you have to remember that FEM only solves the spatial problem. To add time, one need an extra solver to solve for u^{t+delT} from u{t} found by FEM. Then apply FEM again in the new state for the next time step, and so on. This becomes a Dynamic FEM, which is a bit complicated than just static FEM. i.e. to add the time element. – Nasser Jun 23 '14 at 06:52
  • Thanks Nasser. That is very important. My problem is very much about dynamics. What I want to do resembles this, here done with MBDyn. What I am looking for are the softwares that have this capability. – cvr Jun 23 '14 at 07:23
  • There is a blender-interface for mbdyn: blender and mbdyn. – Tobias Jul 24 '14 at 07:42

3 Answers3

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if you need a program with 3D capabilities I would suggest Elmer, that provides a graphical user interface and is easy to use. If 2D capabilities are enough, I would suggest Agros that has a really nice GUI (better than most of commercial software) and its use is intuitive.

According to your description you can model your problem as a set of beams, and this can be done easily in most of the programs.

nicoguaro
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You can model a whip as a solid object (solids or beams) in FEA. You'll need a package that does dynamic(transient) response with nonlinear large displacements. The latter is important because the direction of the force would probably change as the whip bends. For a list of packages showing which support these features, see http://feacompare.com

doikel
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If this is an academic project and you are an university student then you could download student versions of commercial FEA packages like Hyperworks or ANSYS or ABAQUS for free. They have good tutorials to help you model your problem.

Pratronn
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  • It will be more constructive if the downvoters comment as to what exactly is wrong with the answer. – Pratronn Nov 13 '15 at 00:15
  • I am not sure why the down vote. Possibly because the OP says it is a private project. I didn't realize you could get a free ANSYS download though so I will give you a +1 as I think this answer could be useful to some people. =) – James Nov 13 '15 at 15:15
  • Thanks. Yes, ANSYS recently released free student version though there are some limits on number of nodes that can used but still pretty useful. Cheers. – Pratronn Nov 14 '15 at 15:48