FEM Analyst or Developer? 1

[jacksonfem]

I have the oppurtunity to work for a company that develops a Finite Element Solver. I must choose between the next two:
1) Programming of FEM method etc, with C, C#.
2) Performing analyses to check if the solver works properly.

I have worked as a structural engineer, 10 years now, where I have performed FEM structural analyses with softwares such as SOFiSTiK, SAP etc.
From advanced FEM softwares, I have worked with NASTRAN, on static, dynamic, nonlinear (material-geometrical), contact analyses etc. Essentially,
I have done something like the second opportunity, from above. It's something that I like very very much.

If I follow the second opportunity (performing analyses), I will do what I know to do, bit in a more advanced level of course.

If I follow the first opportunity (developer), it will be something new to me. I don't even know programming.
Beside I know very well to perform analyses with FEM, I know very little from FEM theory. But I know very well Strength of Materials, Statics, Dynamics etc.
In the other hand, I 'm very interesting of how these things are programmed (element formulation, analyses methods, newton-raphson, arc-length etc.)

The thing is this: I don't want to lose the "engineering of the whole thing", in case I go for a FEM developer. I have heard that FEM programming, is 90%
programming and 10% engineering. There is no opportunity to do both developing and perfoming analyses. I don't want to be "transformed" in a developer/mathematician and leave behind engineering.

I would like to tell me your opinions.

 

[FeX32]

So Jackson - Stick with #2 and spare the end users (if it ever gets there) some

(this is of course if you don't want to stop most of the engineering side and spend some years programming before you do anything useful)

 

[jacksonfem]

Thank you all guys for your advices!

 

[drawoh]

....

... and that's probably more than you wanted to know. Sorry.

I asked for it.

I specify servo-motors and I think it is our electronics people who write the software. I suspect that they do not account for inertia. I expect mechies to get this right.

I have an Arduino kit at home, but the stepper has a 64:1 reducer. When I figure it out, I will have to get a plain stepper motor and attach a load to it.

--
JHG

 

[MikeHalloran]

drawoh, re stepper inertia:
If there's even one modest gear reduction involved, inertia is not likely to be a problem, so an ME might do a one-time check that the first pinion/pulley is not too heavy, but you don't need to make a career of it.

... but there's another reason to not write super high performance stepper software; the lot to lot variation in a stepper population can drive you crazy. Some of them are much more magnetically 'tight' than others. Whether that's a good thing or not depends on the driver electronics and on the nature of the load.

In something that would be sensible for/to an ME, in one my later deeply embedded projects, I addressed the issue of heat, by running a super simple thermal model of the motor and driver. My controller responded to text commands, and would move a commanded distance on command, then send an acknowledgement to the host system. Unless the motor was in danger of overheating, in which case it would refuse to move, and send a 'not acknowledge' flag to the host.




Mike Halloran
Pembroke Pines, FL, USA

 

[MacGyverS2000]

My frustration with steppers has always been (slowly-increasing) backlash in the gear train. For precision positioning, a few steps here and there can be "okay", but as the drivetrain gets sloppier and sloppier, precision goes out of the window. On my last project, what started as 2-4 steps of backlash with a fresh train would increase to 25-30 steps after a few hours of use. You can train at the beginning of a session, IF you have a limit switch... but I am rarely so lucky, and a limit switch is useless when you need to train in the middle of a use session.

Dan - Owner

http://www.Hi-TecDesigns.com

 

[MikeHalloran]

My first exposure to steppers was a slow-moving mechanism where the relentless click-click-click would brinnell bearings into jig-bored aluminum plates, eventually elongating the holes so much that the gears would slip teeth. I don't know if our custom couplings absorbed or amplified the shock, or if less primitive electronic drivers would have helped. Since then I have tended to use timing belts with steppers, at least for the first pass.



Mike Halloran
Pembroke Pines, FL, USA