Has anyone done FEA analysis improvements on the Midlana?

Goals, budgeting, drivetrain selection, options, driver protection, creating a workshop, etc
Post Reply
Alfalfameister
Posts: 21
Joined: 14 Dec 2015, 16:35
Anti-spam question: 4
Are you a spammer: No

Has anyone done FEA analysis improvements on the Midlana?

Post by Alfalfameister » 20 Mar 2017, 02:44

I know the Midlana is quoted as 7,000+ lb-ft/deg, but even Kurt has said he was skeptical about it.
The one FEA run on my chassis produced a figure of around 7500 lb-ft/deg, which is really good, maybe even too good.
This being "5X stiffer than a Locost".

The problem is, only those with the book can do frame mod suggestions a'la Cymtriks and the Australian mod that they did to the Locost chassis.

FWIW, my Locost has nearly all the Cymtriks mods -- actually, I think it has all of them, for a theoretical 2,683 lb-ft/deg.

Despite that, the Midlana is still 2-3X stiffer than that. Still, as I am starting my build (because I already finished my Locost, though those things are always back at the shop for even more improvements), just wanted to throw it out there to see if anyone has done further mods a'la Cymtriks. Or is that a useless exercise since it's already about 3X stiffer than my Locost, and more stiffness than that is just diminishing returns?

User avatar
freakynami
Posts: 826
Joined: 23 Dec 2008, 17:53
Anti-spam question: 0
Are you a spammer: Yes
Location: Adelaide, Australia

Re: Has anyone done FEA analysis improvements on the Midlana?

Post by freakynami » 20 Mar 2017, 04:36

viewtopic.php?f=5&t=520&hilit=fea&start=50#p5055
viewtopic.php?f=5&t=520&hilit=fea&start=60#p5069
viewtopic.php?f=5&t=520&start=240#p7588
viewtopic.php?f=5&t=520&p=6911&hilit=fea#p6911

Yes, and no.

I can't remember if I ever made any broad statements along the lines of "do this mod to make it X times stiffer", but in general, I found adding the second door diagonal made a big improvement (at the expense of elbow room, possibly making it impossible to drive), and making sure to include the 1" square diagonals across all open sections (like the floor under the cabin and over the top of the footspace) made a pretty significant improvement.

As far as I am aware, no one yet with actual FEA ability has gone the full monty on this chassis design.

Alfalfameister
Posts: 21
Joined: 14 Dec 2015, 16:35
Anti-spam question: 4
Are you a spammer: No

Re: Has anyone done FEA analysis improvements on the Midlana?

Post by Alfalfameister » 20 Mar 2017, 04:53

Oh, good. Didn't think to look in the builder's diaries for gems like these. Thanks!

stankoprowski
Posts: 57
Joined: 25 Dec 2008, 06:49
Anti-spam question: 0
Are you a spammer: Yes
Location: Guadalajara, Mexico

Re: Has anyone done FEA analysis improvements on the Midlana?

Post by stankoprowski » 21 Mar 2017, 07:55

Here's a YouTube link to a guy who used several open source software packages to design a scratch-built Locost-type car.
https://www.youtube.com/watch?v=VigVEbeTtXM&t=88s
Interesting :idea:

Alfalfameister
Posts: 21
Joined: 14 Dec 2015, 16:35
Anti-spam question: 4
Are you a spammer: No

Re: Has anyone done FEA analysis improvements on the Midlana?

Post by Alfalfameister » 23 Mar 2017, 03:00

Whoa! Just watched his video:

Locost chassis as per book is 1,300 Nm/deg.

His chassis (probably with Aussie mods) was 2,150 Nm/deg.

His new chassis (still Locost look) is 15,000 Nm/deg!!! And he had a little 1/10th scale (soldered) to show that his FEA analysis is correct (if I got it right, a 1/10th scale of book chassis would break at the "welds" (or soldered parts in this case), but his new chassis is that much stronger) -- about 25 min mark of the video.

Interesting!

Edit: I keep forgetting that the Locost chassis, even with the Cymtriks mods, still does not have a roll cage. And that another thesis from many years ago (found in the Locost sites) had the Luego up to 9,000 I think, with a roll cage...

Post Reply