Irony
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| posted on 21/2/13 at 11:00 PM |
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What is a Cranfield stress analysis
There is a fella on eBay selling Viento chassis number 4. He claims to have a CRANFIELD UNIVERSITY’S STRESS ANALYSIS FOR THE CHASSIS. What is that
then?
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blakep82
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| posted on 21/2/13 at 11:19 PM |
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I suspect its a stress test, done by cranfield university? If there is a cranfield university...
I guess it could only really be answered by someone that did the test personally
________________________
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don't write OT on a new thread title, you're creating the topic, everything you write is very much ON topic!
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plentywahalla
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| posted on 21/2/13 at 11:58 PM |
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Cranfield University is probably the UK's premier uni for post grad Msc in Automotive Engineering.
Rules are for the guidance of wise men ... and the obedience of fools. (anon)
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eddie99
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| posted on 22/2/13 at 12:04 AM |
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I suspect either it's a physical test been done on that chassis such as torsional, how much force to move it x amount of mm
Or they have taken measurements, created a cad file and run it through FEA
Probably then just a printout of where the stresses are on the chassis and displacement
Having the fea results is one thing, it's only of any real value if they have used it properly and made the chassis any better.
[Edited on 22/2/13 by eddie99]
http://www.elitemotorsporteng.co.uk/
Twitter: @Elitemotoreng
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NOTE:This user is registered as a LocostBuilders trader and may offer commercial services to other users
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fesycresy
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| posted on 22/2/13 at 08:13 AM |
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Wasn't this part of the original sales blurb from the Luego factory?
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The sooner you fall behind, the more time you'll have to catch up.
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designer
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| posted on 22/2/13 at 08:56 AM |
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Maybe he thinks it will make the chassis worth more!
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matt_gsxr
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| posted on 22/2/13 at 09:44 AM |
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The most trivial amount of googling indicates that it was an MSc project
http://www.google.co.uk/url?sa=t&rct=j&q=&esrc=s&source=web&cd=3&cad=rja&ved=0CEUQFjAC&url=http%3A%2F%2Flocost7.info%2
Ffiles%2Fchassis%2FFinal_Thesis_A.doc&ei=Aj0nUau3HKHU0QXc0oCoBQ&usg=AFQjCNHPqbd6uh8X2lxgIn7IdYmLsyinVQ&sig2=ippflsYKnhFFRRyWx-CJOg&bvm
=bv.42768644,d.d2k
All theoretical FEA and applied to all Luego.
I can't find out whether he passed the MSc or not, so it might all be wrong!
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matt_gsxr
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| posted on 22/2/13 at 09:45 AM |
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locost7.info/files/chassis/Final_Thesis_A.doc
better link
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britishtrident
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| posted on 22/2/13 at 11:04 AM |
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NB ANALYSIS not test
All it means is somebody has run a finite element analysis on a CAD model of the chassis --- which actually means nothing unless it was done by an
experience FEM practitioner using a computer model that was valid and representative with the right restraints and loads.
[I] “ What use our work, Bennet, if we cannot care for those we love? .”
― From BBC TV/Amazon's Ripper Street.
[/I]
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phelpsa
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| posted on 22/2/13 at 06:19 PM |
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quote:
Originally posted by britishtrident
NB ANALYSIS not test
All it means is somebody has run a finite element analysis on a CAD model of the chassis --- which actually means nothing unless it was done by an
experience FEM practitioner using a computer model that was valid and representative with the right restraints and loads.
This is from Cranfield University, i'm sure they wouldn't put their name to it unless it showed a reasonable level of validity.
These are the people who make quite a lot of money doing F1 crash testing...
EDIT: Having said that, 1300Nm/Deg sounds quite high!
[Edited on 22-2-13 by phelpsa]
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britishtrident
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| posted on 22/2/13 at 07:09 PM |
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quote:
Originally posted by phelpsa
quote:
Originally posted by britishtrident
NB ANALYSIS not test
All it means is somebody has run a finite element analysis on a CAD model of the chassis --- which actually means nothing unless it was done by an
experience FEM practitioner using a computer model that was valid and representative with the right restraints and loads.
This is from Cranfield University, i'm sure they wouldn't put their name to it unless it showed a reasonable level of validity.
These are the people who make quite a lot of money doing F1 crash testing...
EDIT: Having said that, 1300Nm/Deg sounds quite high!
[Edited on 22-2-13 by phelpsa]
The way I look at it is a project that was part of some bods Msc which isn't quite the same thing
[I] “ What use our work, Bennet, if we cannot care for those we love? .”
― From BBC TV/Amazon's Ripper Street.
[/I]
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NeilP
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| posted on 23/2/13 at 10:55 AM |
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From very dim and distant memory I recall Grant from the original Luego saying that a chassis had torsional measurements done on it. He still on here
occasionally trading as OBP (Original Balance Parts or something similar) - Bet a google would get you a phone number then you'd know if it was
just a virtual test (in which case it's also a feature of my chassis  ) or a physical on number 4 (in which case it's been played with a
bit by undergrads  )...
...think a and a sums to a 
If you pay peanuts...
Mentale, yar? Yar, mentale!
Drive it like you stole it!
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Sam_68
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| posted on 23/2/13 at 12:59 PM |
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quote:
Originally posted by NeilPFrom very dim and distant memory I recall Grant from the original Luego saying that a chassis had torsional
measurements done on it.
The link given by Matt above is only half of the document.
You need Part B as well, which gives details of the physical testing and FEA validation:
http://locost7.info/files/chassis/Final_Thesis_A.doc
http://locost7.info/files/chassis/Final_Thesis_B.doc
It's a very interesting and useful document, but sadly its terms of reference fell short of including the final part of the jigsaw, which would
have been an analysis of predicted chassis deflections compared to the deflection of tyres, road springs and bushes... I did a few fag-packet
calculations of these myself, once upon a time, but unfortunately I've lost them. 
Received wisdom says that you need a torsional stiffness for the chassis of at least 10 times the roll resistance on the road springs/ARB's, but
I think this was just someone's arbitrary rule-of-thumb. From memory, and contrary to popular belief, my sums suggested that the effects of
torsional chassis deflection on suspension geometry were actually quite trivial - the fact that the chassis acts as an undamped spring and the
effect that this has on instantaneous loads at the tyre contact patches is possibly more significant.
quote:
phelpsaHaving said that, 1300Nm/Deg sounds quite high!
I still think in lb.ft/degree, I'm afraid, and that's only about 980 lb.ft/degree, which is distinctly unexceptional?
That was for a largely unpanelled Luego chassis, though - I'd expect the fully panelled chassis to be lower-end ballpark for where you'd
expect a 'typical' Seven-style spaceframe to be, in the region of 1,250-1,800 lb.ft/degree. The 'best' spaceframe
'Seven' chassis I'm aware of test figures for (the Caterham) achieved 2,000-2,500 lb.ft/degree (and they might have improved this
further with recent development).
The predicted 'optimised' stiffness of over 6,000Nm/degree (4,425 lb.ft/degree) takes a bit of swallowing, though!
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