evo3500
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| posted on 30/11/05 at 07:59 PM |
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stress testing and durability testing
Can anyone help?
I am currently working on a new pushrod suspension system when it is made I want to have it stress and durability tested to make sure its up to the
job as I dont want any broken wishbone type issues,it can be tsted either by computor simulation tests or i can supply to someone who can do it the
relavant chassis section and suspension components.
Any help advice would be well appreciated.
Thanks simon
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Avoneer
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| posted on 30/11/05 at 08:20 PM |
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Won't the wishbone be subjected to the same forces wether inboard or outboard suspension?
Pat...
No trees were killed in the sending of this message.
However a large number of electrons were terribly inconvenienced.
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JoelP
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| posted on 30/11/05 at 09:05 PM |
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i think its the rockers etc he wants testing, not the bone itself. 
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Fred W B
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| posted on 1/12/05 at 06:39 AM |
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Some talk on here lately about testing / fatigue limits of parts
The biggest thing with any practical test is deciding what load case and number of cycles to use in your test.
This is arrived at in the real engineering world by looking at data obtained by instumenting with strain gauges actual parts in service .
Anything else will just be guesswork.
Regards
Fred WB
[Edited on 1/12/05 by Fred W B]
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Hammerhead
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| posted on 1/12/05 at 09:06 AM |
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I think Solidworks can be used to test stresses.......I have just got it and feeling my way around it. But someone else on here might know for sure.
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Jeffers_S13
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| posted on 1/12/05 at 02:34 PM |
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quote:
Originally posted by Hammerhead
I think Solidworks can be used to test stresses.......I have just got it and feeling my way around it. But someone else on here might know for sure.
Solidworks is the CAD part and COSMOS is the FEA part. I use it regularly at work for quick jobs, although I use Nastran 90% of the time to guess
when things are gonna break Predicting fatigue failure of components using a computer is mostly guesswork even if you have the most up to date
materials data and have a bullet proof model, anyone that tells you otherwise either doesnt understand or is lying  Its what I attempt do for
a living ! Using a computer gives you a better understanding of the problem and may give you a good indication of the expected life at best. The main
problem is good material data i.e. decent SN curves (the info that tells you how many cycles of a particular stress range a piece of material can take
before its deemed to fail). You can use an FE package like Solidworks/COSOMS to do a simple linear static analysis and predict the
'stresses' in a component, but if you dont constrain the problem correctly or load it wrongly or interpret the results wrong then its just
a load of garbage and plots with pretty colours on them, garbage in=garbage out its not as easy as you may have seen on telly. In terms of if it will
fail, if its aluminium and its having repeated loads applied it WILL fail at some point, as ali has NO endurance limit whereas steel does (although
this is often discussed in journals) it may be after 10e6 cycles but it will fail, obviously the life being dependant on the stress range. Starting
to go on now...so I'll give in.
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evo3500
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| posted on 2/12/05 at 06:41 PM |
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Sorry I should have made myself clearer.
I am currently designing a complete suspension system and possible replacement hub for the sierra front.
I want to make sure everthing is up to scratch in terms of strength and durability as i have heard of cases of people sueing if there is a component
failure.I wonder how many kitcar makers go to the trouble of having there designs evaluated and tested ? Do they now how strong they are ? what would
happen if say a wishbone ,but we wont name any , was to break in half and cause a serious crash and serious injury to the driver ? Do they know if say
after 10,000 miles and some trackdays the part may be ready for failure
I have looked at some designs and felt they look a bit suspect.I would like to avoid this as if i sell any of my components later on the open market,I
would at least like to know they are safe for my own conscience and for the customers peice of mind.
Any veiws thoughts feedback would be appreciated.
Thanks Simon
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