Question about Impact Attenuator

[paullean]

Hi,

Is it possible to do a quasi static test and get a dynamic result for Impact Attenuator ?

I mean testing the prototype IA on a slow compressing machine to obtain the stiffness (force over distance graph) and convert it by calculation to deceleration. which is required by the rule to be avg 20g and maximum of 40g

It is possible? I was told it is possible but I just dont get it into my mind. Any ideas ?

[paullean]

Hi,

Is it possible to do a quasi static test and get a dynamic result for Impact Attenuator ?

I mean testing the prototype IA on a slow compressing machine to obtain the stiffness (force over distance graph) and convert it by calculation to deceleration. which is required by the rule to be avg 20g and maximum of 40g

It is possible? I was told it is possible but I just dont get it into my mind. Any ideas ?

[TorqueWrench]

It is possible to do, but I am not gonna spell out exactly how to do it as that is the fun part to figure out. Go back to your Dynamics class and look at Work-Energy relationships. Should point you in the right direction.

[paullean]

thanks for the reply

I am actually considering either building a test rig and drop test it. Attaching accelerometer and get the result

There is also a "Dartec machine" for concrete compression testing to use in the university which i would be able to test it with my prototype.

Because this is a group project and there is as much as 12 IA types to test it out. Would you recommend doing drop test or compression test ?

thank you

[Æssahættr]

If you can organise it easily, with reasonably repeatable results, a dynamic test (such as a drop test) will give you a much better indication of the true performance. Also, depending on the materials you are using, a dynamic test is sometimes the only way to test accurately as the material properties will change with different strain rates.

That said, quasi-static testing is definitely easier if your uni already has the facilities in place, and probably safer as well. The calculation for equivalent acceleration is pretty easy, think of Newton. Its way less awesome than dropping a metric ****tonne of something onto a tiny little box though.

There are some pretty good threads around for this, have a search. One that comes to mind is this:

http://fsae.com/eve/forums/a/t...48/m/85510167411/p/1 (http://fsae.com/eve/forums/a/tpc/f/125607348/m/85510167411/p/1)

I seem to remember there is also a really long one around but can't find it atm.

[TorqueWrench]

It is going to come down to what facilities your university has. I know we don't have the ability to hoist the required weight to the correct height and drop it safely, so we do a crush test on our MTS rig.

It also depends on what impact attenuator you guys are testing. Some will behave fairly similar under low speed crush as high speed, some wont. Do a search on here, I know its been discussed before. If you don't find the answer, try asking a materials professor.

[Æssahættr]

reply awaiting administrators due to keywords.

[vandit]

http://fsae.com/eve/forums/a/t...48/m/85510167411/p/1 (http://fsae.com/eve/forums/a/tpc/f/125607348/m/85510167411/p/1)