IMPACT ATTENUATOR DROP TOWER TEST

[funsize]

Hi,

Our department has a drop tower capable of holding a 50 kg max mass. This isn't anywhere near 300kg! But is it possible to scale the area of the proposed impact attenuator design down by a similar scale, say 1/6th as 50 kg would be 1/6th of the 300 kg mass?

I'd really appreciate anyones advice.

Thanks

[exFSAE]

Highly nonlinear. I wouldn't use it at all.

When you need max load.. go to Civil Engineering. That's the department that can drop and smash stuff REAL GOOD.

[Drew Price]

You might be able to get creative with your analysis and do it from an energy standpoint, rather than measuring the deceleration directly (at least until the 2009 regs come into place for next year).

We did a slow crush on a tensile test machine for the current design, area under the curve gives energy absorbed, then find the energy you need to absorb to arrest the car within the given parameters without exceeding the required peak G-force. If your design absorbs the same or more energy than is required then it is a viable design.

Best,
Drew

[chavez]

This worked great until we kind of got in trouble.

http://farm4.static.flickr.com/3245/2298824884_4399284b4c.jpg?v=0

[The AFX Master]

We use a big pendulum made with a large steel tube, 300 Kg's of ballast and some bearings in order to crush the attenuator against a concrete wall. you can attach your accelerometers, lift the thing with a freight elevator and then let it smash your crush device. Search for a wall almost 4 or 5 meters high to attach the pendulum

And BTW.. is damn funny!!!

[Mike Sadie]

chavez, how did you measure energy absorbtion with that setup?

[PBandJ]

Mike,
The test was conducted with an accelerometer on the plate and a video camera on the crush zone.
The accelerometer did pretty well but the vibration in the plate caused some noise in the data. The video data with a measuring tape in the background gave a crush distance and a time measurement using the frames in the video.