anyone has seen skid plate made from composite material?

hh ( snipped-for-privacy@myrealbox.com) wrote on Thursday 30 September 2004 07:17 pm:

The only problem I can see is that the metal will bend while the compsite will shatter. I would think this would be especially true on edges, where the compsite may chip away.

if it bends, it is not going to protect, so it doesn't matter if it bends or shatters. for impact (as opposite to slowly load it), composite absorbs more energy than steel does, and you don't need to worry about rust anymore.

anyone knows where to get dimensions of skid plate? I know you can crawl underneath, but if there is some data around ready to use, I would save my energy. since skid plate is basically plates, very easy to make once I get dimension.

I was think more edge-on hits. For instance, a couple of weeks ago I backed into a stump. The stump was too low to be caught by the bumper, but too high to fit past the skidplate. I hit the transmission skid plate pretty hard, but there was no visible damage to the skid plate, nor any of the components it was protecting. Most of the composites I've seen don't stand too well for being hit edge on without at least chipping a bit. If you do find one, turn it on end and slam it with, say, a three pound hammer or iron pipe. I'm not being sarcastic - I'd like to know the results.

When you say composite I think of srtong for their intended application, but not very good with impact/scrape that a skid plate would go through. Many of the off-road competitors use plastic skid plates and they seem to work very well. Here is a link to lots of technical info on skid plates made from various forms of plastic

there are many kinds of composites, not everything that is plastic and stiff. some are much stronger than steel, some weaker, at similar weight. If any hit that did not bend your steel panel, I can easily make on composite panel that will not take any damage from the same hit, all at much lower weight. and if you get a scratch, you don't need to repaint it. doesn't matter if it is on corner or not. bascially, what happens to metal is that it starts to bend (plastic deformation technically), and they break, for composite, it does not bend (or plastic deformation) before break, but composite can withstand much higher load at break. if hit on corner, steel bends, but that already is counted as failure and won't do anything good anymore.

at high production volume, it is cheaper to use steel, but low volume, cheaper to make composite. that is why you see composite in boats and planes, but not that often in cars.

btw, chrysler has been a long time advocator for composite. it has a all composite compact sedan made fifteen years ago (not that super $70k corvette GM makes, but cheap ordinary car), although only experimental.

well, anyone has info on geometry of skid plate? I don't want to lift my zj up to figure out dimension.

depends what kind of and how you design, most fiber reinforced composite take impact better than steel. the armor of modern tanks are made of (partly) kevlar composite, as well as most personal armors.

if you want to make the panel withhold large force without damage, use carbon fiber, if you want it to damage but absorb energy of impact, use kevlar fiber. both of them can be easily designed to be more impact resistant than any steel.

but neither of them take abrasion well.

Dave Milne, Scotland '91 Grand Wagoneer, '99 TJ

not necessarily, but I don't know for sure. even it is true, can simply wrap s think sheet of metal on the bottom surface.

application,