Kevlar can be integrated into fiber glass or urathane body components with high strength epoxy resin, much like putting carbon fiber on fiber glass (the underside). The process will increase the strength of the body component by more than 10 times, stronger than carbon fiber (especially preventing fiber glass from cracking). At a relatively low cost, it should be an excellent way of protecting your investment.

I have not seen anyone else attempt this before, if it has been attempted please let me know. I will be applying Kevlar bonding to a new fiber glass Feed TypeII front bumper. Pictures will be posted as soon as the project is underway.

I was wondering if anybody else with body kits and/or planning on purchasing body kits would be interested in having this done??

 

havent heard anything but i sure as hell would liek to find out more

 

have you ever worked with Kevlar? i have, its a nightmare! and nearly impossable to cut or drill to make holes etc.

 

Kevlar integration is very similar to carbon fiber, there is very little weight difference, but Kevlar is much stronger than carbon fiber (thats why bullet proof clothing uses Kevlar and not CF). The only draw back is that Kevlar doesn't have that nice interweaving pattern like CF. But if it was used on the underside of body components only for reinforcement, it really doesn't matter what it looks like.

 

I have specialized equipment to do the work with. But you are right, the strength of the stuff is totally amazing. The fact that it is nearly impossible to cut or drill with normal tools demonstrats that fact. Just imagine what this stuff can do to protect your 1600 dollar bumper.

 

Isn't kevlar amazingly heavy too?

 

don't know if "plastic kevlar" is right, but here's some density figures (in grams/cm^3)
Plastic Kevlar 29 1.44
Plastic Kevlar 49 1.44
Plastic Kevlar 149 1.47

for comparison

Metal Aluminum 2.643
Metal Titanium 4.5

http://hyochum.physics.sbc.edu/P223_fall2000_densities
.htm

here's some other stuff from another page
( i don't know if it's proper, but it talks about carbon fibre, nevermind the bonding epoxy, etc. .. http://www-personal.umich.edu/~tldull/pro/fibers.html )

Density 1.73 g/cm3

just ballpark figures i guess, to give you an idea.

 

The densities posted shows a good comparison basis. Kevlar is just as light, ifnot, lighter than CF. The strength/weight ratio is way higher.

 

no doubt, anything below the density of aluminum is light enough for me!

 

RE Amemiya already make some parts with Kevlar.

 

You have some misconceptions about kevlar vs carbon fiber. Kevlar has a compressive strangth about 20% higher that cf, but only 50% of the stiffness of cf. it is lighter than cf, and more flexible. Its used for things that should have some give to it, bu laying it onto a fiberglass bumper wont be worth the effort. The fiberglass will break long before the kevlar would. And it wont add much stiffness to the fiberglass, since its stiffness is only 50% of the stifness of cf. The compressive strength is parallel to the fibers, and there will be almost no foces applied to it like that. Bottom line, youre still going to have a mostly fiberglass bumper, and adding kevlar or cf to the back isnt going to make it much stronger. And the fiberglass is still going to be the first thing to break. If you really want to add something, do cf. it will add more strength than kevlar.

 

not if its vacuum extruded carbon fiber parts!

then your talking 10x stronger and 2x lighter!
thats why its used in F1!

 

Just going to mention the same thing... I've seen the vacuum process and how they do everything and it's amazing... Just a lot of money.

 

Depending on what you are trying to accomplish, you may just be wasting your time.

If you are just trying to make the piece stronger go for it, but if you are trying to keep it from cracking forget it. The gel coat is what cracks first and shows through the paint. Only way to solve this problem is to sand off all the gel coat prior to painting. Gel coat is used because it easy to sand and cover imperfections well. If you want to do it right reinforce the backside with cf or more fiberglass and sand the gel coat off. Fill in the imperfections with more fiberglass or fiber reinforced body filler.

On my front end I had a custom bracket welded to the frame the supports the front end from underneath. It's pretty much just to metal rods that stick out and bolt to the under side of the front lip. Keeps the front end from bouncing around. It will still crack someday. I also added more fiberglass to the backside of all my pieces.

 

It's going on my bumper.

 

All speculations aside, I will do a side by side comparison test of the strength properties between FG and Kevlar reinforced FG. Pictures will be posted afterward.
As someone mentioned in a prior post, RE Amemiya have Kevlar components at twice the price of CF parts. The difference in price is certainly not for looks.
We are not arguing over what has better properties, the point is to find an economical way to reinforce body parts from everyday road damage and such. And I wanted to find out how much interest there would be for the process after the test and sample is completed. Only one person actually read and understood the point of this thread??

 

I seriously doubt anyone here has access to an autoclave, so it's all academic.


I agree with the others who say this prob wouldn't be so useful. If the bumper requires re-enforcement, you might as well just layer some extra glass fibre behind it...cheaper and easier.

now a full kevlar bumper...that woudl be interesting.

 

Hey wouldn't Kevlar absorb radar signals and make the car bulletproof too? Where do I sign up for this?

 

I would be interested in this if you guys find how to incorperate this in the bumpers.

 

Now I can do my drive-bys without worrying about bumper damage!

 

Sometimes I wonder about the limited vision in this place.
Let's just visualize for a moment, traveling at 70+ miles an hour, a small rock kicked back from a truck is heading toward your car at a modest 50 mi/hr, the relative speed of the debris hitting the car is 120+ mi/hr. In common situations like this and others, it is not a constant force but rather an impulse not unlike that of a bullet. If you believe that adding FG will give you the necessary strength increase in these situations, how about standing behind a couple of layers of fiber glass (or carbon fiber) while I discharge a 45 at your chest.
I am only posting this becacuse I believe it will help fellow 7 owners, not to start a brainless debate. If you do not have anything constructive to present to the community or if you do not believe this will work after the test data is presented then don't do it, other wise, keep the wise cracks to yourselves, it only makes you smaller.

 

Sounds good, but that's as far as I'll go. Ill start by saying I bring rain.

Where do you get your numbers? 10 times what? Do you realize that fiber strength has little or no relevance to real performance? Did you ever stop to think that stronger body panels won't make a sh*tsniff difference in an accident? How about light weight - how can adding to an existing body panel make things lighter?

Your thinly veiled attempt to start a Kevlar panel business is not only transparent but doomed if you haven't made a Kevlar reinforced panel yet. Carbon fiber isn't easy to work with, but it does well. Adding Kevlar to anything isn't likely to improve over CF. It smells a lot like you're boiling cheap rice.

Here are some facts on Kevlar:
- Its primary advantage is abrasion resistance. There are other fibers with higher strength/denier and strength/weight ratios - see Vectran and PBO Zylon if that's your primary goal.

- Kevlar's main uses are as an ablative material - meaning it takes abuse without allowing damage to what it's protecting. It takes much more energy to abrade through a Kevlar structure than other materials, but the Kevlar gets shredded in the process. So unless you have a half-dozen replacement body panels in the garage, or really thick layers of Kevlar in the panel, it won't do any good.

- Kevlar's tough properties are nearly ruined by encasing it in epoxy or weaving it against itself. It will cut against itself or get cut by the cracking epoxy during impact. Bulletproof vests would not work if the Kevlar was woven tightly or had epoxy in it. If you crashed a car with Kevlar-reinforced epoxy, you'd find most of the fibers were cut along the main crack lines and the fiber would add little to the crush resistance. The only benefit is you wouldn't have to bend it back since it would be hanging on by a few threads.

If you think it will do better with dings and other stuff, I suggest a test: take a metal, fiberglass, carbon fiber, and whatever Kevlar-reinforced stuff you're talking about. Rig it up so that a small hammer (really small - just enough to ding it) strikes it repeatedly with very light force. A rotating wheel mechanism would work. Compare how they look after this abuse. You'll find they all bad, and the composites might be on their way to crumbling. The metal will just be badly deformed. If your fancy product can show improvement under these conditions, it might have a chance at door dings and rock chips. I'll bet it makes no difference at all.

Well, since you've obviously _not_ done any research, I suggest doing your bonding test with something other than the Elmer's glue in your desk. No, rubber cement won't work either. Unless you have access to the right kind of epoxies and resins, you probably won't get far in making the Kevlar stick to anything you have laying around. And if you do, it won't do much good for the reasons mentioned above. Hopefully nobody will send you money for anything until these things are fully worked out.

If anyone has successfully used Kevlar to improve the properties of body panels, I'd like to know how they did it and what benefits it actually provides.

Dave

 

Do people ever bother reading anymore? When did I say anything about possible damages during an accident? Who would be stupid enough to believe anything will survive an accident, even if the whole car is made out of CF or Kevlar? And where the hell did I say you can make things lighter by adding Kevlar re-inforcement?

Your thinly veiled attempt at trying to be intellegent has definitly failed. Where did I say anything about adding Kevlar to improve over CF? These are two different applications with different intent, or is that too complicated for you to understand.

In case I didn't spell it out for you yet, the high abrasion resistance is what's needed due to the nature of common minor body damage. NOT tensile strength.

It's called minimizing damage, not making it indistructable.

I wonder why high speed race boats that experience the sudden hydro impact uses Kevlar reinforcement and most race cars as well. Maybe they are all wrong and they all need to take your advise.

What did I say I was going to do? You know what, I'll take that bet. I'll set up an escroll account and put $500.00 in the account, and I'm betting there will be a difference. I'll ask if a moderator will supervise the account. Just tell me when.

It's called 2000/w 2060 epoxy resin, oops, was that too complicated. I tell you what, I think Elmers is a much better choice. By the way, there is a product called Hooked on Phonics, it's a really good investment.

 

Let's start clean. I'll lay off your sad homonynical spelling errors and I'll assume you have the netiquette-maturity to read thru my rapidly typed and unchecked sentences. These things have nothing to do with engineering a better product.

You say the purpose is to build a 'stronger' panel to handle everyday road damage. What types of damage do you expect to curb?
1) dings and small dents from very light collisions
2) scratches and abrasion
3) chipping from pebbles and debris

What type of existing construction do we intend to surpass?

What do define as successfully improving on durability?
1) holding its gross shape to perform aerodynamically (no mass breakage)
2) also maintaining a smooth surface finish to keep drag down
3) no cracks in the epoxy medium
4) no loose or broken fibers on the surface

Let's first agree on the purpose and metrics for success.

Dave

 

Now we are having a more intelligent conversation. Sorry about my laptop's keyboard sticking, it's getting replaced soon.
Like I said in the initial post, I am planning on applying the laminate on FG. This was suggested by a friend in the raceboat business. Urathane body parts are fine the way they are due to the high degree of material flexability.
By creating a Kevlar/FG/Kevlar sandwich, I want to improve the chances of survival from your typical minor damages. Since the material is so light, there will be very little significant weight penalty. The 2 types of damages I have seen is usually due to the road debris or sudden contact due to the smaller road clearance.
The road debris will essentially create a dent/hole on the body surface, and this should be reduced to scratchs (due to the surface laminate) instead of chunks being missing.
The bigger damage would stem from hitting bumps, curbs, ramps etc. This usually results in cracked body parts (or as you said, mass breakage). The sandwich lamination should minimize the chances of this type of damage. Granted, if there is a severe impact type accident things are going to break, regardless of how strong the laminates are.
I have access to and will be testing three possible laminates (before I put the laminate on the actual bumper). The first being Kevlar, the second is Carbon Kevlar and the third is layered CF and Kevlar. The test will be rigged to simulate the two situations mentioned.