Composite Laminate Samples Lab Test Results

General Composites Discussions Engineering Talk
#1

Well, I don’t have much time right now to do a full write up with details.
But basically we made up some small test samples and took them to a lab to be tested. Our main objective was to compare different layups, using core and no core, with different thicknesses.

Keep in mind these tests are relative only to each other, due to the sizes used and method of testing (small area of load). They can’t be compared to other samples. At least it gives an idea of how glass compares to carbon, and flat panels to cored panels.
We’ll be producing more samples to test in tension and compression. Those companies selling cheap cosmetic carbon parts don’t have this data to back up their products!

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#2




#3

Cool stuff,

My guess whoud be that the top layers alwyas buckle because they are getting compressed while the lower layers are always being pulled if there is a force acting to deflect the sheet.

Cool data but production of cosmetic parts regardless of price don’t need this sort of data, they are just simply…cosmetic.

#4

I’d hope everyone here is not doing ONLY cosmetic stuff, it would make me sad.

TET, thank you for the test, I’ve been looking for a somewhat simple test such as this. Gives sort of an arbitrary rating for simple layups.

#5

Regardless, this type of testing data is hard to find for composites. The companies that do it, generally don’t want to give it away. And the companies selling garbage, don’t even know what this testing is and don’t do it.
What’s really troubling is that nearly all composite parts are structural in some way. Most of them need to hold their shape, and stand up to a certain amount of abuse. Those POS “carbon fiber” hoods from VIS and the like, are often flimsier than the sheetmetal they replace. It should be at least as strong and stiff as the original.

Just figured people here might like to see some actual numbers and comparisons. This is a great place for people looking to learn about composites, and now they have solid info to help them make decisions that they otherwise wouldn’t know about when learning.
At the very least, they can see how different 10 plies of glass is to 10 plies of carbon.
“Hmmm, no wonder carbon fiber is expensive.”
“Wait a second, if carbon fiber is so much better, why does this shiny hood only have one layer of it?”
Let the truth be known!

#6

I would also assume that the resin system of choice would effect the strength/performance in the test. Most places would use polyester too…

#7

What resin system were you using for these test pieces? Also, infusion or not? What resin to fabric ratio? Couple tests I would like to see are a comparison between the resin types, test of some of the more exotic fabrics, and comparison of panel making techniques.

Cool data, good to see.

#8

I read that vinylester is not recommended for carbon fiber. I would like to see test results with compatible resins.

#9

you can use vinylester or polyester for carbon fiber. I just prefer epoxy myself.

#10

it’s not recommended as most (if not all) fibers have been manufactured and surface treated to be compatible with epoxies, not ester-based resins.

#11

That would explain the delamination.

#12

No, the fact that kevlar doesn’t adhere to any resin very well would be the explanation.
Fibers for general purpose use are compatible with esters and epoxies.

#13

TET this tests are amazing. Really we need to make this test and with different resins. It is very important for us because we need to have such these examples. You see it’s not very easy to find this kind of lbs meter machines.

One question, what is the size of these panels? it’s very important.

#14

as I found out with the Saertex material…not sized for VER.
Which explains my interlayer debonding!!!

#15

should always call the manufacturer, but i’d say 80-90% of carbon fiber is produced for industrial/military use, which consequently use epoxies.

Working with pigments (TiO2), I know how much a “simple” surface treatment or “slight” manufacturing difference can totally alter the properties of said material and it’s compatibility with whatever suspension/resin/etc. with which it comes into contact.

We use vastly different treatments/manufacturing conditions when making TiO2 for paint resins, thermoplastics, coatings, or thermal-insulation bricks.

#16

The laminate schedules used can greatly affect final strngth as witnessed. Us the tests TET has done to further your knowledge of impact resistance,load bearing,core assistance in strengh values.
This can be very helpful in deciding a layup schedule/plys etc.It certainly promted some thoughts for some of my parts in process.
Thanks TET for the time .
Cheers,V’.

#17

Hello, that results is with Hs Module or standard ?

#18

AWESOME! Is the lab nearby (in SOCAL)? Looking forward to the next segments - tensile test, then compression. The report would be nice but I know how that goes!
Sent you a PM.
Cheers - Jim

#19

We don’t have a lab in my own company since there’s no need for it. Generally use local labs. But most of the companies that I consult for have in-house labs and I can test a bunch of stuff when studying manufacturing defects and doing employee training.
Got your PM, just been super busy. Remind me if I don’t get back to you soon.

#20

Thanks for that great information. I usually lay up my parts with no idea how strong they are going to be until they are cured. Then I have to add more carbon without getting that chemical bond I would’ve gotten if I had the right amount to begin with.

Or I end up using more than necessary.

Either way - my finished piece is heavier and weaker than it could be.

So seeing this data makes things a LOT easier to figure out the first time. :wink: