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CFRP & FGRP

Posted: Sun Aug 15, 2021 11:29 am
by HAWK21M
Is there a difference between CFRP [Carbon Fibre Reinforced Plastic] & FGRP [Fibre Glass Reinforced Plastic].

CFRP & FGRP

Posted: Mon Aug 16, 2021 9:13 am
by flipdewaf
One is reinforced with carbon fibres and the other reinforced with glass fibres…

CFRP has historically been more expensive (I’m not sure of the current situation with automated manufacturing tech) but is also lighter. One major difference is that GFRP is electrically insulative, whereas CFRP is not and so can have a bearing as to where it’s used. Cutting GFRP needs a respirator for the operator, CFRP also needs a respirator for any electrical equipment (a dremel doesn’t last long). I only have very limited experience with the two (most of the composite manufacturing work I did was ti+paper/al honeycomb but I’d guess the electrical properties of each may mean that GFRP may have some advantages in electrical bays to help with any dam he tolerance.

Fred


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Re: CFRP & FGRP

Posted: Mon Aug 16, 2021 2:17 pm
by gregorygoodwin
In the SRM, they are denoted as CFRP and GFRP. As stated in the above posts, they are carbon fiber (CFRP) and fiberglass (GFRP). What can confuse some is the GFRP reference. I've heard it called graphite fiber reinforced plastic which is not correct. One interesting thing about the fiberglass is that one of the most commonly used types is called E-glass. From what I've read about this, it stands for electric glass fiber. Why this is I'm not sure. When we do repairs that are done with fiberglass they usually have a aluminum flame spray coating over the last fiber lay-up or we use a black anti-static coating over the fiber before final primer and paint goes on. This is to disperse electrical charges across the surface.On some surfaces you will see a hybrid lay-up of carbon, fiberglass, and Kevlar in a specific order of lay-up. This is related to what the engineers want in terms of impact resistance and what temperature the lay-up is subjected to.And the lay-ups can be cured at different temperatures, usually 250 or 350 degrees.Again, this is related to the desired properties needed by the lay-up.


Gregory

Re: CFRP & FGRP

Posted: Tue Aug 17, 2021 8:57 pm
by HAWK21M
flipdewaf wrote:
One is reinforced with carbon fibres and the other reinforced with glass fibres…

CFRP has historically been more expensive (I’m not sure of the current situation with automated manufacturing tech) but is also lighter. One major difference is that GFRP is electrically insulative, whereas CFRP is not and so can have a bearing as to where it’s used. Cutting GFRP needs a respirator for the operator, CFRP also needs a respirator for any electrical equipment (a dremel doesn’t last long). I only have very limited experience with the two (most of the composite manufacturing work I did was ti+paper/al honeycomb but I’d guess the electrical properties of each may mean that GFRP may have some advantages in electrical bays to help with any dam he tolerance.

Fred


Sent from my iPad using Tapatalk


Educational
Any areas of use in Modern Aircraft for both examples.

Re: CFRP & FGRP

Posted: Tue Aug 17, 2021 8:58 pm
by HAWK21M
gregorygoodwin wrote:
This is related to what the engineers want in terms of impact resistance and what temperature the lay-up is subjected to.


Gregory

What would be the Stronger of the two

Re: CFRP & FGRP

Posted: Wed Aug 18, 2021 9:03 pm
by gregorygoodwin
I can only answer this from what I have seen on the aircraft we work on (B757-200, B767-300F, MD10-30, MD11, A300, and B777-200F). In terms of the cure temperature of a composite layup, the higher your cure temp. the more durable your layup will be. A three fifty degree cured layup will be superior to a two hundred fifty degree cured layup. The composite engineers determine this, for instance, the outboard fixed leading edge (outboard of the engine pylon) on the B767-300F is a 250 cure fiberglass layup while the inboard fixed leading edge is a 350 degree fiberglass cured component.These are, as almost all aircraft composites, made from a from a prepreg type fabric with the resin already infused into it.
From what I can see from working with composites, carbon fiber has a greater strength per amount of plies than fiberglass, but fiberglass has better thermal properties and maybe impact resistance. We see in areas where impact damage is likely, such as inboard flap lower skins, main gear door skins, and wing to fuselage fairings, can have a hybrid layup of carbon with maybe a layer of fiberglass and kevlar. Kevlar is very impact tolerant but it is also susceptible to soaking up moisture.
I thank you for asking about this and the briles rivets, structures questions don't come up too often.

Gregory

Re: CFRP & FGRP

Posted: Fri Aug 20, 2021 11:41 am
by HAWK21M
gregorygoodwin wrote:
From what I can see from working with composites, carbon fiber has a greater strength per amount of plies than fiberglass, but fiberglass has better thermal properties and maybe impact resistance. We see in areas where impact damage is likely, such as inboard flap lower skins, main gear door skins, and wing to fuselage fairings, can have a hybrid layup of carbon with maybe a layer of fiberglass and kevlar. Kevlar is very impact tolerant but it is also susceptible to soaking up moisture.
I thank you for asking about this and the briles rivets, structures questions don't come up too often.

Gregory

Thats True Structures is a side which many have little knowledge of.
But to get an Answer one has to read or ask a question....thats Aviation I guess.