in RTM process core-material , generally made of foam, is sandwiched between the resin and the fiber.
what if the part/blade is too thin, and no extra space is available to place the core ?
is it possible if we replace the core with some extra layer of bidirectional fiber glass mat and chopped strand mat?
It exists a lot of composites pieces without core made with the RTM process.
Just care if you have an important thickness that the resin infuse in z (for the simulation it means 3D permeability )
Normally wind turbine blades are produced using vacuum assisted resin infusion technologies due to their large structures. In this case placing the core is less complicated . Having said that, it depends on the structural requirements of the blade whether it needs a core and the type of core.
If you wish to have a core and wish to process the blade in an RTM tool, then just take care of the pressure and the resin infusion, as Kévin said, so that you get dry-spot free finished sandwich.
Yes. Possible to insert the glass matt in the core. But, I suggest insert the core material at an angle to improve the in-plane shear.
Regards,
Kadir Bilisik
As stated before, core materials might or might not be needed depending on the nature of the stresses . In general, core is added in composites in order to increase the laminate inertia and thus its behaviour under bending and its buckling resistance. Therefore, if your question is in regard with the design of the laminate, the answer would be the one most commonly heard in engineering: 'it depends'. If your parts need to be stiffer and no room is available for core, it is likely you'll need stiffer fibers (carbon over glass) or just more fibers. Then your proposition of adding layers of reinforcements might be good enough, you just need to check your design.
If your question is with regard to manufacturing, Core materials are used in sandwich panels and I've never seen them exposed on one side. The core material itself is not very strong or stiff, its purpose is to make the part thicker while having a minimal density. Therefore, it only separates the two facesheets that are providing the laminate strength. In this case, the answer to your question would be: 'Yes, if you need the core in your part, it should be placed between layers of reinforcement materials before the infusion'.
Other aspects that are important is that you should ensure that there is a very gradual transition between areas that have core and those that don't. You should ensure that the core is beveled all around so that you don't end up with structural flaws and/or channels that will provide a preferred path for the resin flow and prevent it from going everywhere during the impregnation process. You should also make sure you have a core material that is dedicated to RTM process as some open cell cores will fill with resin and make the parts very heavy while other cores won't allow the resin to flow through and wet the outer skin.
Good luck..
Laurent Cormier, Can you kindly provide me with a particular reference with which i can defend this answer , i have looked into RTM books by Kevin Potter and Bern Rackers but this point isn't mentioned there. Thanks
Which particular part of the answer do you want supported?
1- The requirement for using core based on bending stiffness and buckling resistance.
2- The requirement for putting core between two facesheets.
3- The requirement for beveling the core and choosing an appropriate core material.
Any of these can be at least partially addressed by the following link, which will bring you to a technical paper GURIT, from an important resin and core manufacturer. It is not as citable as a textbook or research paper but is a good primer on the topic of composite manufacturing.
http://www.gurit.com/files/documents/guide-to-compositesv5webpdf.pdf
Otherwise, look for ASM hanbdbook Volume 21. (http://products.asminternational.org/hbk/index.jsp), which is definitely more citable and will provide an in-depth discussion of all things composites. It includes discussions on core materials, analysis of sandwich panels and manufacturing of sandwich panels.
If you need anything more specific, please ask again being... well more specific.
- Badges
- Science topic
- Similar topics
- Psychology