HI guys,
so last time i did infusion with divinycell core it was very successful and I have made 2 more splitters that way and they are perfect. (http://www.compositescentral.com/showthread.php?t=7427&highlight=divinycell) HOWEVER, I tried the same procedure and got less than perfect result.
I tried my best to take a pic that shows the imperfections, there is no pinholes or anything but after infusion and curing (on the mold side) you can see where the holes were drilled in the foam.
In my previous times I used 12K carbon with no problem however this time I used 9oz 3k 4x4 fabric. is it caused because fabric is too thin? if that is the case how can I fix it next time? btw lay up is
mold (glass)
4x4 carbon
1/8" divinycell
4x4 carbon
peel ply
flow media
I was thinking maybe if I use a layer of fiberglass between foam and carbon on the mold side?
what resin did you use, and what is the hole size?
i used adtech 820 epoxy and holes are 3/32" (2.3mm)
2.3 is on the large side (but not alarming). You can try and source some foam with smaller holes, or make it yourself.
We had similar issues, and now make densely perforated foam. Many small holes. (about 1mm)
In your case your laminate is so thin, that the 2,3mm causes problems. Beefing up the laminate is an option as well, at a weight cost.
Thanks Herman , how much gap do you put between holes when you perforate it with 1mm holes?
11 to 30 mm.
It also depends on the laminate thickness and properties. If there is a lot of flow, you can get away with less holes.
I am gonna make a test sample with 1mm holes… if I wanted to biff up the laminate do you think a layer of 10oz glass would do the trick?
Any weight of glass helps…
Hi Bryanhaj,
You are right most probably the reason is very thin skin so you are able to notice the perforations on the core. DIAB has 2mm diameter with 20x20mm square pattern and 3mm diameter with 100x100 diamond pattern perforations as standard finishing. However those diameters are too large for such a thin skin. So as Herman pointed out 1mm diameter perforations would probably work but you have to do the perforations manually by yourself without damaging the core.
Regarding the distance 20x20mm between perforations are recommended for infusion however for such a thin reinforcement you can increase the distance between the perforations. But please make sure epoxy wets out properly middle of perforations squares during the infusion. If you increase the perforations distance too much then the fibre fraction might be getting higher further away from the perforations which will result inconsistent fibre fraction in the part.
I hope tests using 10oz glass and 1mm perforations will give you a good result. Please feel free to contact me if you have any questions.
Regards,
Cengiz Uluduz
Naval Architect, B.Eng, MIEAust
E-mail: [COLOR=blue]uluduz@ae.diabgroup.com [/COLOR]
DIAB Middle East | PO Box 25906 | Concord Tower Media City 26th Floor Office 2607 | Dubai, UAE
Phone: +971 4 429 86 04 | Fax: +971 4 429 86 06 | Web site: [COLOR=blue]www.diabgroup.com [/COLOR]
Any views or opinions presented in this message are solely those of the author and may not necessarily reflect the opinion of DIAB or its affiliates. Data and recommendations are the results of tests and experience, but are given without liability to DIAB. As the use of this information is beyond the control of DIAB and DIAB will not be liable for any loss or injury arising from it’s use. Final determination of suitability of the information is the sole responsibility of the designer and/or builder, and it is strongly recommended that actual samples be manufactured and tested prior to any final determination of suitability.
Thanks boatlands, while we are on the subject, is it ok to stack a 1/4" and 1/8" foams together to reach 3/8" foam thickness ? I just have some 1/4 and 1/8" at shop left over from another project so i wanted to see if I can use them instead of buying 3/8" foam.
I appreciate the help very much.
Bryan
Hi Bryan,
Sure you can put thin sheets top of each other to make thicker sheet. But you need to bond them together without leaving any air between sheets. You can make breeder holes into top sheet around 3" distance square pattern to make sure air will not be trapped between sheets. You can use core bonding adhesive for bonding such as Divilette 600.
http://www.diabgroup.com/americas/u_products/u_prods_5.html
Keep in mind the bonding adhesive density is around 600kg/m3 so it will increase the density of our final sheet. I mean your bonded 3/8” will be heavier than getting new unbounded sheet. Just to let you know in case you have a weight sensitive project.
If you want to use your bonded 3/8” core for infusion then you will need to make perforations again since the holes you did for bonding will be closed due to bonding adhesive. For infusion we recommended around 1x1” distance square patterns but if you have light reinforcement you can increase the perforation distance.
I assume you will not have grooves on the surface of the foam so you will apply peel ply and flow net for the resin flow.
Feel free to contact me if you need further explanations or any other questions.
Regards,
Cengiz Uluduz
Naval Architect, B.Eng, MIEAust
E-mail: uluduz@ae.diabgroup.com
DIAB Middle East | PO Box 25906 | Concord Tower Media City 26th Floor Office 2607 | Dubai, UAE
Phone: +971 4 429 86 04 | Fax: +971 4 429 86 06 | Web site: www.diabgroup.com
Any views or opinions presented in this message are solely those of the author and may not necessarily reflect the opinion of DIAB or its affiliates. Data and recommendations are the results of tests and experience, but are given without liability to DIAB. As the use of this information is beyond the control of DIAB and DIAB will not be liable for any loss or injury arising from it’s use. Final determination of suitability of the information is the sole responsibility of the designer and/or builder, and it is strongly recommended that actual samples be manufactured and tested prior to any final determination of suitability.