Safe Infusion Strategies

General Composites Discussions Composites Talk
#1

Hi to all, I will soon “embark” myself into the making of a 11 meter sportfishing boat hull and me and my partner have decided to infuse it, we will be doing that in female moulds and use epoxi resin ( SP system´s Prime LV)and a sandwhich construction where corecell will be the core of our choice.

When talking with some knowledgeable composites friends about it, I found that they say the best layup for the resin feeder lines is the “fishbone” approach where maximum economy of consumable materials can be achieved. I argued with them that despite the economy of materials I intuitively find safer to use the sequential approach where you can manually and sequentially can open the feeder lines starting on the bottom and thus filling the mould from the bottom up allowing for any trapped gas to be evacuated through the perimetral top installed vaccuum absorbing line.

I am very probably wrong and " full of fear " because of this being our first attempt to infuse a hull.

It will certainly be very reassuring for us to hear your opinion on this as surely there are many infusion experts around this forum who “has been there and done that”

So the question is: Is for some reason safer to use the sequential approach or is it really an unnecessary waste of materials because it does not offer any significative advantage when compared with the fishbone setting of feeder lines ?:confused:

#2

This is where LIMS and FEA come into play. Standard practice would be the fishbone, however you are also right. Sequentially opening one feedline, waiting till it hits that one, and then opening the next is a way to make sure your material is permeated. However, unless you know exactly HOW the front will flow (core changes, extra material somewhere for a bulkhead fitting, etc) might not lead to an even flow front to your next infusion line.
I’m no expert on boat hull infusions, but I think if you want to run a line or 2 at the bottom middle, and another one at the mid point, and vent the top perimiter, you should have no fear. In the end, as long as you wait till the flow front passes the next infusion line, it should be ok. You might have a slow spot, or some resin sucking into the vent line…but you can at least make sure that there are no voids between two fishbone flow fronts that collide and close off an area of dry fabric.

#3

Thank you riff42, you expressed my ideas better than myself … what you said is exactly what I think about the subject.

About the resin flow front, I believe that as we have purposedly designed the layout of reinforcement tissues simple and with the overlapping of fiberglass parallel to corners and edges, the flow front should develop evenly and parallel to our resin lines which will (If sequential infusion) also be parallel to the main edges so in theory nothing strange should happen.

I am having trouble to upload some pictures ( rendered 3d drawings) of approximately how we plan on doing it but will hopefully soon insert them here for a better view of the two ionfusion strategies.