Recently infused three test panels inside one vacuum bag. All three panels were four ply. First panel was 3K 6 oz twill. Second panel was 3k 12 oz flat tow plain weave. Third panel was 12K 18 oz flat tow plain weave. The first panel full infused but the other two did not. The question I have is did the vastly different architecture of the materials cause the incomplete infusion? What other factors might have been at fault. 

I couldn't open your picture.

Did the infusion go across all the panels at once or through one after the other?

Which first? The thick or the thin first.

I think the only way is to see a picture of your set up.

In flow dynamics, liquid will always take the easiest path, perhaps you gave it an easier path around the stack than through it.

Fred

can't see the picture as well picture would help a lot I think

Sorry the picture didn't show up. I had cut/past into the body of the post. Anyway, the three panels were between two layers of peel ply with a common vacuum bag and common flow media. The 6 oz twill was in the middle between the two heavier panels with about an inch gap between all of the panels. All three panels were infused at the same time with spiral wrap ontop of the flow media along the bottom edges and a breather along the opposite edges to the vacuum source. Flow pattern was normal.

Can't advise much on your situation but I have found that the top fabric does have an effect on the way a part infuses. I recently did a 1msq flat sheet panel with 1 layer 450g carbon twill with 600 glass bi-ax (45, 135). On top of that I had my normal stack of infusion layers. I have the spiral running a full length one one side and a single vac port in the middle opposite.

It seems your tow is the problem. I tried unidirectional carbon once. It didn't infuse at all. It was in the middle of a twill stack and the tow acted like it was a sheet of plastic. It just stopped dead. Make real sure your mold and the resin is nice and warm. A thick viscosity can really mess things up I have found through experience.

Fred

I have never had a problem infusing Uni directionals, bi-axials, tri-axials, quad-axials or even 3D woven stacks, normally the thicker the laminate the easier it is. And have done the same in have wildly differing stacks in the same infusion.  Without seeing a diagram of how you set up your infusion it would be difficult to say exactly what was wrong, my gut feeling is that you had a leak at some point or the resin made it to you vacuum point before it had fully wet out your stacks.

Far UK