Layup schedule help

Thanks Sam Sam, my thinking right now is to use the schedule provided but with a product that is compatible with epoxy. I'll review with the supplier and post back here msybm it will help someone else.

 

Not talking about the typical sales person you'd find at the lower levels of the market, the sales people are in direct contact with the engineers and the engineers are the ones giving you the laminate schedule. And the sales people for the manufactures are a completely different group of people than what would be selling you any glass, they deal with much larger and more technical accounts. Composites One puts on schools and training seminars where the resin, glass, core, release agent, catalyst, suppliers (manufacturer's technical staff, chemists, engineers etc.) give multi day courses to explain the products in detail and how to use them correctly. What's being discussed here is just the very basics.

 

Ondarvr - why isn't something like the various ways to measure the attributes of something like 1700 vs 1708 vs 1715 well known and published and standardized(not weights)? It seems like a glass weaver would be required to test their product as part of typical qa.

Yet, when we get the tds for glass, it usually only has weights.

Isn't some of the confusion here related to industry, notwithstanding clerical matters?

For example, I don't like the way 1700 peels and I'd like to find a suitable alternative. Hexcel sent me a 16-17 oz woven to test. Is the only means to determine the attributes testing done by me the end user a/o builder experience or a designer putting his finger in the air and saying this works?

 

Something like this

http://vectorply.com/wp-content/uploads/2015/06/KE-BXM-1708.pdf


I'll be fishing with the Vectorply Rep next month in Alaska.

 

Would this level of support apply for someone like myself who is doing a single project and I would guess from their perspective a small amount of product. The training is something I would be interested in .. do you know if they offer seats if there is additional room? The spec sheet was interesting as well particularly the difference between infusion and hand layup. I also read what I could find on their vectorfusion .. there wasn't a lot but that does sound promising if you are using that approach. Do you have any experience with that?

 

They will run the numbers for just about anybody, the issue is getting in touch with them to ask.

Composites One will let anyone into the training classes, but again, they need to know who you are so you can be contacted.

There are regional shows where the glass suppliers are on hand, CAMX, IBEX, SAMPE, plus a few others.

 

SamSam you have a sharp eye. I meant to reply earlier but is swamped with work.

Fabric technology can be confusing because it can be expressed in oz/ft2, oz/yd2 or gr/m2.

The standard coding system for the DB+mat is as follows. The first two number is the total weight of the bias cloth in oz/yd2, the second set of two numbers is the weight of the mat in oz/yd2. If the second set starts with a zero, it is a decimal. It is usually rounded off so a 0.75 is denoted as 08 or 0.8.

Thus, a DBM 1715 means 17 oz of biax cloth plus 1.5 oz of mat, a total of 18.5 oz/yd2. To convert to grams/meter2,we have to do some conversion. An ounce has 28.35 grams, an a square meter has 1.2 units of a square yard (a square meter is bigger than a square yard). Thus 17 x 28.35 x 1.2 = 576 gr/m2 for the double bias. For the mat, 1.5 x 28.35 x 1.2 = 51 gr/m2. This totals to 18.7 oz/yd2 (627 gr/m2)

See sample computation Raka, Inc. 772-489-4070 http://www.raka.com/fiberglass_cloth.html

Now the confusion. The table list in accordance with the column as TOTAL weight of 31.2 oz/yd2 (1058 gr/m2). Let us check the conversion. 31.2 oz/yd2 x 28.35 x 1.2 = 1058 gr/m2. Correct.

There is a discrepancy. The table list it as TOTAL 31.2 oz/yd2. Whereas the weight as computed is 18.5 oz/yd2. There is a missing 12.7 oz/yd2 to make 31.2 oz/yd2.

To package the fabric as a single unit, it is either stitched or powder coated to make the mat stick to the biax or both. That "extra" accounts for the total weight.

 

No, it's 17 oz a square yd for the fabric. The mat weight is 1.5 oz per sq ft, so a square yd (9 x 1.5 = 13.5) would amount to 13.5 oz. Add them together and you get 30.5 oz per sq yd.

From the Raka site you posted ...
Example: 1708 is a very common biaxial. 17 is the weight in ounces of the 2 layers of glass and the 08
means a third layer of mat at 8 ounces per sq. yard to give you a total weight of 25
ounces per sq. yard. 1710 would have 10 ounces of mat and 1715 would have 15 ounces.

I think even Raka has it wrong. If the mat weighed 15 oz per sq yd, that would divide out to 1.66oz per sq ft and nobody makes that.

Raka's weight is 17 +15 = 32oz per sq yd.
My calculations as above would say 30.5 oz.
The chart you posted said it would be 31.2 oz.
For some reason they are different, but they are close enough.

As you posted in post #84,

So, with the mat weighing not 51 but more like (488 grms?) per sq m and the thickness exceeding 1.1 mm, does the mat now need to be taken in as part of the structural equation in the OP's layup?
It seems like 3 such layers in the Op's layup schedule would constitute a major part of the structure and strength of the schedule.

 

Raka says it is 15 oz. Knytex says 1.5 oz. If Raka is correct, then total is 32 oz/yd2 (1085 gr/m2). A bit closer to 31.2 oz/yd2.

If as you say 1.5 oz/ft2 (13.5 oz/yd2) for mat is the correct unit. Round it off to 14 oz/yd2 (475 gr/m2) and the total weight is 31 oz/yd2 (1051 gr/m2). Very close to 31.2. The only thing wrong is that there is a mix of the units. The biax is computed as oz/yd2 and the mat is oz/ft2 (by Knytex) then added together. Inconsistent.

If I go by Raka's method, 1715 is 17 oz/yd2 biax + 15 oz/yd2 mat, total would be 32 oz/yd2. A little bit over than Knytex' 31.2 but close still. I still have to figure out where to add the stitches and powder coat.

Twice you have posted #84 (actually 3 including your message). What is the point if we could not yet figure out the units the manufacturer gave us? We can only be guessing.

Thickness equation is a little bit complex as there is a mixture of 52% Gc for Biax and 30-33% Gc for mat. More so with the laminate schedule. Only the outermost layer receives the highest stress, the second receives less, the third, the least. Might as well just use mat for the remaining layers after biax.

 

OK found it. This should educate us all. Searching Knytex, Owens Corning came up.

Seems that this manufacturer uses oz/yd2 for fabric and oz/ft2 for mat. It uses M for mat, and V for veil cloth as there are fabric suppliers that supplies Biax/BD with veil cloth in the 50grs/m2. When it is 280 grs/m2, it is described as light mat.

Since the fabric in topic is DBM 1715, It can be interpreted as a 17 oz/yd2 fabric + 15 oz/ft2 mat. Whoa, that comes out to 137 oz/yd2 of mat. That means if we follow the original data by Knytex where it say 1.5 oz mat (they meant 1.5 oz/ft2=13.5 oz/yd2). Confusing.

Thanks SamSam for being persistent.

https://www.tapplastics.com/uploads/pdf/Knytex Pro-Mat Data.pdf

 

The mat then accounts for almost half the weight of the cloth. That's a significant amount of the weight associated to the laminate. The other schedule called for 34oz. WR I'd need to look to see how much mat was called for there I believe it was similar.

Since it's against the core it doesn't provide impact resistance? If not what strength does it provide? Thanks so much for the replies I've learned a lot.

 

Scuff- Nothing to do with impact resistance. Its main purpose is to provide a good adhesion from the biax to the rough core. Sometimes called the bondline.
The mat also serves as promoter of adhesion when the lamination stops for more than 4 hours and may require sanding in between coats.

When laid up continously, layer by layer, "wet on wet", a 1.5 oz/yd2 of veil cloth will suffice as interface.

 

Its been a long time Scuff but I noticed in my library I did play with your design to evaluate. I used ISO and played around with 1 meter length panel and a 25 mm core. With 28 kN/m2 of bottom pressure, planing craft mode, I can get by with just a layer of 600 gr/m2 of fabric with a light CSM for corebond. The skin is not even stressed to the limit. 0.3 is the max stress ratio and I am getting only 0.1.

If you look closely at the right hand side equation, the stress diminishes from the outer layer to the inner layer. The second layer, though a CSM, is not even stressed.

3 layers of 1715 seems overdesigned.

 

Chopped strand mat and epoxy - West System https://www.jamestowndistributors.com/userportal/document.do?docId=384&title=Chopped+strand+mat+and+epoxy+-++West+System

 

It's a single layer of the 1715 .. the three layers is just at the keel. That was what I was thinking that the mat was for a good bond between the core and laminate. What would be a good weight of CSM to use as a veil? Thank you!!!