Fastening stainless steel hinges to glass fiber 3

[aldotoscano]

Hi! I need to design/fabricate some fiber glass pressurized cabinets that will be utilized in offshore, hazard, corrosive enviroments. My first question is regarding the resin, should I use vinyl ester? my supplier recomends it as the best option against epoxy or polyester resins for this type of enviroment. My second question is how to fix/bolt the stainless steel hinges. I'm very concern about creep; or the material just cracking as I bolt the hinge. Should I add a molded stainless steel insert? is this feasible? or, is it better to use some adhesive instead? or to "ducktape" the hinges with reinforcement fabric tapes?

Any suggestion will be more than welcome.

Thanks in advance!

Aldo

 

[amorrison]

Another consideration:

Some types of stainless steels are good in a salt water environment some are not. The problem is not "rust" but chemical attack on at the grain boundaries resulting in "brittle" crackage.

I am sure Metallurgical will comment further...

 

[MechanicalChef]

You can mold in an insert. This would be a huge no-no for carbon, but glass won't mind galvanically. The first company I worked with manufactured engine covers for Caterpillar earth-movers. The hinge joints mounted through embedded metallic inserts. As long as you're confident your materials will live in the environment, as best I can estimate, they won't have a problem with each other.

 

[Joshmo]

Good practice with any bolted composite or glass joint is to maintian a edge to hole diameter (e/d) ratio of 2.5 to 3 to prevent bearing or shear out issues. Additionally, metallic hole sleeves can be bonded into the holes... check out products such as "PANDOR™ Clearance Fit Sleeves for Hole Protection" at Clickbond's website:

http://www.clickbond.com/index.php

 

[aldotoscano]

Guys, thank you all for your advice. I've taken into consideration all of your suggestions. I will go for the inserts solution, but I still have a question, should I install the inserts during the molding process or should I wait until hardened and then drill the holes and "glue" the inserts with the same resin?

Thanks again!

Aldo

 

[MechanicalChef]

In the example I referenced, both inserts and stiffening elements were added between layers of glass/resin during layup. Naturally, they also added a small ply-buildup over the insert.

 

[Tmoose]

Successful Secondary bonding (and even the initial cure) using vinyl ester resins can be QUITE tricky. We paid about a million bucks to find that out the hard way. The big name supplier just sounds genuinely concerned, acts surprised and makes a face kind of like that kid in Home Alone .

http://images.amazon.com/images/P/B00000K3CL.01.LZZZZZZZ.

Some MIL specs would not allow a structural joint in composite part that relied on secondary bonding without a 100% redundant mechanical retention back up. Neither would I.