Talk Composites - The Forum for Advanced Composites

Question regarding Delamination

http://www.talkcomposites.com/Topic21969.aspx

By engineer - 9/16/2016 4:48:30 PM

Hello Talkcomposites,

I've a question that's recently come up in an exam i sat and i just cannot come to a specific answer. I've gone through all my material to hand and it doesn't mention it.

Question was.

In a composite material that has been impacted, what makeup will show the largest delamination?
1. Curved
2. Thin
3. Thick

I put thin, my thoughts being it'll have a large flex and therefore delaminate further, but i think all three could have arguments for being right.

What do you guys think?

E
By Hanaldo - 9/20/2016 1:21:15 AM

Delamination is a bit of a 2-stage process, you've got onset and progression. A curved plane is stronger than a flat plane, and takes a higher amount of energy for delamination onset to occur. But once it has occurred, the delamination progression is higher in a curved laminate. So if I am correct in saying that the question implies that all three laminates have catastrophically delaminated, then the curved laminate will show the largest delamination by area. 

I've attached a case study that I think sums it up quite well. Figure 9 in particular gives a good visual.