I'm looking for a non-metallic material that will deliver > 50% elongation at break and flex modulus > 800ksi. Is this possible to achieve with composites?
A quick search using matweb did not yield anything that I would consider to meet your criteria. The modulus that you are requesting is just beyond that of most engineering thermoplastics (PEEK is one of the highest unreinforced at ~ 600 ksi). It is easily obtainable with only a slight addition (5-10%) of glass fiber, however, this lowers the elongation to failure, usually less than 10%.
Perhaps you could elaborate on your request, and maybe we can come up with something suitable. You can try your own search using the following link:
What I'm looking for is a material that can be used for a rod with diameter of .014" and a length of 75" that will not behave like a wet noodle and that will not break easily when flexed.
Sounds like a fishing rod. Unidirectional prepregs, glass or carbon will work for rods like this if they are oriented more circumferencially than longitudinal. Search for a site on fishing rod construction.
If you are looking for high elongation at failure - you should look at fibers used in ballistics applications. The name of the game there IS high elongation and energy dissipation.
Carbon and glass are too brittle to work as a continuous pultruded product. You might get there with some kind of discontinuous media.
as far as achieving a modulus of 800 ksi, I imagine that it won't be difficult. Kevlar has a Young's Modulus of 60 to 180 GPa, depending on type. Even a low fiber volume in a composite will give you the 800 ksi you seek.
I could really narrow the field for you if I knew more about the application....
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