Hi Roo,
Composite or not - Hmmm? Not all composites are made from resins. I take a rather more composite view (if you'll pardon the pun) that a composite is one in which the material is not pure - such as aluminum or iron or copper or polyester (untreated, of course). All organic cord is by definition composite in that it is comprised of several different fiber thicknesses from different plants grown under different conditions. Now that may not accord with your definition, but that is what I referred to. Not to worry - Roy has it right when he says that all that was wanted was to know what the average Joe could exert. First, find an average Joe....
After that, all is simple. Give him (or her!) an average piece of (undefined) cord on an average day in an average climate in an average year of his or her life and you'll have an answer, on average. A great math teacher once told me that, if I have one foot on the stove (lit, of course) and one foot in the refrigerator (set below freezing of course) on average (assuming I have no protection and no hardened calluses) I'll be comfortable. I have added nothing to this post and I have taken nothing away, so on average I think it must have evened out!

squarerigger