A question on a recent test asked me to determine what the stress inside a uniaxial composite was at a given strain value. The given strain value was below the failure strain for the fibers and matrix material, but above the yield strain for the matrix. I was docked points for assuming that the matrix material would still be bearing load once it was beyond yielding, and my professor says that once the matrix has begun yeilding, it won't carry any of the load. Why is this so? I'm still not 100% sure about my professor's explanation.
Thanks in advance, Dave