Question

16.0 (40 pts) The metal matrix of the composite described in Prob. 15 is known to contain internal flaws up to 2.9 E-6 m is size while the fiber has edge notches up to 8.4 E-6 m. Determine (a) which cracks first, the matrix or the fiber and (b) determine the critical composite stress (iso-strain and applied in the direction of the fibers) at which the first critical crack forms. Assume Y=1 and Kic (matrix) and Kic(fiber) are 7.8 and 7.6 MPa-m^1/2, respectively. (a) Matrix OR Fiber will crack first (choose one) _ (b) First crack at applied stress of: __________________

Q 15 ) A composite is made up of a metal oxide matrix and continuous carbide reinforcement fibers all aligned in one direction. The fiber volume is 18 %. In the isostrain orientation, a 8.2 E6 N load is applied in the direction of the fibers and over a surface area of 75 cm^2.   Determine the elastic strain in the composite in mm/m. The modulus of the metal oxide matrix and carbide fiber are 400 GPa and 440 GPa, respectively.

Answer 1