It is desired to produce an aligned carbon fiber-epoxy matrix composite having a 0.11 volume fraction of fibers. Calculate (a) the critical fiber length, and (b) the longitudinal strength of the composite (in MPa), assuming the following: (1) the average fiber diameter is 0.014 mm, (2) the average fiber length is 5.2 mm, (3) the fiber fracture strength is 3.2 GPa, (4) the fiber-matrix bond strength is 80 MPa, (5) the matrix stress at fiber failure is 16.5 MPa, (6) the matrix tensile strength is 71 MPa. (a) mm (b) MPa

Afoot bridge is made as a simple deck, 4 m long, with a cross section 2 m (wide) and 20 cm thick, and made of wood. the deck is supported at the two ends. the maximum load allowable on the bridge is 10 tons, provided it is uniformly distributed on the deck. to sense this load, a strain gauge is placed at the center of the bridge and its resistance is monitored. if the sensor has a nominal resistance of 350 s2 and a gauge factor of 3.6, what is the reading of the strain gauge at maximum load? the modulus of elasticity for the wood used in the construction is 10 gpa.