Fiber pullout can be a large energy, especially if the interfacial friction is high. Usually a broad spread of strengths is bad, but here this allows fracture to occur away from the crack plane where the stress is highest. Fracture within the matrix leads to long pullout. Easy debonding is important for the same reason. A high Weibull modulus also leads to distributed fractures in the composite with neighboring fibers taking up the load, rather than getting a fast-moving localized crack tip.
Interface is weak so the fiber is unstrained.
Discuss the joining of composites See the notes. Try to avoid interlaminar shear, transverse stress. Use balanced joints and stepped junctions. Use many large bolts, hollow to reduce weight.