Grade 1 titanium plates with both symmetrically and anti-symmetrically waisted cracks were due to tension tests first to receive the load vs. displacement diagrams and mechanical properties of strength and stiffness. Next from cyclic tests the load vs. cycles curves were constructed and fatigue life obtained. The numerical results of crack growth and life were obtained by using the finite element method and ANSYS workbench. From fracture mechanics the critical crack length was considered as final failure, then the modified numerical results were received. The results in load vs. cycles curves from two numerical method were found within acceptable errors with the experimental data.

The fiber metal laminates (FMLs) of both Ti/APC-2 neat and nanocomposite laminates were fabricated. The double-edged cracks of both symmetry and anti-symmetry were cut in FMLs. From tensile tests we received the load vs. displacement curves and mechanical properties. From cyclic tests the load vs. cycles (P-N) curves, residual life, and failure mechanisms were obtained. The mechanical properties of symmetrically cracked specimens were slightly lower than those of anti-symmetrically cracked counterparts. As the crack length increasing and inclined angle decreasing, the fatigue life decreased. The enhancement of nano-powder improved the ultimate load and fatigue life. The local stress intensity at the crack tip dominates the fatigue responses. The piece of elliptical part was observed from cyclic tests at failure. Although the attraction of two crack tips accelerated the crack growth rate, however, the delay to failure was caused by forming a small piece of ellipse centrally.

The mechanical properties and fatigue responses of double-edge-cracked Ti/APC-2 hybrid nano-composite laminates by tensile and cyclic tests were obtained. The double-edged cracks were cut with the crack lengths of 2.0 mm and 3.0 mm symmetrically and anti-symmetrically. The mechanical properties of symmetrically cracked samples are more detrimentally than those of anti-symmetrically counter parts. The greater the cracked angles, the greater the maximum load, however, the results of crack lengths were on the contrary. The fatigue life increased with the crack angle increasing, and also decreased with the crack length increasing. The enhancement of laminates by adding nano-powder did improve the fatigue life and maximum load, but not significantly. It is attributed to the local stress intensity factors at the crack tips mainly dominating the mechanical properties. Hence, the spreading of nano-power at the interface does not effectively strengthen the resistance to fatigue and fracture globally.