An aircraft component is fabricated from an aluminum alloy that has a plane strain fracture toughness of 38 . it has been determined that fracture results at a stress of 223 mpa when the maximum (or critical) internal crack length is 2.85 mm. a) determine the value of for this same component and alloy at a stress level of 334 mpa when the maximum internal crack length is 1.43 mm. g

Aloaded platform of total mass 500 kg is supported by a dashpot and by a set of springs of effective stiffness 72 kn/m. it is observed that when the platform is depressed through a distance x = 12.5 cm below its equilibrium position and then released without any initial velocity; it reaches its equilibrium position in the shortest possible time without overshoot. find the position and velocity of the loaded platform 0.10 sec. after its release. if a further load of 400 kg is added to the platform, find, i) the frequency of damped vibrations, and i) the amplitude of vibration after 2 complete oscillations, given that the initial amplitude is 15 cm.