Complete all the problems and show all your work.
(1.5 G means that the airplane needs to be able to withstand a stress 1 and half times as much as it would be subjected to instill air without yielding.)
1. If an airplane wing spar must sustain cracks up to 10 mm in length and the airplane weighs 50,000 kg, how thick must the spar be if made out of Titanium with a tensile strength of 900 Mpa and modulus of 114 Gpa.
- Airplanes must sustain 1.5G safety factor
- Assume the spar is 20 cm wide
- Note 1Kg/cm2 = ~100 Kpa
- For simplicity, we will assume the stress is in pure tension (It's not necessarily, for 5 bonus points, tell me what stress state would be more appropriate and why)
2. Calculate the ratios of the shear stresses required to activate the slip systems in alpha iron
- All you need to know is in the notes
- But you may have to dig a little
3. Given a BCC single crystal
Apply a normal stress, s, perpendicular to the 110 plane
What is the shear stress on a likely slip system?
4. For an isotropic non-crystalline solid (a glass), what would be the maximum shear stress and what would be the angle to an applied uni-axial stress, σ.