the propeller on a ship shown in figure qi is subjected to a compressive axial force f of 180 kn as it pushes the water backward and a torsional load t of 15 kn.m as it turns through the water. the...

the propeller on a ship shown in figure qi is subjected to a compressive axial force f of 180 kn as it pushes the water backward and a torsional load t of 15 kn.m as it turns through the water. the solid shaft has a diameter of 150 mm. it is made of c1018 steel with yield strength of 220 mpa, young's modulus of 200 gpa and poisson's ratio of 0.3.

a) at the most critical material point of the shaft, calculate the stress state and sketch the corresponding stress element.
b) what is the factor of safety of the shaft if it is designed according to:
i) tresca criterion?
ii) von mises criterion?

c) by sketching the principal stresses on the tresca and von mises yield loci, briefly explain the reason for the difference in the factor of safety according to both criteria.

d) without performing any calculation, would the factor of safety become higher, lower or the same according to tresca criterion if a hollow shaft with an inner diameter of 130 mm and an outer diameter of 150 mm of the same material is used? explain the reason for your answer.