- #1

series111

- 54

- 0

## Homework Statement

assuming that the maximum shear stress and torsion are the same in both shafts design a hollow shaft to replace the solid one . the ratio diameters is to be 0.6 for the maximum shear stress i calculated 79.95 x 10 ^6 mn/m2 and for the torsion i calculated 122.78x10^3 in the previous question.

## Homework Equations

(T) torque/ (J) polar second moment of area and (t) shear stress/ ( r) radius

polar second moment of area = pie (d4-d4)/32

radius = D/2

## The Attempt at a Solution

(j)= pie ((0.6)4-d4)/32 = 0.08545 d4

(r) = 0.6/2 = 0.3

solid shaft = j/r = 152.41x10^6 / 99.25 x 10 ^-3 = 1.535 x 10^-3values from previous question

hollow shaft = j/r = 0.08545/0.3 = 284.83 x 10^ -3

d 3 square root with 1.535 x 10^-3/284.83 x 10^-3 under it = 175.32 x 10^-3

D= 0.6 x D = 0.6 x 175.32 x 10^-3 = 105.19 x 10^-3

therefore the dimensions are 175mm and 105mm

i think these values are wrong as the solid shaft is 198.5mm and i always thought the hollow shaft would be larger in diameter please help as i don't no what i have done wrong..