Hi, Would appreciate if someone can enlighten me.
"A hollow steel shaft has an internal diameter to external diameter ratio of 0.6".
so how do we determine the diameter of both the internal and external diameter?
thanks and regards,
Daijiro

Hi, Would appreciate if someone can enlighten me.
"A hollow steel shaft has an internal diameter to external diameter ratio of 0.6".
so how do we determine the diameter of both the internal and external diameter?
thanks and regards,
Daijiro
Hi tk421, thanks for the reply.
i understand how the hollow shaft looks like, but its only i need to know how to get the diameter as the question only indicate the internal diameter to external diameter ratio of 0.6.
Here's the full question;
A hollow steel shaft has an internal diameter (d) to external diameter (D) ratio of 0.6. It is required to transmit 5MW when rotating at a constant speed of 300rpm. If the shear stress is not to exceed 55MN/m2,
a) Show that the polar second of area J = 0.0855 D4
and hence calculate the value of D.
b) calculate the minimum shear stress in the shaft.
okay, lets narrow down to this;
2nd polar moment of area equals to J = pie(D4d4)/32
any expert knows how to resolve it till J = 0.0855 D4 ?
Since this is a homework problem, I will give you only minimum hints. I'll also suggest that you doublecheck your maths.
That said. you are given the ratio of d to D. You have your equation of J in terms of D and d. Now you have two equations, two unknowns (not counting J).
Where are you stuck?
Last edited by tk421; 02252014 at 04:10 PM.
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