Recent content by Drew112233

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    Percentage saving in weight of Hollow Shaft vs Solid Shaft

    line 6: (1.57 x 10^-4) x 2*ri(hollow) = ((Pi*((2ri)^4 - ri^4))/2) line 7: 2*(1.57 x 10^-4) x 2*ri(hollow) =Pi*((2ri)^4 - ri^4 line 8: 2*(1.57 x 10^-4) x 2*ri(hollow) = (Pi*(2ri)^4) - (Pi*ri^4)) line 9: 2*(1.57 x 10^-4) x 2*ri(hollow) = Pi*ri^4 line 10: (2*(1.57 x 10^-4) x 2*ri(hollow)/pi =...
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    Percentage saving in weight of Hollow Shaft vs Solid Shaft

    Ok, So my Steps were ar follows: J(solid)/R(solid) = J(hollow)/R(hollow) We know that... J(solid)/R(solid) = ((Pi x 0.1^4)/2) / 0.1 = 1.57 x 10^-4 So then... 1.57 x 10^-4 = J(hollow)/R(hollow) Move R(hollow) across (1.57 x 10^-4) x Ro(hollow) = J(hollow) We also know...
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    Percentage saving in weight of Hollow Shaft vs Solid Shaft

    I've tried to derive, re-derive and re-arrange the formula ll week and I'm still struggling. Just to be clear, the R (hollow) which I use for the main equation is the same as Radius Outer (Ro) isn't it? I just can't seem to get it right, any more hints?
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    Percentage saving in weight of Hollow Shaft vs Solid Shaft

    I'll get straight on it! Thanks again nvn!
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    Percentage saving in weight of Hollow Shaft vs Solid Shaft

    I think I'm having trouble re-arranging the J(hollow) formula to find the unknown ro. Is the answer which I was provided with by my tutor actually correct? 102mm id 204mm od? the transposition I keep coming to is the post above is that correct?
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    Percentage saving in weight of Hollow Shaft vs Solid Shaft

    Thanks! I still can't get the answer... I feel so dumb! I have used the equation to get the new J/r(solid) figure of 1.57x10^-3 Then I get the full transposition for the outer radius of the hollow shaft (to get 'ro') to be: ro= (4x(1.57x10^-3)/Pi)^(0.33333) When I apply this...
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    Percentage saving in weight of Hollow Shaft vs Solid Shaft

    So I know: J(solid) r(Solid) J/r (solid) = 3.14x10^-3 Then by transforming J(hollow) into Pi(ro^4 - ri^4)/2 and letting that = r(hollow) x 3.14x10^-3, I can then transpose the equation to find ro. Is this all correct? I find the transposition to be 0.01256 x 2r(hollow) = Pi x...
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    Percentage saving in weight of Hollow Shaft vs Solid Shaft

    expanded and transposed so that the equation is ro=...
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    Percentage saving in weight of Hollow Shaft vs Solid Shaft

    Thanks for your help nvn, but I am still stuck... I have used the equations J(soild)/r(solid) = J(hollow)/r(hollow) (I have canceled out the Torques and the stresses from the equations due to the fact they must remain constant to both shafts) I have then transposed the J (Pi(ro^4 -...
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    Percentage saving in weight of Hollow Shaft vs Solid Shaft

    1. Hey everyone, I'm brand new to this site and am requiring some help and a push in the right direction. Here's my problem, I have a solid circular shaft of 200mm diameter, and it is to be replaced with a hollow shaft having a diameter ratio of 2. I need to determine the dimensions of the...
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