niravpshah
Mechanical
Dear Experts,
I have been struggling with this question since last couple of days. I have bolted joint connection which I want to analyze.
I have cantilever type of configuration for my flange connection. And the bolt carries all the dead weight load, pressure load and thermal expansion load. We have got the “in-house” spreadsheet which calculates,
Bending Stress,
Tensile Stress,
Shear Stress
&
Separation Margin.
Unfortunately, the developer of the spreadsheet is not available. But from what I understand we have got pretty good experience with the designs made by this spreadsheet.
The criteria it uses for the calculation is comparing all the stresses with 0.02% yield value and if the ratio of the stress to allowable (0.02%) is less than 1 then the design is ok.
e.g
Bending Stress – 80%
Tensile Stress, - 90%
Shear Stress- 60%
And the separation margin has to be higher than 15% for the design acceptance.
My question is,
1) Don’t we have to combine the loading and compare it to allowable stress? The scenario I ran gave me above numbers. What if have find say, Von misses stress, chance are that it will exceed the allowable..
2) I haven’t yet gone into detail to find out the logic of the spreadsheet, but in general for bolted joint, do we compare stresses individually to allowable? Say, shear will be carried by threads..
I am working onto find the theory used for the calculation in the spreadsheet, it’s taking lot of time since its pretty cumbersome. I am looking for general answers for bolted joint calculation. I would really appreciate your most valuable response. Does anyone know of good reference material for the subject?
Thanks again,
Nirav
I have been struggling with this question since last couple of days. I have bolted joint connection which I want to analyze.
I have cantilever type of configuration for my flange connection. And the bolt carries all the dead weight load, pressure load and thermal expansion load. We have got the “in-house” spreadsheet which calculates,
Bending Stress,
Tensile Stress,
Shear Stress
&
Separation Margin.
Unfortunately, the developer of the spreadsheet is not available. But from what I understand we have got pretty good experience with the designs made by this spreadsheet.
The criteria it uses for the calculation is comparing all the stresses with 0.02% yield value and if the ratio of the stress to allowable (0.02%) is less than 1 then the design is ok.
e.g
Bending Stress – 80%
Tensile Stress, - 90%
Shear Stress- 60%
And the separation margin has to be higher than 15% for the design acceptance.
My question is,
1) Don’t we have to combine the loading and compare it to allowable stress? The scenario I ran gave me above numbers. What if have find say, Von misses stress, chance are that it will exceed the allowable..
2) I haven’t yet gone into detail to find out the logic of the spreadsheet, but in general for bolted joint, do we compare stresses individually to allowable? Say, shear will be carried by threads..
I am working onto find the theory used for the calculation in the spreadsheet, it’s taking lot of time since its pretty cumbersome. I am looking for general answers for bolted joint calculation. I would really appreciate your most valuable response. Does anyone know of good reference material for the subject?
Thanks again,
Nirav