Hi Brian, my comment wasn't about the logic of this method (which I use and don't have a problem with), but the optimistic/unrealistic view that because we've not seen any failures to date means there is no problem with our methods. Maybe I'm just becoming cynical with old age though! :) Pete.
HI, von mises is fine to combine the shear and bending, just have in the back of your mind that the average bending and shear calculations are a gross simplification of the actual stress field which is complicated, and that if you are getting close to the limit you should probably redesign or...
From the wording in that ESDU web page 'failure by rupture' is it coming at this from a limit load perspective? (I've not got access to the document). If so, it gets tricky trying to use this philosopy when the code/standard/industry accepted targets are based on significant margins against...
I'd be careful about stating combined pinned-pinned bending and shear as conservative. These problems have very complex stress fields and are very sensitive to the geometry and material properties. The peak stresses are likely to be significantly higher than those predicted by the hand calc. I...
Hi, I had an idea to reduce the bending on the shoulder bolt (see attached pdf with sketch - note in the pdf I say 'pin load' but I meant 'bolt load'). Pete.http://files.engineering.com/getfile.aspx?folder=39f51d98-486d-4246-842f-93f5aeb088a5&file=hook_bracket_modification.pdf
Typical, I just remembered one other thing as I hit reply :)
6) I'm not sure what country/industry you are in, but in my experience any lifting equipment must be proof tested with recorded evidence of this. Usually we try to aim for 2x maximum design load. So in this case, with an impact factor...
Hi, a couple of other comments...
4) Remember to check bearing stresses on the inner beam, outer plates, and the bolt. As a quick check I usually assume half the projected areas.
5) Finally, don't forget fatigue!
Cheers,
Pete.
Hi, several comments...
1) What did you assume for your bending stress? Have you assumed a fixed-fixed beam? I wouldn't because unless the bolt is an interference fit into the side plates it will provide little to no moment restraint for the very small bending deflections the bolt will be...
I was bored so plotted what these test specs looked like as common displacement, velocity, or accelerations over the frequency range! :) Agree with the others that they are not a PSD input.
Pete.http://files.engineering.com/getfile.aspx?folder=1c27fe0d-8596-48d9-adec-6db2a0b904cf&file=test_spec.pdf
Hi Tikina, I think it becomes more complex for the situation you are describing because it has a non-linear boundary condition, ie stiffness for one direction, zero stiffness for the other. If it has a net load such that the edge is always sat down in compression, then this is effectively a...
Actually you talk about resonance, so it is a dynamic G load. Where is the dynamic loading coming from? A fluctuating pressure? A component mounted to the plate? It would be useful if you could provide a bit more info about the problem you're thinking about, specifically the boundary conditions...
thread552-268056
Just for info, I came across this old unresolved thread above, and have posted the solution in case anyone is interested. Can a moderator move this answer under that thread to keep it together?
Thanks,
Peter Goodman.