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I am interested in analyzing the effects of vibration due to a helopad over office space.  I am planning on using FE analysis but I am running into some difficulty generating a forcing function of the helicopter sitting on the pad idling.  I imagine it would depend somewhat on the blade pass frequency. And the load while on the pad shouldn't be any greater than the aircraft itself.  Any suggestions???

RE: Vibration

That's a good way of thinking about it. I'd use a square wave forcing function of blade passing frequency (BPF) fundamental, with an average level equal to the weight of the helo, and a mark space ratio of say 0.3. Your safety factor might need to be rather large. Have you searched the literature for anybody else's WAGs, or even experimaental data? or contacted a helicopter manufacturer?



Greg Locock

RE: Vibration

Military helo crash load specs call for 20 g's to the helo and somewhere between 8 to 16 g's for hard landings, so your roof should be able to hand that without collapsing.


RE: Vibration

how we can control the vibration of boiler feed water pumps
in steam power plants?

RE: Vibration

To Feed Water Pump,
By starting a new thread either here or in Pump Engineering and by fully describing your pump(s) and the kinds of vibration problems being experienced with as much detail as you can muster.

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