Fatigue Vibration Ansys

[IanBmech]

All,

We are desinging a frame that is to be attached to the bottom of a rail car. This frame must withstand the following acceleration criteria:

Vertical
1 ±0.2 g
5.8 x 107 cycles

Lateral
0 ±0.2 g
5.8 x 107 cycles

Longitudinal
0 ±0.2 g
1.6 x 107 cycles

What is the best way to model this in ANSYS? I'm having trouble determining whether to use random vibration, response spectrum or even transient structural.

Thanks in advance.

 

[Twoballcane]

I'm not an ansys user, but these are sine vibration in each axis. You can either subject your model to each axis separately to see the responses or you can use Dunkerly's equation as an estimate for one frequency.



Tobalcane
"If you avoid failure, you also avoid success."
“Luck is where preparation meets opportunity”

 

[rb1957]

i'd model the static loadcases, you've possibly got 8 cases (+++, ++-, +-+, +--, -++, -+-, --+, ---), extract the stress peaks (same element, different cases), and do a fatigue analysis ...

 

[IanBmech]

Thanks for the responses.

I too had reached the conclusion of a static anlysis of all load cases.


I may have made this post in haste.

 

[rb1957]

you might want to look into canned fatigue analysis, eg ncode.