Greg,
If your forcing function is dependent on time, then you should run a
Dynamic Time, not shock which uses acceleration, velocity, or
displacment versus frequency for input. Another point: You may already
be aware, but you need to capture all potential affected modes in your
modal analysis. If you are not sure which modes are important, then
specify (request) modes from something like 0 to 800. That would
capture all modes that have any sort of measurable structural
displacement, hence any significant stress magnitudes. Hope this helps.
Randy Speed
Speed Consulting,LLC
www.speedconsulting.com
(214) 213-4440
Quoting Stephen Seymour <sseymour@seymourecg.com>:
> Greg,
>
>
>
> For a dynamic shock analysis your independent variable is frequency not
> time. For what you are trying
>
> to accomplish you would need to run a dynamic time analysis. Mechanica is
> probably rejecting your
>
> equation due to the presence of the time variable.
>
>
>
> Hope this helps,
>
>
>
> Steve
>
>
>
>
>
> Stephen Seymour, P.E.
>
> Principal Engineer
>
> Seymour Engineering & Consulting Group, LLC
>
> 3600 NW 138th Street
>
> Suite #102
>
> Oklahoma City, OK 73134
>