Designing a Damper: Needing Guidance

[mholland]

Hi I'm a bit stuck on a problem I'm trying to figure out.
I am trying to design a damper, the layout is show below:

(apologies for the poor 'cad' drawing!)
So far i know:
I for the beam, how much energy needs to be absorbed by the damper (4500j) and the stroke (15mm). The maximum loading allowed on the fixings is 400kN
From these I've figure out that that ω of the beam is 2.289rad/s. I do not know the initial velocity.
I'm just after some pointers to calculate damper requirements/ζ
I'm a bit confused as to how to calculate the frequency of the system as it is to absorb a single impact effectively, and have a hard stop

 

[OldEngr63]

Does gravity act in this problem? Which way? Is there any spring? What is the black arrow? How high is the red post at the left end where the damper is connected? Is the 0.3 m leg fixed? Is the disk a fixed pivot?

It would help if you would show how you have figured out the beam frequency and what your assumptions were.

 

[mholland]

Thanks for taking the time to reply, for the red bar, say 20cm (i'm still waiting on cad drawings for accurate measurements), and yes the .3m post is fixed
Yer gravity acts downwards and there is a spring, which is the main slider tube shown below, forcing the bar to rotate as it extends.
The only data I've been given to work off is what i gave in the first post

 

[OldEngr63]

It looks to me like the left end of the damper goes to a fixed point on the frame, not related in any particular way to the moving red lever. Do you agree, or not?

 

[mholland]

The short .3m vertical red strut is stationary, and the long 1.3m (and the red triangular attachment) are rotating clockwise, with the ends of the damper attached where shown