Im trying to do a dynamic analysis on a cylinder structure. As i need to excite the structure, im trying to put a point load at the end of the structure (its a traffic light). I use the split line function to make a small circle and to put the load on it to simulate a point load. But, when i run the analysis, this load does not produce anything, neither stress or displacement. Do you know what im doing wrong? thanks!

"However, your replies make me think that the magnitude of the load would affect the number of frequencies that the structure would have, im not sure."

The magnitude of the load has no effect on the what frequencies the structure has. All 'real-world' structures have an infinite number of modes of vibration (if we assume they are truly continuous). All finite element models will have a finite number of modes of vibration, where the highest mode of vibration is typically a dilatation mode of one of the elements. The modes of a vibration for a finite element model are determined by solving an eigenvalue problem with the model's mass and stiffness matrix. This means that the modes of vibration associated with a structure are purely a function of the stiffness of the structure, and the amount and distribution of mass within the structure (if a linear assumption holds true, which for most cases it does).

Now, as far as the load in concerned, the magnitude has no effect on what frequencies are excited; however, the temporal shape of the load does. In other words, how your load varies with time will determine what frequencies are excited. If your load is constant with respect to time, then the 'period of vibration' for this load is infinite; this means that the frequency of the load (1/T) is 0 Hz (ie no motion) and zero modes are excited. If you load looks like a direct-delta function (ie a impulse load over an infinitely small window of time), then the frequency of your load is infinite meaning that all frequencies are excited (this is partly why shock loads can be so damaging).

"i just need to excite the first frequency of the structure, which when i do a modal analysis, it is close to 1.86 hertz. So, reading your comments i would change to 1 frequency both in the properties of the analysis and in the modal damping."

Exciting only one frequency is typically not enough, and this will result in modal truncation error. Dynamic analyses are rather tricky because you need to make sure you capture enough modes to reflect the excitation nature of your forcing function. You also need to make sure that you have good modal results, as they are the foundation of a good dynamic analysis.

"Also, i got the second lab from a research paper and what they did was a physical test but the purpose of this simulation of solidwors is to simulate that, so thats why i need a graph that behaves similar than that!"

So this paper measured the time-history response of a traffic light post to some dynamic load? Can you provide a link to the paper? Are you sure you've accurately reproduce what they tested in your FEM?