FUNDAMENTALS OF DYNAMIC ANALYSIS
Problem size
A dynamic analysis will always be more expensive in computation time and memory requirements than an equivalent static analysis.
A dynamic analysis will produce much more output, as the results are a function of time or frequency.
Response
Maximum dynamic response is usually greater than the static response for the same level of load, due to a magnification factor if the excitation is close to a resonance.
For frequencies considerably below the 1st resonance or slowly varying time history, a static analysis will be valid.
Resolution methods
The solution may be performed in the time or the frequency domains.
The next choice is whether a modal or direct solution is adopted.
Modal: Based on an initial modal analysis. Physical dofs are transformed to modal dofs to reduce the problem size and decouple the equations.
Direct: Step by step numerical integration of the complete, coupled system of equations.