Nastran reference manual : Dynamic Design

Provides the solution type and control information for Dynamic Analyses. Each dynamic load used in a Dynamic Analysis must have the appropriate Solution Method activated.

Figure 20 – Dynamics Section



- Solution Method and Domain of Solution : chooses the type of Dynamics Solution to be performed. The four following options are available: (1) Direct Transient, (2) Modal Transient, (3) Direct Frequency, and (4) Modal Frequency. The inappropriate boxes for each Solution Method will be inactivated automatically.
-Equivalent Viscous Damping: These statements provide damping information of a structure. The Overall Structural Damping Coefficient is an input for all four-solution methods.
-Equivalent Viscous Damping Conversion: Information for both System Damping and Element Damping is provided in this box. These values are only inputs for Direct and Modal Transient Analysis.
-Transient Time Step Interval: For transient analyses, these options control the number of steps, steps sizes, and the output interval.
-Frequency Step : The Solutions Frequencies are defined in this section. These statements define analyzed frequencies for both Direct and Modal Frequency Analysis.
-Response Based On Modes: For modal solution methods, these options allow choosing the number and/or range of modes to include in the frequency response or transient formulation.
-Select Range of Frequencies for Output: Allows to set which frequencies will be printed in the output file. In some cases it is interesting to run analysis for more frequencies that can be studied later.