Configuring a direct-solution steady-state dynamic procedure

1. Display the Edit Step dialog box following the procedure outlined in Creating a step (Procedure type: Linear perturbation; Steady-state dynamics, Direct), or Editing a step.

2. On the Basic and Other tabbed pages, configure settings such as frequency range and equation solver preferences as described in the following procedures.

1. In the Edit Step dialog box, display the Basic tabbed page.

2. In the Description field, enter a short description of the analysis step. Abaqus stores the text that you enter in the output database, and the text is displayed in the state block by the Visualization module.

3. Choose one of the following options:

   • Choose Compute real response only if you want Abaqus/Standard to ignore damping terms. This option can significantly reduce computational time.

   • Choose Compute complex response if you want to include damping terms and allow a complex system matrix to be factored.

   For more information, see Damping.

4. Choose a Scale option to indicate whether you want the frequency range(s) of interest to be divided using a Logarithmic or Linear scale.

5. Toggle on Use eigenfrequencies to subdivide each frequency range if you want the frequency range(s) of interest to be subdivided using the system's eigenfrequencies. This option requires a preceding frequency step. For more information, see Selecting the type of frequency interval for which output is requested.

6. Toggle on Include friction-induced damping effects to include friction-induced contributions to the damping matrix. For more information, see Contact conditions with sliding friction.

7. Enter the following data in the Data table:

   Lower Frequency

   The lower limit of the frequency range or a single frequency, in cycles/time.

   Upper Frequency

   The upper limit of the frequency range, in cycles/time. If you enter zero, Abaqus/Standard assumes that results are required only at the frequency specified in the Lower Frequency column.

   Number of Points

   The number of points in the frequency range at which results should be given.

   If you toggled on Use eigenfrequencies to subdivide each frequency range, this is the number of points at which results should be given, including the end points, from the lower limit of the frequency range to the first eigenfrequency in the range; in each interval from eigenfrequency to eigenfrequency; and from the highest eigenfrequency in the range to the high limit of the frequency range.

   If you toggled off Use eigenfrequencies to subdivide each frequency range, this is the total number of points in the frequency range, including the end points.

   Bias

   The bias parameter. This parameter is useful only if you request results at 4 or more frequency points. It is used to bias the results points toward the ends of the intervals so that better resolution is obtained there. This option is recommended if you have toggled on Use eigenfrequencies to subdivide each frequency range, since the ends of each interval are the eigenfrequencies where the response amplitudes vary most rapidly.

   For more information, see The bias parameter.

   For detailed information on how to enter data, see Entering tabular data.

1. In the Edit Step dialog box, display the Other tabbed page.

   (For information on displaying the Edit Step dialog box, see Creating a step, or Editing a step.)

2. Choose a Matrix storage option:

   • Choose Use solver default to allow Abaqus/Standard to decide whether a symmetric or unsymmetric matrix storage and solution scheme is needed.

   • Choose Unsymmetric to restrict Abaqus/Standard to the unsymmetric storage and solution scheme.

   • Choose Symmetric to restrict Abaqus/Standard to the symmetric storage and solution scheme.

   For more information on matrix storage, see Matrix storage and solution scheme in Abaqus/Standard.

When you have finished configuring settings for the step, click OK to close the Edit Step dialog box.