14.3.1 What is a step?

An ABAQUS/CAE model uses the following two types of steps:

The initial step

ABAQUS/CAE creates a special initial step at the beginning of the model's step sequence and names it Initial. ABAQUS/CAE creates only one initial step for your model, and it cannot be renamed, edited, replaced, copied, or deleted.

The initial step allows you to define boundary conditions, fields, and interactions that are applicable at the very beginning of the analysis. For example, if a boundary condition or interaction is applied throughout the analysis, it is usually convenient to apply such conditions in the initial step. Likewise, when the first analysis step is a linear perturbation step, conditions applied in the initial step form part of the base state for the perturbation.

Analysis steps

The initial step is followed by one or more analysis steps. Each analysis step is associated with a specific analysis procedure. There is no limit to the number of analysis steps you can define, but there are restrictions on the step sequence. (For more information, see “Step sequence restrictions,” Section 14.3.3.)

You use items from the Step menu to create a step, to select and define the analysis procedure used during the step, and to manage existing steps. Alternatively, you can select StepManager from the main menu bar to display the Step Manager.

For example, consider the following analysis of a section of a piping system:

Initial Step:

Apply boundary conditions to fix the left end of the pipe and to allow only axial movement at the right end.

Step 1: Compress

Apply a compressive force to the right end of the pipe. This step is a general analysis step.

Step 2: Eigenmodes

Calculate the frequencies and modes of vibration of the pipe in its compressed state. This step is a linear perturbation step.

Figure 14–1 shows the Step Manager after you create these steps.

Figure 14–1 The Step Manager.

The manager lists all of the steps in the analysis as well as a few salient details concerning each step. Step 2, Eigenmodes, is indented to show that it is a linear perturbation step based on the state of the model at the end of Step 1, Compress.

For detailed information on creating, editing, and replacing steps, see the following sections:

For information on related topics, click any of the following items: