Abaqus general and linear perturbation steps are the two main step classes used to define an Abaqus analysis history. General steps can include linear or nonlinear response; linear perturbation steps compute linear response about the current preloaded and predeformed state.
How It Works
Abaqus defines the analysis history as a sequence of steps. Each step selects an analysis procedure and then attaches step-dependent history data such as loads, boundary conditions, interactions, output requests, and controls.
General analysis steps update the model state through the load or time history. Material history, contact status, geometric configuration, temperatures, and other state variables carry forward from one general step to the next.
Linear perturbation steps are available in Abaqus/Standard and do not advance the subsequent general analysis history. They are used for linear analyses such as eigenvalue buckling, frequency extraction, steady-state dynamics, response spectrum, random response, and matrix generation about an existing base state.
Why It Matters
The step type controls how results should be interpreted. A natural frequency extraction after a nonlinear preload can include preload stiffness, while the perturbation results themselves do not become a new nonlinear state for later general steps.
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