Defining Static Riks Steps | ||||
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From the Procedures section of the action bar,
click Static Riks Step
.
- Optional: Enter a descriptive Name.
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In the Maximum increments field, specify the upper limit for the
number of increments in the step.
The app ends the analysis if it exceeds this maximum before arriving at the complete solution for the step.
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From the Arc length incrementation selection options, select
one of the following:
Option Description Automatic Allows the solver to choose the size of the arc length increments based on computational efficiency. Fixed Uses an arc length increment that you specify as the constant increment size throughout the step. In general, this method is not recommended for a Riks analysis since it prevents the solver from reducing the arc length in cases of severe nonlinearity.
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If you selected the Automatic incrementation method:
- Enter the Initial arc length increment, which is the initial increment in arc length along the static equilibrium path in scaled load-displacement space.
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Enter the Minimum arc length increment.
If you enter zero, the app uses a default value of the suggested initial arc length or 10–5 times the total arc length, whichever is smaller.
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Enter the Maximum arc length increment.
If you do not specify a value, no upper limit is imposed.
-
Enter the Total arc length, which is the total arc length
scale factor associated with this step.
If you do not specify a value, or specify zero, the app assumes a default value of 1.0.
- If you selected the Fixed incrementation method, enter a value for the Arc length increment, which is the arc length increment along the static equilibrium path in scaled load-displacement space.
- Optional:
In the Stopping Criterion section, enter the Maximum
load proportionality factor.
The step ends if this value is exceeded.
- Optional:
From the Maximum displacement options, select
Translation or Rotation, then:
- Select the Node to monitor.
- From the DOF options, select the degree of freedom to monitor.
-
Enter the value for Maximum displacement or
Maximum rotation, which sets the limit on the displacement of
the selected node.
The step ends if this value is exceeded.
- Optional:
Select Include geometric nonlinearity to account for geometric
nonlinearity during the step.
By default, geometric nonlinearity is active in a Riks analysis. It is highly recommended that you keep this default setting.
Once you select this option, it remains active during all subsequent steps in the simulation.
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Optional: From the Matrix storage options, select
one of the following:
Option Description Solver default Uses a matrix storage and solution scheme chosen by the Abaqus solvers to store the stiffness matrix. Symmetric Uses the symmetric matrix storage and solution scheme to store the stiffness matrix. Unsymmetric Uses the unsymmetric matrix storage and solution scheme to store the stiffness matrix. For more information about these options, see Matrix Storage and Solution Scheme in Abaqus/Standard.