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*Tolerance |
 
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*Tolerance
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*Tolerance |
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To define the analysis convergence tolerance measure and related data.
Refer to Solution Convergence for further information on this feature.
Block of two lines with the appropriate tolerance data, all of which are optional.
The first line defines the analysis type.
ANALYSIS=Analysis Type
The format of the second line depends on the analysis type.
For all static and time domain dynamic analysis the format is:
[Displacement Tolerance] [, Max. Iterations] [, Small Torque Value], [Rigid Seabed Threshold Penetration] [,
Rigid Seabed Negative Reaction Value] [, Energy Tolerance]
For frequency domain dynamic analysis the format is:
[Tolerance] [, Max. Iterations] [, Relaxation Parameter]
Analysis Type can be STATIC/TIME or FREQUENCY. Displacement Tolerance defaults to 0.001 for static analyses and 0.025 for dynamic. Max. Iterations defaults to 20. Small Torque Value defaults to 10. If no value is specified for Rigid Seabed Threshold Penetration, Rigid Seabed Negative Reaction Value or Energy Tolerance, the corresponding convergence check is not applied. Where a value is specified for any of these parameters, it should be a positive value. Tolerance defaults to 0.025 for frequency domain analyses. Relaxation Parameter defaults to 0.8.
Input: |
Description |
Tolerance Measure: |
The tolerance used in determining if convergence has been achieved between successive iterations at a particular solution time. This entry is optional. If you do not specify a value, then Flexcom chooses a default based on the analysis type. Specifically, the default for static analyses is 0.001 (0.1%), while for dynamics it is 0.025 (2.5%). See Note (a). |
Maximum Number of Iterations: |
The maximum number of iterations Flexcom may perform at a particular time. The default number of iterations is 20. |
Small Torque Value: |
A value of torque below which Flexcom does not enforce convergence on torque for each element. The default value is 10. See Note (b). |
Rigid Surface Threshold Penetration: |
A threshold value to use in checking seabed penetration as part of the convergence calculations. This entry is left blank by default. See Note (c). |
Negative Reaction Threshold: |
A threshold value to use in checking reactions at seabed nodes as part of the convergence calculations. This entry is left blank by default. See Note (c). |
Energy Residual Tolerance: |
An alternative convergence criteria based on energy residuals. This entry is left blank by default. See Note (d). |
(a)Refer to Solution Convergence for further information on convergence measures.
(b)Refer to Solution Convergence for further information on the significance of the Small Torque Value.
(c)Refer to Seabed Penetration and Negative Contact Reactions for further information on the significance of the Rigid Surface Threshold Penetration and Negative Reaction Threshold inputs, respectively.
(d)The energy residual criterion works alongside the standard convergence criterion. If you do not specify an energy residual tolerance level, the criterion is not checked. A converged solution is achieved when both criteria are satisfied for a particular iteration. Refer to Energy Residual Convergence for a detailed discussion of the energy residual criterion.
(e)The parameters of this Tolerance menu should be only rarely varied. The default values are adequate for the majority of analyses.
Input: |
Description |
Tolerance Measure: |
The tolerance used in determining if convergence has been achieved between successive iterations. The default value is 0.025 (2.5%). |
Maximum Number of Iterations: |
The maximum number of iterations that Flexcom may perform. The default number of iterations is 20. |
Relaxation Parameter: |
The relaxation parameter used by Flexcom to improve the rate of convergence of dynamic analyses. See Note (a). |
(a)Refer to Frequency Domain Convergence for further information on the significance of the Relaxation Parameter.