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Whichever option is chosen, the output will always be written at the zero-increment and last increment of the analysis and, for a low-cycle fatigue analysis, at the end of each cycle. The zero-increment output represents the initial conditions for the current analysis step and is essential for sequential thermal-stress analyses and analyses involving submodeling, for which a complete solution history (including the solution state at the beginning of the step) is needed to ensure proper interpolation in time. The zero-increment state is written at the beginning of the step, before the solution of the incremental nonlinear finite-element equations for the step commences, and is therefore in general not an equilibrium solution. Particular examples where the solution is not in equilibrium include the first step of an analysis in which an initial stress state is defined and when loads or boundary condition changes are discontinuous between steps.

Usually, the zero-increment output in any step corresponds to the base state, which is the state of the model at the end of the last general step. The exception to this is modal transient dynamic analysis, where the zero-increment output represents the linear perturbation response at time zero.

By default, when convergence difficulties are encountered in a general step, output is written for the last converged increment. To recover the requested results variables for this last converged increment, a new attempt is performed. There is no message written to the status file or the message file to show this additional attempt. In the output database file you will see an extra attempt and an additional frame. If the previous increment was written to the output database and convergence difficulties are encountered during the current increment, the last converged increment is still written to the output database, which will result in a duplicate output frame at the end of the analysis.

Time domain analysis: specifying output frequency in increments

You can specify how frequently you want output in terms of increments. Specify an output frequency of zero to suppress output.

Input File Usage: \*OUTPUT, FREQUENCY=n

Abaqus/CAE Usage: Step module: field or history output request editor: Frequency:

Every n increments: n

Time domain analysis: specifying output frequency in number of intervals

You can specify the output frequency in number of intervals, n. The specified number of intervals must be a positive integer.

By default, Abaqus/Standard adjusts the time increment (in some cases Abaqus/Standard might violate the minimum time increment specified) to ensure that data are written at the exact times calculated by dividing the step into n equal intervals. Alternatively, you can specify that the data be written immediately after each time mark. In this case no adjustment of the time increment is necessary.

Input File Usage: Use the following option to request results at the exact time intervals:

\*OUTPUT, NUMBER INTERVAL=n, TIME MARKS=YES

Use the following option to request results at the increments ending immediately after each time interval:

\*OUTPUT, NUMBER INTERVAL=n, TIME MARKS=NO

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<table><tr><td>Abaqus/CAE Usage:</td><td>Use the following option to request results at the exact time intervals:Step module: field or history output request editor: Frequency: Evenly spaced time intervals, Interval: n, Timing: Output at exact timesUse the following option to request results at the increments ending immediately after each time interval:Step module: field or history output request editor: Frequency: Evenly spaced time intervals, Interval: n, Timing: Output at approximate times</td></tr></table>

Time domain analysis: specifying output frequency in regular time interval size

You can write the results at specified regular intervals throughout the step as well as at the end of the step.

By default, Abaqus/Standard will adjust the time increment (in some cases Abaqus/Standard might violate the minimum time increment specified) to ensure that data will be written at the exact times, as defined by multiples of the time interval, t. Alternatively, the data can be written immediately after each time mark. In this case no adjustment of the time increment is necessary.

Input File Usage: Use the following option to request results at the exact time intervals:

\*OUTPUT, TIME INTERVAL=t , TIME MARKS=YES

Use the following option to request results at the increments ending immediately after each time interval:

\*OUTPUT, TIME INTERVAL=t , TIME MARKS=NO

Abaqus/CAE Usage: Use the following option to request results at the exact time intervals:

Step module: field or history output request editor: Frequency: Every x units of time: t, Timing: Output at exact times

Use the following option to request results at the increments ending immediately after each time interval:

Step module: field or history output request editor: Frequency: Every x units of time: t, Timing: Output at approximate times

Time domain analysis: specifying output frequency in time points

You can write the results at specified time points throughout the step.

By default, Abaqus/Standard adjusts the time increment (in some cases Abaqus/Standard might violate the minimum time increment specified) to ensure that data are written at the exact time points specified. Alternatively, you can specify that the data be written immediately after each time point. In this case no adjustment of the time increment is necessary.

Input File Usage: Use the following options to request results at the exact time points:

\*TIME POINTS, NAME=time points name

\*OUTPUT, TIME POINTS=time points name, TIME MARKS=YES

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Use the following options to request results at the increments ending immediately after each time point:

\*TIME POINTS, NAME=time points name

\*OUTPUT, TIME POINTS=time points name, TIME MARKS=NO

# Abaqus/CAE Usage:

Use the following option to request results at the exact time points:

Step module: field or history output request editor: From time points,

Name: time points name, Timing: Output at exact times

Use the following option to request results at the increments ending immediately after each time point:

Step module: field or history output request editor: From time points,

Name: time points name, Timing: Output at approximate times

# Time domain analysis: time incrementation

If the output frequency is specified at exact times and in terms of the number of intervals, in regular time intervals, or in time points, Abaqus/Standard adjusts the time increments to ensure that data are written at the exact time points. In some cases Abaqus may use a time increment smaller than the minimum time increment allowed in the step in the increment directly before a time point. However, Abaqus will not violate the minimum time increment allowed for consolidation, transient mass diffusion, transient heat transfer, transient couple thermal-electrical, transient coupled temperature-displacement, and transient coupled thermal-electrical-structural analyses. For these procedures if a time increment smaller than the minimum time increment is required, Abaqus will use the minimum time increment allowed in the step and will write output data at the first increment after the time point.

When the output frequency is specified at exact times and in terms of the number of intervals, in regular time intervals, or in time points, the number of increments necessary to complete the analysis might increase, which might adversely affect performance.

# Controlling the output frequency for field output in Abaqus/Explicit

Field output data are always written at the start and end of each step in which the output request is active. In addition, you can specify the output frequency in terms of the number of intervals during the step, the size of regular time intervals throughout the step, or time points throughout the step. The times at which the results are written are referred to as time marks.

# Specifying field output frequency in number of intervals

You can specify the output frequency in number of intervals, n. The specified number of intervals must be a positive integer. For example, if the specified number of intervals is 10, Abaqus/Explicit will write field data 11 times: the values at the beginning of the step and at the end of 10 equal time intervals throughout the step.

By default, field data will be written at the increment ending immediately after each time mark. Alternatively, when you specify the output frequency in number of intervals, you can choose to have the

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time increment size adjusted so that an increment will end exactly at each of the time marks calculated by dividing the step into n equal intervals.

<table><tr><td>Input File Usage:</td><td>Use the following option to request results at the increments ending immediately after each time interval:*OUTPUT, FIELD, NUMBER INTERVAL=n, TIME MARKS=NOUse the following option to request results at the exact time intervals:*OUTPUT, FIELD, NUMBER INTERVAL=n, TIME MARKS=YES</td></tr></table>

<table><tr><td>Abaqus/CAE Usage:</td><td>Use the following option to request results at the increments ending immediately after each time interval:Step module: field output request editor: Frequency: Evenly spaced time intervals, Interval: n, Timing: Output at approximate timesUse the following option to request results at the exact time intervals:Step module: field output request editor: Frequency: Evenly spaced time intervals, Interval: n, Timing: Output at exact times</td></tr></table>

Specifying field output frequency in regular time interval size

Alternatively, you can write the results at specified regular intervals throughout the step as well as at the beginning and end of the step. The time increment size will not be adjusted to meet the specified time marks; results will be written at the increment ending immediately after each time mark, as defined by multiples of the time interval, t.

Input File Usage: \*OUTPUT, FIELD, TIME INTERVAL=t

Abaqus/CAE Usage: Step module: field output request editor: Frequency: Every x units of time: t

Specifying field output frequency in time points

You can write the results at specified time points throughout the step. Regular time intervals between time points are not required; you can specify any desired time points at which the field output is to be written.

Input File Usage: Use the following option to request results at the exact time points:

<table><tr><td>*TIME POINTS, NAME=time points name</td></tr><tr><td>*OUTPUT, FIELD, TIME POINTS=time points name, TIME MARKS=YES</td></tr><tr><td>Use the following option to request results at the increments ending immediately after each time point:</td></tr><tr><td>*TIME POINTS, NAME=time points name</td></tr><tr><td>*OUTPUT, FIELD, TIME POINTS=time points name, TIME MARKS=NO</td></tr></table>

Abaqus/CAE Usage: Use the following option to request results at the exact time points:

Step module: field output request editor: Frequency: From time points, Name: time points name, Timing: Output at exact times

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Use the following option to request results at the increments ending immediately after each time point:

Step module: field output request editor: Frequency: From time points,

Name: time points name, Timing: Output at approximate times

# Default field output

If you do not specify the output frequency (in either number of intervals, time interval size, or time points), field output will be written at 20 equally spaced intervals throughout the step.

# Controlling the output frequency for history output in Abaqus/Explicit

If history output is selected, you can specify the output frequency in terms of either increments or regular intervals throughout the step.

# Specifying history output frequency in increments

You can specify the output frequency in increments. The data will be written at this frequency as well as at the end of each step of the analysis.

Input File Usage: \*OUTPUT, HISTORY, FREQUENCY=n

Abaqus/CAE Usage: Step module: history output request editor: Frequency: Every n time increments: n

# Specifying history output frequency in regular time interval size

Alternatively, you can write the results at specified regular intervals throughout the step as well as at the end of the step. The time increment size will not be adjusted to meet the specified time marks; results will be written at the increment ending immediately after each time mark, as defined by multiples of the time interval, t.

Input File Usage: \*OUTPUT, HISTORY, TIME INTERVAL=t

Abaqus/CAE Usage: Step module: history output request editor: Frequency: Every x units of time: t

# Default history output

If you do not specify the output frequency (in either increments or time interval size), history output will be written at 200 equally spaced intervals throughout the step.

# Controlling the output frequency for field output in Abaqus/CFD

Field output data are always written at the start and end of each step in which the output request is active. In addition, you can specify the output frequency in terms of increments, the number of intervals during the step, or the size of regular time intervals throughout the step. By default, field output will be written at 20 equally spaced intervals throughout the step.

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Specifying field output frequency in increments

You can specify the output frequency in increments. The data will be written at this frequency as well as at the beginning and end of each step of the analysis.

Input File Usage: \*OUTPUT, FIELD, FREQUENCY=n

Abaqus/CAE Usage: Step module: field output request editor: Frequency: Every n time increments: n

Specifying field output frequency in number of intervals

You can specify the output frequency in number of intervals, n. The specified number of intervals must be a positive integer. For example, if the specified number of intervals is 10, Abaqus/CFD will write field data 11 times: the values at the beginning of the step and at the end of 10 equal time intervals throughout the step.

Input File Usage: \*OUTPUT, FIELD, NUMBER INTERVAL=n

Abaqus/CAE Usage: Step module: field output request editor: Frequency: Evenly spaced time intervals, Interval: n

Specifying field output frequency in regular time interval size

Alternatively, you can write the results at specified regular intervals throughout the step as well as at the beginning and end of the step. The time increment size will not be adjusted to meet the specified time marks; results will be written at the increment ending immediately after each time mark, as defined by multiples of the time interval, t.

Input File Usage: \*OUTPUT, FIELD, TIME INTERVAL=t

Abaqus/CAE Usage: Step module: field output request editor: Frequency: Every x units of time: t

# Controlling the output frequency for history output in Abaqus/CFD

You can specify the output frequency in terms of increments, the number of intervals during the step, or regular intervals throughout the step. By default, no history output is automatically written to the output database.

Specifying history output frequency in increments

You can specify the output frequency in increments. The data will be written at this frequency as well as at the beginning and end of each step of the analysis.

Input File Usage: \*OUTPUT, HISTORY, FREQUENCY=n

Abaqus/CAE Usage: Step module: history output request editor: Frequency: Every n time increments: n

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Specifying history output frequency in number of intervals

You can specify the output frequency in number of intervals, n. The specified number of intervals must be a positive integer. For example, if the specified number of intervals is 10, Abaqus/CFD will write history data 11 times: the values at the beginning of the step and at the end of 10 equal time intervals throughout the step.

Input File Usage: \*OUTPUT, HISTORY, NUMBER INTERVAL=n

Abaqus/CAE Usage: Step module: history output request editor: Frequency: Evenly spaced time intervals, Interval: n

Specifying history output frequency in regular time interval size

Alternatively, you can write the results at specified regular intervals throughout the step as well as at the end of the step. The time increment size will not be adjusted to meet the specified time marks; results will be written at the increment ending immediately after each time mark, as defined by multiples of the time interval, t.

Input File Usage: \*OUTPUT, HISTORY, TIME INTERVAL=n

Abaqus/CAE Usage: Step module: history output request editor: Frequency: Every x units of time: t

# Requesting output in multiple steps

Output requests apply to the step in which they are defined and to all subsequent steps until they are respecified.

The only exception occurs when the step type changes from general to linear perturbation (available only in Abaqus/Standard). Output requests defined in general steps apply only to subsequent general steps; output requests defined in linear perturbation steps apply only to subsequent consecutive linear perturbation steps. In other words, output defined in a general step is independent of output defined in a linear perturbation step. Propagation between linear perturbation steps occurs only for consecutive linear perturbation steps. If a general analysis step occurs between perturbation steps, output defined in the first perturbation step will not propagate to the next perturbation step.

In any given step you can add or selectively replace the output requests that are continued from previous steps. Alternatively, you can discontinue all requests from previous steps and request a completely new set of output. The preselected field variables and preselected history output variables (see “Preselected output requests” below) are requested by default for the first step of an analysis; you can modify this request as in any other step.

# Specifying new output requests

By default, all output requests defined in previous steps are removed when new requests are defined, regardless of the type of output request being defined. In other words, a new field output request in a step removes all field and history output requests defined in previous steps.

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Because all existing output requests are removed when a new request is defined in a step, all output requests within the same step are treated as new (i.e., additional output requests or replacement output requests are treated as equivalent to new output requests).

Input File Usage: Use one of the following options to remove all existing output requests and to specify new requests:

$$
\begin{array}{l} * \text { OUTPUT,   FIELD,   OP = NEW } \\ * \text { OUTPUT,   HISTORY,   OP = NEW } \\ \end{array}
$$

Abaqus/CAE Usage: Step module: Create Field Output Request or Create History Output Request

Abaqus/CAE automatically respecifies all previously defined output requests when you create a new request.

# Specifying additional output requests

Alternatively, you can specify additional output requests without removing all default and previously defined output requests.

Input File Usage: Use one of the following options to specify additional output requests without removing all default and previously defined output requests:

$$
\begin{array}{l} * \text { OUTPUT,   FIELD,   OP } = \text { ADD } \\ * \text { OUTPUT,   HISTORY,   OP = ADD } \\ \end{array}
$$

Abaqus/CAE Usage: Step module: Create Field Output Request or Create History Output Request

Abaqus/CAE automatically respecifies all previously defined output requests when you create a new request.

# Replacing or removing an output request

You can replace an output request of the same type (e.g., field or history) and frequency with a new request. No other previously defined requests will be affected.

You cannot replace an output request to change its frequency. If no matching request is found, the request specified is simply added to the step.

To remove a previously defined request, you can replace the output request without specifying any new output variables.

Input File Usage: Use one of the following options to replace an output request with a new request:

$$
\begin{array}{l} * \text { OUTPUT,   FIELD,   OP } = \text { REPLACE } \\ * \text { OUTPUT,   HISTORY,   OP } = \text { REPLACE } \\ \end{array}
$$

Abaqus/CAE Usage: Step module: Field Output Requests Manager or History Output Requests Manager: Edit or Delete

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# Suppressing output requests defined in previous steps

To suppress completely all output requests that have been defined in previous steps, you can specify an output frequency of 0.

# Preselected output requests

There are two ways to define output variable requests quickly and easily. Both methods are available for field and history output requests and for the individual output requests used for requesting specific variable types (e.g., nodal, element). There are no preselected output variables for surface output requests in Abaqus/CFD. The use of these methods with individual output requests for specific variable types is explained in detail later in this section.

# Requesting procedure-specific preselected output requests

You can activate a procedure-specific set of commonly requested output variables. See Table 4.1.3–1 for a list of procedure types and their accompanying preselected variables. The variables written to the output database may change if the procedure type changes between steps.

If you request preselected field or history output and request additional output variables using individual output requests for specific variable types, the variables requested will be appended to the variables contained in the preselected list.

For geometrically nonlinear analysis in Abaqus/Standard, E is not available for output and LE is output by default. For linear perturbation analyses and geometrically linear analyses in Abaqus/Standard, LE and NE strain output requests yield the same output as E. For geometrically linear analysis in Abaqus/Explicit, LE is output.

Abaqus may omit some preselected variables from the analysis results. Abaqus omits preselected output variables if they are not applicable for the element type used to mesh the model or if other factors make the variables unsuitable for the analysis. No preselected variables are available for surface output in an Abaqus/CFD analysis.

Input File Usage: Use one of the following options:

\*OUTPUT, FIELD, VARIABLE=PRESELECT

\*OUTPUT, HISTORY, VARIABLE=PRESELECT

Abaqus/CAE Usage: Step module: field or history output request editor: Preselected defaults

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Table 4.1.3–1 List of preselected variables for various procedure types. 

<table><tr><td>Procedure type</td><td>Preselected element variables (field; history for Abaqus/CFD)</td><td>Preselected nodal and surface variables (field)</td><td>Preselected energy variables (history)</td></tr><tr><td>Annealing</td><td>none</td><td>none</td><td>none</td></tr><tr><td>Complex frequency extraction</td><td>none</td><td>U</td><td>none</td></tr><tr><td>Coupled pore fluid diffusion/stress</td><td>S, E, VOIDR, SAT, POR</td><td>U, RF, CF, PFL, PFLA, PTL, PTLA, TPFL, TPTL</td><td>ALLAE, ALLCCDW, ALLCCE, ALLCCEN, ALLCCET, ALLCCSD, ALLCCSDN, ALLCCSDT, ALLCD, ALLFD, ALLIE, ALLKE, ALLPD, ALLSE, ALLVD, ALLDMD, ALLWK, ALLKL, ALLQB, ALLEE, ALLJD, ALLSD, ETOTAL</td></tr><tr><td>Coupled thermal-electric</td><td>HFL, EPG</td><td>NT, RFL, EPOT</td><td>ALLAE, ALLCCDW, ALLCCE, ALLCCEN, ALLCCET, ALLCCSD, ALLCCSDN, ALLCCSDT, ALLCD, ALLFD, ALLIE, ALLKE, ALLPD, ALLSE, ALLVD, ALLDMD, ALLWK, ALLKL, ALLQB, ALLEE, ALLJD, ALLSD, ETOTAL</td></tr></table>
