Abaqus Keywords Reference Guide  
How to find keyword examples

*UNLOADING DATA
Provide unloading data for uniaxial behavior models in connectors or unloading data from uniaxial and shear tests for fabrics.

This option is used to define unloading response for the uniaxial behavior of connector elements when used in conjunction with the *CONNECTOR BEHAVIOR, *CONNECTOR UNIAXIAL BEHAVIOR, and *LOADING DATA options.

This option is used to define the unloading response from a uniaxial or a shear test for fabric materials when used in conjunction with the *FABRIC, *UNIAXIAL, and *LOADING DATA options. A fabric uniaxial test is specified with increasing strains along the specified yarn direction. A fabric shear test is specified with increasing shear strains as the fill and the warp yarns rotate with respect to each other.

Product: Abaqus/Explicit  

Type: Model data

Level: Model  

References:


Defining the unloading response for uniaxial behavior in connectors

Required parameter:

DEFINITION

Set DEFINITION=COMBINED to define an unloading path based on the specified unloading curve and a transition slope to transition from the loading to the unloading curve.

Set DEFINITION=EXPONENTIAL to define an exponential unloading path.

Set DEFINITION=INTERPOLATED CURVE to define an unloading path based on an interpolation between the specified unloading curves.

Set DEFINITION=QUADRATIC to define a quadratic unloading path.

Set DEFINITION=SHIFTED CURVE to define an unloading path based on shifting the specified unloading curve to the point of unloading.

Optional parameter:

RATE DEPENDENT

Include this parameter to define rate-dependent unloading data. If this parameter is omitted, the data are assumed to be rate independent. This parameter can be used only if the loading data are elastic and rate dependent.

Data lines for DEFINITION=COMBINED to define rate-independent unloading behavior that does not depend on independent components: 

First line:

  1. Transition slope.

Second line:

  1. Force or moment. (Provide the absolute value.)

  2. Constitutive relative displacement or rotation. (Provide the absolute value.)

  3. Temperature.

  4. First field variable.

  5. Etc., up to five field variables.

Subsequent lines (only needed if the DEPENDENCIES parameter has a value greater than five):

  1. Sixth field variable.

  2. Etc., up to eight field variables per line.

Do not repeat the first data line. Repeat the subsequent data lines as often as necessary to define the unloading curve data.

Data lines for DEFINITION=COMBINED to define rate-independent unloading behavior that depends on independent components: 

First line:

  1. Transition slope.

Second line:

  1. Force or moment. (Provide the absolute value.)

  2. Constitutive relative displacement or rotation. (Provide the absolute value.)

  3. Constitutive relative motion in the first independent component.

  4. Constitutive relative motion in the second independent component.

  5. Etc., up to entries as identified on the loading data definition.

  6. Temperature.

  7. First field variable.

  8. Second field variable.

    9. If the number of data entries exceeds the limit of eight entries per line, continue the input on the next data line.

Do not repeat the first data line. Repeat the subsequent data lines as often as necessary to define the unloading curve data.

Data line for DEFINITION=EXPONENTIAL and DEFINITION=QUADRATIC: 

First (and only) line:

  1. Energy dissipation factor.

  2. Permanent deformation factor. (Should be defined only in conjunction with the *LOADING DATA, TYPE=PERMANENT DEFORMATION option.)

Data lines for DEFINITION=INTERPOLATED CURVE and DEFINITION=SHIFTED CURVE to define rate-independent unloading behavior (the RATE DEPENDENT parameter is omitted) that does not depend on independent components: 

First line:

  1. Force or moment. (Provide the absolute value.)

  2. Constitutive relative displacement or rotation. (Provide the absolute value.)

  3. Temperature.

  4. First field variable.

  5. Etc., up to five field variables.

Subsequent lines (only needed if the DEPENDENCIES parameter has a value greater than five):

  1. Sixth field variable.

  2. Etc., up to eight field variables per line.

Repeat this set of data lines as often as necessary to define the unloading curve data.

Data lines for DEFINITION=INTERPOLATED CURVE and DEFINITION=SHIFTED CURVE to define rate-independent unloading behavior (the RATE DEPENDENT parameter is omitted) that depends on independent components: 

First line:

  1. Force or moment. (Provide the absolute value.)

  2. Constitutive relative displacement or rotation. (Provide the absolute value.)

  3. Constitutive relative motion in the first independent component.

  4. Constitutive relative motion in the second independent component.

  5. Etc., up to entries as identified on the loading data definition.

  6. Temperature.

  7. First field variable.

  8. Second field variable.

    9. If the number of data entries exceeds the limit of eight entries per line, continue the input on the next data line.

Repeat this set of data lines as often as necessary to define the unloading curve data.

Data lines for DEFINITION=INTERPOLATED CURVE to define rate-dependent unloading behavior (the RATE DEPENDENT parameter is included) that does not depend on independent components: 

First line:

  1. Force or moment. (Provide the absolute value.)

  2. Constitutive relative displacement or rotation. (Provide the absolute value.)

  3. Relative velocity. (Provide the absolute value.)

  4. Temperature.

  5. First field variable.

  6. Etc., up to four field variables.

Subsequent lines (only needed if the DEPENDENCIES parameter has a value greater than four):

  1. Fifth field variable.

  2. Etc., up to eight field variables per line.

Repeat this set of data lines as often as necessary to define the unloading curve data.

Data lines for DEFINITION=INTERPOLATED CURVE to define rate-dependent unloading behavior (the RATE DEPENDENT parameter is included) that depends on independent components: 

First line:

  1. Force or moment. (Provide the absolute value.)

  2. Constitutive relative displacement or rotation. (Provide the absolute value.)

  3. Relative velocity. (Provide the absolute value.)

  4. Connector relative position or constitutive relative motion in the first independent component.

  5. Connector relative position or constitutive relative motion in the second independent component.

  6. Etc., up to entries as identified on the loading data definition.

  7. Temperature.

  8. First field variable.

    9. If the number of data entries exceeds the limit of eight entries per line, continue the input on the next data line.

Repeat this set of data lines as often as necessary to define the unloading curve data.


Defining the unloading response data from uniaxial tests of fabric materials

Required parameter:

DEFINITION

Set DEFINITION=COMBINED to define an unloading path based on the specified unloading curve and a transition slope to transition from the loading to the unloading curve.

Set DEFINITION=EXPONENTIAL to define an exponential unloading path.

Set DEFINITION=INTERPOLATED CURVE to define an unloading path based on an interpolation between the specified unloading curves.

Set DEFINITION=QUADRATIC to define a quadratic unloading path.

Set DEFINITION=SHIFTED CURVE to define an unloading path based on shifting the specified unloading curve to the point of unloading.

The available unloading path types depend on the behavior type assigned to the test data (as defined on the *LOADING DATA option).

Optional parameter:

RATE DEPENDENT

Include this parameter equal to define rate-dependent unloading data. If this parameter is omitted, the data are assumed to be rate independent. This parameter can be used only if the loading data are elastic and rate dependent.

Data lines for DEFINITION=COMBINED: 

First line:

  1. Transition slope.

Second line:

  1. Nominal stress. (Provide the absolute value.)

  2. Nominal strain. (Provide the absolute value.)

  3. Temperature.

  4. First field variable.

  5. Etc., up to five field variables.

Subsequent lines (only needed if the DEPENDENCIES parameter has a value greater than five):

  1. Sixth field variable.

  2. Etc., up to eight field variables per line.

Do not repeat the first data line. Repeat the subsequent data lines as often as necessary to define the unloading curve data.

Data line for DEFINITION=EXPONENTIAL and DEFINITION=QUADRATIC: 

First (and only) line:

  1. Energy dissipation factor.

  2. Permanent deformation factor. (Should be defined only in conjunction with the *LOADING DATA, TYPE=PERMANENT DEFORMATION option.)

Data lines for DEFINITION=INTERPOLATED CURVE and DEFINITION=SHIFTED CURVE to define uniaxial rate-independent unloading behavior (the RATE DEPENDENT parameter is omitted): 

First line:

  1. Nominal stress. (Provide the absolute value.)

  2. Nominal strain. (Provide the absolute value.)

  3. Temperature.

  4. First field variable.

  5. Etc., up to five field variables.

Subsequent lines (only needed if the DEPENDENCIES parameter has a value greater than five):

  1. Sixth field variable.

  2. Etc., up to eight field variables per line.

Repeat this set of data lines as often as necessary to define the unloading curve data.

Data lines for DEFINITION=INTERPOLATED CURVE to define uniaxial rate-dependent unloading behavior (the RATE DEPENDENT parameter is included): 

First line:

  1. Nominal stress. (Provide the absolute value.)

  2. Nominal strain. (Provide the absolute value.)

  3. Strain rate. (Provide the absolute value.)

  4. Temperature.

  5. First field variable.

  6. Etc., up to four field variables.

Subsequent lines (only needed if the DEPENDENCIES parameter has a value greater than four):

  1. Fifth field variable.

  2. Etc., up to eight field variables per line.

Repeat this set of data lines as often as necessary to define the unloading curve data.