Eigenstrain-Based Simulation of Powder Bed–Type Additive Manufacturing Processes

Special-purpose techniques and user subroutines are available for eigenstrain-based simulation of powder bed–type additive manufacturing processes. These internal built-in user subroutines are accessed by starting names and types with "ABQ_" as described below.

This page discusses:

Specifying Element Activation and Eigenstrain Using the Pattern-Based Method
Visualization of a Scan Pattern
Specifying Element Activation and Eigenstrain Using the Trajectory-Based Method

Specifying Element Activation and Eigenstrain Using the Pattern-Based Method

The following steps are required to use the pattern-based eigenstrain method:

Create a table collection with a name that begins with "ABQ_EIG". The table collection must contain a parameter table of type "ABQ_AM_EigenStrain_Method" as well as the other parameter tables listed below.
In the parameter table of type "ABQ_AM_EigenStrain_Method", set the activation type to "PatternBased".
Define parameters of rectangular patches that make up a rectangular unit cell (see Scan Pattern–Mesh Intersection), which is repeated to cover the cutting plane or a layer, in a parameter table of type "ABQ_AM_EigenStrain_PatternBased_Define". You can define the following parameters: a local angle, $φ$ ; the extents of a patch $(x_{\min}, y_{\min})$ and $(x_{\max}, y_{\max})$ ; and a label of the parameter table defining an eigenstrain to apply to this patch.
Define the six eigenstrain components in a parameter table of type "ABQ_AM_EigenStrain_Define".
Define the parameters of the bounding box, inside which a particular scan-pattern strategy is active, in a parameter table of type "ABQ_AM_EigenStrain_PatternBased_ScanStrategy_Define".
Define the build parameters (such as slice or layer thickness and build coordinate system) in a parameter table of type "ABQ_AM_EigenStrain_PatternBased_Activation".
Optionally, include a parameter table of type "ABQ_AM_EigenStrain_Activation_Advanced" to specify advanced options.
Refer to the table collection in the progressive element activation.

A dedicated collection of parameter table, property table, and event series types is available to include all of the definitions required by special-purpose techniques for additive manufacturing. You can use the abaqus fetch utility to obtain the file containing all of the type definitions of parameter tables, property tables, and event series required by the special-purpose techniques for additive manufacturing as follows:

abaqus fetch job=ABQ_am_special_purpose_types.inp

Input File Usage

Use the following options to define scan pattern parameters and eigenstrains:

TABLE COLLECTION, NAME="ABQ_EIG.user-defined name"
PARAMETER TABLE, TYPE="ABQ_AM_EigenStrain_Method"
"PatternBased"
PARAMETER TABLE, TYPE="ABQ_AM_EigenStrain_PatternBased_Activation"
 $h$ , coordinates defining the build system  $I - J - K$ 
"Total Time", print start time, print end time
PARAMETER TABLE, TYPE="ABQ_AM_EigenStrain_Activation_Advanced"
"LAYERBYLAYER" or "SWEEP", True or False
PARAMETER TABLE, TYPE="ABQ_AM_EigenStrain_PatternBased_ScanStrategies"
list of labels of parameter tables of type 
"ABQ_AM_EigenStrain_PatternBased_ScanStrategy_Define" in analysis
PARAMETER TABLE, TYPE="ABQ_AM_EigenStrain_PatternBased_ScanStrategy_Define", 
LABEL="ABQ_AM_EigenStrain_PatternBased_ScanStrategy1"
"label of a table of type ABQ_AM_EigenStrain_PatternBased_Define",  $θ$ 
 $x_{\min}, y_{\min}, z_{\min},$  $x_{\max}, y_{\max}, z_{\max}$  
include as many parameter tables of type 
"ABQ_AM_EigenStrain_PatternBased_ScanStrategy_Define" as needed
PARAMETER TABLE, TYPE="ABQ_AM_EigenStrain_PatternBased_Define", LABEL=user-defined label
 $x_{\min}, y_{\min}, x_{\max}, y_{\max}$ , label of a table of type "ABQ_AM_EigenStrain_Define",  $φ$ 
additional data lines to define more patches                                                       
PARAMETER TABLE, TYPE="ABQ_AM_EigenStrain_Define", LABEL=user-defined label
 $ε_{11}^{*}, ε_{22}^{*}, ε_{33}^{*}, ε_{12}^{*}, ε_{13}^{*}, ε_{23}^{*}$ 
include as many parameter tables of type "ABQ_AM_EigenStrain_Define" as needed
...
ELEMENT PROGRESSIVE ACTIVATION, NAME="EigenstrainActivation", ELSET=printElements
...
STEP
STATIC
...
ACTIVATE ELEMENTS, ACTIVATION=activation name
"ABQ_EIG.user-defined name"
...

Visualization of a Scan Pattern

A scan pattern can be visualized over the part geometry by requesting element solution-dependent field variables for output and plotting them as contours over the finite element mesh. For a pattern-based eigenstrain analysis, the first two element solution-dependent field variables are internally set to the patch ID and scan region ID, respectively (see Figure 1). For a trajectory-based eigenstrain analysis, the first element solution-dependent field variable is internally set to the rule ID.

Input File Usage

Use the following options to visualize a scan pattern:

SOLID SECTION, ELSET=element set name, MATERIAL=material property name
ELEMENT SOLUTION-DEPENDENT VARIABLES
2
1, RegionID,
2, Patch/IslandID,
…
OUTPUT, FIELD, FREQUENCY=1
ELEMENT OUTPUT
ESDV

Specifying Element Activation and Eigenstrain Using the Trajectory-Based Method

The following steps are required to use the trajectory-based method:

Create a table collection with a name that begins with "ABQ_EIG". The table collection must contain a parameter table of type "ABQ_AM_EigenStrain_Method" as well as the other parameter tables listed below.
In the parameter table of type "ABQ_AM_EigenStrain_Method", set the activation type to "TrajectoryBased".
Define parameters of the rectangular cross-section of the activation front (see Figure 1 in Thermomechanical Analysis of FDM- and LDED-Type Additive Manufacturing Processes) and the name of the event series of type "ABQ_AM_HeatSourceTrajectory_RuleID" that describe that laser spot motion trajectory in a parameter table of type "ABQ_AM_EigenStrain_TrajectoryBased_Activation".
Define the six eigenstrain components in a parameter table of type "ABQ_AM_EigenStrain_Define".
Define a scan rule by including a parameter table of type "ABQ_AM_EigenStrain_TrajectoryBased_Rule_Define" that refers to a parameter table defining an eigenstrain. All the scan rules used in the analysis must be listed in a parameter table of type "ABQ_AM_EigenStrain_TrajectoryBased_Rules". The position index of the rule in this list is the rule ID number that is specified as the first field in the event series of type "ABQ_AM_HeatSourceTrajectory_RuleID".
Optionally, include a parameter table of type "ABQ_AM_EigenStrain_Activation_Advanced" to specify advanced options.

Input File Usage

Use the following options to define trajectory-based activation in an eigenstrain-based analysis:

EVENT SERIES, NAME=event series name, TYPE="ABQ_AM_HeatSourceTrajectory_RuleID"
data lines to define the motion of the nozzle
TABLE COLLECTION, NAME="ABQ_EIG.user-defined name"
PARAMETER TABLE,  TYPE="ABQ_AM_EigenStrain_Method"
"TrajectoryBased",
PARAMETER TABLE,  TYPE="ABQ_AM_EigenStrain_TrajectoryBased_Rules"
list of labels of parameter tables of type 
"ABQ_AM_EigenStrain_TrajectoryBased_Rule_Define" in analysis
PARAMETER TABLE,  TYPE="ABQ_AM_EigenStrain_TrajectoryBased_Rule_Define", LABEL=user-defined label
label of a parameter table of type "ABQ_AM_EigenStrain_Define"
PARAMETER TABLE,  TYPE="ABQ_AM_EigenStrain_Define", LABEL=user-defined label
 $ε_{11}^{*}, ε_{22}^{*}, ε_{33}^{*}, ε_{12}^{*}, ε_{13}^{*}, ε_{23}^{*}$ 
PARAMETER TABLE,  TYPE="ABQ_AM_EigenStrain_TrajectoryBased_Activation"
event series name, stack direction, bead height, bead width, deposition position
...
ELEMENT PROGRESSIVE ACTIVATION, NAME="EigenstrainActivation", ELSET=printElements
...
STEP
STATIC
...
ACTIVATE ELEMENTS, ACTIVATION=activation name
"ABQ_EIG.user-defined name"
...