AMBUILD

AMBUILD, Option, Value1, Value2, Value3, Value4, Value5, Value6
Specifies printer parameters for the build and other options in an additive manufacturing (AM) analysis.

SOLUTION: Additive Manufacturing

Option

Option:

LAYERT

—

Value1 – Deposition-layer thickness.

Value2 – Mesh height.

Value3 – Error-checking flag. Set to 0 (default) or 1. Setting to 1 causes the application to omit error checks for consistent element size and elements spanning across layers.

SCAN

—

Value1 – Hatch spacing.

Value2 – Beam-travel speed.

TIME

—

Value1 – Inter-layer dwell time. Default = 0.0.

Value2 – Dwell-time multiplier for multiple parts on the build plate or number of repeated symmetry sectors in simulations with symmetry. Default = 1.0.

Value3 – Heating step time for use with beam power option (AMBEAM,,POWER).

Value4 – Scan time table.

PLATE	—	`Value1` – Z-coordinate of the top of the build plate. Default = 0.0.
CHECK	—	`Value1` – If YES, create the build-summary file but do not solve. Default = NO.
RTHFILE	—	`Value1` – Name of the thermal-results file (including its path). Default = file.rth in the current working directory.
SSF	—	`Value1` – Strain Scaling Factor. Default = 1.0.
SEQUENCE	—	Use `Option` = SEQUENCE to build up a sequence of heating and cooling options for each layer of the build. When specifying multiple steps, the sequence must end in a dwell step scoped to ALL. If no sequence steps are specified, a default build sequence of 1 heating step and 1 cooling step per layer is assumed and the AMBUILD,SEQUENCE command does not need to be specified directly. See "Command Specification for `Option` = SEQUENCE".

Command Specification for `Option` = SEQUENCE

AMBUILD, SEQUENCE, `Action,Position,Item,Value4,Value5,Vlaue6`

Action --

Action for the sequence.

ADD: Adds a new sequence step at the specified position.
DELETE: Deletes a sequence step at the specified position.
EDIT: Edits a sequence step item.
LIST: Lists current sequence.
CLEAR: Deletes all sequence steps.
OPTION: Sets sequence related options.

Position --

Step position in the sequence.

n: n-th position in the sequence.
FIRST: First position in the sequence.
LAST: Last position in the sequence.

Item (with ADD/DELETE Action) --

Item to be added or deleted in the sequence.

HEAT,cmName

Adds or deletes a heating step in the sequence. Can be preheating or melting, it doesn't matter.

cmName = component or named selection to be heated by this step. If blank or ALL, heat is applied to all elements in each layer.

DWELL,cmName

Adds or deletes a dwell or cooling step in the sequence. Used for timing calculations. A dwell step must be specified as the final step in the sequence.

cmName = component or named selection used to find layer volume in time calculations for typeOpt = AREA, VOLUME, or PARAMETERS for this step. If blank or ALL, all elements in each layer are used to find volume for timing calculations on this step.

Item (with EDIT Action) --

Item to be edited in the sequence.

TIME,Value,typeOpt,volOpt

Time-related options.

Value

Time value for the step.

typeOpt

Defines what the time value represents for this step.

TIME: Units in seconds. This is a basic time value for the step (default).
LAYER: Units in seconds per layer. The layer here is the physical layer height (not the mesh). LAYERTHICKNESS must be defined for this sequence step.
AREA: Units in seconds/(length²) per layer. This represents the time it takes per unit area on a physical layer. LAYERTHICKNESS must be defined for this sequence step.
VOLUME: Units in seconds/length³. Represents the time to melt a volume of material.
PARAMETERS: Value4 is not needed, time will be determined based on the specified component’s layer volume and the parameters defined for this step. SCANSPEED, LAYERTHICKNESS, and HATCHSPACING must be defined for this step.

volOpt

Sets flag identifying how time is adjusted to account for the difference between layer thickness and mesh height.

0: When possible, adjust to use a time based on how long it would take to heat the entire volume. Affects AREA and PARAMETERS options where the time to scan the area will be identified then multiplied by the number of layers in a superlayer (default).
1: Adjust time values based on the difference between the layer thickness and mesh height derived from an instantaneous heat source on semi-infinite domain (affects all typeOpt options). Useful on dwell steps after temperature loading.
2: Do not adjust time based on how many layers are present in the element layer (affects AREA and PARAMETERS options only).

Example:

AMBUILD, SEQUENCE, EDIT, 7, TIME, 0.2, AREA,1

POWER,Value

Power value to use with power heating option.

AREA,Value

Area over which the heat or timing calculations are applied. This allows for the representation of the total affected area, irrespective of whether the area is represented by elements or not. If unspecified, uses the active layer. This field only affects steps with either POWER heating or TIME options of AREA, VOLUME, or PARAMETERS.

TEMP,Value

Heating temperature for heating.

Note: Only one of TEMP and POWER is required. Defaults to power if both are provided.

SCANSPEED,Value

Scan speed for the sequence step.

LAYERTHICKNESS,Value

Layer thickness for the sequence step.

HATCHSPACING,Value

Hatch spacing for the sequence step.

ABSORPTIVITY,Value

Power absorptivity for the sequence step. Default = 1.

Item (with OPTION Action) --

Specifies options for the entire sequence rather than for individual positions within the sequence. (Position field not relevant.) Example: AMBUILD, SEQUENCE, OPTION,Opt1,Opt2,Opt3.

HEAT

Options for heating.

SINGLE

Combines the sequence workflow into one heating and one cooling step.

FLASH

Heat in a very short period of time and cool for a majority of the layer time. (This will get higher peak temperatures when using power heating.) Max applied temperature at a specific location will be applied when using temperature heating.

SCAN

Heat for the amount of time that it takes to go through all defined sequence steps except for the final dwell step.

With the SINGLE,SCAN option, the cooling step will be the length of the final dwell step in the sequence and the other steps will be used to define the length of the heating.

STEP

Goes through each sequence step one by one (default).

Command Default

None. An Option label is required.

Notes

This command specifies printer parameters for the build and other options in an additive manufacturing (AM) analysis. When specifying printer parameters, the command is usually used in one of two ways: to set parameters for a single, non-sequence solve, or to set up a solver sequence (Option = SEQUENCE) on each step between adding a new layer and cooling at the end of the layer. A solver sequence provides flexibility for the following:

Specifying different preheats for different steps of the electron beam melting (EBM) process simulation.
Enabling location specific process parameters for both laser powder bed fusion (LPBF) and EBM process simulations.
Modeling multi-material builds for both LPBF and EBM process simulations.

Non-sequence options:

If using a layered tetrahedral mesh, specify the mesh height (AMBUILD,LAYERT,MESHHEIGHT). For Cartesian meshes, the mesh height is determined automatically.

When setting the error-checking flag (AMBUILD,LAYERT,,,1), verify your model and results carefully. Using the flag may lead to improper setup of layers or boundary conditions.

The hatch spacing and beam travel speed are the average values used during the build.

The inter-layer dwell time (AMBUILD,TIME,DWELLTIME) is the span of time from the end of the deposition of a layer to the start of the deposition of the next layer. It includes the time required for recoater-blade repositioning and powder-layer spreading.

The dwell-time multiplier (AMBUILD,TIME,,MULTIPLIER) accounts for more than one part being printed on the build plate, or it is used to reconcile build time in simulations using symmetry. For multiple parts on a build plate, if the additional parts are the same part as the one being simulated and are arranged in the same orientation on the build plate, the multiplier is the total number of parts. If different parts exist on the plate, the multiplier is an estimate of the time required to build the other parts relative to the part being simulated. In simulations with symmetry, the dwell-time multiplier is the total number of repeated symmetry sectors: 2 for half symmetry, 4 for ¼ symmetry, and so on.

The heating step time (AMBUILD,TIME,,,HEATTIME) is used along with other defined process and geometric parameters (power, scan speed, hatch spacing, deposition thickness, superlayer volume) to set the time duration and magnitude of heat generation on new element layers. A value of 0 (default) sets the heating time to the minimum time step constraint. See General Options in the Thermal Analysis Guide. When power has been specified, you can alternatively enter SCAN in this field to set the heating time to the amount of time it would take to scan the volume of material in each element layer. With the SCAN option, the cooling between layers will still be the recoater time. Setting Value3 = SCAN may give better temperature results at the end of the layer and is more stable across different mesh sizes. Note that the SCAN option will have a different end time of the simulation because the layer thickness adjustment for cooling will not be used.

The scan time (AMBUILD,TIME,,,,SCANTIME) represents the amount of time it takes to scan a real layer. By default, the scan time will be determined from each layer’s cross-sectional area and other process parameters. When specified, it must be defined as a table with times specified on the Z primary variable. Times that are averaged or interpolated from the table should not include recoating time and will be adjusted to account for superlayer size compared to the deposition thickness.

The strain scaling factor (AMBUILD,SSF,SSF) scales the thermal strains in the structural portion of thermal-structural simulations by the specified value.

Sequence options:

When using a stepwise build sequence (AMBUILD,SEQUENCE,OPTION,HEAT,STEP, which is the default setting when using a sequence), the top layer of the build is never set to powder properties in thermal analyses as it is with other non-sequence AM workflows and is therefore not affected by the powder factor (MATFACTOR from AMPOWDER command).

If process parameters (layer thickness, hatch spacing, scan speed) are needed in certain build steps but were not explicitly provided in the sequence step, values from the AMBUILD,LAYERT and AMBUILD,SCAN commands are used.

One of either TEMP or POWER is required for heating sequence steps. If both are provided, the power option will be used for heating.

TIME is required for all steps. Other inputs are optional based on time and heating settings.

A dwell step scoped to ALL elements must be defined as the last step in the sequence, for example: AMBUILD, SEQUENCE, ADD, LAST, DWELL.

The AMBUILD,SEQUENCE options can be used for thermal-structural analyses in addition to just thermal.

Other general options:

When specifying the name of the thermal-results file (AMBUILD,RTHFILE,RthPath), omit the .rth extension. The program also looks for the thermal.build file in the same path.

This command is also valid in PREP7.

For more information, including a list of the elements and commands used in an additive manufacturing analysis, see Additive Simulation in the Mechanical Application in the LPBF Simulation Guide.

Example Usage

As an example, assume that typical Mechanical APDL commands, including normal AM commands, are used to set up the melting step. Then an 8-part sequence is defined for each step between adding a new layer and cooling at the end of the layer. The input below shows the Option = SEQUENCE commands:

!Sequence step 1 - heat
AMBUILD, SEQUENCE, ADD, 1, HEAT,ALL              !Add heating step to all build elements
AMBUILD, SEQUENCE, EDIT, 1, POWER, 450000        !Specify power value
AMBUILD, SEQUENCE, EDIT, 1, AREA, 10000          !Specify area value that is being heated instead of calculating it from the elements
AMBUILD, SEQUENCE, EDIT, 1, TIME, 10,            !Specify sequence time, defaults to using TIME option - value is in seconds
AMBUILD, SEQUENCE, EDIT, 1, ABSORPTIVITY, 0.5    !Specify power absorptivity
 
!Sequence step 2 - heat
AMBUILD, SEQUENCE, ADD, 2, HEAT,SEL1             !Add heating step to component SEL1
AMBUILD, SEQUENCE, EDIT, 2, POWER, 650000        !Specify power value
AMBUILD, SEQUENCE, EDIT, 2, TIME, 1.5, TIME      !Specify sequence time with TIME option - value is in seconds
AMBUILD, SEQUENCE, EDIT, 2, ABSORPTIVITY, 0.2    !Specify power absorptivity
 
!Sequence step 3 - heat
AMBUILD, SEQUENCE, ADD, 3, HEAT,SEL3             !Add heating step for component SEL3
AMBUILD, SEQUENCE, EDIT, 3, POWER, 100000        !Specify power value
AMBUILD, SEQUENCE, EDIT, 3, TIME, 0.5, LAYER,1   !Specify time with LAYER option - value is in seconds per deposition layer
AMBUILD, SEQUENCE, EDIT, 3, LAYER, 0.05          !Specify layer thickness, required due to use of LAYER option
AMBUILD, SEQUENCE, EDIT, 3, ABSORPTIVITY, 0.5    !Specify power absorptivity
 
!Sequence step 4 - heat
AMBUILD, SEQUENCE, ADD, 4, HEAT,SEL4             !Add heating step for component SEL4
AMBUILD, SEQUENCE, EDIT, 4, POWER, 5000          !Specify power value
AMBUILD, SEQUENCE, EDIT, 4, TIME, 0.4, AREA,2    !Specify time with AREA option - value is in seconds/length^2 per deposition layer
AMBUILD, SEQUENCE, EDIT, 4, LAYER, 0.05          !Specify layer thickness, required due to use of AREA option
AMBUILD, SEQUENCE, EDIT, 4, ABSORPTIVITY, 0.4    !Specify power absorptivity
 
!Sequence step 5 - dwell/cool
AMBUILD, SEQUENCE, ADD, 5, DWELL, ALL            !Add a dwell step for cooling (no heating BCs applied)
AMBUILD, SEQUENCE, EDIT, 5, TIME, 1.5, VOLUME,1  !Specify time with VOLUME option - value is in seconds/length^3
 
!Sequence step 6 - heat
AMBUILD, SEQUENCE, ADD, 6, HEAT, ALL             !Add heating step for all build elements
AMBUILD, SEQUENCE, EDIT, 6, POWER, 800000        !Specify power value
AMBUILD, SEQUENCE, EDIT, 6, TIME, , PARAMETERS,2 !Specify time with PARAMETERS option - value not needed as it will be determined by parameters
AMBUILD, SEQUENCE, EDIT, 6, SCAN, 1000           !Specify scan speed
AMBUILD, SEQUENCE, EDIT, 6, LAYER, 0.05          !Specify layer thickness
AMBUILD, SEQUENCE, EDIT, 6, HATCH, 0.1           !Specify hatch spacing
AMBUILD, SEQUENCE, EDIT, 6, ABSORPTIVITY, 0.5    !Specify power absorptivity
 
!Sequence step 7 - heat
AMBUILD, SEQUENCE, ADD, 7, HEAT,SEL24            !Add heating step for component SEL24
AMBUILD, SEQUENCE, EDIT, 7, POWER, 200000        !Specify power value
AMBUILD, SEQUENCE, EDIT, 7, TIME, 2, VOLUME,1    !Specify time with VOLUME option - value is in seconds/length^3
AMBUILD, SEQUENCE, EDIT, 7, ABSORPTIVITY, 0.5    !Specify power absorptivity
 
!Sequence step 8 - dwell/cool
AMBUILD, SEQUENCE, ADD, 8, DWELL, ALL            !Add a dwell step for cooling (no heating BCs applied)
AMBUILD, SEQUENCE, EDIT, 8, TIME, 10             !Specify time with VOLUME option - value is in seconds/length^3
 
!Specify that we want to heat in a single step for the length of the defined sequence
AMBUILD, SEQUENCE, OPTION, HEAT, SINGLE, SCAN

Menu Paths

This command cannot be accessed from a menu.