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app_style am/ellipsoid command

Syntax:

app_style am/ellipsoid nspins spot_width melt_tail_length melt_depth cap_height HAZ tail_HAZ depth_HAZ cap_HAZ exp_factor

am/ellipsoid = application style name

nspins = number of possible spins

spot_width = maximum width of the melt pool

melt_tail_length = maximum length of the melt pool trailing the melt spot

melt_depth = maximum depth of the melt pool

cap_height = maximum length of the melt pool leading the melt spot

HAZ = width of the heat affected zone (haz) surrounding the melt pool (must be larger than width)

tail_HAZ = Length of the haz trailing the meltpool (must be larger than tail_length)

depth_HAZ = depth of the heat affect zone (haz) below the melt pool (must be larger than depth)

cap_HAZ = Length of haz leading the melt pool (must be larger than cap_length)

exp_factor = Coefficient that controls the rate of exponential decay of the haz mobility gradient

Examples:

app_style am/ellipsoid 1000 30 40 20 5 50 60 30 7 0.1

Description:

This is an on-lattice application derived from the app_style potts/neighonly application that simulates the rastering of a molten pool and its accompanying heat-affected zone (HAZ) through a domain. Rastering is achieved through the specification of layer-by-layer patterns, which can be combined into an overall pattern specifying the translation of the molten zone through the entire simulation domain. The application allows for arbitrary numbers of paths in each layer and an arbitrary number of layers in each pattern. Thus, the user can construct any scan strategy desired by specifying individual layer patterns and how these patterns should be repeated.

The molten pool is defined as a double ellipsoid. The ellipsoids share identical values for two of their axes (defined by the melt_width and melt_depth parameters). The third axis of each ellipsoid is defined by either the melt_tail_length or cap_height parameters. The haz is also defined by four equivalent parameters: HAZ, tail_HAZ, depth_HAZ, and cap_HAZ. A schematic of these eight parameters is shown below.

The model also requires specification of the exp_factor variable, which determines the value of the coefficient in the mobility equation, M = exp(-exp_factor * x), where x is the shortest distance from the lattice site to the molten pool boundary.

This application was used in the paper by Rodgers and collaborators.

The following additional commands are typically used by this application. A layer must be defined by using am cartesian_layer or am path_layer. A layer requires one to many am path commands or at least one am pass command.

am pass: Specify pass parameters used to construct cartesian_layer.
am path: Specify arbitrary paths via start/end points on a layer; sequence of am paths are used to construct an am path_layer.
am cartesian_layer: A scan pattern on rectangular layer constructed from am pass and other parameters.
am build: May be used for combinations of layers that comprise a pattern.

The examples/potts_additive directory has input files which illustrate use of these additional commands.

Restrictions:

This application is only compatible with square and square cubic lattices.

This application can only be evolved by a rejection KMC (rKMC) algorithm. See the sweep command for more details.

The settings for melt pool width + haz must be <= xhi & yhi.

Related commands:

app_style potts/weld, app_style potts/weld/jom

Default: none

(Rodgers) T.M. Rodgers, J.D. Madison and V. Tikare, "Simulation of Metal Additive Manufacturing Microstructures Using Kinetic Monte Carlo", Computational Materials Science (2017).