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app_style potts/weld/jom command

Syntax:

app_style potts/weld/jom nspins width length cap_length linear haz start_weld velocity weld_type exp_factor

potts/weld/jom = application style name
nspins = number of possible spins
width = maximum width of the melt pool
length = maximum length of the melt pool trailing the melt spot
cap_length = specify the length of the heat source region leading the melt spot
haz = width of the heat affected zone (haz) surrounding the melt pool
start_weld = timestep at which to begin welding (usually 0)
velocity = velocity of heat source motion (lattice sites per Monte Carlo step)
weld_type = heat source shape (valid options are 1-5, see below)
exp_factor = rate of exponential decay of the haz mobility gradient

Examples:

app_style potts/weld/jom 10000 30 25 10 40 0 10.0 1 0.01

Description:

This is an on-lattice application derived from the app_style potts/neighonly application which simulates a weld heat source traveling along the y-axis from y = 0 to yhi. The heat source is centered along the x-axis at x = xhi / 2 and top plane is located at zhi.

The model simulates melting and re-solidification by randomizing the spin at a lattice site when it falls within the melt pool's volume. Upon exiting the melt pool, a rejection kinetic Monte Carlo event is performed at the site, and the spin is flipped to the value of one of its neighbors (in the style of the potts/neighonly application).

The mobility of each site within the haz decreases exponentially with increasing distance from the melt pool surface. The maximum mobility is 1 at the melt pool boundary and the minimum mobility is 0 at the outer haz boundary. The mobility gradient is similar to that in potts/grad, but is restricted to a portion of the simulation domain defined by haz. Outside of the melt pool and haz, grain boundary mobility is set to 0, and grain evolution does not occur.

This program was used in the paper by Rodgers et al.

There are five different heat source shapes available defined by the integer (between 1 and 5) of "weld_type":

1 = "ellipsoid", An Goldak-style double ellipsoid heat source whose melt pool dimensions are defined with "width", "length", "cap_length", and ellipsoid_depth
2 = "keyhole", A keyhole heat source comprised of the union of two ellipsoids. A "shallow" ellipsoid whose dimensions are defined with "width", "length", and ellipsoid_depth, and a "deep" ellipsoid whose dimensions are defined with deep_width and deep_length. The "deep" ellipsoid is assumed to penetrate the entire depth of the simulation domain
3 = "linear", A heat source with linearly varying boundaries. The heat source's cross-section is constant along the z-axis
4 = "cap", A heat source with a power-law dependent boundaries. The heat source's cross-section is constant along the z-axis
5 = "circle", A heat source with circular boundaries. The heat source's cross-section is constant along the z-axis

The following additional commands are defined by this application:

ellipsoid_depth	define the maximum depth of the ellipsoid-shaped melt pool, or the maximum depth of the shallow melt pool in the keyhole model
deep_width	define the maximum width of the deep ellipsoid in the keyhole model
deep_length	define the maximum length of the deep ellipsoid in the keyhole model

Restrictions:

Only compatible with square and square cubic lattices.

Can only be evolved by a rejection KMC (rKMC) algorithm. See sweep for more information.

Melt pool width + haz must be =< xhi.

Related commands:

app_style potts, app_style potts/grad, app_style potts/weld

Default: none

(Rodgers) T.M. Rodgers, J.D. Madison and V. Tikare, "Predicting Mesoscale Microstructural Evolution in Electron Beam Welding", JOM 68[5] 1419- 1426 (2016).