*TRAN: Transient Analysis Timing Control

*TRAN

r1, r2, r3, r4, r5, r6, i1, i2

r1: r*8: start time

r2: r*8: end time

r3: r*8: initial time increment

r4: r*8: maximum allowable time increment

r5: r*8: minimum allowable time increment

r6: r*8: incrementation tolerance

i1: i*4: maximum number of cutbacks

i2: i*4: maximum number of increments

This card sets the simulation start and end time as well as the initial, maximum, and minimum time increments. The card is also used to specify the incrementation tolerance which controls how quickly time steps increase to the maximum value during cooling. Also sets the maximum number of allowable cutbacks and increments. If the maximum number of cutbacks or increments is exceeded, the analysis will be terminated.

For DED simulations the *TRAN card is optional. These options and *TAUT will be set according to best practices and the values specified by the *LSRF card. This will add an hour of cooling time after the build simulation has completed, to account for post process cool down.

Best Practices

• r3: To avoid aliasing, analysis of direct processes and moving source models should have increments so that the time steps are equal to the time it takes for the laser to move 1 laser radius. This can be automated by using *TAUT to control the time incrementation.
• r4: Allowing for larger maximum time increments (10-1000s) can decrease the time it takes to complete a simulation for those builds with larger deposition times or long post-process cool down times. However if the time steps are large compared to the time scale of the cool down periods, there may be an undesirable loss of resolution.
• i2: If the simulation will take more than 99,999 increments, ensure *OFNS is used so the simulation does not end prematurely.