Large-strain effects, large displacements, and large rotations are included in the analysis (NLGEOM,ON).
Automatic time-stepping adjustments (based on element-level time incrementation) are in effect; however, they are overridden if a fixed number of substeps (NSUBST) or a fixed time-step size (DELTIM) is specified, or if automatic time stepping is disabled (AUTOTS,OFF).
For each of the three impact scenarios, three transient analyses are performed using the following settings and commands:
Full method with the Newmark time-integration scheme and no damping:
TRNOPT,FULL,,,,,NMK TINTP,0.0
Full method with the Newmark time-integration scheme and damping:
TRNOPT,FULL,,,,,NMK TINTP,0.1
Full method with the HHT time-integration scheme and damping:
TRNOPT,FULL,,,,,HHT TINTP,0.1
The solution options for each of the three impact scenarios are set to fully capture the simulated responses:
The transient analysis is carried up to time 0.1e-4 seconds with an initial minimum number of substeps of 100, and a maximum number of substeps of 10000:
TIME,0.1e-4 NSUBST,100,10000,100
The total time (simulation time) represents a slightly larger time than the time needed for the bar to impact the rigid wall; the bar moving at a velocity of 227 m/s requires about 0.4405e-5 seconds to cover a 1 mm gap before impacting the rigid wall.
The minimum of 100 substeps ensures a smooth response. The maximum of 10000 substeps allows the automatic time-stepping method to cut back the time increment to satisfy the impact constraints. Because the goal in this case is to study the displacement and velocity response of the bar at some points of interest over the total time period, the nodal displacement and velocity solution data is written at every substep to the results file:
OUTRES,NSOL,ALL OUTRES,V,ALL
The same solution settings are used as for the rigid case with the only difference being the total time. The total time in this case must take into account the time that the stress wave created from the impact needs to travel back and forth through the elastic bar. The calculated time of impact is 0.4405e-5 seconds and the release time is calculated analytically as 0.223e-4 seconds, so a total time of 0.28e-4 seconds is used for the elastic impact.
The same solution settings are used as in the rigid and elastic cases, except for the total time. Because the bar undergoes large plastic deformation and remains in contact with the rigid wall for a longer time period, the total time is increased to 0.8e-4 seconds.
The nodal-displacement solution data is written to the results file at every substep, and stresses and plastic strains are written at the last substep only, as follows:
OUTRES,NSOL,ALL OUTRES,STRS,LAST OUTRES,EPPL,LAST