| Field | Options | Description | 2D | Restart |
|---|---|---|---|---|
| Number of Steps |
See Defining Multiple Analysis Steps and Activation/Deactivation of Loads in Explicit Dynamics for more information. This field is not available for LS-DYNA. | |||
| Current Step Number |
Shows the step ID for the current load step End Time. The currently selected step is also highlighted in the bar at the bottom of the Graphics window. Note that Explicit analysis settings are not step aware except for the Static Damping Coefficient. This field is not available for LS-DYNA. | |||
| Load Step Type |
Currently, the only option is Explicit Time Integration. This field is not available for LS-DYNA. | |||
| End Time | (Required input) The maximum length of time (starting from time zero) to be simulated by the explicit analysis. You should enter a reasonable estimate to cover the phenomena of interest. | Yes | Yes | |
| Resume From Cycle | Allows you to select the integration cycle from which to start the solution upon selecting Solve. A cycle of zero (default setting) indicates the solution will clear any previous progress and start from time zero. A non-zero cycle, on the other hand, allows you to revisit a previous solution and extend it further in time. A solution obtained from a non-zero cycle is considered to have been "resumed" or "restarted". Note that the list will only contain non-zero selections if a solve was previously executed and restart files have been generated. When resuming an analysis, changes to analysis settings will be respected where possible. For example, you may wish to resume an analysis with an extended termination time. Changes to any other features in the model (geometry suppression, connections, loads, and so on) will prevent restarts from taking place. See Resume Capability for Explicit Dynamics Analyses for more information. This field is not available for LS-DYNA. | Yes | Yes | |
| Maximum Number of Cycles | The maximum number of cycles allowed during the analysis. The analysis will stop once the specified value is reached. Enter a large number to have the analysis run to the defined End Time. | Yes | Yes | |
| Maximum Energy Error | Energy conservation is a measure of the quality of an Explicit Dynamics analysis.
Large deviations from energy conservation usually imply a less than optimal model
definition. This parameter allows you to automatically stop the solution if the deviation
from energy conservation becomes unacceptable. Enter a fraction of the total system energy
(measured at the Reference Energy Cycle) for which you want the
analysis to stop. For example, the default value of 0.1 will cause the analysis to stop if
the energy error exceeds 10% of the energy at the reference cycle. For LS-DYNA this field requires a percentage to be entered. Thus the field name changes to Maximum Energy Error (%). | Yes | Yes | |
| Reference Energy Cycle | The cycle at which you want the solver to calculate the reference energy, against
which it will calculate the energy error. Usually this will be the start cycle (cycle = 0).
You may need to increase this value if the model has zero energy at cycle = 0 (for example
if you have no initial velocity defined). This field is not available for LS-DYNA. | Yes | Yes | |
| Initial Time Step | Enter an initial time step you want to use, or use the Program
Controlled default. If left on Program Controlled, the time
step will be automatically set to ½ the computed element stability time step. The
Program Controlled setting is recommended. This field is not available for LS-DYNA. | Yes | Yes | |
| Minimum Time Step | Enter the minimum time step allowed in the analysis, or use the Program
Controlled default. If the time step drops below this value the analysis will
stop. If set to Program Controlled, the value will be chosen as 1/10th
the initial time step. This field is not available for LS-DYNA. | Yes | Yes | |
| Maximum Time Step | Enter the maximum time step allowed in the analysis, or use the Program Controlled default. The solver will use the minimum of this value or the computed stability time step during the solve. The Program Controlled setting is recommended. | Yes | Yes | |
| Time Step Safety Factor | A safety factor limit is applied to the computed stability time step to help keep the solution stable. The default value of 0.9 should work for most analyses. | Yes | Yes | |
| Characteristic Dimension | Diagonals (default setting) |
The characteristic dimension used to determine the time-step for hex elements will be calculated as the volume of the element divided by the square of the longest element diagonal and then scaled by sqrt(2/3). This field is not available for LS-DYNA. | Yes | No |
| Opposing Face |
The characteristic dimension used to determine the time-step for hex elements will be based on the minimum distance between opposing faces. Select this option to obtain the optimal time step for hex solid elements. Experience to date has shown that this option can significantly improve the efficiency of 3D Lagrange simulations. However, in certain circumstances when cells become highly distorted, instabilities have been observed causing the calculation to terminate with high energy errors. The correct choice of erosion strain can reduce these problems. It is therefore recommended that users only utilize this option if efficiency is critical. This field is not available for LS-DYNA. | |||
| Nearest Face |
The characteristic dimension used to determine the time-step for hex elements will be based on the minimum distance between neighboring faces. Experience to date has shown that this option can significantly improve the efficiency of 3D Lagrange simulations. However, in certain circumstances when cells become highly distorted, instabilities have been observed causing the calculation to terminate with high energy errors. The correct choice of erosion strain can reduce these problems. It is therefore recommended that users only utilize this option if efficiency is critical. This field is not available for LS-DYNA. | |||
| Automatic Mass Scaling | If set to Yes, activates automatic mass scaling and exposes the following options. | Yes | Yes | |
| Minimum CFL Time Step |
The time step that you want to achieve in the analysis. Caution: Mass scaling introduces additional mass into the system to increase the computed CFL time step. Introducing too much mass can lead to non-physical results. Note: Employ User Defined Results MASS_SCALE (ratio of scaled mass/physical mass) and TIMESTEP to review the effects of automatic mass scaling on the model. | Yes | Yes | |
| Maximum Element Scaling | This value limits the ratio of scaled mass/physical mass that can be applied to each
element in the model. This field is not available for LS-DYNA. | Yes | Yes | |
| Maximum Part Scaling | This value limits the ratio of scaled mass/physical mass that can be applied to an
individual body. If this value is exceeded, the analysis will stop and an error message is
displayed. This field is not available for LS-DYNA. | Yes | Yes | |
| Update Frequency | Allows you to control the frequency at which the mass scaling will be calculated
during the solve. The frequency equates to the increment in cycles at which the mass scale
factor will be recomputed, based on the current shape of the elements. The default of 0 is
recommended and means that the mass scale factor is only calculated once, at the start of
the solve. Post cycle 0 adjustment will only take place for solid elements (excluding ANP and NBS tetrahedra). In parallel solutions the update frequency is always set to 0. This field is not available for LS-DYNA. | Yes | Yes |