Performing Modal Time History Analysis To perform modal time history analysis: Create a linear dynamic study by clicking the down arrow on Simulation Advisor and clicking New Study. You can define a solid, shell, or mixed mesh study. Beams are not supported. Select Linear Dynamic, and under Options, click Modal Time History . Define the frequency and dynamic properties of the study. You can create a linear dynamic study from an existing frequency study. Right-click the frequency study icon and select Copy to New Dynamic Study. Define material for each solid and shell. To define a material for a solid or shell right-click its icon in the Simulation study tree and select Apply/Edit Material. Define restraints. Right-click the Fixtures icon in the Simulation study tree and select from the options. You can also apply spring-damper connectors. Define damping. Right-click the Damping folder in the Simulation study tree and select Edit/Define. You can define modal, composite modal or Rayleigh damping. Define loads. You can define time-dependent force, and pressure loads, uniform and selected base excitations, and initial conditions. It is recommended to enter time curve data that cover the whole time range for the solution defined in the Modal Time History - Dynamic Options tab. You can enter up to 10000 time curve data points to define a load history. For example, if you define a uniform base excitation curve that starts at a point that is not at the beginning of the solution range defined in study properties, the initial value is linearly interpolated. It the last point on the curve is smaller than the end time of the solution range, the solution time range is truncated. Define Result Options. Right-click the Result Options folder in the Simulation study tree and select Edit/Define. Mesh the model and run the study. First the program calculates the natural frequencies (if not available), and then it proceeds to the modal time history solution. You can request to run the study only for frequencies. Right-click the study icon and select Run frequency. View the results: Double-click an icon in the Results folder to display the associated plot. To define a new plot, right-click the Results folder and select the desired option. You can plot displacements, accelerations, velocities, stresses, strains, and deformations for a specified solution step or extreme values across all solution steps. To define a time history plot at a specified node, right-click the Results folder and select Define Response Graph. To list results, right-click the Results folder, and select the desired option. You can list natural frequencies, mass participation factors, stresses, displacements, accelerations, velocities, strains, and reaction forces. Parent topicPerforming Linear Dynamic Analysis Copy to New Dynamic Study Performing Harmonic Analysis Performing Random Vibration Analysis Modal Time History - Dynamics Options The Dynamics Options tab in the Modal Time History dialog box sets solution related options: Time range Start time Starting solution time in seconds. End time Ending solution time in seconds Time increment Solution time increment. The limit on the total number of solution steps is 10000. Dead load effects Dead loads from static study When checked, you can superimpose the results of a static study to the dynamic study. Select one of the following: Multiplication factor The factor that the dead loads are multiplied by. For example, if you enter 2 for the multiplication factor, the results from the selected static study are multiplied by 2, and added to the dynamic study results at every solution step. The results are valid only if they are within the linear stress range.
Performing Modal Time History Analysis To perform modal time history analysis: Create a linear dynamic study by clicking the down arrow on Simulation Advisor and clicking New Study. You can define a solid, shell, or mixed mesh study. Beams are not supported. Select Linear Dynamic, and under Options, click Modal Time History . Define the frequency and dynamic properties of the study. You can create a linear dynamic study from an existing frequency study. Right-click the frequency study icon and select Copy to New Dynamic Study. Define material for each solid and shell. To define a material for a solid or shell right-click its icon in the Simulation study tree and select Apply/Edit Material. Define restraints. Right-click the Fixtures icon in the Simulation study tree and select from the options. You can also apply spring-damper connectors. Define damping. Right-click the Damping folder in the Simulation study tree and select Edit/Define. You can define modal, composite modal or Rayleigh damping. Define loads. You can define time-dependent force, and pressure loads, uniform and selected base excitations, and initial conditions. It is recommended to enter time curve data that cover the whole time range for the solution defined in the Modal Time History - Dynamic Options tab. You can enter up to 10000 time curve data points to define a load history. For example, if you define a uniform base excitation curve that starts at a point that is not at the beginning of the solution range defined in study properties, the initial value is linearly interpolated. It the last point on the curve is smaller than the end time of the solution range, the solution time range is truncated. Define Result Options. Right-click the Result Options folder in the Simulation study tree and select Edit/Define. Mesh the model and run the study. First the program calculates the natural frequencies (if not available), and then it proceeds to the modal time history solution. You can request to run the study only for frequencies. Right-click the study icon and select Run frequency. View the results: Double-click an icon in the Results folder to display the associated plot. To define a new plot, right-click the Results folder and select the desired option. You can plot displacements, accelerations, velocities, stresses, strains, and deformations for a specified solution step or extreme values across all solution steps. To define a time history plot at a specified node, right-click the Results folder and select Define Response Graph. To list results, right-click the Results folder, and select the desired option. You can list natural frequencies, mass participation factors, stresses, displacements, accelerations, velocities, strains, and reaction forces. Parent topicPerforming Linear Dynamic Analysis Copy to New Dynamic Study Performing Harmonic Analysis Performing Random Vibration Analysis Modal Time History - Dynamics Options The Dynamics Options tab in the Modal Time History dialog box sets solution related options: Time range Start time Starting solution time in seconds. End time Ending solution time in seconds Time increment Solution time increment. The limit on the total number of solution steps is 10000. Dead load effects Dead loads from static study When checked, you can superimpose the results of a static study to the dynamic study. Select one of the following: Multiplication factor The factor that the dead loads are multiplied by. For example, if you enter 2 for the multiplication factor, the results from the selected static study are multiplied by 2, and added to the dynamic study results at every solution step. The results are valid only if they are within the linear stress range.
Modal Time History - Dynamics Options The Dynamics Options tab in the Modal Time History dialog box sets solution related options: Time range Start time Starting solution time in seconds. End time Ending solution time in seconds Time increment Solution time increment. The limit on the total number of solution steps is 10000. Dead load effects Dead loads from static study When checked, you can superimpose the results of a static study to the dynamic study. Select one of the following: Multiplication factor The factor that the dead loads are multiplied by. For example, if you enter 2 for the multiplication factor, the results from the selected static study are multiplied by 2, and added to the dynamic study results at every solution step. The results are valid only if they are within the linear stress range.