Create and Edit Analyses

In MotionView, an analysis is a container entity that can contain collections of the loads, motions, and entities that describe the event to be simulated for a model. A model can contain any number of analyses but only one analysis can be active at a given instance. When a model is run in MotionView, a particular analysis is selected and MotionView includes the loads and motions described in the analysis when it submits the model to the solver.

An analysis is represented by the following characteristics:

  • An analysis can be added only to the root system Model.
  • It can contain any other modeling entities like points, bodies, joints, forces, etc.
  • An analysis can have a system as its child entity.
  • Only one analysis can be a active at a given instance. The MDL statement that sets an analysis active is *Self-analysis. The Run panel and Export Solver Deck pre-selects the active analysis.
  • The analysis takes attachments in a similar way as systems and assemblies.
Note: When an inactive analysis is set active, the current active analysis is deactivated automatically. The inactive analysis instance would be listed in the model browser tree, but its child entities would not be shown and are not accessible until the analysis is made active.

Similar to an assembly, which is an extended version of systems, the analysis container entity is also extended to have a distributed file approach. However, the extension is contained within the same entity called "Analysis". The analysis container comes in two variations:

Inline Analysis

This refers to the existing style of using the Analysis feature, where the analysis definition and properties are saved inline within the model MDL file.

  • In MDL, an inline analysis is created by instantiating a definition using the *Analysis statement that refers to a *DefineAnalysis block.

Distributed Analysis

This refers to the distributed files based analysis, similar to an assembly entity. This type of analysis works on a similar concept as assemblies with some rules and exceptions:

  • Distributed analysis refers to a data file and data file subsequently refers to a definition file, which is similar to an assembly entity.
  • An assembly can be added to a distributed analysis, but not to an inlined analysis.
  • Unlike assemblies, a placeholder for a distributed analysis is not available.
  • A distributed analysis has a ALLOWED_MODEL_TYPE attribute that can be used to restrict the application of the analysis for a particular type of model.
  • In MDL, a distributed analysis is instantiated using the *BeginAnalysis block. This block has a *DataInclude statement that refers to a data file. The data file contains a *BeginAnalysisDataFile block that has *DefinitionInclude that refers to a definition file. The definition file holds *BeginDefinitionFile that contains the *DefineAnalysis block. This structure is consistent with that of the assembly entity.

Example

The following simple example model demonstrates the concept of an analysis. This model is available at ~hw_install/demos/mv_hv_hg/modeling/container_entities/system_analysis/door.mdl. The model has been arranged into a system called hatchback system, which in turn has two child systems; the door system and the damper system. The images below show a simplified model of a hatchback door of a car with the model MDL file shown alongside.

One analysis to be preformed on the above model is a kinematic analysis, which is accomplished by adding a motion to the hinge joint in the door system.

Another analysis is a dynamic analysis, which is accomplished by applying a force at the end of the door. These two events are exclusive. For example, the motion of the hinge joint is not applied when the force is applied and vice-versa.

MDL file:
  • The entire model information is contained within a *BeginMDL - *EndMDL block in the door.mdl (model file).
  • Apart from the two system instances and their definition block, the model contains an *Analysis statement that instantiates the kinematic analysis (ana_kin). This analysis instance refers to the analysis definition (def_ana_kin) within the *DefineAnalysis block in the model file.
    • The door hinge joint from the door system is passed as an attachment to the analysis. A motion is defined that uses this attachment.
    • The data related to the motion is within the *BeginContext (ana_kin) block.


      Figure 1.
  • The model file also contains a *BeginAnalysis block that instantiates the dynamic analysis.
    • This block refers to the data file (dyn_data.mdl) which in turn refers to the definition file (dyn_def.mdl).
    • The door body and the center end point at the door are passed as attachments to this analysis. A force entity is defined that uses these attachments.
    • The force data is contained in the data file.
    • The MDL structure is similar to that of the assembly. The data is contained within *BeginAnalysisDataFile. The analysis definition block *DefineAnalysis in the definition file is contained within *BeginAnalysisDataFile.


      Figure 2.
  • The *SetActiveAnalysis statement controls which analysis is active.

Add an Analysis

Use the Analysis tool to add an analysis to the model.

  1. From the Model Browser right-click on the Model label (or any system of your choice) and selecting Add > Analysis.
    The Add Analysis dialog is displayed.
  2. Select the type of analysis to add.
  3. If you selected Uses data and definition file, complete the steps below:
    1. Select how to add the analysis.
    2. Depending on the method selected, use the fields to create a new file, or browse to select an existing file.
  4. Assign a variable name and label to the analysis.
  5. Specify a definition name for the system.
  6. Click OK to close the window or Apply to continue creating entities.
    The analysis is added to the model.

Adding Attachments to an Analysis

Each analysis has a list of attachments that connect it to other systems or assemblies. These are listed on the Attachments tab. You can modify an attachment by highlighting it in the attachments list and using the entity collector to the right of the list.

  1. From the Model Browser, select an analysis.
    The Analysis panel is displayed.
  2. Select the Attachments tab.
  3. Click Add.
    The Add an Attachment dialog is displayed.
  4. Specify a label and variable name.
  5. Select the attachment entity from the drop-down menu.
  6. Select Single only or Pair or single for Type.
    Note: Certain entities cannot be modelled in pairs so these options may be disabled.
  7. Optional: Enter any notes.
  8. Click OK to close the window or Apply to continue creating entities.
    The new attachment is added to the list.
  9. Click the collector associated with the created entity and make your selection in the modeling window, or double-click the collector to display the Model Tree (from which the desired entity can be selected).
Tip:
  • To specify a tag for the attachment, click in the Attachment Tag field and enter in a tag string.
  • Delete an attachment by selecting it from the list and clicking Delete.
  • Modify an attachment's properties by selecting it from the list and clicking Edit.

Adding an Analysis to the Current Model Using an Existing Data File

  1. From the Add Analysis dialog, activate the Uses data and definition files radio button and click Next.
  2. Select the Existing data file radio button and click Next.
  3. Click the Existing Data File browser icon.
    The Select Data File dialog is displayed.
  4. Browse and select the data file that you want to use, and then click Open.
    The definition file, name, and type referenced by the data file are automatically displayed in their respective fields.
  5. Assign a label to the analysis.
  6. Click OK to close the window and add the analysis to the model or Apply to continue creating analyses.

Edit an Analyses

Modify attachments, set initial conditions, define options, and import/export the analysis.

  1. Each analysis has a list of attachments that connect it to other systems or assemblies on the Attachments tab. You can modify an attachment by highlighting it in the Attachments list and using the entity collector to the right of the list.
    1. Select the Attachments tab.
    2. Click Add.
    3. In the dialog, specify a label and variable name.
    4. Select the attachment entity from the drop-down menu.
    5. Select Single only or Pair or single for Type.
      Note: Certain entities cannot be modeled in pairs so these options may be disabled.
    6. Enter any notes.
    7. Click OK to close the dialog.
  2. Click the Options tab.
    A list of the options belonging to the current analysis is displayed. An option is used to customize an entity definition within an analysis. Options can perform operations such as turning entities on or off, or converting joints in an analysis from compliant to non-compliant.
  3. Each analysis has a Compliant option by default. This option can be used to toggle the state of joints within the system. Specify whether to make the analysis compliant or non-compliant from the drop-down menu.
    Selecting Yes makes all the compliant joints in the analysis compliant while selecting No makes all compliant joints non-compliant.
  4. Select the Initial Conditions tab.
    1. Enter values in the x, y, and z directions to set the initial translational and rotational velocity of all bodies in the analysis.
      Note: Initial conditions can be applied to any analysis in the model. The initial conditions applied to an analysis are automatically applied to its sub-analyses. If the initial conditions of sub-analyses are set separately, the settings override those of the system above it. Each initial setting that is overridden by a sub-analysis is listed on the right side of the parent analysis’ Initial Conditions tab.
  5. Select the System Translation tab.
    If symmetry is on, system symmetry is maintained. If symmetry is off, the entire system moves in the specified direction.
    1. Define a translation direction.
    2. Enter the distance to move the system along the coordinates in the Translation distance text box.

Export an Inline Analysis

Analyses can be individually exported to an .mdl file by clicking the Import/Export tab on the panel. You can export the entire analysis, including the topology information to the file, or you can export only the model properties for reading into another model. Only inline analyses can be exported to a definition file.

  1. From the Model Browser, select the inline analysis to save.
    The Analysis panel is automatically displayed.
  2. Click the Import/Export tab.
  3. Select the Export radio button.
  4. Click the file browser icon.
    The Export system definition file browser is displayed.
  5. Select a path and file name and click Save.
    The system is exported.
Tip:
  • Re-export to the same file without opening the browser by clicking Quick Export.
  • Use the Export topology as: drop-down menu to specify entity definition statements and definition blocks (that define systems, datasets, templates, etc.).
  • The Property Data options refers to *Set statements that assign values to the entity.

Import a System to an Analysis from a File

Systems can be imported into an Analysis from an .mdl file through the Import/Export tab on the panel.

Note: To import an inline analysis from an existing file, use the Import/Export tab on the Model.
  1. From the Model Browser, select an analysis.
    The Analysis panel is automatically displayed.
  2. Click the Import/Export tab.
  3. Select the Import radio button.
  4. Use the file browser icon to select a system definition.
  5. Click Import.
    The Specify entity details dialog is displayed with a list of the system definitions that are available in the selected file.
  6. Select System from the drop-down menu.
  7. Select a system definition from the Select a definition list.
  8. Specify a label and a unique variable name for the system definition.
  9. Add any notes.
  10. Click OK.
    The system is added to the analysis.

Adding an Inline Analysis to the Current Model

  1. Right-click on the Model label and select Add > Analysis.
    The Add Analysis dialog is displayed.
  2. Select the Inlined in model file radio button and click Next.
  3. Assign a variable name to the analysis.
    The variable name is required and cannot be changed after it is defined.
  4. Assign a label to the analysis.
    The system label can be changed at any time.
  5. Assign a definition name to the analysis.
  6. Click OK to close the window and add the analysis to the model or Apply to continue creating inline analyses.

Adding a New Analysis Data File Which References an Existing Definition File

  1. From the Add Analysis dialog, select the Uses data and definition files radio button and click Next.
  2. Select the New data file radio button and click Next.
  3. Select the Existing definition file radio button and click Next.
  4. Click the New Data File browser icon.
  5. Select a path and file name and click Save.
  6. Click the Existing Definition File browser icon.
  7. Browse and select the definition file that you want to use and then click Open.
    The definition name, and type referenced by the data file are automatically displayed in their respective fields.
  8. Assign a variable name to the analysis.
    The variable name is required and cannot be changed after it is defined.
  9. Assign a label to the analysis
    The analysis label can be changed at any time.
  10. Click OK to close the window and add the analysis to the model or Apply to continue creating analyses.

Adding a New Analysis Data File and a New Definition File

  1. From the Add Analysis dialog, select the Uses data and definition files radio button and click Next.
  2. Select the New data file radio button and click Next.
  3. Select the New definition file radio button and click Next.
  4. Click the New Data File browser icon.
  5. Select a path and file name and click Save.
  6. Click the New Definition File browser icon.
    The Select Definition File dialog is displayed.
  7. Select a path and file name and click Save.
  8. Assign a definition name to the definition file (or accept the default name).
  9. Assign a type for the definition file (if necessary).
  10. Assign a variable name to the analysis.
    The variable name is required and cannot be changed after it is defined.
  11. Assign a label to the analysis.
    The analysis label can be changed at any time.
  12. Click OK to close the window and add the analysis to the model or Apply to continue creating analyses.

Defining the Initial Conditions of an Analysis

The Initial Conditions tab on the Analysis panel enables you to specify initial conditions for analyses.

  1. From the Model Browser, select an analysis
    The Analysis panel is automatically displayed.
  2. Select the Initial Conditions tab.
  3. Enter values in the x, y, and z directions to set the initial translational and rotational velocity of all bodies in the analysis.

    The check box to the left of each initial condition indicates whether the initial condition is to be applied. When the check box is on, the solver default is used.

    Initial conditions can be applied to any analysis in the model. The initial conditions applied to an analysis are automatically applied to its sub-analyses. If the initial conditions of sub-analyses are set separately, the settings override those of the system above it. Each initial setting that is overridden by a sub-analysis is listed on the right side of the parent analysis’ Initial Conditions tab.

Defining the Options of an Analysis

An option is used to customize an entity definition within an analysis. Options can perform operations such as turning entities on or off, or converting joints in an analysis from compliant to non-compliant.

When you select the Options tab on the Analysis panel, a list of the options belonging to the current analysis is displayed. Each analysis has a compliant option by default. This option can be used to toggle the state of joints within the analysis. The joint or bushing within the analysis should be modeled within an *if(Op_Compliant == "Yes") loop in the MDL language using a text editor.

  1. From the Model Browser, select an analysis.
    The Analysis panel is displayed.
  2. Select the Options tab.
  3. Specify whether to make the system compliant or non-compliant from the drop-down menu.
    Selecting Yes makes all the compliant joints in the system compliant while selecting No makes all compliant joints non-compliant.

    In addition to converting compliant joints, MotionView can turn other entities on or off in a system according to predefined system settings. For example, MotionView can turn off specific entities such as springs or stabilizer bars when the system is made non-compliant.

    Note:
    • The Compliant option is applied to all subsystems beneath the current system.
    • The Compliant option can be overridden for individual joints in the Joints panel.
    • Not all joints can be compliant. The rules for converting joints from compliant to non-compliant are built into each model using the MDL language.
    • See *Option() in the MDL Language Reference for more information on creating options.

Defining the Translation of an Analysis

The System Translation tab on the Analysis panel allows you to change the position of an analysis within a model. If symmetry is on, analysis symmetry is maintained. If symmetry is off, the entire analysis moves in the specified direction.

  1. From the Model Browser, select an analysis.
    The Analysis panel is displayed.
  2. Select the System Translation tab.
  3. Define a translation direction.
    • Double-click the Vector collector and select a vector from the Select a Vector dialog.
    • Using the arrow button to the left of the collector, select DxDyDz, click the collector to display the DxDyDz Values dialog and enter vector coordinates.
  4. Enter the distance to move the analysis along the coordinates in the Translation distance text box.
  5. Click the + or - buttons to move the analysis.