90 - creating mechanism loads

7/27/2019 90 - Creating Mechanism Loads

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StructuralLoadsCreatingMechanismLoadsLecture

CreatingMechanismLoads.mp3

Creating Mechanism Loads

Mechanism Loads enable you to import loads on the model from a

Pro/ENGINEER Mechanism Assembly.

Mechanism

Mechanism analyzes rigid body assemblies Calculates Acceleration, Momentum, and Forces No deformation or stress calculations

Mechanism Load in Mechanica

Imports Mechanism results Automatically creates

o Gravity loads (acceleration)o Centrifugal loads (rotation)o Force/Moment loads (joint reactions)

Assembly with Mechanism Analysis


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Mechanism Load imported into MechanicaLectureNotes

Mechanism Loads

Mechanism Dynamics is Pro/ENGINEERs tool for analyzing motion of rigid bodies.Mechanism can calculate the acceleration, momentum, and forces acting on each bodyin an assembly. However, because it is analyzing rigid bodies, it cannot estimatedeformation or stress.

Mechanism loads in Mechanica Structure enable the user to import the loads beingacted on an assembly component in Pro/ENGINEER. These loads will not constitute anew load type, but will take the form of gravity loads (to simulate acceleration),

centrifugal loads (to simulate rotation), and Force/Moment loads from joint reactions.

Mechanism Load Definition

In Mechanism, the user has to define the body and the part that the loads will beexported for. Loads cannot be exported for the entire assembly. The user will alsospecify if the loads should be exported for a specific time index or maximum for theentire duration of the Mechanism Dynamics analysis.


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With the specific part opened, the user will import the loads in Mechanica. AnyForce/Moment loads created will need to be edited so they are associated with a

surface.

Best Practices

Mechanism performs dynamic analyses to determine all the forces acting on the

model. As with any assembly that has moving parts, inertia is a significant force. Ifthere are parts in the assembly that do not have a material property assigned, they

will get a nominal density of 1.0. This will lead to incorrect results. When relying on

values reported by Mechanism, double check all material properties and densities

reported by Pro/ENGINEER because unlike Mechanica, Mechanism will not stop you

when you do not have material properties assigned.

CreatingMechanismLoadsDemonstrationCreatingMechanismLoads_demo.mp4

CreatingMechanismLoadsProcedureProcedure: Creating Mechanism Loads

ScenarioExport results from a mechanism analysis, then import the loads in Mechanica.

MechLoad engine.asm

Task 1. Open the Mechanism Application, run a Mechanism Analysis, and export theresults for use in Mechanica.

1. Click Applications > Mechanism from the Main toolbar.

2. Click + next to Analyses to expand the section. Right-click Dynamic1(DYNAMICS) and select Run as shown in the figure.


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3. From the Main menu, click File > Use in Structure....

4. Select CONNECTING_ROD.PRT from the model tree to select it as the Bodyreference.

5. Click Select Reference Entity next to the Component field and selectCONNECTING_ROD.PRT from the model tree to select it as the Component

reference.

6. Select Max for All Loads from the Evaluate At drop-down menu.

7. The Load Export dialog box should appear as shown in the figure. Click OK tocomplete the export and close the dialog box.


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Task 2. Open CONNECTING ROD.PRT, enter the Mechanica application, and importits Mechanism Load.

1. Right-click on CONNECTING_ROD.PRT in the model tree and click Open. Click Yes

to confirm the exit from Mechanism without saving results.

2. Click Applications > Mechanica > OK.

3. From the Main menu, click Insert > Mechanism Load....

4. The dialog box should now appear as shown in the figure.


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5. Click OK to create the Load.

6. Click + next to Loads/Constraints to expand the section. Click + next to Load

Set MechanismLoadSet1 to expand this section as well. Examine the 6 Loads that

have been added.


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Note that a Force Load and a Moment Load have been added at each end of

the CONNECTING_ROD.PRT accounting for four loads. These loads are due

to Mechanism reaction forces at each end of the part. Also note the addition

of a Gravity Load (to account for linear acceleration of the part in the

Mechanism) and a Centrifugal Load (to account for Centrifugal force due to

the rotation of the part in the Mechanism).

Task 3. Save the model and erase it from memory.

1. Return to the Standard Pro/ENGINEER mode by clicking Applications > Standard.

2. Click Save from the main toolbar and click OK to save the model.

3. Click File > Close Window > File > Close Window to close all open windows.

4. Click File > Erase > Not Displayed > OK to erase all models from memory.

This completes the procedure.

90 - creating mechanism loads

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