Integrating CAD Models and Collision Detection in MotionView

Welcome to the Multibody Dynamics for Automotive Applications using MotionView and MotionSolve blog series! In this chapter, we will integrate the four-bar mechanism with real-world CAD models, apply collision detection algorithms, and refine our simulation using multibody dynamics software. 

Importing the Trunk Lid and Car BIW Model 

To enhance our vehicle dynamics simulation, we import: 

• Trunk Lid CAD Model (.hm format) 
• Car Body-in-White (BIW) Model 

Using MotionView’s CAD Import Utility, we follow these steps: 

• Go to File → Import → Geometry. 
• Select the second import option (Import CAD without mass/inertia properties). 
• Choose the appropriate file format (HyperMesh, Parasolid, STEP, etc.). 
• Define mesh refinement settings (set to 5 for automatic meshing). 
• Finalize the import and validate geometry alignment. 

After importing, we attach the trunk lid to the input link of the four-bar mechanism and assign the BIW to the ground body. 

Running the Trunk Lid Simulation 

After the setup is complete, we save the multibody dynamics model and run the simulation using MotionSolve. In HyperView, we visualize the trunk lid movement. 

Observing Incorrect Motion Behavior 

Upon running the simulation, we notice that the trunk lid moves beyond its expected position. This is a common issue in automotive dynamics analysis, where motion constraints must be carefully fine-tuned. 

Applying Collision Detection in HyperView 

Why Collision Detection is Important 

In automotive multibody simulation, collision detection algorithms are crucial for identifying interference between components. In our case, the trunk lid must stop when it contacts the car BIW. 

Steps to Enable Collision Detection in HyperView 

1. Activate the Collision Detection Tool

• Navigate to View → Toolbars → HyperView → Tools. 
• Select the Collision Detection Icon. 

2. Define Collision Sets 

• Group A: Trunk Lid. 
• Group B: Car BIW. 

3. Enable Proximity Checking 

• Set a minimum distance threshold (e.g., 1mm). 

4. Select Display Mode 

• Elements Mode: Highlights only contacting elements. 
• Components Mode: Highlights the entire contacting part. 

5. Define Animation Events 

• Ignore Collision: Allows simulation to continue after contact. 
• Stop on Collision: Halts animation upon contact detection. 

Validating the Motion and Collision Analysis 

Once collision detection is applied, we re-run the MotionSolve simulation. The trunk lid now correctly stops upon impact, validating the use of collision detection in multibody dynamics simulation. 

Plotting Displacement Outputs in HyperGraph 

To confirm our results, we use HyperGraph to analyze: 

• Displacement Magnitude (DM) of the Input Link. 
• Maximum Displacement (~1545mm), confirming correct motion constraints. 

Conclusion 

With the successful integration of CAD models and collision detection algorithms, we now have a fully functional automotive trunk lid mechanism simulation. This marks the transition from beginner-level multibody dynamics modeling to intermediate-level simulation techniques, where real-world constraints and interactions are analyzed in detail. 

In the next module, we will dive deeper into advanced multibody dynamics techniques, including contact simulations, flexible bodies, and real-world automotive applications. Stay tuned for more insights on multibody dynamics training and certification! 

This blog is part of our ongoing Multibody Dynamics blog series. If you missed the previous posts, check them out here.  

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