Assembly modeling and motion simulation are crucial aspects of CAD, allowing engineers to create and test virtual prototypes. These tools enable the assembly of complex products from individual components, ensuring proper fit and function before physical production.

Motion simulation takes assembly modeling further by analyzing how parts move and interact. This helps engineers identify potential issues, optimize designs, and create realistic animations to visualize product operation, streamlining the development process and reducing costly errors.

Assembly Modeling

Inserting and Constraining Components

• Insert components into an assembly by selecting the desired parts from a library or file system and placing them in the assembly environment
• Define mate constraints between components to establish their relative positions and orientations
  • Coincident mate aligns selected faces, edges, or points of two components
  • Concentric mate aligns cylindrical faces of two components along their axes
  • Parallel mate aligns selected faces or edges of two components to be parallel
  • Perpendicular mate aligns selected faces or edges of two components at a 90-degree angle
  • Tangent mate aligns a selected face or edge of one component to be tangent to a curved surface of another component
  • Distance mate sets a specific distance between selected faces, edges, or points of two components
• Use subassemblies to organize and simplify complex assemblies by grouping related components together (engine subassembly in a car assembly)

Verifying and Visualizing Assemblies

• Perform interference detection to identify and resolve any physical clashes or overlaps between components in the assembly
  • Interference detection algorithms analyze the geometry of the components and highlight any areas where they intersect or occupy the same space
  • Resolve interferences by modifying component designs, adjusting mate constraints, or defining clearances between components
• Create exploded views of the assembly to visualize the individual components and their relationships
  • Exploded views separate the components along predetermined paths to show how they fit together and in what order they are assembled (exploded view of a gearbox showing gears, shafts, and housing)
  • Use exploded views for assembly instructions, parts catalogs, or presentation purposes

Motion Simulation

Kinematic Analysis and Motion Paths

• Perform kinematic analysis to study the motion and behavior of the assembly under different conditions
  • Kinematic analysis calculates the positions, velocities, and accelerations of the components based on the defined mate constraints and input motions
  • Evaluate the assembly's range of motion, detect collisions or interferences during motion, and optimize the design for smooth operation
• Define motion paths for components to simulate their movement within the assembly
  • Motion paths can be linear, circular, or follow a spline curve (piston moving up and down in an engine cylinder, gears rotating in a transmission)
  • Specify the start and end positions, velocities, and accelerations for the motion paths

Animation and Visualization

• Create animations of the assembly motion to visualize and communicate the behavior of the product
  • Animations can show the assembly process, product operation, or demonstrate specific features or functions (animation of a robotic arm performing a pick-and-place operation)
  • Export animations as video files or interactive 3D models for presentations, marketing materials, or user manuals
• Use motion simulation to validate the design, identify potential issues, and make informed design decisions before physical prototyping or manufacturing