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KP3213 CAD/CAM

KP3213 CAD/CAM. Snapshot Lecture 6 Objective of Lecture 7 Understand Assembly Modelling Learn FEM Lecture 7. Assembly Modelling. Assembly Modelling. An assembly consists of two or more parts located relative to each other in space Normally the relative motion is constrained

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KP3213 CAD/CAM

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  1. KP3213 CAD/CAM • Snapshot Lecture 6 • Objective of Lecture 7 • Understand Assembly Modelling • Learn FEM • Lecture 7

  2. Assembly Modelling

  3. Assembly Modelling • An assembly consists of two or more parts located relative to each other in space • Normally the relative motion is constrained • Most assemblies are fully constrained • Mechanisms are partially constrained

  4. Applications of Assembly Models • Interference checking • Visualization • rendered • exploded • Animation • Mechanism analysis

  5. Assembly Example

  6. Exploded Assembly

  7. Assembly Hierarchy • The assembly hierarchy defines relationships of parts to each other • There can be multiple levels of sub-assemblies

  8. Multiple instances subassembly Assembly Hierarchy Example • Pump Assembly • Link assembly • offset link • offset link • Piping assembly • well casing • well seal • … • Handle assembly • ...

  9. Another View Assembly Subassemblies Parts

  10. Positioning Parts in an Assembly • Parts can be positioned by translating and rotating them into the right locations • This requires careful measurement of relative locations, knowledge of coordinate systems, and entry of numerical values • If position or dimensions of one part change, this has to be redone

  11. Example Assembly Position and orientation Subassemblies Parts

  12. Using Assembly Constraints • Constraints can be used to create permanent relationships between parts • In I-DEAS, these use the same commands as 2D constraints • Typical constraints: • two faces meet • axes coincident • two faces parallel at fixed distance • etc.

  13. Example Assembly Constraints Subassemblies Parts

  14. Animations and Motion • If the assembly is not fully constrained, relative motion is possible • In I-DEAS, you can reposition the parts and create “snapshots”, saved as configurations • A sequence of configurations can be animated

  15. Mechanism Design • A mechanism is an assembly that allows relative motion between parts • The mechanism consists of links connected by joints • Types of joints: • rotational • sliding • spherical • cylindrical • screw

  16. Mechanism Analysis • I-DEAS allows the mechanism to be “driven” by defining an input motion for one of the links • The other links move based on the kinematics • I-DEAS can calculate reaction forces based on gravity and applied forces

  17. Examples (click on the images to see the animation)

  18. Dynamic Analysis • More advanced software can model and analyse complete dynamics • Applications: • vehicle dynamics • suspension analysis • biomechanics • robotics

  19. A Simple Example:Pendulum Dynamic analysis software will generate the motion by solving the equations of motion

  20. FEM • Continue Lec. 10

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