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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 • Snapshot Lecture 6 • Objective of Lecture 7 • Understand Assembly Modelling • Learn FEM • Lecture 7
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
Applications of Assembly Models • Interference checking • Visualization • rendered • exploded • Animation • Mechanism analysis
Assembly Hierarchy • The assembly hierarchy defines relationships of parts to each other • There can be multiple levels of sub-assemblies
Multiple instances subassembly Assembly Hierarchy Example • Pump Assembly • Link assembly • offset link • offset link • Piping assembly • well casing • well seal • … • Handle assembly • ...
Another View Assembly Subassemblies Parts
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
Example Assembly Position and orientation Subassemblies Parts
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.
Example Assembly Constraints Subassemblies Parts
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
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
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
Examples (click on the images to see the animation)
Dynamic Analysis • More advanced software can model and analyse complete dynamics • Applications: • vehicle dynamics • suspension analysis • biomechanics • robotics
A Simple Example:Pendulum Dynamic analysis software will generate the motion by solving the equations of motion
FEM • Continue Lec. 10