Vade Mecum

Modelling for X:


Modelling aims at a purpose. If the modelling purpose is to ease:
    • the design activity, that is, facilitate the definition and modification of shapes, then we will adopt a "Modelling for Design" strategy where we will focus on the use of parametric modelling.
    • the simulation activity, that is, facilitate the definition and modification of meshes and boundaries conditions, then we will adopt a "Modelling for Simulation" strategy where we will focus on the features (easy for defeaturing) and symmetries.
    • the manufacturing activity, that is, facilitate the definition and modification of manufacturing instructions, then we will adopt a "Modelling for Manufacturing" strategy where we will focus on the choice of features (e.g. hole, pocket, round, chamfer, etc.).

In practice, it is difficult to satisfy all viewpoints in a single CAD model. Usually, we will start with a model that meets the design and simulation needs - the so-called AS-DESIGNED Digital Mock-Up - and, later in the design process, we will create a second model that meets the manufacturing needs - the so-called AS-BUILT Degital Mock-Up.


Modelling Method:

  1. Start modelling the main volumes
  2. Add details using the features (holes, ribs, rounds, chamfers, etc.)
  3. Finish using patterns (symmetries, patterns, etc.)


Do's & Dont's:

  • Sketches
    • Make sure sketches are iso-constrained
    • Prefer geometrical constraints (e.g. perpendicularity, coincidence, etc.) rather than dimensional constraints (e.g. 90° angles, 0 mm dimension)
    • Use parameters to control varying dimensions for trade-off analysis
    • Make the design intents explicit (e.g. use relations for constraining length and width of a sketch, use relations to specify the equality between two dimensions in a sketch rather than repeating the dimension twice, etc.) 

  • Volumes
    • Use suitable features (e.g. a "hole" rather than a "pocket")
    • Use suitable feature options (e.g. "Through all" option for setting the depth through all surfaces of a part rather than a dimension)

                  Last modified: Thursday, 7 February 2019, 11:11 AM