By the end of this topic, you should be able to...
construct and interpret surface, solid and virtual models.
Guiding Question
Why is it necessary for designers to prototype ideas as part of a design process?
💡 Did You Know? A single CAD file contains more information than 10,000 hand-drawn technical drawings—yet most designers only use 20% of what their software can actually tell them.
Why Use CAD?
Computer Aided Design isn't just "drawing on a computer"—it's creating intelligent geometry that can be interrogated, analyzed, and transformed. Surface models define exterior form through mathematically precise curves and patches—essential for aerodynamic optimization or aesthetic refinement where smooth, flowing shapes determine success.
Solid models go deeper, representing complete 3D objects with calculable volume, mass, center of gravity, and material properties—enabling engineers to simulate stress, predict failure, and validate assembly before manufacturing begins. Virtual models extend further, embedding behavior: animations show mechanisms in motion, finite element analysis predicts structural performance, and VR environments let users inhabit spaces before they're built. But here's the critical literacy gap: interpreting these models matters as much as constructing them.
Can you read a surface model's curvature continuity to spot manufacturing problems?
Can you analyze a solid model's draft angles to predict molding challenges?
Can you extract meaningful data from simulation results?
Professional designers don't just make CAD models—they interrogate them, using software as a design intelligence partner that reveals truths invisible to the human eye.
Case in Point
When SpaceX designed Starship's heat shield, engineers constructed solid models with embedded thermal properties, then ran virtual simulations modeling 1,650°C re-entry temperatures across 18,000 hexagonal tiles. The CAD model wasn't a drawing—it was a predictive laboratory that revealed which tile placements would fail, which geometries would survive, and where structural reinforcement was needed, reducing physical testing cycles by 70% while accelerating development timelines.
Learning Goals
In this topic, you'll master the construction and interpretation of surface, solid, and virtual models—learning to extract design intelligence from digital geometry and leverage CAD as an analytical tool, not just a documentation platform, for your IA project.
Linking Questions
When creating physical prototypes, which ergonomic considerations should be taken into account? (A1.1)
To what extent are user-centred research strategies useful to gather feedback on models and prototypes of proposed design solutions? (A2.1)
How do designers use their knowledge of prototyping techniques to ensure effective modelling and prototyping? (A2.2)
Which aspects of material properties can be explored through modelling? (A3.1)
How can information about a proposed structural system, such as a product housing, be gathered using CAD modelling and contribute to the development of a design solution? (A3.2, B3.2)
How effectively can mechanical systems be mocked up and tested using modelling and prototyping? (A3.3, B3.3)
How can effective electronic systems be modelled virtually? (A3.4, B3.4)
How does the development of prototypes inform the choice of manufacturing techniques and production systems for a product? (A4.1, B4.1)
How can modelling and prototyping be used to inform the development of a product following a user-centred design (UCD) strategy? (B1.1)
To what extent is modelling and prototyping essential for inclusive design? (B2.2)
To what extent can the same materials used for modelling and prototyping be used in the material selection of a commercial product? (B3.1)