IB Design Technology / Topic 3: Modelling

Role of conceptual modelling

Communicate ideas/concepts that might otherwise be difficult to understand.

Users can interact with objects, systems and environments.

It can be graphical, virtual or physical.

Advantages of conceptual modelling

- Shares big picture

- Easier/simpler communication (overcome language barriers)

- Gauge reaction to idea/concept

- Helps establish proportion

- Can manipulate ideas

Disadvantages of conceptual modelling

- Lacks detail

- Possibly misleading, can be misunderstood

- Simplicity of models = vital aspects left out

- Might not reflect final choices of materials

What are 2D/3D graphical models and when are they used?

Sketches or freehand drawings. Used in early stages of design cycle; allows quick jotting down of ideas and communication of initial ideas.

Perspective drawings

Natural representations of objects/environments, includes foreshortening.

Isometric drawings

Equal dimensions, 30 and 60 degree angles used. Unnatural representations.

Orthographic drawings

Used to communicate completed designs, as it shows details, dimensions, scale, multiple angles. Useful to manufacturer.

Parts and assembly drawings

Indicates size and relative position of parts

Scale models

Smaller or larger physical copy

Aesthetic models

Designed to look/feel like final product. Useful tor ergonomic testing and judging visual appeal but can be expensive (surface finish required, and it is lifesized)

Mockups

Scale or full-size model for design evaluation, promotion and understanding proportions - no functionality.

Prototypes

Built to test a concept/process (full functionality), used by development team for tests.

Fidelity ranges

How closely a model looks/will look to the final product.

Low fidelity range

Conceptual representation, comparable in certain aspects

Medium fidelity range

Representation of aspects of an idea

High fidelity range

As close as possible to the final product

instrumented models

Physical models that can take measurements to give quantitative feedback

CAD

Computer aided design: generation, creation, development and analysis of design using computer software

Surface model

Photorealistic images of product; offers some machining data but not the interior of the product

Solid model

Clear representation of the final product, provides a complete set of data for product to be realised (internal dimensions, volume included)

Data modelling

Acts as a bridge from real-world information to database

Statistical modelling

Predictions, information extraction, stochastic structures

Virtual prototyping

Involves use of surface and solid modelling to develop photorealistic interactive models. Used in design development. Advantages = allows for less material waste, which is associated with creation of physical models

Finite element analysis

Able to test forces/stress on product. Iterations improve and increase in number because of reduction in manufacturing costs of prototypes. Can test mechanical stress, vibration, fatigue, electrostatics, motion, heat transfer, fluid flow

Bottom-up modelling

Involves existing parts (in different files) that are added to assembly file

Top-down modelling

Shape, size, location of parts can be designed into the assembly file.

Digital humans

Computer simulations of a variety of mechanical and biological aspects of the human body.

Can interact with virtual prototype and represent joint resistance, discomfort, reach envelopes and visual field and human performance.

Motion capture

Process of recording patterns of movement digitally using markers (LED, magnetic, reflective) to capture movements.

Virtual reality

Simulation of a real life environment, interactive and immersive. Simulates user's physical presence.

Animations

Imitates operation of real-world system, models must be created first. Used for performance optimization, safety engineering, testing, etc. Reduces need to produce physical product.

Haptic technology

Relating to touch - tactile sensation and control interacting with technology, gives feedback to user.

Kinesthetic feedback

Position, orientation, forces

Tactile feedback

Felt on skin (pressure, vibration, slip, temperature)

Rapid prototyping

Production of a physical model from CAD data

Stereolithography

Additive; starts with excess of liquid plastic (photopolymers), some of which is cured (hardened) under UV light

Laminated object manufacturing

Takes sliced CAD data (from 3D model) and each layer is cut out and adhered to form the model.

Fused deposition modelling

Additive; melted filaments of material (plastic or metal) pushed it through a heated nozzle that can move up/down, in patterns controlled by CAD data.

Selective laser sintering

Uses a high power laser to fuse small particles of glass, plastic, metal, ceramic or glass into a 3D shape.

Advantages to rapid prototyping

Decrease development time, mistakes and increase product variants, complexity. Can provide proof of concept.

Disadvantages to rapid prototyping

Important steps would be omitted to have a quick/cheap working model. Fails in replication of real system if not accurate. Can be unsuitable for large-size applications. Problems can be over looked.