IB DT: Topic 3.4: Computer-aided design (CAD)

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what is a computer aided design, why is it so beneficial?

the generation, creation, development and analysis of a design or system using computer software. the ability to virtually prototype, visualise and share designs enhances the whole design cycle from data analysis through to final designs as it allows the designer to gain valuable data at a low cost.

what is CAD used for?

• conceptual design and layout of a product

• can ultimately eliminate the high costs of testing and manufacturing

• used in fashion, construction, automotive, architecture and planning

what are surface models?

photo-realistic images of a product offering limited machining date - nothing about a product’s interior

what is solid modelling?

clear representations of the final product, provide a complete set of data for the product to be realised

what is data modelling (also known as mathematical/statistical modelling)?

• explicitly determines the structure of data and its relationships, often used to categorise and simplify complex databases

what is virtual prototyping?

the use of solid and surface modelling to develop photo-realistic interactive models - digital mock ups

what is bottom up modelling?

when the designer creates each part geometry independent of the assembly or any other component. although some design criteria are established before modelling, this information is not shared between models. once all part models are completed, they are brought together for the first time in the assembly.

how is a bottom up model assembled?

place existing parts and subassemblies into an assembly file, and position components by applying assembly constraints. place the components in the order they would be assembled during manufacturing.

what is top down modelling?

a product development process obtained through 3D CAD systems - characterised by the method of the idea originating as a concept and gradually evolving into a complete product involving assemblies and sub-assemblies. begins with design criteria and designers create components that fit these known parameters.

what is a digital human and what can it be used for?

• computer simulations of a variety of mechanical and biological aspects of the human body

• interact with a virtual prototype

what does the use of digital humans enable?

• products can be developed more quickly (more iterations in less time)

• higher quality products that meet human requirements more accurately (more iterations)

• cheaper to use in testing than physical testing with real humans

• resulting products are safer as a result of more thorough analysis of safety aspects

• improved productivity from enhanced automation of the development process (more iterations, less time(

what is motion capture?

the recording of human and animal movement by any means - could be video, magnetic, reflective, or electro-mechanical devices. a person wears a set of acoustic, inertial, LED, magnetic or reflective markers at each joint and sensors track the position of the markers as the person move to develop a digital representation of the motion

what are the benefits of motion capture (compared to traditional animation)?

• reduce the cost of animation, which otherwise requires the animator to draw each frame and then link them together.

• saves time

• creates more natural movement (however is limited to what is anatomically possible)

what is haptic technology?

a technology that interfaces the user via the sense of touch. also known as force feedback technology.

• works by using mechanical actuators (motors) to apply forces to the user. by simulating the physics of the users virtual world, it is possible to compute these forces in real time.

• allows the user to become part of a computer simulation and interact with it - in design testing this allows the designer to observe the user’s performance and design a better outcome

• can also be used in situations where it is difficult to train in the real environment

• used in the feedback devices used in home entertainment consoles

what is virtual reality?

the ability to simulate a real situation on a screen and interact with it in a near-natural way

what is animation?

the ability to link graphic screens together in such a way as to simulate motion

what is finite element analysis (FEA)?

involves the calculation and simulation of unknown factors in products using CAD systems, for example, simulating stresses within a welded car part.

uses colour indication to show:

• structural load (stress and strain)

• aerodynamics

• thermodynamics