Topic 3

Conceptual Models

*A model that exists in the mind used to help us know and understand ideas.*

They are:

* a model of concepts or ideas (abstract) that exist in the mind.
* used to help us know and understand, design thinking, ideas, casual relationships, principles, data, systems, algorithms or processes.
* used to illustrate relationships that is in the designers mind to others.
* able to help explain the thinking behind  new ideas.
* able to help us to communicate with other members of  design team, manufacturer or client.
* able to help us visualise ideas through graphic, physical and virtual models.

Graphical Model

A visualization of an idea, often created on paper or through software, in two or three dimensions.

Physical Model

The creation of a smaller or larger tangible version of an object that can be physically interacted with.

Virtual Model

Photorealistic CAD-based interactive models that use surface and solid modelling. They can be considered ‘digital mock-ups’.

Advantages:

* To help explain features in data sets.
* Help with project planning.
* Put abstract ideas into a visual understandable form that might not be imaginable otherwise.
* Promote communication between designer, design team members, manufacturer or clients.
* Gauge peoples’ reaction.

Disadvantages:

* Make assumptions that which in reality do not work
* may lack details – too simplistic.
* scale may distort perceptions or understandings.
* materials might reflect the final selection.
* Graphic models such as flow charts may be difficult for people to understand.

Projection Drawings

Systems of drawings that are accurately drawn, the two main types are isometric projection (formal drawing technique) and orthographic projection (working drawing technique).

Scale Drawings 

Drawings that are bigger or smaller than the real product, but exactly in proportion with product.

 Working Drawings

Drawings that are used to guide the production of a product, most commonly orthographical projection, section drawings, part drawings, assembly drawings and plan drawings.

Orthogonal/Orthographic Drawings/Projections

* A series of flat (2D) views of an object showing it exactly as it is in shape and size i.e. constructional details.
* An orthographic drawing shows all details and dimensions and is usually used as a production/working drawing.
*  It is a convergent thinking style of drawing.
* Orthographic drawings are produced at the final solution stage and are used as working drawings in the realization stage.

Isometric Drawing/Projection

* An isometric drawing depicts the proposed solution in 3D showing shape and form.
* They are drawn on a 30/90/30 degree axis.

**Exploded Isometric Drawing**

* An isometric drawing of an object with more than one component that depicts how the parts of assemblies fit together.
* The drawing is exploded to show component parts of a product and/or the sequence of assembly.
* Isometric  drawings are produced at the final solution stage and are used as working drawings in the realization stage

**Perspective drawing**

A set of formal drawing techniques that depicts an object as getting smaller and closer together the further away they are. The techniques are one-point perspective, two-point perspective, and three-point perspective.

Assembly Drawing

A diagram that shows how components fit together to make a whole.drawings Typically presented in an exploded view.

* Assembly drawings show how different parts \[components\] go together, identify those parts by number, and have a parts list, often referred to as a bill of materials.

Parts (Component) Drawing

*Orthographic drawings of the components of an assembly containing details just about that component.*

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Sketches

Rough drawings of ideas used to convey or refine the idea.

Formal drawing techniques

*A type of drawing technique that has fixed rules, the most widely used being isometric projection and perspective drawing.*

Sketching or freehand drawings

* Are spontaneous representation of ideas on paper without the use of technical aids.
* Designers use a range of freehand drawings in the early stages of developing ideas to explore shape and form (3D) and constructional details (2D).
* Divergent thinking is prominent at this stage.

Annotations

* Explain the thinking behind the visual image represented by the drawing.
* They allow the designer to consider the implications of the ideas for further development.
* Annotated drawings are an alternative form of expression of ideas that allows one to indicate links between the ideas.

Formal drawings

* Include: orthogonal, isometric, exploded isometric, sectional, parts and assembly drawings which are done with great precision and usually with mechanical drawing aides (ruler, square, compass) or in CAD programs (Autodesk Fusion).
* Designers use these drawings at the realisation/development stage where the product is to be made. They are used to communicate to the manufacturer.
* Convergent thinking is prominent at this stage.

Orthogonal

Advantages

* Detailed
* Contains all necessary information.
* Can construct from it.
* Accurate and precise.
* Easy to communicate with manufacturer.

Advantages

* Need specialised skills such as using CAD
* Specialised equipment needed.
* Time consuming.
* Not easily understood by a lay person (e.g. client).

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Isometric

Advantages

* Shows all views at once
* Easy to communicate with manufacturer and client

Disadvantages

*  Not all details are included.
* May not look like the real thing because the dimensions are all true.
* Need specialised skills such as using CAD
* Specialised equipment needed.

Perspective

Advantages

* Looks like the real thing, it is pictorial
* Easy to communicate with client

Disadvantages

* No details – dimensions, etc
* Time consuming

Assembly

Advantages

* Easy to communicate with manufacturer and client.
* Show how product should be assembled.

Disadvantages

* Time consuming
* Specialised knowledge and skills required.

Freehand

Advantages

* Quick.
* Easy.
* No specialised skills required.
* No specialised equipment required.
* Easy to communicate with manufacturer and client.
* Allows spontaneous creative (Divergent) thinking.

Disadvantages

* May not look like the intended outcome.
* Lacks details.

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Scale Models

 A model that is either a smaller or larger physical copy of an object.

* accurate physical representations of objects or features of objects.
* able to allow the design team, client or manufacturer visualise and/or manipulate (examine) the object.
* scaled down or up keeping all sizes of the features in relation to each other.
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Aesthetic models 

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*A model developed to look and feel like the final product.*

* An aesethic/appearance prototype or appearance model is as its name suggests.
* It does not function or operate in any way.
* Aesthetic/appearance models are only concerned with form, color, style, texture and how the product fits in its visual environment.
* They can be used for ergonomic testing, evaluating visual appeal, allow the non-designer to see and feel how the real product will be,  or production engineers collect data that will help them assess the feasibility for matching manufacturing systems.

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Mock-ups 

A scale or full-size representation of a product used to gain feedback from users.

* Mock-ups are used to test ideas and gather feedback from users.
* They can be either full-scale or scaled models of products
* They can have  *some form* of functionality, which means they could be considered a prototype as well.
* A good example of how a design begins and gets to the mock up stage. It shows gathering of information to graphical and finally physical modelling.

Prototypes 

A sample or model built to test a concept or process, or to act as an object to be replicated or learned from. Prototypes can be developed at a range of fidelity and for different contexts.

* Prototypes are to test and evaluate ideas.
* A prototype can be a real working product made to real specifications that can be used throughout design development.
* It has functionality unlike that of a mock-up (minimal) or lack of it in aesthetic models.
* It is particularly useful in testing before production begins.
* Prototypes help the development team discover and issues related to manufacturing the final product.
* It also allows the development team to learn from the user through user feedback and user trials/interaction with the final prototype.

Prototype Fidelity

The degree to which a prototype is exactly like the final product.

Instrumented Models

Prototypes that are equipped with the ability to take measurements to provide accurate quantitative feedback for analysis.

* *Instrumented physical models are equipped with the ability to take measurements to provide accurate quantitative feedback for analysis.*
* *They can be used effectively to investigate many phenomena such as fluid flows in hydraulic systems or within wind tunnels, stress within structures and user interaction with a product.*
* *For example, an instrumented model of a keyboard can record the actions of the user and provide data on how often keys are used and the number of errors a user makes (that is, the number of times the backspace or delete key is used).*
* *These models can be scaled in terms of both geometry and important forces.*

Applications of Physical Models

* Product design
* Architecture and Engineering
* Medical research
*  Automative industry

Advantages and Disadvantages of Physical Models

Advantages

* Explore and test ideas
* Easily understandable
* Communication with clients
* Communication with team members
* Ability to manipulate ideas better than with drawings
* Is tangible
* Can be used in user trails and user research more readily.

Disadvantages

* Designers can easily make assumptions about how accurately a model represents reality
* It may not work like the final product
* Might not be made of the same material
* Time consuming to make
* Level of skill required
* Can be costly (prototypes)

Computer Aided Design (CAD)

The use of computers to aid the design process.

CAD is using computers to aid the design process, this could include creating and modifying designs (products), graphic design, data processing, analysis (FEA) or simulations.

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**Advantages and Disadvantages of Using Computer-Aided Modelling**

Advantages

* Changes to ideas can be made quickly and easily.
* Communicate with client, manufacture more easily.
* Electronically transferred.
* Avoid costly mistakes.
* Reduce costs as extra prototypes are not needed.
* Saves time through efficient work practises.
* High accuracy/fidelity.

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Disadvantages
* Software/Hardware costs.
* Special training needed.
* Steep learning curve.

 Surface Modelling

*A realistic picture of the final model, offering some machining data. Surface models contain no data about the interior of the part.* 

Solid Modelling

*Solid models are clear representations of the final part. They provide a complete set of data for the product to be realized.*

* Comparison of the differences between solid and surface modelling techniques.
* Solid modelling techniques contain more information for the designer,
* In order to produce a 3D model using CNC (computer numerical control) or RP (rapid prototyping) technologies
* Surface modelling only has wall thickness.

“Top down” 

Product development process obtained through 3D, parametric and associative CAD systems. The main feature of this new method is that the design originates as a concept and gradually evolves into a complete product consisting of components and sub-assemblies.

“Bottom Up”

 *A designer creates part geometry independent of the assembly or any modelling other component. Although there are often some design criteria established before modelling the part, this information is not shared between models. Once all parts are completed, they are brought together for the first time in the assembly.*

* This allows for a database of parts that could be used elsewhere.
* Is carried out by adding components to existing parts/bodies/components.

Virtual prototyping 

Photorealistic CAD-based interactive models that use surface and solid modelling. They can be considered ‘digital mock-ups’.

* designers can simulate a design visually and/or mathematically
* reduce lead times
* reduce development costs
* reduce or eliminate  errors (as humans are not involved)
* improve quality
* easily scalable – such as in nanotechnology or aeroplanes.
* *Discuss the cost-effectiveness offered by animation and virtual reality. This helps to reduce full-scale prototyping, which leads to a reduction in tooling costs, labour costs, energy and materials*

Digital humans:

Motion capture, haptic technology, virtual reality (VR), and animation

Digital humans:

* are computer simulations of the biomechanics of the human body.
* help to predict how a human (real) will react in a variety of situation or environments (places or locations).
* *Discuss how digital humans can enhance human factors research.*
* Digital humans can be used to represent joint resistance, discomfort, reach envelopes and visual fields.
* They can be used, for example, to measure the impact of clothing on human performance.

Haptic technology 

* is an emerging technology that interfaces the user via the sense of touch.
* How it works is by mechanical actuators apply forces to the user which gives them feedback.
* *By simulating the physics of the user’s virtual world, it is possible to compute these forces into real time.*
* *Haptic technology allows the user to become part of a computer simulation and to interact with it, enabling the designer to observe the user’s performance and to design a better outcome.*

Animation 

*The ability to link graphic screens together in such a way as to simulate motion or a process.*

Motion capture 

The recording of human and animal movement by any means, for example, by video, magnetic or electro-mechanical devices.

* *Explain how motion capture is used to digitally represent motion*.
* A person wears a set of acoustic, inertial, LED, magnetic or reflective markers at each joint.
* Sensors track the position of the markers as the person moves
*  this produces a digital representation of motion.

Finite element analysis (FEA)

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

Compare FEA with testing physical models

* Compare finite element analysis with real-life testing.
* when testing vehicles consider
* costs
* type of environment,
* weather
* the user.

**Use of FEA systems when designing and developing products**

* Explain how FEA can be used to show the forces acting upon an object while in use.
* the maximum load of a vehicle and the stresses acting upon the vehicle
* from the differences in terrain.
* allow to redesign areas of weakness discovered through FEA

**Rapid Prototyping (RP) and RP Machines**

* entails a machine that produces a complete product including internal details, at a fairly quick rate.
* reduce product development time as prototypes are quickly made and can be tested
* one-off products are made for different or specialised  situations
* is an additive manufacturing technique as opossum to subtractive manufacturing (mills, lathes, etc).
* less waste (good for environment and save money)

RP Process

* Using CAD software produce a full scale model
* Export or convert model in STL (Standard Triangle Language and Standard Tessellation Language).
* send to RP machine
* manufacture the item
* clean up the item

Stereolithography

Stereolithography (SLA) is a 3D printing process.

* that uses a vat of photosensitive resin and a vertically moving platform.
* It uses a laser beam, directed onto the surface of the photosensitive resin, to print the pattern of the current model layer by hardening the photosensitive resin.
* The platform then moves down by a layer thickness so the next layer can be printed*.*
* Also known as optical fabrication, photo-solidification, solid free-form fabrication and solid imaging.
* Used for producing models & prototypes, casting patterns,  production parts and products.

Laminated object manufacturing (LOM)

* LOM machines take the sliced CAD data from the 3D model and cut out each layer from a roll of material, using a laser or plotter cutter. These sliced layers are glued together to form the model, which is either built on a movable platform below the machine or on pins when using card. *(IB TSM 2015)*
* A rapid prototyping systems that creates a 3D product by manufacture (LOM) converting it into slices, cutting the slices out and joining the slices together

Fused deposition modelling (FDM)

An FDM machine is

* A heated extrusion nozzle (extruder) that moves through the x & y axis
* A plastic (such as ABS, PLA), metal or composite (such as30% metal,  bamboo, etc  fill PLA) filament is fed through he extruder
* basically a CNC robot that holds a small extrusion head. The extrusion head moves back and forth along a platform, building up a 3D model by feeding heated plastic wire through the extrusion head.
* Either the platform or extruder move through the Z axis place a layer if build material
* Controlled by CAM software.

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Selective laser sintering (SLS)

* A high powered CO2 laser is used to sinter a thin layer of heat-fusible powder that gradually builds up the 3D model.
* Powders include, plastic, metal, ceramics and glass

Advantages and disadvantages of rapid prototyping techniques

* *Describe different design contexts where SLS, LOM and FDM would be applicable.- Consider quality, cost and accuracy of outcome.*

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roduct design
*  More intricate
* many prototypes can be quickly and accurately produced
* prototypes can be used in user trials

Time/Speed
*  reduced design development time
* changes to ideas can be quickly done


* Slow process -have to build internal structure, supports and raft.
* Slower that other CAM techniques – e.g. CNC routing, laser cutting, etc

Cost
* reduce design development costs
* reduce costly mistakes


* initial capital cost can be high

Accuracy
*  increased complexity of designs
* parts produced with finer tolerances
* can produce intricate designs better other CAM processes

Waste
* No or minimal waste – it is additive manufacturing. Other CAM techniques a subtractive.

Volume production
* not suitable as it is slow. Other cam techniques would be better suited for volume.
* this can be due to the need to build the internal structure.

 Materials
*  A wide range of materials can be used.
* Advantage over other CAM processes which are limited in their material use.

Communication
* improved with the client, designer  and the manufacturer
* changes to ideas can be easily communicated

Size
* limited to size of the bed or work area – may result in numerous parts (sub assemblies)
* not suited for large scale applications