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Shad Valley MUN

Introduction to Product Design and Development

Lecture 4: Part 2Prototyping

Dr. Leonard M. Lye, PEng, FCSCEProfessor of Civil EngineeringProgram Director, MUN Shad

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Introduction• Prototype = an approximation of the product

along one or more dimensions of interest.• Alpha prototypes: Used to assess whether

product works as intended. Similar in material and geometry as production version, but made differently. E.g. machined instead of molded.

• Beta prototype: Used to assess reliability and to identify remaining bugs in the product. Given to customers for testing in the use environment. Parts are usually made with the actual production process and supplied by intended parts suppliers. Assembled by team rather than the manufacturer.

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Four Uses of Prototypes• Learning

– answering questions about performance or feasibility– e.g., proof-of-concept model

• Communication– demonstration of product for feedback– e.g., 3D physical models of style or function

• Integration– combination of sub-systems into system model– e.g., alpha or beta test models

• Milestones– goal for development team’s schedule– e.g., first testable hardware

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Physical vs. Analytical PrototypesPhysical Prototypes

• Tangible approximation of the product.

• May exhibit unmodelled behavior.

• Some behavior may be an artifact of the approximation.

• Often best for communication.

Analytical Prototypes

• Mathematical model of the product.

• Can only exhibit behavior arising from explicitly modelled phenomena. (However, behavior is not always anticipated.

• Some behavior may be an artifact of the analytical method.

• Often allow more experimental freedom than physical models.

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Focused vs. Comprehensive Prototypes

Focused Prototypes• Implement one or a few

attributes of the product.• Answer specific

questions about the product design.

• Generally several are required.

Comprehensive Prototypes• Implement many or all

attributes of the product.• Offer opportunities for

rigorous testing.• Often best for milestones

and integration.

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Comprehensive Prototypes

Cost of Comprehensive PrototypeHighLow

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One prototype may be used for verification.

Few or no comprehensiveprototypes are built.

Many comprehensiveprototypes are built.

Some comprehensiveprototypes build (and sold?).

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Prototyping Strategy• Use prototypes to reduce uncertainty.• Make models with a defined purpose.• Consider multiple forms of prototypes.• Choose the timing of prototype cycles.

–Many early models are used to validate concepts.

–Relatively few comprehensive models are necessary to test integration.

• Plan time to learn from prototype cycles.–Avoid the “hardware swamp”.

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Rapid Prototyping Methods

• Most of these methods are additive, rather than subtractive, processes.

• Build parts in layers based on CAD model.

• SLA=Stereolithography Apparatus• FDM=Fused Deposition Modelling• 3D Printing• LOM=Laminated Object Manufacturing• Others every year...

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3-D Printing

• Similar to a photocopier except that it prints in 3-D. – Check out http://www.fabathome.org

• Build it yourself 3-D printing device

– And http://www.cc.utah.edu/~asn8200/rapid.html

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Virtual Prototyping• 3D CAD models enable many kinds of

analysis:– Fit and assembly– Manufacturability– Form and style– Kinematics– Finite element analysis (stress, thermal)– Crash testing– more every year...

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BMW Virtual Crash Test

From: Scientific American, March 1999

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Traditional Prototyping Methods

• CNC machining• Rubber molding + urethane casting• Materials: wood, foam, plastics, etc.

• Model making requires special skills!

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Planning for Prototypes – 4 steps • Step 1: Define the purpose of the prototype.

– What is the prototype for? Is it for learning, communication, integration, or milestone?

• Step 2: Establish Level of Approximation.– Is an analytical prototype good enough or a physical prototype

necessary? Should it “works like” or just “looks like”?

• Step 3: Outline an Experimental Plan– Decide on what measurements have to be taken. What combinations

of configurations need to be tested? Test conditions?

• Step 4: Create a Schedule for Procurement, Construction, and Testing.– Prototyping is a sub-project within the overall product development

project. What parts need to be ordered, assembled? When must it be completed? How much time for testing?

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Summary• Prototypes are used for learning, communication,

integration, and milestones.

• Physical prototypes are best for communication, and comprehensive prototypes are best for integration and milestones.

• Analytical prototypes are generally more flexible than physical prototypes.

• Physical prototypes are required to detect unanticipated phenomena.

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Summary (Continue)

• 3-D computer modelling and free-form fabrication technologies have reduced the relative cost and time required to create prototypes.

• A 4-step method for planning prototype is:– Define the purpose of the prototype– Establish the level of approximation of the prototype.– Outline an experimental plan– Create a schedule for procurement, construction, and

testing.

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Thought Question

• Some companies have reportedly abandoned the practice of doing a customer test with the early prototypes of their products, preferring instead to go directly and quickly to market in order to observe the actual customer response. For what types of products and markets might this practice make sense?