(Class 23) Evaluation

How is AHP used twice?

• First we use it to prioritize (weight) the key characteristics for design selection • Second we will use the AHP to help identify the best design from a set of alternatives

What is modeling like in conceptual design?

The emphasis is on geometrical modeling using multiple hand sketches supplemented with quick physical prototypes.

What is a weighted decision matrix?

A method of evaluating competing concepts by ranking the design criteria with weighting factors and scoring the degree to which each design concept meets the criterion.

What is a Pugh chart?

A particularly useful method for identifying the most promising design concepts among the alternatives generated.

What is an Ionic Model?

A physical model that looks like the real thing but is a scaled representation.

What is the Analytic Hierarchy Process (AHP)?

A problem solving methodology for making a choice from among a set of alternatives when the selection criteria represent multiple objectives, have a natural hierarchical structure, or consist of qualitative and quantitative measurements.

What is a Symbolic model?

Abstractions of the important quantifiable components of a physical system that use symbols to represent properties of the real system.

What is the AHP Process for Determining Weights?

1) Complete criteria comparison matrix [C] using 1-9 ratings described in Table 7.8. 2) Normalize the matrix [C] to give [NormC]. 3) Average row values. This is the criteria weight vector {W}. 4) Perform a consistency check on [C] as described in Table 7.10.

What models do we use in conceptual design?

Both iconic and symbolic.

When are proof-of-concepts prototypes typically made?

By the end of conceptual design.

What are systematic methods for determining weight factors?

Direct Assignment, Objective Tree, and Analytic Hierarchy Process (AHP)

What are the three categories of models?

Ionic, Analog, and Symbolic

How does a Pugh Chart work?

It is a relative comparison technique that compares each concept relative to a reference or datum concept and for each criterion determines whether the concept in question is better than, poorer than, or about the same as the reference concept.

How is AHP used?

It's used throughout a number of fields in which the selection criteria used for evaluating competing solutions do not have exact, calculable outcomes.

What is a simulation model and why are they created?

It's when we exercise the model by inputting a series of values to determine the behavior of the proposed design under a stated set of conditions. These models are created to imitate the behavior of a part or system under a particular set of conditions.

What is modeling like in embodiment design?

Major emphasis is given to establishing shape, dimensions, and tolerances, the level of detail in mathematical and physical models increases.

What is an Analog Model?

Models that are based on an analogy, or similarity, between different physical phenomena like using electricity flow to simulate heat flow.

What is modeling like in parametric design?

More complex mathematical modeling may be conducted to optimize some product characteristic or to improve its robustness. Also a proof-of process prototype will be tested using the exact materials and processes that will be used to manufacture the product.