Chapter 6 Concept Evaluation

6.1 Introduction

6.2 Information representation in concept evaluation

6.3 Evaluation Based on Feasibility judgment It is not feasible. It is conditional It is worth considering Example: the bikeE suspension

6.4 Evaluation Based on Go/Nogo Screening

1.Are the critical parameters that control the function identified? 2.Are the safe operating latitude and sensitivity of the parameters known? 3.Have the failure modes been identified? 4.Can the technology be manufactured with known processes? 5.Does hardware exist that demonstrates positive answers to the preceding four question? 6.Is the technology controllable throughout the product’s life cycle?

6.5 Evaluation Based on A Basic Decision matrix

Example: Using the decision matrix:

6.6 Robust Decision Making Improve the method used to evaluate the alternatives (step 4 of decision matrix): Satisfaction= belief that an alternative meets the criteria Belief = knowledge + confidence Redefine: Belief=confidence placed on an alternative’s ability to meet a target set by a criterion, requirement, or specification, base on current knowledge.

Knowledge: A Measure of the information held by a decision-maker about a feature of an alternative defined by a criterion. One way to measure knowledge is to consider the words that are generally used to describe knowledge and compare them with the probability of having correct information. Another way of knowledge measurement: five points measurement

Two factors help keep the decision-maker self-assessment: Confidence: The first scale: The second scale: five point scale:

Belief=p(k)*p(c)+(1-p(k))*(1-p(c)) (8.1)

Eg. Elastomer eliminate the shocks from bumps:

6.7 Evaluation Based on an advanced Decision matrix Step 1: choose the criteria for comparison. Step 2: Develop Relative importance weightings Step 3: Select Relative Importance Weightings Step 4: Evaluate Alternatives. Step 5 Compute Satisfaction Satisfaction =Σ(belief*importance weighting)

Example:

CriteriaImportanceAlternative Linear guideVoice coil 1Can support the optical system Move fast Can correct the light abbreviation Can Do small adjustment Satisfaction6255 CD Driving system

Fred’s quotes:

6.8 Product Safety and Liability Product Safety 1.Design safety into product. 2.Add protection device. 3.Warning Product Liability

Product liability due to: 1.The product was defectively designed a. keep good records to show all that was considered during the design process. b. use commonly accepted standards when available c. Use state-of –the-art evaluation techniques for providing the quality of the design before it goes into production d. Follow rational design process.

2. The design did not include proper safety devices. 3. The design did not foresee possible alternative uses of the produce MIL-STD 882B