Engineering design procedures and cost considerations

ergo

with a good theory, model, or formula

predictions

is theory valid for reality

cannot trust output of theory without its validation for various conditions of use

powerful combination

theory and data

signal detection

concludes differences by being correct or incorrect

scientist vs engineer

engineers settle for practical answers, trade off multiple criteria without any satisfactory trade off values

five steps of engineering design procedure

DAMES

define the problem broadly

detail-free, discuss problem first, include criteria, get input early and often

analyze in detail

define statement with more details, identify limits, include variability in users and components

what should the design achieve

cost accounting, scheduling, tradeoffs of criteria

what are the needs of the design users

productivity, style, comfort, accuracy, esthetics

what are the design limits

constraints and restrictions in fabrication and assembly techniques and sequence

include variability in components

consider not only main activities but also the get ready and put away activities

what are the characteristics of the population using the design

variability in users

who is affected by the design

operators, supervisors, other departments, maintenance

make machine adjust to person

fit task to worker

make search of solution space

don’t eliminate alternative designs too early, don’t be limited by imagined constraints, optimum solution not feasible solution, more than one solution

benchmarking

if you stand on someone’s shoulders, you can see farther than that person can

evaluate alternatives

trade off multiple criteria, calculate benefit per cost

specify and sell solution

accept a partial solution rather than nothing, follow up on design’s implementation and if it reduces problem

pareto principle

80% consequences come from 20% causes

don’t waste time on small problems

insignificant 80% and mighty few 20%

identify products with maximum

cost, storage requirements, profit, energy consumption, emissions