Optimization

Abstract

Specifications for particulate composites focus on the property combination required to deliver the required performance. Engineers focus on features (such as tolerances, strength, hardness, and toughness), while users focus on benefits (long lasting, scratch resistant, resists corrosion). For example, a coffee cup should have a low thermal conductivity as a feature. The benefit is an ability to hold hot coffee without burning your hand. Design transforms consumer perceived benefits into specific engineering features against which design optimization occurs. Sales and marketing appropriately focus on the benefits derived from included features, while engineering focuses on the properties and specifications:

$$ \mathrm{benefits}\ \leftrightarrow\ \mathrm{features}\ \leftrightarrow\ \mathrm{properties}\ \leftrightarrow\ \mathrm{specifications}. $$

Optimization is frequently mentioned in advertising. Automotive companies tout “optimal cornering” or “optimum ride comfort”. These messages are telling us about design compromises. Although not explicitly stated, a trade-off is made to settle on a perceived balance. Hidden in these statements are many assumptions and constraints. Unfortunately optimization against multiple objectives is difficult. What is optimal for one application is not necessarily optimal for another. Two-wheel drive transmissions are better for fuel economy, but four-wheel drive is better for winter driving. This is a case of different situations with different “optimal” designs—one for fuel economy and one for inclement weather. A compromise of three-wheel drive is rejected since a more realistic solution is part time four-wheel drive, switching from two-wheel drive in dry conditions to four-wheel drive in snow.