ENGR 100 Lecture Notes - Lecture 13: Overhead Projector, Traffic Bridge, Reverse Engineering
Engr 100
Intro to Engineering
Spring 2019
Problem Definition: Identifying Constraints
● Identifying constraints (section 5.1)
● Objectives – constraints tree (section 5.2)
● Constraints are limits/restrictions on the design’s behaviors
● They can be expressed in a binary (yes-no) fashion
● They are “lines” that cannot be crossed
Differences between expressing and objective and a constraint
Objective
● A ladder design should meet the requirements under OHSA
Constraint
● A ladder design must meet the requirements under OHSA
● Too many constraints may limit options available in the early stage of the design process
○ For example: deflection in ladder steps in limited to 0.05”
○ Consider limits/restrictions on the product/design as a whole rather that parts of it
○ Be cautious of treating the same feature as an objective and a constraint at the
same time
■ For example: low cost as an objective, cost cannot exceed certain dollar
amount as a constraint
○ Be cautious of “double constraining”
■ F0r example”
● Must meet requirements under OHSA as a constraint
● Must not slip as a constraint
○ Keep the one that’s more stringent and/or wider in scope
Problem Definition: Establishing Functions (Chapter 6)
→ Establishing functions (sec 6.1)
→ Tools for establishing functions (sec 6.2)
→ Function-means tree (section 6.2.4)
Establishing Functions
→ Objectives and constraints do not have a clear “cut”
Document Summary
Constraints are limits/restrictions on the design"s behaviors. They are lines that cannot be crossed. They can be expressed in a binary (yes-no) fashion. Differences between expressing and objective and a constraint. A ladder design should meet the requirements under ohsa. A ladder design must meet the requirements under ohsa. Too many constraints may limit options available in the early stage of the design process. For example: deflection in ladder steps in limited to 0. 05 . Consider limits/restrictions on the product/design as a whole rather that parts of it. Be cautious of treating the same feature as an objective and a constraint at the same time. For example: low cost as an objective, cost cannot exceed certain dollar amount as a constraint. Must meet requirements under ohsa as a constraint. Keep the one that"s more stringent and/or wider in scope. Objectives and constraints do not have a clear cut .
