Product Development R. Fries Chapter 6 Product Development R. Fries

Hardware & Software Techniques Block diagram the system (Visio) Consider Redundancy – active or standby Active: failure of one parallel component - the second still works Standby: failure of component – replacement MTBF =mean time between failures = 1/λ Active MTBF=3/(2λ) Standby MTBF=2/λ

Hardware/Software Cont. Consider component reliability Vendor assessment (Hx, failure, etc.) Vendor audit (check facility) Vendor evaluation (inspect incoming) Vendor qualification (on-list?) Consider component history – military & reliability groups, government info bases Consider safety (FMEA, etc.)

Hardware/Software Cont. Consider component derating Use 2 watt R in 1 watt situation, decrease failure rate >30% (T, humidity, P, V, I, friction, vibration) Usage ratio = max stress/stress rating (.5-.9) Goal is reliability! Pacemaker example

Hardware/Software Cont. Safety margin must be considered Safety margin=safety factor-1 =(mean strength/mean stress)-1 Elevator – safety margin~2 Medical devices – Fries - .5 and up. Load protection must be considered Environment must be considered (see 112) Product misuse – consider Design for variation (6 sigma?)

Software Engineering Management Planning for safety (FDA!) Planning for risk assessment Planning for method Waterfall Incremental delivery Spiral Cleanroom Code and fix, …

Software Engineering Management Choose design method Top-down Data driven OOP Language (Assembler/C++/Qbasic?etc.) Testing Requirements Hazard Analysis!!! (FDA)

Software Engineering Management Requirements traceability (FDA) Software architecture design Well defined modules (logical) Other vendor – standalone Single purpose modules Cohesion & coupling Naming Integration

Structured/Unstructured Design Techniques Computer/database assisted: Ideation International IWB TRIZ Techoptimizer Others… Example done in class, another in text

Structured/Unstructured Design Techniques Axiomatic Design Nam Suh, MIT Requirements, design parameters, process variables, customer needs = vectors Try to solve, disassociate functional requirements and design parameters Highly mathematical Acclaro Software

Structured/Unstructured Design Techniques Structured, step by step, 8 steps Pahl and Beitz Semistructured – Wilcox, Engineering Design for Electrical Engineers, Ulrich and Eppinger Product Design and Development

Structured/Unstructured Design Techniques Reverse engineering Redesign Etc.