Post on 13-Jan-2016
description
Product Development
Chapter 6
Hardware & Software Techniques Block diagram the system (Visio) Redundancy
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
MIL-HDBK-217
Where to get λ? Google MIL-HDBK-217…
For example, see www.sqconline.com/reliability/index.html
Try wire wound resistor in a missile…
Component Selection Considerations Component reliability
Vendor assessment (Hx, failure, etc.) Vendor audit (check facility) Vendor evaluation (inspect incoming) Vendor qualification (on-list?)
Component history military & reliability groups government info bases
Safety (FMEA, etc.)
Hardware & Software Techniques ctd. Component Derating
Practice of limiting the stresses 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 Techniques ctd. Safety Margin
=(mean safety factor) - 1
=(mean strength/mean stress) - 1 Elevator – safety margin~2 Medical devices – Fries - .5 and up.
Load Protection Environment (see 112) Product misuse Design for variation (6 sigma)
Experimental Design
Statistical Approach Effective approach for
multivariable situations Taguachi method
Design Process System design Parameter design Tolerance design
Two types of variables Control factors Noise factors
Apply this to design
Software Development and Engineering Management Planning for safety
(FDA!) Planning for risk
assessment Planning for method
Waterfall Incremental delivery Spiral Cleanroom Code and fix, …
Software Development and Engineering Management Choose design method
Top-down Data driven OOP
Language (Assembler/C++/Qbasic etc.) Testing Requirements Hazard Analysis!!! (FDA)
Software Development and Engineering Management
Requirements traceability (FDA)
Software architecture design Well defined modules (logical) Other vendor – standalone Single purpose modules Cohesion & coupling
Implementation (coding) Integration
Structured/Unstructured Design Techniques Computer/database assisted:
Ideation - ‘Innovation Workbench’
TRIZ Techoptimizer Others…
Example done in class, another in text
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
Reverse Engineering and Redesign Opportunities increase with age of technology Disassembly of product and inventory and
analysis of parts Allows for the potential update or modification
of the parts with technological advances Can drastically increase productivity or
effectiveness in a dated product
Design Techniques
Very structured approach Pahl and Beitz, Engineering Design Design method contains 8 distinct steps
Semistructured Wilcox, Engineering Design for Electrical
Engineers Ulrich and Eppinger Product Design and
Development
The Clean-Room Approach To Reverse-Engineering: “One person or group takes a device apart and
describes what it does in as much detail as possible at a higher level of abstraction than the specific code. That description is then given to another group or person who has absolutely no knowledge of the specific device in question. This second party then builds a new device based on the description. The end result is a new device that works identically to the original but was created without any possibility of specifically copying the original. “
-Mathew Schwartz