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/(2 λ) 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

Apply this to 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

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