This is the first of a series of four webinars being put on by Ops A La Carte, ASTR, and ASQ
Reliability Division
Each webinar will also be presented as a full 2 hour tutorial at our ASTR Workshop Oct 9-11 th , San Diego.
Abstracts for presentations are due Apr 30.
Accelerated Stress Tes-ng and Reliability Workshop
October 9-‐11, 2013 San Diego, CA
Accelerating Reliability into the 21 st Century
Keynote Presenter Day 1: Vice Admiral Walter Massenburg
Keynote Presenter Day 2: Alain Bensoussan, Thales Avionics
CALL FOR PRESENTATIONS: We are now Accep,ng Abstracts.
Email to: don.gerstle@gmail.com
.
Guidelines on website www.ieee-‐astr.org
For more details, click here to join our LinkedIn Group:
IEEE/CPMT Workshop on Accelerated Stress TesIng and Reliability
BY
Lou LaVallee, Senior Reliability Consultant, Ops A La Carte
• Introduction
• Robust Design
• Questions
5 min
45 min
10 min
Lou LaVallee, CRE, Senior Reliability/Quality Consultant
• Lou has over 30 years of experience as a quality and reliability engineer.
• Lou has a strong technical background in physics, engineering materials/
polymer science and a solid grounding in consumer product design,
development, and delivery.
• His comprehensive background includes electronic films , robust design, modeling & analy,cs, cri,cal parameter management, six sigma DFSS & DMAIC, op,miza,on of product quality/reliability, experimental design, reliability test methods, and design tool development and deployment.
• He successfully managed systems engineering groups for development of ink jet print heads at Xerox Corp.
• Mr. LaVallee has held other technical management posi,ons in manufacturing technology, engineering excellence (trained several thousand engineers worldwide). He also managed the robust engineering center at Xerox for 10 years, managed a high volume prin,ng product quality and reliability group, and worked extensively with high volume prin,ng product service organiza,on.
• He has strong valida,on experience of design quality and reliability through product reviews and customer interac,on
• Mr. LaVallee holds a Bachelor of Science degree in Physics (BS), and an MS from the
University of Rochester in materials/polymer engineering.
• He holds several U.S. patents involving fluidics and engineering design processes.
• Mr. LaVallee is an ASQ cer,fied reliability engineer. Lou works in the upstate New York area.
Upcoming Reliability Webinars
Title: Prognos-cs as a Tool for Reliable Systems
Author: Doug Goodman of Ridgetop Group
Date: May 1, 2013, 11:30am PDT haps://www2.gotomee,ng.com/register/657949994
Location: Webinar
Electronics are the keystone to successful deployment of complex systems (50+ MPUs in an automobile). Large MTBF and Statistical Process Control and Centering methods are not sufficient alone for reliability due to “outliers” (e.g. Toyota Prius,
Deepwater Horizon Drilling Rig, Boeing 787). Ridgetop technology exists to pinpoint degrading systems before they fail; supporting operational readiness objectives and costsaving Prognostics/Health Management (PHM) and Condition
Based Maintenance (CBM) initiatives.
Title: Accelerated Reliability Growth Tes-ng
Author: Milena Krasich of Raytheon IDS
Date: June 12, 2013, 8:30am PDT haps://www2.gotomee,ng.com/register/283538530
Location: Webinar
This webinar will cover the following:
1) Reliability Growth Test overview/objec,ves
2) Explain tradi,onal Reliability Growth test methodology
3) Show shortcomings of the tradi,onal methods
4) Show principles of the Physics of Failure test methodology
5) Show how the Reliability growth test based on PoF is constructed
6) Show how the expected stresses are applied and accelerated
7) Show reliability measures
8) Show advantages of the test PoF test design and accelera,on
9) Show achieved considerable test cost reduc,on.
•
th
• (see Ops site for past webinar topics/content at hap://www.opsalacarte.com/Pages/resources/resources_techpapers.htm#webinars
• We run these webinars once a month
• We partner with other companies
• We partner with socie,es
(IEEE, ASQ, and others for broader reach)
• This webinar is brought to you by Ops, ASTR, and ASQ
Reliability Division.
• All past webinars are archived on our site www.opsalacarte.com/Reliapedia.
• For this webinar we have signed up
•
•
BY
Lou LaVallee, Senior Reliability Consultant, Ops A La Carte
• Robust Design
• Questions
45 min
10 min
Robust or Just Strong & Dangerous
Polling Ques,on 1:
For engineering ac,vi,es in hardware development, when do you typically start to act on design robustness and reliability concerns.
a) When field problems and customer complaints begin.
b) When system and subsystem DVT tests indicates hardware
failures
c) When technology readiness tests indicate hardware failures
d) When concepts and architecture are being selected
Abstract for full tutorial
Robust Design (RD) Methodology is discussed for hardware development. Comparison is made with reliability engineering (RE) tools and practices. Differences and similarities are presented.
Proximity to ideal function for robust design is presented and compared to physics of failure and other reliability modeling and prediction approaches. Measurement selection is shown to strongly differentiates RD and reliability engineering methods When and how to get the most from each methodology is outlined. Pitfalls for each set of practices are also covered. (This presentation is a preview of a larger presentation to be delivered @ ASTR conference, October,
San Diego)
Choice of Many Design Methods & Interfaces
AXD
TRIZ
QFD
DFR
PUGH
VA/VE
DOE
ROBUST
DESIGN
CP/CS MNGMT
DFSS 6
σ
≠
Quality
Loss
S/N
P-diagram
Tolerance Design transformability
Expt Layout
Lean
6
σ
Ideal Function
Response Tuning
Flexibility
Robust Design
Reuse
RSM
Online QC
Parameter design
DOE
Engineering
Scienc e
Simulation
Math Models
Planning
ADT
Life Tests
Root cause
Analysis
RCM
Maintainability
ALT
Physics of Failure
FTA
CBM
Reliability
Warranty
FMECA
Life prediction
Tes,ng
HALT/HASS
Redundancy
Availability
Generic Function RBD
Robust Design Definition
A systematic engineering based methodology
(which is part of the Quality Engineering Process) that develops and manufactures high reliability products at low cost with reduced delivery cycle.
The goal of robust design is to improve R&D productivity and reduce variation while maintaining low cost before shipment and minimal loss to society after shipment.
Dr Taguchi , who died this year, always used to say “lets find a way to improve reliability without measuring reliability”
Defini-ons
Robustness is …
“ The ability to transform input to output as closely to ideal function as possible. Proximity to ideal function is highly desirable. A design is more robust if ratio of useful part to harmful part [of input energy ] is large. A design is more robust if it operates close to ideal, even when exposed to various noise factors, including time”
Reliability is …
“The ability of a system, subsystem, assembly, or component to perform its required functions under stated conditions for a specified period of time”
Variation is the Enemy of Robustness & Reliability
• Search for root cause & eliminate it
• Screen out defectives (scrap and rework, HASS)
• Feedback/feed forward control systems
• Tighten tolerances (control, noise, signal factors)
• Add a subsystem to balance the problem
• Calibration & adjustment
• Robust design (Parameter design & RSM)
• Change the concept to better one
• Turn off or reduce the power , component derating
• Correct design mistakes (e.g. putting diodes in backwards, … )
6
σ
Fundamental Concept
Y=f(X)+e
Ø Response Y
Ø Dependent
Ø Output
Ø Effect
Ø Symptom
Ø Monitor
Ø X
1
, X
2
, … ,X
N
Ø Independent
Ø Input
Ø Cause
Ø Problem
Ø Control
In reliability engineering for example , Y is the continuous stochastic variable (time-to-failure) and f(x) is the failure mechanism, or mechanistic model . In RD, smooth transformability between input and output is most important.
Reliability Growth
Historically, the reliability growth process has been treated as, a reactive approach to growing reliability based on failures “discovered” and fixed during testing or, most unfortunately, once a system/product has been delivered to a customer. This reactive approach ignores opportunities to grow reliability during the earliest design phases of a system or product.
Delayed fix jump
New build jump
Cumulative test time
Robustness
Growth
Factors Can be changed today
S/N time
Factors Can be changed in
1 week
S/N
Factors Can be changed in
2 weeks
S/N time
Competition at launch
Robustness gains time
Progression of Robustness to Ideal Function Development
LSL USL
Zero Defects
C pk
Static S/N
Dynamic S/N Ratio
When a product’s performance deviates from target, its quality is considered inferior. Such deviations in performance cause losses to the user of the product, and in varying degrees to the rest of society.
Polling ques,on 2
Have you ever used robust design methods for hardware development ?
a) Yes, it is a part of our group’s engineering culture
b) Yes, but mostly on high risk issues
c) Yes but mostly on low risk issues
d) No we do not see any advantage over tradi,onal build-‐test-‐fix methods
Taxonomy of Design Function --P Diagram
Input signals
M i
Main Function
Y=f(x)+ ε
Useful
Output
Harmful
Output
Noise
Factors
Control
Factors
Force F
Simple Metal Helical Compression Spring
Force vs Displacement ideal Func,on
0,0
Ideally, all points fall on dashed line passing through origin.
Noise factors add varia,on
Varia,on may exceed tolerable limits
Simple Helical Spring Design
Y =
M +
Input signal
X
Main Function
F=-kX+e
Useful
Output F
Zero Point Proportional Ideal Function
Forc e
N
Ideal (Hooke’s Law)
Actual with Noise Factor effect
0,0 Displacement X (mm)
Response
Transformability & Robustness Improvement
Before and After Improvement
Response
0,0
N
1
N
1
N
2
N
2
M signal
0,0 M signal
Minimizing the effects of noise factors on transformation of input to output . Improves robustness & reliability. Sensitivity increase (tuning) can be used for power reduction, which also improves reliability. Tuning to different spring constants enabled
Typical Failure Modes and Failure
Causes for Mechanical Springs
TYPE OF SPRING/
STRESS CONDITION
FAILURE MODES FAILURE CAUSES
- Static (constant deflection or constant load)
- Load loss
- Creep
-Compression Set
- Yielding
- Parameter change
- Hydrogen embrittlement
- Cyclic (10,000 cycles or more during the life of the spring)
- Fracture
- Damaged spring end
- Fatigue failure
- Buckling
- Surging
- Complex stress change as a function of time
- Corrosive atmosphere
- Misalignment
- Excessive stress range of reverse stress **
- Cycling temperature
…
- Dynamic (intermittent occurrences of a load surge)
- Fracture
- Fatigue failure
- Surface defects
- Excessive stress range of reverse stress
- Resonance surging
If data remain close to ideal func-on, even under predicted stressful usage condi-ons, and there is no way for failure to occur without affec-ng func-onal varia-on of the data, then moving closer to ideal func-on is highly desirable.
For example, spring fracture, if it did occur would drama-cally change force-‐deflec-on (F-‐D) data and inflate data varia-on. Similarly, for yielding, F-‐D results would change and inflate the varia-on. Other failure modes would follow in most cases.
Reliability Improvement with Robust Design early in design cycle
1. Power reduc-on by enabling changes in sensi,vity
β
to input power without increasing sensi,vity to noise
σ
. (Higher signal-‐to-‐noise ra,o)
Higher
β
with lower
σ .
2. Reducing varia-on of useful and harmful output. Prevent ing overlap of stress PDF with strength limits, and keeping distribu,on away from failure limits
3.
Focus on energy related response op-miza-on , not dysfunc,on.
Reduced complexity of design
Improvements in Product/
Process Varia,on
Best
4.
A product produced off target is inferior to one produced close to target , and is more likely to have later reliability issues due to driq and degrada,on.
Beaer
Good
5.
Develop robustness against noise factor ‘,me’ – not a life test
LFL
Target
UFL
Input signal
M
Main Function
Y=f(x)+ ε
Useful
Output
Main function is to transform input signal to useful output.
Energy transformation takes many different forms, (but usually not 2 nd order polynomials, as in RSM)
Common Ideal Function Forms:
Y = M + ε
Y
Y = β M + ε
Y
=
=
[
β
1 −
+ β
* ( M * e − β M
− M
+ ε
* ) ]
M + ε
Y
Y
− Y
0
= α
= β ( M
+ β M
− M
0
) + ε
+ ε
Y = β M x
+ ε
Y
Y
=
=
β M
1
M
2
β
M
1
M
2
+ ε
+ ε
Y
Y Y
=
=
α
( R
+ β
+ jX )( R −
( M − M )
+ jX
ε
) ) + ε
...
Y
Y
M
Automotive Brake Example
One Signal Factor
Ideal
Y
Observe d Ideal Function=Y= β M
Y=Torque Generated
M=Master cylinder
Pressure
M
Ideal
Two Signal Factors
Y Observe d
Ideal Function=Y= β MM*
Y=Torque Generated
M=Master cylinder
Pressure
M*= Pad surface area
MM*
MM*
Braking Ideal Function=Y= β MM *
M*=Pad surface area
Control factors: pressure,
Raw Materials
Raw material prep process parameters
Pad manufacturing process parameters
Dimensions, …
Symptoms & side effects (ideally zero) :
M=master cylinder
Brake Noise
Part Breakage
Wear
Vibration,
squealing … (GM Working on this one for many years!)
Noise factors:
Temperature/humidity variability
Deterioration and aging, wheel number
Brake fluid type and amount
Manufacturing variability
Raw materials lot-to-lot & within lot
Variability in process parameter settings
Measurement System Ideal Function
Y=
β
M+e
M=true value of measurand
Y=measured value
Auto Steering Ideal function
Y=
β
M+e
M=steering wheel angle
Y=Turning radius
Communication system ideal function
Y=M+e
M=signal sent
Y=signal received
Cantilever beam Ideal Function
Y= β M/M*+e
M=Load
M*=Cross sectional area
Fuel Pump Ideal Function
Y=
β
M
Y=Fuel volumetric flow rate
M=IV/P current, voltage,& backpressure
Polling ques,on 3
Has your organiza,on ever used both robust design methods and design for reliability in the same program?
a) Yes, we have used both
b) No, only used RD
c) No, only used DFR
d) No, used neither
Comparison
Robust Design
Focus on design transfer functions, ideal function development
Engineering focus, empirical models,
Generic Models , statistics
Optimization of functions with verification testing requirement
Orthogonal array testing, Design of
Experiments planning
Multitude of Control, noise, and signal factor combinations for reducing sensitivity to noise and amplifying sensitivity to signal
Actively change design parameters to improve insensitivity to noise factors, and sensitivity to signal factors
Reliability
Focus on design dysfunction, failure modes, failure times, mechanisms of failure
Mechanistic understanding, science oriented approach
Characterization of natural phenomena with root cause analysis and countermeasures
Life tests, accelerated life tests, highly accelerated tests, accelerated degradation & survival tests,
Single factor testing, some multifactor testing .
Fixed design with noise factors, acceleration factors
Design-Build-test-fix cycles for reliability growth
Robust Design
Failure inspection only with verification testing of improved functions
Reliability
Design out failure mechanisms.
Reduce variation in product strength. Reduce the effect of usage/environment.
Simplify design complexity for reliability improvement. Reuse reliable hardware
Synergy with axiomatic design methodology including ideal design, and simpler design
Hierarchy of limits including functional limit, spec limit, control limit, adjustment limits
Measurement system and response selection paramount
Ideal function development for energy relate measures
Compound noise factors largest stress. Reduce variability to noise factors by interaction between noise and control factors, signal and noise factor.
Identify & Increase design margins, HALT &
HASS testing to expose design weaknesses.
Temperature & vibration stressors predominate
Time-to-failure quantitative measurements supported by analytic methods
Fitting distributions to stochastic failure time data
Time compression by stress application
HALT & HASS highly accelerated testing to reveal design vulnerabilities and expand margins. Root cause exploration and mitigation
Summary
• RD methods and Reliability methods both have functionality at their core. RD methods attempt to optimize the designs toward ideal function, diverting energy from creating problems and dysfunction.
Reliability methods attempt to minimize dysfunction through mechanistic understand and mitigation of the root causes for problems.
• RD methods actively change design parameters to efficiently and cost effectively explore viable design space. Reliability methods subject the designs to stresses, accelerating stresses, and even highly accelerated stresses, [to improve time and cost of testing].
First principle physical models are considered where available to predict stability.
• Both RE and RD methods have strong merits, and learning when and how to apply each is a great advantage to product engineering teams.
a) Yes and I plan on submitng an abstract by
April 30 b) Yes I will come but will not be submitng an abstract c) Maybe, I will check it out d) No because I have no ,me e) No because I have no travel budget
a) Would you consider joining by webinar if it were free ? b) Would you consider joining by webinar if it was < $50 ? c) Would you consider joining by webinar if it was $50-‐100 ? d) Would you consider joining by webinar if it was $100-‐150 ?
a) Would you want streaming video of audience and presenter ? b) Would you want webconference only ? c) Would you want both?
st
haps://www2.gotomee,ng.com/register/657949994
s
Ops A La Carte, LLC
Mike Silverman
Managing Partner
(408) 472-‐3889 mikes@opsalacarte.com
www.opsalacarte.com