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Susan Lee‐[email protected] [email protected] Silverman [email protected]
Integrating Simulation into your Reliability Program
During this Webcast you will…Receive an overview of simulation elements of a solid reliability program and learn how to… • Combine simulation into your reliability program and improve results
• Take advantage of Accelerated life testing and Simulations benefits
• Save time and money
Agenda• Introduction• Current Status and Issues• Simulation Overview
– Multi‐Body Dynamics ‐MBD – Finite Element Analysis – FEA
• Reliability Testing– HALT– ALT
• Wind Turbine Case Study• Summary• Special Promotion• Q & A
Results of Registration Questions
Q1: What Simulation Tools Do you Currently Use?– Finite Element Analysis (FEA)‐21%– Monte Carlo Analysis or Probabilistic Design ‐22%– Tolerance and Worst Case Analysis‐7%– Don’t Know/No Answer 49%
Results of Registration Questions
Q2: What Reliability Tests Do You Currently Perform?– Highly Accelerated Life Testing (HALT) or (ALT) 48%– Reliability Demonstration Testing (RDT) or Reliability Growth Testing (RGT) 22%
– Don’t Know/No Answer 29%
Results of Registration Questions
Q3: Do You Currently Integrate Any Simulation Tools With Your Reliability Testing Program?
– All the Time‐5%– Occasionally‐23%– Never/Maybe Once‐39%– Don’t Know/No Answer‐30%
Tribal Overview‐What is Tribal?
Engineering Services Provider
Engineering Services Provider Software DeveloperSoftware Developer
Engineering Software Integrator
Engineering Software Integrator Technology Marketing PartnerTechnology Marketing Partner
Software ResellerSoftware Reseller
Ops Overview
Today’s Speakers
Dr. Kim ParnellParnell Engineering & ConsultingMechanical Design and Reliability Expert
Mike SilvermanOps A La Carte Managing Member
So why are we really here?• $100 or $1,000,000• Better Ideas• More Reliable Products• Larger Market Share
Introduction to Simulation Tools
Multi‐Body Dynamics (MBD)
• Rigid members connected through joints & contact
• More complexity with embedded flexible components
• Provides loads• Ex: MSC MD‐Adams
Finite Element Analysis (FEA)• Deformable bodies discretized into elements
• Detailed material models including elastic, plasticity, elastomeric
• Interactions defined by contact or constraints
• Detailed stress & disp• Ex: MSC.Nastran, Marc
Finite Element Analysis (FEA)
• FEA is generally applicable for analyses such as stress, thermal, vibration, and dynamic cases– Create a geometric model; subdivide into
elements to create a finite element mesh– Specify material properties for all components– Apply loads and boundary conditions: thermal,
pressure, deadweight, wave loads, etc.• Linear analysis typically used for design; nonlinear
analysis frequently required for failure investigation
FEA Concepts• Linear Analysis
– Small Deflection & Small Strain– Elastic material
• Nonlinear Analysis– Large Deflection &/or Large Strain– Nonlinear material
• Elastic/plastic• Rubber & Polymers• Temperature dependent properties
– Contact– Shock & impact
• Multi‐physics: thermal, fluid, electromagnetic, etc.
FEA Load Types• Static or Dynamic• Mechanical• Thermal• Multi‐Physics
Polling Question
Simulation & Testing
• Simulation and physical testing are complementary• A comprehensive program needs to include both components
• With judicious experimental validation, FEA & MBD may be used to reduce the amount of physical testing that is needed and shorten the design cycle
• MBD loads to FEA for detailed analysis
FEA Simulation ToolsFEA simulation can• Be a cost effective way to evaluate design choices.• Provide insight into how varying parameters affects the design
outcome.• Simulate expensive processes where downtime is
unacceptable.• Help establish the critical relationship between design
parameters and process parameters.
Reliability Tests After Simulation• Accelerated tests can be performed after simulation to validate the simulation models– HALT– ALT
HALT is best techniques
ALT is best technique
Failure Rate
HALT vs. ALTHighly Accelerated Life Testing (HALT) is a great reliability technique to use for finding failure mechanisms due to insufficient product margins.
Accelerated Life Testing (ALT) is a great technique to use for finding failure mechanisms due to wearout.
Highly Accelerated Life Testing
HALT, How It Works
Fundamental Technological Limit
HALT, Why It WorksClassic S‐N Diagram(stress vs. number of cycles)
N0
S1
S2
N1N2
Point at which failures become non-relevant
S0
Product Operational
Specs
Stress
Upper Oper. Limit
Upper Destruct
Limit
Lower Destruct
Limit
LowerOper. Limit
HALT Margin Improvement Process
Product Operational
Specs
Stress
Upper Oper. Limit
Upper Destruct
Limit
Lower Destruct
Limit
LowerOper. Limit
Operating Margin
Destruct Margin
HALT Margin Improvement Process
Accelerated Life Testing
ALTReliaSoft Weibull++ 7 - www.ReliaSoft.com
Probability - Lognormal
Folio1\Data 2: m=12.2726, s=0.2212, r=0.9834Folio1\Data 1: m=5.2258, s=0.2355, r=0.9876
Time, (t)
Unr
elia
bilit
y, F
(t)
100.000 1000000.0001000.000 10000.000 100000.0001.000
5.000
10.000
50.000
99.000 Probability-Lognormal
Folio1\Data 1Lognormal-2PRRX SRM MED FMF=10/S=0
Data PointsProbability Line
Folio1\Data 2Lognormal-2PRRX SRM MED FMF=11/S=0
Data PointsProbability Line
Fred SchenkelbergConsulting9/19/200611:47:45 AM
Acceleration Factor
HALT vs ALTHALT ALT
OBJECTIVESDiscover product weaknesses and design marginsTESTING REQUIREMENTSDetailed product knowledge to determine how to stress productACCELERATION MODELNone
OBJECTIVESDetermine life of dominant wear-out componentTESTING REQUIREMENTSDetermine test parameters:1. Types of stresses2. Number of samples3. Length of the test4. Confidence level5. Beta (β)ACCELERATION MODELExamples of models:1. Weibull2. Arrhenius3. Coffin-Manson
Simulation with HALT and ALTIf a simulation model uncovers a failure mechanism which has a sudden failure point, then HALT is the best reliability test to validate the simulation model.
If a simulation model uncovers a failure mechanism which has a gradual wear, then ALT is the best reliability test to validate the simulation model.
Simulation with ReliabilitySimulation provides value for Reliability by:• Predicting behavior under test conditions• Quantifying critical parameters• Assessing parameter/load sensitivity• Identifying potential failure modes
Simulation with ReliabilitySimulation makes Reliability testing more effective by:• Identifying primary failure mechanisms • Identifying stress(es) to accelerate this mechanism• Indicating how much stress is acceptable
Accelerated tests increase stressors or loads like:• Applied force• Applied temperature• Loading rate• Others
Polling Question
Wind Turbine ReliabilityApplication
Wind Turbine Trends & ChallengesTrends• Increase of power generated per WT• Result: Growing sizeEngineering challenges• Reliability vs. reduction of “Top Head” mass
E.g. relative gear box weight down, failure rates up Growing size increasing structural elasticity/flexibility
• Acoustic performance (noise reduction)• Maximum efficiency and aerodynamic performance
Also at low wind speeds• Offshore expansion
1980 1985 1990 1995 2000 2005 2010
160140120100806040200
50kW300kW
500kW600kW
1.5MW
2.5MW
6.5MW
10MW?Ro
tor D
iameter
Wind Turbine Load Examples• Dynamic• Asymmetric
Wind Loads
Responses
Blade flapwisebending
Tower bending
Blade edgewise bending
Drivetrain torsionNacelle tilt
Tower torsion
• Understanding system responses• Design for 20 year life expectancy
Off shore: Additional Wave Loads
Wind Turbine Simulation Overview• Broad range of requirements
• Accuracy for reliability/fatigue predictions– Motion analysis with multiple flex bodies– Consider system responses
Aero‐dynamic loads
Power‐Train Modeling Noise Predictions
System Performance
Rotor Blade Modeling
Fatigue Predictions
Structural Integrity
Loads: Wind Turbine Example
Wind Scenarios
System-WideLoads Prediction
Tower, etc.
Dynamic Loads
Gearbox
Bearings
Rotor Blades
Hub
Stress Histories
Sub-System and Component Design and Analysis
Fatigue Life Prediction
Loads: Wind Turbine Example• Gearbox Loads
– Apply wind loading event to wind turbine model
– Predict shaft loads– Evaluate alternate shaft
design– Stress recovery on high‐speed
shaft – Output loads for detailed
component FEA
High-speed shaft
Gear modeling• Idealized constraints
– The most simple approach– Add gear ratio between axles– No back lash
• Simplified gear contact– Analytical contact calculation, based on true gear
geometry– Very fast to simulate– Spur gears, helical gears, bevel gears, planetary gears– Takes back lash into account– Load investigation of shafts and bearings– Study of gear rattle and general system behavior due to
lash and losses in gears
Increased accuracy
Gear modeling• Detailed 3D contact
– Generates accurate gear geometry in Adams
– 3D contact between rigid gears– Load investigation of gears, shafts and
bearings– Study of gear rattle and general system
behavior due to lash and losses in gears– Friction in tooth contact
• Flexible gear contact– Uses Nastran as pre‐processor to generate
accurate data for flexible tooth contact in Adams
– High level of detail, takes local tooth flexibility into account
Increased accuracy
Loads: Wind Turbine Example
Wind Scenarios
Dynamic Loads
High Accuracy Here
• Accuracy of FEA and fatigue results entirely depends on input loads
= Reliable Results Here
Fatigue Life Prediction
Stress Histories
HALT and ALT on Wind Turbine
Perform HALT on the Turbine Inverter
Perform ALT on the Turbine Gears/Motors
HALT on Wind Turbine Inverter
Looking for failures due to‐ Lightning‐ Grid spikes‐ Temperature extremes‐ Component aging
ALT on Wind Turbine Gear/MotorLooking for failures due to loads we determined during simulation such as wind loading.
Based on the simulation models, instead of doing system level reliability tests, we set up component ALT’s to focus on:‐ Wear on Bearings and Gearbox‐ Fatigue of Gearbox and Blades
Combining Simulation with ALT
1. Review loads and stress history2. Review fatigue life prediction model3. Determine environmental stresses that
accelerate fatigue4. Develop acceleration model5. Perform accelerated test6. Compare results to simulation model
Summary• The benefits of Test with Simulation
– Using simulation and accelerated testing allows you to try more concepts sooner
– Create products that will perform better and last longer, reducing warranty costs
– Allow you to get to market sooner and capture a larger chunk of the revenue
• Improves results– Reduces time– Reduces costs
Polling Question
Special offer for webinar participants:
• Free 2 hour Reliability Consultation or Simulation process Audit
• Offer expires on 11/30/11
Dan J. AbirTribal Engineering LLC+1 310-429-2887 mobile+1 562-508-4404 office+1 562-481-3780 fax
Mike SilvermanOps A La Carte LLC
+1 408-472-3889 mobile+1 408-654-0499x204 office
+1 408-654-0497 [email protected]
www.opsalacarte.com
Q&A
Thank you for your timeLooking forward to working with you in 2011‐
2012Dan J. Abir
Tribal Engineering LLC+1 310-429-2887 mobile+1 562-508-4404 office+1 562-481-3780 fax
Mike SilvermanOps A La Carte LLC
+1 408-472-3889 mobile+1 408-654-0499x204 office
+1 408-654-0497 [email protected]
www.opsalacarte.com
