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NDE Engineering- Materials Durabilityby John C. Duke, Jr., Virginia Tech
• BackgroundBackground– Faculty Grant- Sustainable System Design
Other Needs identified– Other Needs identified• Overview of Materials Durability for NDE
E i iEngineering– Mechanical– Thermal– Chemical
Background• ASNT Faculty Grant
T hi M d l D l d•Teaching Module Developed
•Sustainable System Design
• Other needs were identified
f C fDeveloped by Virginia Tech Professor John C. Duke, Jr. with support of a Faculty Grant of the American Society for Nondestructive Testing, Inc.
Traditional Scheme w/Life Extension
Requirements• capabilities
Quality Assurance NDI+
Commissioning NDI to support minor maintenance
Planning
• capabilities• service life
Commissioning
&Design
Fabrication Operation/Service
C t i t Region not well definedC
ondi
tionConstraints
• cost• environment
Region not well defined so it was avoided with the original design
Design Life Life Extension
C
Note- The “Condition” plot is hypothetical since typically the condition is not being monitored.
Elements to support sustainable d i d idesign education
• Material Science– Properties– Modes of degradation
• Manufacturing Processes and d f tdefects
• Mechanical Behavior– Fatigue
Fracture
SensingEnergy
– Fracture– Creep
• NDE capabilities– Method capabilitiesEnergy – Method capabilities– Reliability (POD, POI, POF)– Interaction of probing energy
with material degradation
Stuff degradesStuff degrades
June 7, 2010 One Dead after gas pipeline explosion, Texas.
September 10, 2010 San Bruno gas line explosion kills four
February 10, 2011 Allentown, PA neighborhood rocked by gas line explosion
January 24 Massive Water main break closes I-495 MD/DC
BridgesBridges
Power plants
Planes
Critical Systems Beyond Their S i LifService Life
Materials begin to deteriorate as soon as th l d i ithey are placed in service.
• When does a reliablyWhen does a reliably detectable flaw appear?– Uniaxial tension– Cyclic loading
Sustained loading– Sustained loading
• The NDE Engineer needs to know what
7075-T6 Al
needs to know what form the deterioration will take, where it will occur and when!
Materials Scientist use methods to understand d t i ti th t d t k f NDT!deterioration that do not work for NDT!
Life: 1 1 million cyclesLife: 1.1 million cycles(N=0 failure )
50 μm50 μm
Service Induced DeteriorationService Induced Deterioration
• The NDE Engineer must understand how materials gdegrade, the type of damage modes this degradation causes how the synergistic effects of the environment?
Elements to support sustainable d i d idesign education
• Material Science– Properties– Modes of degradation
• Manufacturing Processes and d f tdefects
• Mechanical Behavior– Fatigue
Fracture
SensingEnergy
– Fracture– Creep
• NDE capabilities– Method capabilitiesEnergy – Method capabilities– Reliability (POD, POI, POF)– Interaction of probing energy
with material degradation
Modes of Service Induced Degradation
– MechanicalChemical– Chemical
– Thermal and radiation– CombinationsCombinations– References are limited
• “Materials Degradation and Its Control by Surface E i i ” b B t h l t l I i l C ll PEngineering,” by Batchelor et. al. Imperial College Press
• NASA NESC Academy- Materials Durability- Understanding Damage Modes, Piascik et al. NASA
Materials degradation- mechanicalMaterials degradation mechanical
• Mechanical causesMechanical causes– Wear
• Abrasion• Abrasion• Erosion
– Mechanical loading (quasi-static monotonic)Mechanical loading (quasi static monotonic)– Creep (sustained)– Fatigue (cyclic)– Fatigue (cyclic)– Fracture (when macroscopic cracks are
present)present)
Materials degradation- chemicalMaterials degradation chemical
• Corrosion of metalsCorrosion of metals• Oxidation reactions with oxygen, sulphur and
halogensg• Softening/embrittlement of wood and polymers• Corrosion of concrete and ceramicsCorrosion of concrete and ceramics• Dissolution of metals and ceramics in liquid
metals and inorganic salts and alkaliseta s a d o ga c sa ts a d a a s• Biochemical and biological modes
Materials degradation –Thermal and Radiation
• Thermal degradationThermal degradation– Elevated
Cryogenic temperatures– Cryogenic temperatures• Photochemical• High energy radiation
Materials degradation –synergistic effects
• Wear in a chemically active environmentWear in a chemically active environment– Corrosive-abrasive
Corrosive effects on fretting– Corrosive effects on fretting– Abrasive wear in liquid metals
C i f ti d f t• Corrosion fatigue and fracture• Corrosive embrittlement
Course or Database??Course or Database??
• Some haveSome have suggested that information of thisinformation of this sort should be placed in aplaced in a database for engineers to accessengineers to access.
Course or Database??Course or Database??
• Often the dataOften the data needed to make these decisionsthese decisions has not been collectedcollected.
• NDE Engineer often needs to dooften needs to do R&D not just selectionselection.
Materials Durability affects NDT th d l timethod selection
• For many NDI applications existing specifications determine what NDT method should be used to detect flaws of concern.
• WHEN NO SPECIFICATION EXISTS-– NDE Engineers must
• Identify what to measure• Identify types of data required to assess the affects
of the deteriorationof the deterioration• Identify or overcome limitations imposed by
constraints
The NDE Engineer must understand not only how NDT methods detect typical flawsonly how NDT methods detect typical flaws,
but also other forms of deterioration–
NDT methods using mechanical energy
• Ultrasound• Acoustic Emission• Acousto ultrasound• Acousto-ultrasound• Dial gage• Liquid Penetrant• Impact echo• Impulse response• Resonance
Modes of detecting degradation-l t ti NDTelectromagnetic NDT
• Magnetic particles• Magnetic flux leakage• Electrical resistance
Edd t• Eddy current• Infrared thermography• Microwave/radar• Microwave/radar• Radiography X&N• Optical Fiber gagesOptical Fiber gages• Resistance Strain gage• LVDT• Visual
Modes of detecting degradation-practical issues
Selection of appropriate nondestructive methods depends pp p pon:
• The nature of the degradation• The process for analyzing the characterization data
collected• Constraints associated with the specific application• Constraints associated with the specific application
– Access– Environment– Critical imperfection size– Etc.
Discipline Experts to support Sustainable design
Planning and design teams typically consult discipline g g yp y pexperts for in depth input regarding aspects of the design. Examples of discipline experts:
St t l l i– Structural analysis– Loads associated with operation– Materials– Materials
Since it is unrealistic to expect all design engineers to have strong background knowledge of materials degradation and the associated methods for detecting and tracking it a new discipline expert is needed- The NDE Engineer.
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