realtime nondestructive evaluation in the future frank c. beall university of california at berkeley
TRANSCRIPT
REALTIME NONDESTRUCTIVE EVALUATION IN THE FUTURE
Frank C. Beall
University of California at Berkeley
FORECASTING
Those who have knowledge don’t predict; those who predict don’t have knowledge
Lao Tzu, 6th Century BC Chinese Poet
Past predictions (personal)
• FPRS Plenary presentation (1988)
• NDT of Wood Symposium paper (1990)
• NDT of Wood Symposium keynote (1996)
Future of NDE of Wood and Wood-based Materials (1996)
• Megatrends
• Limitations and barriers
• Opportunities
1996 Limitations and Barriers
• Low cost of wood• Fragmentation of the industry• Lack of critical mass for research• Past failures and overselling• Limitations of technologies• Harsh processing conditions• Inherent and processing defects• Variation in materials• Negative impact of moisture• Adhesive role in integrity
Future Opportunities
• Assessment of service deterioration• Surface roughness• Duration of load and creep• Treatment levels and gradients• Stress grading• Fire performance• Adhesive curing and bond quality• Curing and integrity of coatings/finishes• Accelerated aging
Assumptions for 2100—Raw Material
• 80% of structural wood is from plantations• Juvenile wood is an insignificant factor for
fast-growth softwoods• Carbon credits substantially increase the
value (and cost) of wood• Some plantations produce genetically-
altered wood resistant to biodeterioration• Adhesive cost is relatively low
Assumptions for 2100—Processing
• Most processes are continuous
• Most structural material is reconstituted
• Structural grading is a minor issue
• Adhesive bonding has greater efficiency
• Non-conventional bonding for some laminates
Assumptions for 2100—Products
• Structural materials include LVL, SCL, OSB/PW, etc
• Solid wood for special appearance only
• Increased resin content for reconstituted materials
• Adhesively-bonded materials have minimal creep
Assumptions for 2100—Older Structures
– Not engineered– Substantially stick-built– Have biodeterioration issues
Assumptions for 2100—New Structures
– Engineered (including residential)– Prefab/unitized construction– Fasteners for easy deconstruction– Have minimal biodeterioration issues
Roles of NDE--1
• Monitoring tree growth/stress/defects
• Verification testing of structural material and assemblies for all key mechanical properties
• Providing in-service monitoring for degradation/stress development
Roles of NDE--2
• Closed-loop feedback control for processes– Drying monitoring and control– Cutting tool performance– Adhesive curing
• Laboratory/service testing for accelerated aging
NDE Technologies
• Future technologies are currently available
• Advances will be in software and miniaturization
• Scanners with integrated technologies will be both on-line and fully portable
Means of accomplishing role
• Processing: noncontacting gauges for measuring properties on line
• Service: smart embedded sensors with indefinite lifetime (relative to lifetime of material)