AIR-COUPLED ULTRASOUND

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ULTRASONIC TESTING OF FORESTRY PRODUCTS

• JAN STRYCEK

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AIR-COUPLED ULTRASOUND

• Challenges and History

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CHALLENGES OF AIR-COUPLED ULTRASONICS

• SPECIMEN 60 - 90 dB
• TRANSDUCERS 90 dB
• TOTAL REFLECTION LOSSES 180 dB

• REFLECTION LOSSES

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METHODS FOR AIR-COUPLED ULTRASONICS

• High Ultrasonic Pressure

• High Voltage Transducers
• Toneburst / Resonant Transducers

• High Sensitivity

• Low Noise Pre-Amplifiers
• Digital Filters

• Impedance Matching Layers

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TRANSDUCER CONFIGURATIONS
longitudinal wave
plate wave
shear wave
TWO SIDED INSPECTION
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TRANSDUCER CONFIGURATIONS
pseudo pulse-echo
plate wave
ONE SIDED INSPECTION
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DEVELOPMENT AND HISTORY

• Hp. Loertscher, B. Grandia, J. Strycek, W.G.
  Grandia
• Airscan Transducers, Technique and Applications.
• NDT net, Sept. 1996
• J. Strycek, W.A. Grandia, Hp. Loertscher
• Wave Modes Produced by Air-coupled Ultrasound.
• NDT net, May 1997
• J. Strycek, Hp. Loertscher
• Ultrasonic Air-coupled Inspection of Advanced
  Material.
• NDT net, Dec. 1999
• J. Strycek, Hp. Loertscher, et.al
• High Speed Large Area Scanning Using Air-coupled
  Ultrasound.
• 15th WCNDT 2000 Roma, NDT net 2000.

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DEVELOPMENT AND HISTORY

• Our First Instrument for Air-coupled Ultrasound
  1986

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AEROSPACE APPLICATIONS
ARIANE AND CHANDRA
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AEROSPACE APPLICATIONS

• F22 AND B-2

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AEROSPACE APPLICATIONS

• HIGH SPEED LARGE AREA SCANNER

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AEROSPACE APPLICATIONS

• HIGH SPEED LARGE AREA SCANNER

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INDUSTRIAL APPLICATIONS

• FOAM SCANNER

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SOLID LUMBER

• Eucalyptus and Radiata Pine

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RADIATA PINE

• Air-Coupled Ultrasonic C-scan

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EUCALYPTUS

• Air-Coupled Ultrasonic C-scan

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SOLID LUMBER CRACK DETECTOR

• 2 CHANNEL LINEAR SCANNER

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SOLID LUMBER CRACK DETECTOR

• High Speed Scanner

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16 CHANNEL CRACK DETECTOR

• SOLID EUCALYPTUS LUMBER

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16 CHANNEL CRACK DETECTOR

• TRANSDUCERAND INK MARKING

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BLOW DETECTORS

• FRAME WITH TRANSDUCERS

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BLOW DETECTOR

• 12 CHANNELS WITH THICKNESS GAGES

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BLOW DETECTOR

• CABINET, PNEUMATICS, ELECTRICAL BOX

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BLOW DETECTOR

• TESTING LVL BILLETS

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BLOW DETECTOR

• LVL 3.5 INCH THICK

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BLOW DETECTOR - FEATURES

• High Reproducibility

• High Signal to Noise Ratio
• Specifically adapted Noise Filters

• Suitable for very harsh environments

• Works close to Ripsaws
• Works close to Press

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BLOW DETECTOR - FEATURES

• High Product / Customer Adaptability

• Cluster defined Blows
• Auto-Calibration and Gain Control

• Low Maintenance

• Robust Ceramic Transducers
• All non contact sensors
• Laser Encoder
• Remote Maintenance

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BLOW DETECTOR - FEATURES
LVL 3.5 inches

• Standard and New Receiver Cards at min. Gain

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CLUSTERS

• TILE

Area for which the ultrasonic signal is tested
and marked as accepted or rejected Each channel
represents one column of tiles, typically 1 inch
long

• CLUSTER

Several rejected tiles can be defined to be
connected in various ways The size of a cluster
is defined by the number of connected tiles
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CLUSTERS
VARIOUS ENSEMBLES OF TILES
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CLUSTERS

• INK MARKING

Clusters which include the minimal number of
rejected and connected tiles are
rejected Rejected clusters are marked by ink on
the test part and entered as such into the
database
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BLOW DETECTOR - INSTRUMENT

• EACH CHANNEL 1 PULSER 1 RECEIVER

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BLOW DETECTOR - INSTRUMENT

• 16 CHANNELS

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BLOW DETECTOR - CABINET

• MONITOR,
• INSTRUMENT, PC,
• ELECTRICAL PANEL

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BLOW DETECTOR - CABINET

• CABINET COOLER

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BLOW DETECTOR - MONITOR

• BILLET MAP, MARKED CLUSTERS, THICKNESS

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BLOW DETECTOR USER INTERFACE

• ADMINISTRATION

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BLOW DETECTOR - CALIBRATION

• TESTING CALIBRATION STANDARD

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BLOW DETECTOR - CALIBRATION

• CALIBRATION STANDARD

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BLOW DETECTOR - CALIBRATION

• CALIBRATION STANDARD IN PLACE

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BLOW DETECTOR - CALIBRATION

• AUTOCALIBRATION ON CALIBRATION STANDARD

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BLOW DETECTOR - PNEUMATICS

• FOR AIR KNIVES
• AND MARKING

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BLOW DETECTOR - PERIPHERALS

• TRANSDUCERS WITH AIR KNIFE

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BLOW DETECTOR - PERIPHERALS

• AIR KNIFE AND SHEAR PLATES

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BLOW DETECTOR - PERIPHERALS

• DYE SPRAYS AND THICKNESS GAGES

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BLOW DETECTOR PERIPHERALS

• DYE SPRAYS AND THICKNESS GAGES

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BLOW DETECTOR PERIPHERALS

• LASER THICKNESS GAGES

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BLOW DETECTOR PERIPHERALS

• LASER THICKNESS GAGES

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BLOW DETECTOR PERIPHERALS

• LASER THICKNESS GAGES
• AND
• AIR KNIVES

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BLOW DETECTOR PERIPHERALS

• NON CONTACT LASER ENCODER

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BLOW DETECTOR PERIPHERALS

• INFRARED TEMPERATURE SENSOR

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BLOW DETECTOR RESULTS

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BLOW DETECTOR RESULTS

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BLOW DETECTOR INVESTIGATION

• TRANSDUCER SPACING

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R D

• PLYWOOD STANDARD FREQUENCY

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R D

• PLYWOOD MEDIUM FREQUENCY

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R D

• PLYWOOD HIGH FREQUENCY

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INSTRUMENTS

• 2 CHANNEL COMPACT CASE

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INSTRUMENTS

• 2 CHANNELS RACK MOUNT

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INSTRUMENTS

• 2 CHANNELS WITH PC
• AND ELECTRICAL CONTROLPANEL

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INSTRUMENTS

• AIRSTAR AIR-COUPLED TRANSDUCERS

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INSTRUMENTS

• HIGH SPEED DETECTORS

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INSTRUMENTS

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INSTRUMENTS

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INSTRUMENTS

• RECEIVER CARD

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INSTRUMENTS

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INSTRUMENTS

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INSTRUMENTS

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BLOW DETECTOR - SUMMARY

• UP TO 8 INCH THICK BILLETS
• ADJUSTABLE BLOW MARKING CLUSTERS
• NO IMPACTS FROM RIPSAWS OR PRESSES
• NON CONTACT LASER ENCODER
• LASER THICKNESS GAGES
• LARGE DATABASE FOR OFF-LINE ANALYSIS
• LOW MAINTENANCE
• REMOTE SOFTWARE MAINTENANCE

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CONTINUING EDUCATION
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OUR FUTURE