ULTRASONIC TESTING OF

FORESTRY PRODUCTS

JAN STRYCEK

AIR-COUPLED ULTRASOUND

Challenges and History

CHALLENGES OF AIR-COUPLED ULTRASONICS

REFLECTION LOSSES

♦ SPECIMEN : 60 - 90 dB

♦ TRANSDUCERS: 90 dB

♦ TOTAL REFLECTION LOSSES: 180 dB

METHODS FOR AIR-COUPLED ULTRASONICS

♦ High Ultrasonic Pressure

♦ Impedance Matching Layers

♦ High Voltage Transducers

♦ Toneburst/ Resonant Transducers

♦ Low Noise Pre-Amplifiers

♦ Digital Filters

♦ High Sensitivity

TRANSDUCER CONFIGURATIONS

TWO SIDED INSPECTION

longitudinalwave

shearwave

platewave

TRANSDUCER CONFIGURATIONS

ONE SIDED INSPECTION

pseudo pulse-echo plate wave

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.

DEVELOPMENT AND HISTORY

Our First Instrument for Air-coupled Ultrasound 1986

AEROSPACE APPLICATIONS

ARIANE AND CHANDRA

AEROSPACE APPLICATIONS

F22 AND B-2

AEROSPACE APPLICATIONS

HIGH SPEED LARGE AREA SCANNER

AEROSPACE APPLICATIONS

HIGH SPEED LARGE AREA SCANNER

INDUSTRIAL APPLICATIONS

FOAM SCANNER

SOLID LUMBER

Eucalyptus and Radiata Pine

RADIATA PINE

Air-Coupled Ultrasonic C-scan

EUCALYPTUS

Air-Coupled Ultrasonic C-scan

SOLID LUMBER CRACK DETECTOR

2 CHANNEL LINEAR

SCANNER

SOLID LUMBER CRACK DETECTOR

High speed scanner

16 CHANNEL CRACK DETECTOR

SOLID EUCALYPTUS LUMBER

16 CHANNEL CRACK DETECTOR

TRANSDUCER AND INK

MARKING

BLOW DETECTORS

FRAME WITH TRANSDUCERS

BLOW DETECTOR

12 CHANNELS WITH THICKNESS GAUGES

BLOW DETECTOR

CABINET, PNEUMATICS, ELECTRICAL BOX

BLOW DETECTOR

TESTING LVL BILLETS

BLOW DETECTOR

LVL 3.5 INCH THICK

BLOW DETECTOR

LVL 16-CHANNEL

BLOW DETECTOR

LVL 16-CHANNEL

BLOW DETECTOR

PLYWOOD 32-CHANNEL

BLOW DETECTOR

PLYWOOD 32-CHANNEL

BLOW DETECTOR - FEATURES

♦ High Reproducibility

♦ High Signal to Noise Ratio

♦ Specifically adapted Noise Filters

♦ Works close to Ripsaws

♦ Works close to Press

♦ Suitable for very harsh environments

BLOW DETECTOR - FEATURES

♦ Low Maintenance

♦ User friendly interface

♦ Robust Ceramic Transducers

♦ Non contact Laser Encoders

♦ Remote maintenance

♦ Cluster defined Blows

♦ Auto-Calibration and Gain Control

BLOW DETECTOR - FEATURES

Standard and New Receiver Cards at min. Gain

LVL 3.5 inches

CLUSTERS

♦ TILE

♦ CLUSTER

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

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

CLUSTERS

VARIOUS ENSEMBLES OF TILES

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 into the database

BLOW DETECTOR - INSTRUMENT

EACH CHANNEL: 1 PULSER + 1 RECEIVER

BLOW DETECTOR - CABINET

MONITOR, INSTRUMENT, PC,

ELECTRICAL PANEL

BLOW DETECTOR - CABINET

CABINET COOLER

BLOW DETECTOR - MONITOR

BILLET MAP, MARKED CLUSTERS, THICKNESS

BLOW DETECTOR - SOFTWARE

ADMINISTRATION

BLOW DETECTOR – CALIBRATION

TESTING CALIBRATION STANDARD

BLOW DETECTOR - CALIBRATION

CALIBRATION STANDARD

BLOW DETECTOR – CALIBRATION

CALIBRATION STANDARD IN PLACE

BLOW DETECTOR - CALIBRATION

ON CALIBRATION STANDARD

BLOW DETECTOR - PNEUMATICS

FOR AIR KNIVES

AND MARKING

BLOW DETECTOR – PERIPHERALS

TRANSDUCERS WITH AIR KNIFE

BLOW DETECTOR - PERIPHERALS

AIR KNIFE AND SHEAR PLATES

BLOW DETECTOR – PERIPHERALS

DYE SPRAYS AND THICKNESS GAGE

BLOW DETECTOR – PERIPHERALS

DYE SPRAYS AND THICKNESS GAGE

BLOW DETECTOR – PERIPHERALS

LASER THICKNESS GAUGES

BLOW DETECTOR – PERIPHERALS

LASER THICKNESS

GAUGES

BLOW DETECTOR – PERIPHERALS

LASER THICKNESS

GAUGESAND

AIR KNIVES

BLOW DETECTOR – PERIPHERALS

NON CONTACT LASER ENCODER

BLOW DETECTOR – PERIPHERALS

INFRARED TEMPERATURE SENSOR

BLOW DETECTOR – RESULTS

BLOW DETECTOR – RESULTS

BLOW DETECTOR

INVESTIGATING TRANSDUCER SPACING

R & D

PLYWOOD STANDARD FREQUENCY

R & D

PLY WOOD MEDIUM FREQUENCY

R & D

PLYWOOD HIGH FREQUENCY

INSTRUMENTS