CONTENTS 



Page 



INTRODUCTION 1 



BACKGROUND 1 



DAMAGE 1 



MEASUREMENT ACCURACY REQUIREMENTS 2 



POTENTIAL TECHNIQUES 5 



Passive Sonic Testing 5 



Low Frequency Ultrasonics 6 



ASSESSMENT OF POTENTIAL TIMBER NDT TECHNIQUES 8 



Indirect Ultrasonic Analysis 8 



Impact Analysis 9 



X-ray Tomography 10 



Real Time X-ray Imaging 10 



Acoustic Emission 10 



Dielectric Measurement 11 



EVALUATION OF TIMBER INSPECTION TECHNIQUES 11 



TOMOGRAPHY 11 



INDIRECT ULTRASONIC TESTING 15 



Commercial Demonstration 15 



NCEL Ultrasonic Laboratory Testing 16 



NCEL Ultrasonic Field Testing 31 



IMPACT TESTING 35 



Theory 35 



Types of Impact Testing 36 



Equipment 37 



Laboratory Procedure 39 



Laboratory Test Results 41 



Impact Field Testing 43 



Field Test Results 47 



Summary of Impact Test Results 50 



CONCLUSIONS AND RECOMMENDATIONS 50 



REFERENCES ' 51 



