Non-Contact Velocity Measurement of Japanese Cedar Columns Using Air-Coupled Ultrasonics

Masumi Hasegawa,Misaki Mori,Junji Matsumura

doi:10.4236/wjet.2016.41005

Masumi Hasegawa, Misaki Mori + Show 1 more

Open Access

https://doi.org/10.4236/wjet.2016.41005

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Abstract

The ultrasonic wave velocities of Japanese cedar columns were measured using a non-contact method. An air-coupled ultrasonic wave was propagated through the axial and lateral directions of wood. The velocities in the axial direction (VL) showed the minimum values around the pith. The averaged VL increased from 3600 m/s towards the outside of measurement area and attained the maximum values (=4010 m/s). The velocities in the lateral direction (VRT ) showed no tendency among measurement points. The averaged VRT was 1450 m/s. The velocities obtained using the non-contact method showed a significant positive relationship with those obtained using the contact method. The averaged ratio of VL to VRT was measured to be approximately 2.2 to 2.8. These ratios were in agreement with those from a contact method. These findings suggest that it is possible to measure the velocity in Japanese cedar columns with the non-contact method by using air-coupled ultrasonics.

Highlights

Japanese cedar is a popular tree cultivated in Japan
It was possible to evaluate the surviving strength using the ultrasonic velocity in the longitudinal direction
At the edge of Ultrasonic wave velocities in the axial and lateral directions on Japanese cedar columns can be measured with a non-contact method by using air-coupled ultrasonics

Summary

Introduction

Japanese cedar is a popular tree cultivated in Japan. The distribution area of Japanese cedar is the largest among planted forestry species, accounting for 26% of the country’s total. (2016) Non-Contact Velocity Measurement of Japanese Cedar Columns Using Air-Coupled Ultrasonics. It was possible to evaluate the surviving strength using the ultrasonic velocity in the longitudinal direction. Air-coupled ultrasonic waves have been studied for use in the quality control of sawing timber and the maintenance of posts and beams in a wooden construction [5]-[9]. This technique makes it possible to evaluate the current state of the wood without contacting the wood. We tried to measure the ultrasonic wave velocity in Japanese cedar columns with a non-contact method. The velocities obtained using the non-contact method were compared with those obtained using the contact method

Materials

Ultrasonic Measurement

Receiving Waveform for Air-Coupled Ultrasonics

Ultrasonic Wave Velocities in the Axial and Lateral Directions

Method

Conclusion