scholarly journals Inspection and Evaluation of Decay Damage in Japanese Cedar Trees Through Nondestructive Techniques

2016 ◽  
Vol 42 (3) ◽  
Author(s):  
Cheng-Jung Lin ◽  
Chia-Ju Lee ◽  
Ming-Jer Tsai
Keyword(s):  
Wave Velocity ◽  
Stress Wave ◽  
Japanese Cedar ◽  
Stress Wave Velocity ◽  
Nondestructive Techniques ◽  
Standard Values ◽  
Wood Deterioration ◽  
The Difference ◽  
Non Destructive ◽  
Evaluation Parameters

The purpose of this study was to investigate the standard values of living, undamaged Japanese cedar (Cryptomeria japonica) trees through different nondestructive techniques. This study also detects the stress wave velocity (V) and tomogram (VT), and resolves corresponding V maps of Japanese cedar trees with and without decay damage for tree risk assessment. A visual tree inspection form, with seven categories of tree damage, is proposed for tree hazard assessment. Different nondestructive evaluation parameters can serve as an index for diagnosing standard values (with or without decay). The VT and corresponding stress wave velocity maps of decay-damaged and damaged Japanese cedar trees can detect the general location and area of wood deterioration. The transversal acoustic velocity values increased with increasing diameter in undamaged trees, and the difference between the maximum and minimum V value of the trunks in undamaged trees fell within a range of constants. The proposed approach can be combined with other non-destructive techniques to better examine and confirm the situation of trees.

Propagation velocity model of stress waves in larch wood (Larix gmelinii) three-dimensional space with different moisture contents

BioResources ◽  
2020 ◽  
Vol 15 (3) ◽  
pp. 6680-6695
Author(s):  
Xiwen Wei ◽  
Liping Sun ◽  
Hongjv Zhou ◽  
Yang Yang ◽  
Yifan Wang ◽  
...  
Keyword(s):  
Moisture Content ◽  
Wave Velocity ◽  
Stress Wave ◽  
Propagation Velocity ◽  
Dimensional Space ◽  
Three Dimensional ◽  
Stress Waves ◽  
Moisture Contents ◽  
Direction Angle ◽  
Stress Wave Velocity

Based on the effects of stress wave propagation in larch (Larix gmelinii) wood, the propagation mechanism of stress wave was explored, and a theoretical model of the propagation velocity of stress waves in the three-dimensional space of wood was developed. The cross and longitudinal propagation velocities of stress wave were measured in larch wood under different moisture contents (46% to 87%, 56% to 96%, 20% to 62%, and 11% to 30%) in a laboratory setting. The relationships between the propagation velocity of stress waves and the direction angle or chord angle with different moisture contents were analyzed, and the three-dimensional regression models among four parameters were established. The analysis results indicated that under the same moisture content, stress wave velocity increased as the direction angle increased and decreased as chord angle increased, and the radial velocity was the largest. Under different moisture contents, stress wave velocity gradually decreased as moisture content increased, and the stress wave velocity was more noticeably affected by moisture content when moisture content was below the fiber saturation point (FSP, 30%). The nonlinear regression models of the direction angle, chord angle, moisture content, and the propagation velocity of stress wave fit the experiment data well (R2 ≥ 0.97).

STRESS WAVE VELOCITY AND CRACK SYSTEM OF A MEDIUM *

1974 ◽  
Vol 22 (4) ◽  
pp. 710-721
Author(s):  
V. SCHENK ◽  
Z. SCHENKOVA
Keyword(s):  
Wave Velocity ◽  
Stress Wave ◽  
Crack System ◽  
Stress Wave Velocity

scholarly journals Influence of moisture content on estimating Young’s modulus of full-scale timber using stress wave velocity

2017 ◽  
Vol 63 (3) ◽  
pp. 225-235 ◽  
Author(s):  
Mariko Yamasaki ◽  
Chika Tsuzuki ◽  
Yasutoshi Sasaki ◽  
Yuji Onishi
Keyword(s):  
Moisture Content ◽  
Young’S Modulus ◽  
Wave Velocity ◽  
Stress Wave ◽  
Young's Modulus ◽  
Full Scale ◽  
Stress Wave Velocity

Stress Wave Velocities in Bovine Patellar Tendon

1998 ◽  
Vol 120 (3) ◽  
pp. 321-326 ◽  
Author(s):  
J. J. Crisco ◽  
T. C. Dunn ◽  
R. D. McGovern
Keyword(s):  
Elastic Modulus ◽  
Strain Rate ◽  
Wave Velocity ◽  
Patellar Tendon ◽  
Stress Wave ◽  
Stress Waves ◽  
Force Transmission ◽  
Static Testing ◽  
Wave Velocities ◽  
Stress Wave Velocity

The velocity of longitudinal stress waves in an elastic body is given by the square root of the ratio of its elastic modulus to its density. In tendinous and ligamentous tissue, the elastic modulus increases with strain and with strain rate. Therefore, it was postulated that stress wave velocity would also increase with increasing strain and strain rate. The purpose of this study was to determine the velocity of stress waves in tendinous tissue as a function of strain and to compare these values to those predicted using the elastic modulus derived from quasi-static testing. Five bovine patellar tendons were harvested and potted as bone–tendon–bone specimens. Quasi-static mechanical properties were determined in tension at a deformation rate of 100 mm/s. Impact loading was employed to determine wave velocity at various strain levels, achieved by preloading the tendon. Following impact, there was a measurable delay in force transmission across the specimen and this delay decreased with increasing tendon strain. The wave velocities at tendon strains of 0.0075, 0.015, and 0.0225 were determined to be 260 ± 52 m/s, 360 ± 71 m/s, and 461 ± 94 m/s, respectively. These velocities were significantly (p < 0.01) faster than those predicted using elastic moduli derived from the quasi-static tests by 52, 45, and 41 percent, respectively. This study has documented that stress wave velocity in patellar tendon increases with increasing strain and is underestimated with a modulus estimated from quasi-static testing.

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