Stress Wave Velocities in Bovine Patellar Tendon

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

BioResources ◽

10.15376/biores.15.3.6680-6695 ◽

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).

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Assessing the Bearing Capacity of Backfills by Stress Wave Velocity and Cone Penetration Resistance

Infrastructure Sustainability Through New Developments in Material, Design, Construction, Maintenance, and Testing of Pavements - Sustainable Civil Infrastructures ◽

10.1007/978-3-030-79644-0_9 ◽

2021 ◽

pp. 109-116

Author(s):

Jiunnren Lai ◽

Ming-Hong Lai ◽

Chiung-Fen Cheng

Keyword(s):

Bearing Capacity ◽

Wave Velocity ◽

Stress Wave ◽

Penetration Resistance ◽

Cone Penetration ◽

Stress Wave Velocity ◽

Cone Penetration Resistance

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Stress wave velocity measured in intact pig lungs with cross-spectral analysis

Journal of Applied Physiology ◽

10.1152/jappl.1994.76.2.565 ◽

1994 ◽

Vol 76 (2) ◽

pp. 565-571 ◽

Cited By ~ 12

Author(s):

M. Jahed ◽

S. J. Lai-Fook

Keyword(s):

Spectral Analysis ◽

Stress Wave ◽

Intratracheal Instillation ◽

Weight Ratio ◽

Transpulmonary Pressure ◽

Dry Weight ◽

Stress Waves ◽

Wave Velocities ◽

Esophageal Balloon

In anesthetized pigs (25–40 kg), we generated stress waves in the lung by rapid deflation of an esophageal balloon. The source distortion was measured by an accelerometer (1 g wt) bonded to the balloon. Stress waves were detected by three accelerometers bonded to intercostal muscle and to the skin near midchest. The distance between the source and chest receivers were measured radiographically. Cross-spectral analysis was used to calculate transit times. We measured stress wave velocities at airway pressures of 0 (functional residual capacity) and 25 cmH2O. Transpulmonary pressure (Ptp) was measured by an esophageal balloon. In vivo, stress wave velocities increased from 291 +/- 117 (SD) cm/s at 3.0 +/- 0.9 cmH2O Ptp to 573 +/- 73 cm/s at 13.8 +/- 3.5 cmH2O Ptp (n = 6). These velocities agreed with longitudinal wave velocities measured in isolated sheep lungs and predictions based on the elastic moduli of lung parenchyma. Post-mortem edema was induced by intratracheal instillation of 200 ml of saline, resulting in a wet-to-dry weight ratio of 7.7 +/- 1.4 (n = 5). At 15 cmH2O Ptp, stress wave velocities decreased from 565 +/- 155 cm/s before edema to 445 +/- 130 cm/s after edema. This decrease correlated well with predictions based on the increased lung density, as dictated by elasticity theory.

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Variation in tree growth characteristics, stress-wave velocity, and Pilodyn penetration of 24-year-old teak (Tectona grandis) trees originating in 21 seed provenances planted in Indonesia

Journal of Wood Science ◽

10.1007/s10086-013-1368-9 ◽

2013 ◽

Vol 59 (6) ◽

pp. 512-516 ◽

Cited By ~ 3

Author(s):

Fanny Hidayati ◽

Futoshi Ishiguri ◽

Kazuya Iizuka ◽

Kazuko Makino ◽

Yuya Takashima ◽

...

Keyword(s):

Wave Velocity ◽

Stress Wave ◽

Tree Growth ◽

Tectona Grandis ◽

Growth Characteristics ◽

Stress Wave Velocity ◽

Pilodyn Penetration

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An Image-Based Impact Test for the High Strain Rate Tensile Properties of Brittle Materials

EPJ Web of Conferences ◽

10.1051/epjconf/201818302042 ◽

2018 ◽

Vol 183 ◽

pp. 02042

Author(s):

Lloyd Fletcher ◽

Fabrice Pierron

Keyword(s):

Tensile Strength ◽

Elastic Modulus ◽

High Strain Rate ◽

Strain Rate ◽

Stress Wave ◽

High Strain ◽

Brittle Materials ◽

Test Method ◽

Strain Rates ◽

High Strain Rates

Testing ceramics at high strain rates presents many experimental diffsiculties due to the brittle nature of the material being tested. When using a split Hopkinson pressure bar (SHPB) for high strain rate testing, adequate time is required for stress wave effects to dampen out. For brittle materials, with small strains to failure, it is difficult to satisfy this constraint. Because of this limitation, there are minimal data (if any) available on the stiffness and tensile strength of ceramics at high strain rates. Recently, a new image-based inertial impact (IBII) test method has shown promise for analysing the high strain rate behaviour of brittle materials. This test method uses a reflected compressive stress wave to generate tensile stress and failure in an impacted specimen. Throughout the propagation of the stress wave, full-field displacement measurements are taken, from which strain and acceleration fields are derived. The acceleration fields are then used to reconstruct stress information and identify the material properties. The aim of this study is to apply the IBII test methodology to analyse the stiffness and strength of ceramics at high strain rates. The results show that it is possible to identify the elastic modulus and tensile strength of tungsten carbide at strain rates on the order of 1000 s-1. For a tungsten carbide with 13% cobalt binder the elastic modulus was identified as 516 GPa and the strength was 1400 MPa. Future applications concern boron carbide and sapphire, for which limited data exist in high rate tension.

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