scholarly journals Linear and nonlinear ultrasound fields formed by planar sources with random pressure distributions

2015 ◽  
Vol 36 (3) ◽  
pp. 208-215 ◽  
Author(s):  
Tomoo Kamakura ◽  
Hideyuki Nomura ◽  
Gregory T. Clement
Keyword(s):  
Nonlinear Ultrasound ◽  
Pressure Distributions ◽  
Linear And Nonlinear

Linear and nonlinear ultrasound simulations using the discontinuous Galerkin method

2018 ◽  
Vol 143 (4) ◽  
pp. 2438-2448 ◽  
Author(s):  
James F. Kelly ◽  
Simone Marras ◽  
Xiaofeng Zhao ◽  
Robert J. McGough
Keyword(s):  
Galerkin Method ◽  
Discontinuous Galerkin ◽  
Discontinuous Galerkin Method ◽  
Nonlinear Ultrasound ◽  
Linear And Nonlinear

Waveless Free-Surface Pressure Distributions

1985 ◽  
Vol 29 (03) ◽  
pp. 151-158
Author(s):  
J.-M. Vanden Broeck ◽  
E. O. Tuck
Keyword(s):  
Free Surface ◽  
Surface Pressure ◽  
Free Surface Flows ◽  
Two Dimensional ◽  
Surface Flows ◽  
Pressure Distributions ◽  
Potential Applications ◽  
Linear And Nonlinear ◽  
Uniform Stream

Linear and nonlinear studies are made of two-dimensional free-surface flows under gravity, in which a disturbance is caused to an otherwise uniform stream by a distribution of pressure over the free surface. In general, such a disturbance creates a system of trailing waves. There are special disturbances that do not, however, and some categories of such disturbances are discussed here. This work has potential applications to design of splashless ship bows.

IWSHM 2017: Structural health monitoring of the loosening in a multi-bolt structure using linear and modulated nonlinear ultrasound acoustic moments approach

2018 ◽  
Vol 17 (6) ◽  
pp. 1349-1364 ◽  
Author(s):  
Gian Piero Malfense Fierro ◽  
Michele Meo
Keyword(s):  
Structural Health Monitoring ◽  
Health Monitoring ◽  
Correlation Method ◽  
Detection Accuracy ◽  
Monitoring Method ◽  
Nonlinear Ultrasound ◽  
Structural Health ◽  
Repair Costs ◽  
Linear And Nonlinear ◽  
Bolt Loosening

Applying highly accurate clamp loads in bolted joints during assembly and inspections is essential for estimation of the integrity of a joint and reduction of disastrous failures. Non-destructive post-assembly and in-service inspections of joint integrity are vital and significantly reduce maintenance and associated repair costs. Therefore, a bolt control technology able to provide precise direct measurement of bolt loosening state during assembly and in-service is needed. This work proposes an in situ structural health monitoring approach based on the evaluation of linear and nonlinear modulated acoustic moments for the assessment of the loosened state of bolts in a multi-bolted structure. Linear and nonlinear ultrasound methods’ detection accuracy and robustness can be highly dependent on correct frequency selection. The structural health monitoring method suggested uses material resonance and a frequency sweep methodology coupled with a cross-correlation method which identifies significant frequency pairs or higher harmonics used to determine bolt loosening. The proposed approach was tested and successfully validated on three different bolted structures showing that loosening of the structure can be identified accurately with a limited number of transducers. The solution provides a qualitative solution, which identifies degradation in the torque of a bolted structure; furthermore, the developed structural health monitoring method has the potential to become an automatic tool for monitoring the loosened state of bolts in critical complex structural components.

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