A numerical study of defect detection in a plaster dome ceiling using structural acoustics

2009 ◽  
Vol 126 (1) ◽  
pp. 140-148 ◽  
Author(s):  
J. A. Bucaro ◽  
A. J. Romano ◽  
N. Valdivia ◽  
B. H. Houston ◽  
S. Dey
Keyword(s):  
Defect Detection ◽  
Numerical Study ◽  
Structural Acoustics

Predictions of defect detection performance of air-coupled ultrasonic rail inspection system

2017 ◽  
Vol 17 (3) ◽  
pp. 684-705 ◽  
Author(s):  
Stefano Mariani ◽  
Francesco Lanza di Scalea
Keyword(s):  
Field Test ◽  
Defect Detection ◽  
Guided Waves ◽  
Numerical Study ◽  
Detection Performance ◽  
Probability Of Detection ◽  
Inspection System ◽  
False Alarms ◽  
Operating Variables ◽  
Rail Inspection

A rail inspection system based on ultrasonic guided waves and non-contact (air-coupled) ultrasound transduction is under development at the University of California at San Diego. The system targets defects in the rail head that are major causes of train accidents. Because of the high acoustic impedance mismatch between air and steel, the non-contact system poses severe challenges and questions on the defect detection performance. This article presents an extensive numerical study, conducted with a local interaction simulation approach, to model the ultrasound propagation and interaction with defects in the proposed system. This model was used to predict the expected detection performance of the system in the presence of various defects of different sizes and positions, and at varying levels of signal-to-noise ratios. When possible, operating variables for the model were chosen consistently with the field test of an experimental prototype that was conducted in 2014. The defect detection performance was evaluated through the computation of receiver operating characteristic curves in terms of probability of detection versus probability of false alarms. The study indicates that despite the challenges of non-contact probing of the rail, quite satisfactory inspection performance can be expected for a variety of defect types, sizes, and positions. Beyond the specific cases examined in this article, this numerical framework can also be used in the future to examine a larger variety of field test conditions.

3D numerical study for defect detection with nonlinear elastic wave spectroscopy and time reversal techniques

2008 ◽  
Vol 123 (5) ◽  
pp. 3832-3832 ◽  
Author(s):  
Thomas Goursolle ◽  
Samuel Callé ◽  
Serge Dos Santos ◽  
Olivier Bou Matar
Keyword(s):  
Elastic Wave ◽  
Defect Detection ◽  
Time Reversal ◽  
Numerical Study ◽  
Nonlinear Elastic ◽  
Nonlinear Elastic Wave

Numerical study of the low-frequency atomic dynamics in a Lennard-Jones glass

1998 ◽  
Vol 77 (2) ◽  
pp. 473-484 ◽  
Author(s):  
M. Sampoli, P. Benassi, R. Dell'Anna,
Keyword(s):  
Numerical Study ◽  
Low Frequency ◽  
Lennard Jones

Experimental and numerical study of the response of steel sheet Hopkinson specimens

2006 ◽  
Vol 134 ◽  
pp. 541-546 ◽  
Author(s):  
P. Verleysen ◽  
J. Degrieck
Keyword(s):  
Steel Sheet ◽  
Numerical Study

SOURCE CHARACTERIZATION IN STRUCTURAL ACOUSTICS

1990 ◽  
Vol 51 (C2) ◽  
pp. C2-193-C2-196
Author(s):  
J. M. MONDOT
Keyword(s):  
Structural Acoustics ◽  
Source Characterization

Numerical simulation of the tree higro-thermal response in forest fire environment

2020 ◽  
pp. 57-65
Author(s):  
Eusébio Conceiçã ◽  
João Gomes ◽  
Maria Manuela Lúcio ◽  
Jorge Raposo ◽  
Domingos Xavier Viegas ◽  
...  
Keyword(s):  
Forest Fire ◽  
Numerical Study ◽  
Thermal Response ◽  
View Factor ◽  
Tree Model ◽  
Pine Tree ◽  
Surface Temperatures ◽  
Fire Environment ◽  
Fire Front ◽  
Heat Exchanges

This paper refers to a numerical study of the hypo-thermal behaviour of a pine tree in a forest fire environment. The pine tree thermal response numerical model is based on energy balance integral equations for the tree elements and mass balance integral equation for the water in the tree. The simulation performed considers the heat conduction through the tree elements, heat exchanges by convection between the external tree surfaces and the environment, heat exchanges by radiation between the flame and the external tree surfaces and water heat loss by evaporation from the tree to the environment. The virtual three-dimensional tree model has a height of 7.5 m and is constituted by 8863 cylindrical elements representative of its trunks, branches and leaves. The fire front has 10 m long and a 2 m high. The study was conducted taking into account that the pine tree is located 5, 10 or 15 m from the fire front. For these three analyzed distances, the numerical results obtained regarding to the distribution of the view factors, mean radiant temperature and surface temperatures of the pine tree are presented. As main conclusion, it can be stated that the values of the view factor, MRT and surface temperatures of the pine tree decrease with increasing distance from the pine tree in front of fire.

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