摘要:

A fundamental approach to quantitative ultrasonics must be based on mathematical modeling of ultrasonic wave phenomena. Measurement models must be developed to predict from first principles a measurement system's response to specific anomalies in a given material or structure. Once a mathematical model has been verified by comparison with a sufficiently wide range of experimental data, reliable synthetic data can be generated with little effort. The modeling approach aids in the design of efficient testing configurations and in the interpretation of experimental results and field data. Measurement models can be used to optimize the operation of NDE systems. Synthetic data can play an important role in the training of a neural network or to establish a knowledge base for an expert system.

ISSN:1058-9759    

DOI:10.1080/10589759208952716

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

Various numerical models using nodal equations have been proposed to simulate the behavior of ultrasonic waves in materials precisely. These simulation methods are effective for the investigation of the property of elastic waves inside solid, but they give discrepancy on the calculation of boundary phenomena of ultrasonics, i.e. surface wave behavior.

ISSN:1058-9759    

DOI:10.1080/10589759208952717

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

In order to obtain a physical interpretation of experimental data obtained in ultrasonic-acoustic measurements, we simulate the experiment by numerical calculation on a supercomputer. The composite we discuss here is a two dimensional rectangular beam which has one reinforcement layer located at middepth. The Finite Strip Method (FSM) is used to formulate the composite and modal analysis and Duhatnel integral equation are also used to obtain its dynamic response for the impulsive incident wave. Making use of the Visualization Technique of Stress Wave Propagation (VTSWP) we obtain the animated simulation of stress wave propagation in a composite. The effect of gradient distribution of the stiffness in the interphase layer on the wave energy transmission from matrix to fiber is also analyzed as an amplitude transmission coefficient (ATC).

ISSN:1058-9759    

DOI:10.1080/10589759208952718

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

The scattering problem of elastic waves by a three-dimensional inclusion with a nonlinear interface condition is solved. The nonlinear interface condition is represented by using a distribution of nonlinear springs inserted at the matrix-inclusion interface. The springs have perfect elastoplastic characteristics, while the inclusion and the surrounding matrix are linear at all times. Thus, the problem is reduced to the boundary-type dynamic nonlinear problem. A time-domain boundary integral equation method is applied to obtain numerically dynamic behaviors of the nonlinear interface. In numerical examples, a spherical inclusion subjected to an incident plane L-wave is considered. Results as functions of time are obtained for displacements and tractions at the nonlinear interface and the scattered far-field.

ISSN:1058-9759    

DOI:10.1080/10589759208952719

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

The probe index and beam angle of angle probes are very important characteristics in ultrasonic angle beam examination, which are recommended to be measured by using a standard specimen, STB-A1 (IIW-l/ISO-2400). However, it has not been made clear how sound velocity anisotropy, if it exists, affects those characteristics in the STBs or in similar specimens.

ISSN:1058-9759    

DOI:10.1080/10589759208952720

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

The most effective way of ultrasonic defect sizing currently recognized is the tip echo method, and it has broad and practical applications. Tip waves have very weak intensity, about 20 dB lower than the mean echo, and this prevents their use in many instances. Recently, low noise full digital flaw detectors have been developed, which make it very easy to catch tip waves. In the reflection by a small crack, we are now able to catch several tip waves easily in one shot. Moreover, the distances between two tip echoes are more stable for the fluctuation of experimental condition than the conventional method. Thus giving us more information than by the conventional method. Numerical experiments must be used, in order to distinguish each tip echo.

ISSN:1058-9759    

DOI:10.1080/10589759208952721

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

A neural network is applied to a quantitative evaluation of defects. The training data for learning of neural network are prepared from a numerical analysis based on an elastic wave theory. The question posed here is to. evaluate the depth of surface-breaking cracks in a structural component. The numerical analysis is carried oui for ten cracks ranging from 0.6 mm to 2.4 mm separated by 0.2 mm in depth. Waveforms in the time and frequency domains are calculated by the use of the boundary element method for these ten types of crack depth.

ISSN:1058-9759    

DOI:10.1080/10589759208952722

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

In this paper, the stress distribution around the apex of dissimilar materials is calculated for both two and three dimensional bonded structures by using an improved Boundary Element Method (BEM), and the order of stress singularity is obtained from the numerical solution. It is shown that the numerical solution is very accurate even near the boundary or apex, and for the samples of ceramics (Al2O3) bonded with Cu, it is proved that the order of the stress singularity obtained in this way is in good agreement with Bogy's theory and the numerical solution can be used as an evaluating standard of nondestructive testing. For the three dimensional bonded structure, it is found that the stress singularity is very strong around the apex. This reveals that the possibility of crack generation in this area is very high. Through some detailed investigations about the stress field, a simple method to moderate the stress singularity is suggested.

ISSN:1058-9759    

DOI:10.1080/10589759208952723

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

Special problems associated with ultrasonic wave propagation in anisotropic materials are discussed. Included in the treatment are modes of propagation, energy flux deviation, diffraction beam spreading, and th6 influence of non-linear effects. Comments will be made with respect to the possibility of successfully implementing ultrasonic tomographic imaging in anisotropic materials.

ISSN:1058-9759    

DOI:10.1080/10589759208952724

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

The in-process evaluation of texture of thin steel sheets using non destructive methods would considerably improve the process control during manufacture, and the monitoring of product quality. This type of method can be used to control the homogeneity of steel coils and to detect any changes which can occur in the product characteristics during production.

ISSN:1058-9759    

DOI:10.1080/10589759208952725

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor