No abstract

The typical application of ultrasonic tomography is the determination of process parameters like component flow rates and material fractions in industrial environment. Another promising application is non-invasive health monitoring in medical care. Both acoustic attenuation and acoustic impedance inhomogeneity are the main physical quantities that are used to reconstruct the image. When transmission ultrasonic waves are shadowed by hard tissue because of severe attenuation, the reflection mode can be an effective supplement. This paper provides multi-objects reconstruction images by reflection ultrasonic tomography, demonstrating the multi-objects imaging capability of an immersion circular array system. The circular array consists of 36 ultrasonic transducers with 0.5MHz frequency which are ring arranged and embedded in the container wall to serve as both transmitter and receiver. Each time one transducer is fired and in the meantime other transducers are enabled to receive signals. Ultrasonic transmitting, propagating and receiving of the circular array system are simulated by COMSOL Multiphysics® software, after that a series of image reconstructions of the objects with different numbers are obtained through ellipse algorithm.

Scanning acoustic microscopy (SAM) is a powerful non-destructive testing tool used in electronic, material and medical testing area. Commercial SAM products are generally too expensive to be extended to common users. Therefore, a practical SAM system had been developed using high-frequency ultrasonic focus transducers, a wide-band pulse transmitter/receiver, a high-speed data acquisition card, and a high-precision motion system. The SAM　system's precision and function can meet the requirement of practical test adequately, and the cost is much lower compared to commercial products. Several kinds of imaging method were introduced, and the SAM system has the ability to accomplish full-wave data acquisition.

Scanning acoustic microscopy (SAM) is a powerful non-destructive testing tool used in the field of electronic package, micro-and nanomaterial and medication. The capability to distinct how minimum of defect is very important to detect the flaw in electronic packages. The detection resolution of SAM depends on the frequency of ultrasonic focus transducers. In this paper, the Multi-Gaussian Beam model to simulate the sound field of the focused transducers is discussed. Mainly the frequency domain imaging algorithm and 2D-Deconvolution method for better image quality and high resolution is analyzed. Finally, the calibration experiments for the detection resolution of 100MHZ transducer is carried out. In addition, the micro flaws with different dimensions are observed at different defocusing location. It is concluded that the detection resolution decreases with the deviating from focus plane, so the flaws should be sensitive on the focus area by precisely controlling the vertical position for better detection resolution.

Stiffnend panels are used to investigate the fracture behavior of the fuselage components within the framework of the damage tolerance analysis. Integral structure are gradually replace butilt-up structure in recent years. This paper presents an improved method based on displacement compatibility principle to calculate stress intensity factors. A finite element method based on intgral contour is introduced and used for verifying the solutions. Stress intensity factor solutions of built-up structure and integral structure were both calculated using these two methods. From the comparison, these two solutions are in good agreement both in built-up structure and integral structure.