Ultrasonic Phased Array Imaging Research Articles

Parameter Optimization of Linear Phased Array Transducer for Defect Detection

An optimization design method was proposed for linear phased array ultrasonic imaging testing. In the method, main lobe width and the amplitude ratio of side lobe to main lobe were served as optimization objectives to judge the test- ing precision of phased array beam directivity. The combination of element of width and inter-element space was served as optimize parameter for the optimization objectives. The combination of optimal parameters for phased array transducer was finally achieved and applied to phased array B-mode imaging ultrasonic testing on a flat bottom hole in standard test block. The results show that the method can not only obtained the optimal parameters for linear array of phased array transducer, but also improve the accuracy of the location and size for defect detection.

Ultrasonic Phased Array 3D Imaging for the Steel Butt Weld Defects

Ultrasonic phased array imaging detection technology combinating the focused beam and array probe movement can get powerful test information. It has been widely used in the steel butt weld detection. For making up the limitations of 2D view, in this paper,we used one-dimensional linear array probe, got 2D slice view data obtained by phased array ultrasonic S-scan, through software programming algorithm to realize 3D reconstruction of steel butt weld typical defects. Experiment shows that it can display more intuitive performance of the defects in space. Revealing a better shape, size and orientation information. Providing a reference for the final evaluation of the defect.

Nonlinear ultrasonic phased array imaging.

This Letter reports a technique for the imaging of acoustic nonlinearity. By contrasting the energy of the diffuse field produced through the focusing of an ultrasonic array by delayed parallel element transmission with that produced by postprocessing of sequential transmission data, acoustic nonlinearity local to the focal point is measured. Spatially isolated wave distortion is inferred without requiring interrogation of the wave at the inspection point, thereby allowing nonlinear imaging through depth.

Evaluation of crack closure stress by analyses of ultrasonic phased array images during global preheating and local cooling

Crack closure stress (CCS) is an important parameter that affects crack propagation rate. However, the method for measuring CCS in practical fields has yet to be developed. In this study, we propose a practical method of estimating CCS. In our experiment, a closed fatigue crack was imaged by a linear phased array (PA) method during crack opening by global preheating and local cooling (GPLC). Here, we assumed that the crack appears in PA images after the thermal stress induced by GPLC exceeds CCS. Therefore, we calculated the thermal stress induced by GPLC using an analytical solution and thereby estimated CCS. Then, to validate the CCS estimation method, we simulated the PA images by a finite difference time domain (FDTD) method with a damped double node (DDN) model, where CCS was relieved by the calculated thermal stress. Consequently, the temporal variation in crack depth observed in the PA image was successfully reproduced in the simulation. Thus, the CCS estimation method was verified by comparing experimental results with analysis results.

Current status of technology development for fabrication of Indian Test Blanket Module (TBM) of ITER

Ever since India decided to install its Lead-Lithium Ceramic Breeder (LLCB) TBM in ITER, various technologies for fabrication of Indian TBM are being pursued by IPR and IGCAR, in collaboration with various research laboratories in India. Welding consumables for joining India specific RAFM steels (IN-RAFMS), procedures for hot isostatic pressing, electron beam welding, laser and laser-hybrid welding have been developed. Considering the complex nature and limited access available for inspection, innovative inspection procedures that involved use of phased array ultrasonic and C-scan imaging are also being pursued. This paper presents the current status of these developments and provides a roadmap for the future activities planned in realizing Indian TBM for testing in ITER.

A Novel Encoded Excitation Scheme in a Phased Array for The Improving Data Acquisition Rate

One of the challenges of phased array (PA) ultrasonic imaging systems is their limited capability to deal with real-time applications, such as echocardiography and obstetrics. In its most basic outline, these systems require emitting and receiving with the entire array for each image line to be acquired; therefore, with many image lines, a higher acquisition time and a lower frame rate. This constraint requires one to find alternatives to reduce the total number of emissions needed to obtain the whole image. In this work, we propose a new PA scheme based on the Code Division Multiple Access (CDMA) technique, where a different code is assigned to each steering direction, allowing the array to emit in several directions simultaneously. However, the use of encoding techniques produces a reduction of the image contrast because of the interferences between codes. To solve this, a new scheme based on merging several images is proposed, allowing the system to get close to the theoretical maximum frame rate, as well as to limit the loss of contrast, intrinsic to the technique.

High-Resolution Phased Array Ultrasonic Imaging with the Subspace Method

High-Resolution Phased Array Ultrasonic Imaging with the Subspace Method

Research on Key Technologies of the Cableless Pipeline Robot

The cableless pipeline inspection robot is a hot topic in current domestic and international oil and gas pipeline in the research of special robot. The functions of robot body for communication with the outside world, energy supply, mobile running gear, and flaw detection module are several key technologies in the pipeline robot in application. This paper presents the measures for those key problems: Fiber-optic conveys video images and data in the pipeline and robot bi-directional cableless communication with the host computer monitoring equipment is completed outside the pipeline; In the aspect of energy supply the transformer secondary coil is generated by Charging stations set up outside the pipeline and lithium batteries is recharged to complete function of robot self-propelled ; Mobile running gear is achieved through the use of the arm of the parallelogram unit peristalsis to walk forward;The flaw detection technology adopts both video acquisition and ultrasonic phased array imaging with dynamic focusing and deflection characteristics to improve flaw detection efficiency and detection identification.

Rapid phased array ultrasonic imaging of large area composite aerospace structures

There has been an increase in the use of composite materials in the aerospace industry which is driving a need for new NDT techniques that can rapidly scan large structures and provide quantitative data on the material integrity. In many applications there are common requirements for the ultrasonic inspection of composites for porosity, delaminations, foreign body contamination and fibre wrinkling. Traditional methods of ultrasonic inspection require the use of a single-point probe or a multiplexed group of probes. NDT Solutions has developed new inspection techniques based on ultrasonic arrays housed within a rubber coupled wheel sensor. The wheel can be manually applied or scanned over the structure with an automated scanning system. Applications for the technology include real-time imaging and reporting of impact damage, porosity sizing, delaminations and fibre wrinkles. Examples and case studies from a range of aerospace applications are given, including inspection of small and large area composite structures.

Method and apparatus for a motorized multi-plane transducer tip

An ultrasonic phased array imaging transducer device is provided which includes a flexible sealing membrane disposed within a housing so as to divide the housing into a wet chamber and a dry chamber. The wet chamber contains a fluid and includes a phased array transducer disposed in the tip end of the housing and oriented so as to provide a sound path extending perpendicular to the longitudinal axis of the housing. A motor provides rotation of the transducer while an encoder determines positional information with respect to the transducer. A flexible cable of electrical circuit connections is electrically connected to the transducer and is coiled relative to the transducer so as to permit transducer rotation of more than 180 degrees. The flexible cable extends from the wet chamber through the flexible sealing membrane to the dry chamber. A torque limitation device limits the torque transmitted to the transducer.

Multiplexed interferometer for ultrasonic imaging applications

A multiplexed laser interferometer is presented that allows for the simultaneous detection of acoustic waves from a number of points on the surface of a specimen. Phase gratings are used to create an array of laser beams that are directed to the specimen. The beams are collected using a lens system, combined with a single reference beam in a photorefractive crystal, and imaged on separate photodetector elements. Detection of surface acoustic waves scattered from a defect in an aluminum specimen is demonstrated using a nine-element receiver. Focusing of the array interferometer, by applying appropriate phase shifts between the detected signals, is also shown. The wide bandwidth and noncontact nature of this receiver make it well suited for phased array detection and ultrasonic imaging applications.

High speed adaptive ultrasonic phased array imaging system

An ultrasonic phased array imaging system is provided which includes a normal mode and an adaptive mode of operation. The adaptive mode adjusts the delay associated with each element in the transducer such that the average image brightness of the region of interest is maximized. A motion detector is provided for determining when the transducer has been moved a distance sufficient to render the previous adaptive measurements possibly invalid whereupon the system automatically reenters the normal mode. A method of operating the ultrasonic phased array imaging system is also provided.

Real-time digital dynamic focusing system

In this paper an inexpensive digital dynamic focusing and deflection technique for real-time phased array ultrasonic imaging equipment is proposed. In this system, operating below 10 MHz, a time delay resolution of 10 ns is adopted to reduce quantization grating lobes effects. This equipment allows a 10 ns delay resolution with an RF signal sampling rate of 20 MHz. The resulting electronic circuitry is simple and inexpensive and can be easily expanded to deal with several reception lines.

超音波と音像定位を利用した盲人用歩行補助装置(<特集>視聴覚の感覚代行)

Many kinds of mobility aid systems for the blind are developed and some of them had come into the market. These systems detect the obstacles in front of the blind using ultrasonic wave or laser beam, and positions of obstacles are transmitted to the blind by coded signals through auditory sense or tactile sense. Therefore these systems have not enough image information on the front view. We are studying the auditory display system which converts visual image into sound image using control of sound localization. This system can support the weak point in above systems. We present a new mobility aid for the blind using ultrasonic phased array imaging for the view of 4 meters in front and auditory localization of sound image. By walking experiments on corridor with man-like obstacles, we found that subject could walk about 4 km/h. This system may be useful for the blind.