AE Source Location Research Articles

AE characteristic of the damage behavior of TiNi/Al6061 SMA composite

TiNi/Al6061 shape memory alloy (SMA) composite was fabricated by a hot press method to investigate the microstructure and mechanical properties. Interface bonding between TiNi reinforcement and Al matrix was observed by using SEM and EDS. Pre-strain was imposed to generate compressive residual stress inside the composite. A tensile test for specimen which underwent pre-strain was performed at high temperature to evaluate the variation of strength and the effect of pre-strain. It was shown that interfacial reactions occurred at the bonding between matrix and fiber, creating two inter-metallic layers. The yield stress increased with the amount of pre-strain. The acoustic emission technique was used to nondestructively clarify the microscopic damage behavior at high temperature and the effect of pre-strain of TiNi/Al6061 SMA composite. In addition, a two-dimensional AE source location technique was applied to clarify the position of damage in composite.

Lamb wave evaluation and localization of transverse cracks in cross-ply laminates

This paper investigates the effect of transverse cracks on the S0 mode velocity in GFRP and CFRP cross-ply laminates, and proposes a new AE source location method that considers the change in the S0 mode velocity due to the transverse cracks. We found experimentally that the stiffness and the velocity decreased as the transverse crack density increased. Analytical predictions deduced from the combination of the complete parabolic shear-lag analysis, the classical plate theory and the laminated plate theory are in good agreement with the experimental results. Utilizing this relationship between the velocity and the mechanical damage, we located AE sources of transverse cracks in cross-ply laminates with the calculated in situ velocity. We were able to show that highly accurate source location requires the reduction of the in situ value of the velocity. The present method is simple but quantitative and useful in health-monitoring for detecting and localizing the damage in composite structures.

Development of the AE Source Location Method for the CFRP Tank

Development of the AE Source Location Method for the CFRP Tank

TiNi/A16061 형상기억복합재료의 미시적 손상거동과 손상위치측정에 관한 연구

TiNi alloy fiber was used to solve the problem of the tensile residual stress as the reinforced material. TiNi alloy fiber improves the tensile strength of composite by occurring compressive residual stress in the matrix using shape memory effect. In order to generate compressinve residual stress in TiNi/A16061 shape memory alloy(SMA) composite, 1, 3 and 5% pre-strains were applied to the composite in advance. It was also evaluated the effect of compressive residual stress corresponding to the pre-strain variation and the volume fraction of TiNi alloy. AE technique was used to clarify the microscopic damage behavior at high temperature and the effect of pre-strain in TiNi/A16061 SMA composite. The results of the microscopic damage evaluation of TiNi/A16061 SMA composite under various pre-strain using AE technique can be divided into three atage corresponding to the AE signals. AE counts and events were useful parameters to evaluate the fracture mechanism according to the variation of pre-strain. In addition, two dimensional AE source location technique was applied for monitoring the crack initiation and propagation in composite.

Effect of transverse cracks on lamb wave velocity in CFRP cross-ply laminates

In the case of cross-ply laminates subjected to uniaxial loading, transverse cracks initiate in the 90◦ plies at the specimen edge and extend across the laminates. As the applied load increases, the crack density increases, resulting in stiffness reduction until it reaches to a limiting value. Therefore, it has been a subject of considerable interest to analyze the effect of the crack density on the stiffness reduction [1] and to monitor the cracks nondestructively, For example, with acoustic emission [2] and embedded fiber Bragg grating sensors [3]. Among the various techniques available, ultrasonic Lamb waves offer a convenient approach for evaluating the damaged composite laminates. As the Lamb were velocity depends on the in-plane stiffness of the laminate, the transverse cracks that cause the stiffness reduction can be monitored by the measurements of the velocity [4]. The acoustic emission method is also useful due to its ability of sensitive detection and source location for damages and impacts [5]. For the accurate AE source location, the in-situ wave velocity should be used in the calculation if the laminate is damaged. So combining the active sensing of measuring the in-situ Lamb wave velocity and the passive sensing of detecting acoustic emission is ideal to monitor the transverse cracks. However, as far as we know, there have been no studies considering the reduced wave velocity for the AE source location. In the present letter, the stiffness and the velocity of the lowest order symmetric (S0) mode for CFRP crossply laminates with various transverse crack densities were measured. The reduction of the stiffness and the S0 mode velocity as a function of the crack density were calculated theoretically and then the predicted values were compared with the experimental results. Furthermore, linear AE source locations were conducted on the damaged specimen and the effect of the reduction of S0 mode velocity on the accuracy of the source location was investigated. The materials studied were CFRP (T300/F593) cross-ply with two stacking sequences of [0/906/0] and

103 ニューラルネットワークを利用したエルボ型管継手における擬似AE源位置標定について(材料力学I)

103 ニューラルネットワークを利用したエルボ型管継手における擬似AE源位置標定について(材料力学I)

Two-dimensional AE source location with two sensors in thin CFRP plates

Two-dimensional AE source location with two sensors in thin CFRP plates

New Approaches to Nondestructive Evaluation of a Filament-Wound Composite Motor Case Using Circumferential Wave.

For reliable quality assurance of filament-wound composite rocket motor (FCRM) cases by use of acoustic emission during hydroproof (AE/H) testing, it is necessary both to detect defects introduced in fabrication process and to monitor damage done due to hydraulic pressurization. The circumferential wave, which has strong directivity and weak anisotropy in wave propagation in the particular FCRM case under present investigation, has high potential to address such a need. To explore these outstanding capabilities of the circumferential wave, two kinds of experiments were conducted. The pitch-catch measurements of the circumferential wave that propagated through the artificial slits demonstrated its high potential for detection of flaws. The experiments for AE source location using a particular, triangular layout of AE sensors declared its capability for monitoring of damages. Inspired from the experiments, new approaches to nondestructive evaluation of the given FCRM case were proposed using the circumferential wave: 1) an ultrasonic pitch-catch scanning and 2) an AE/H testing with a suitable triangular layout of AE sensors.

DAMAGE EVALUATION OF PRESTRESSED CONCRETE-PILES BY ACOUSTIC EMISSION

A fundamental study on fracture mechanisms of concrete-piles under both cyclic and monotonic loadings is performed by using acoustic emission techniques. Full-scale prestressed high-strength concrete piles are subjected to bending and shear loadings. Growth of cracks is monitored by AE, and three-dimensional AE source location is conducted together with identification of crack. These results are compared with results of the pile integrity tests (PIT) and visual observation. It leads to the conclusion that damage inspection by AE is more effective than by PIT in the case where open cracks due to loading would close under unloading. The crack widths evaluated by AE were remarkably compatible to the results of the wave velocity test.

Acoustic Emission Source Location and Its Error Using a Neural Network Technique.

Location of defects in solid can be presumed in terms of arrival time differences of AE-waves to each sensor. A small amount of the arrival time error, however, might influence on the AE source location. Present paper investigates the influence of errors including both the arrival time and sensor location on the AE source. Superiority of the neural network technique over the least square method was discussed on accuracy of location obtained by the arrival time differences. Applicability of source location using simulated AE source to real structure of pipe was also discussed. It was concluded that the neural network technique should provide available means to the AE source location because of less influence characteristics from the noise.

A simplified AE source location technique in the cylidrical vessel

A simplified AE source location technique in the cylidrical vessel

An experimental investigation of lattice-type structures for AE source location and magnitude using smart signal processing

An experimental investigation of lattice-type structures for AE source location and magnitude using smart signal processing

AE source location and orientation determination of tensile cracks from surface observation : Ohtsu, M.; Ono, K. NDT international, vol. 21, no. 3, pp. 143–150 (Jan. 1988)

AE source location and orientation determination of tensile cracks from surface observation : Ohtsu, M.; Ono, K. NDT international, vol. 21, no. 3, pp. 143–150 (Jan. 1988)

AE source location and orientation determination of tensile cracks from surface observation

AE source location and orientation determination of tensile cracks from surface observation

A Multichannel AE Source Location System and its Application to Fatigue Test of Reactor Vessel Model

A Multichannel AE Source Location System and its Application to Fatigue Test of Reactor Vessel Model