This paper deals with recent and advanced visualization measurement techniques in single-and multi-phase flow fields centered on the authors'studies. Measurements introduced here are PIV (Particle Image Velocimetry), Hybrid PIV, fast X-ray CT, fast NMR (Nuclear Magnetic Resonance) imaging and Neutron radiography. The liquid flow in a positive displacement meter and a porous media is shown by use of the PIV with refraction index matching. The characteristics of the gas-liquid two-phase flow, including phase distributions and velocity fields for gas and liquid, are revealed by the Hybrid PIV, fast X-ray CT and so on. By the Hybrid PIV, both bubble motion and liquid flow around the bubble can be measured simultaneously. The phase distribution is shown by both the X-ray CT and the Neutron radiography. The liquid velocity field and the phase distribution are measured by the fast NMR imaging.

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Photoelasticity is a full-field method which enables experimental stress analysis of two- and three-dimensional components to be performed by analyzing the photoelastic fringes, i. e. isochromatics and isoclinics. However, the collection of photoelastic parameters can be a long and tedious process. The advance of automated photoelastic system has allowed the experimentalists to speed up the rate of analysis and to perform more complex investigations. In this paper, a survey of recent methods of automated photoelasticity developed in the last 20 years is provided.

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Strain measurement method in the whole view field using speckle pattern is summarized in this paper. Advantage of the method using random pattern is that it is not necessary to use grid with regular pattern on the object surface. Disadvantage is that it is not easy to adjust accuracy of the measurement for various sizes of the random pattern and much calculation amount is required for correlation method. But CPU power has been raised rapidly these days and is overcoming this disadvantage. And also the resolution of CCD devices has increased recently. These progresses of technology in CPU and image capture devices realize remarkable progress in the strain field measurement using random pattern.

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Electronic Speckle Pattern Interferometry (ESPI) is a promising experimental technique to investigate whole-field deformation analysis. The technique has been developed to make possible to observe dynamic feature of deformation in dynamic ESPI. In this paper, a dual-beam, in-plane sensitive DESPI is applied to observe an entire process of tensile tests of Al-alloy samples. Moving features of strain localized bands (SLB) which propagate over the sample is precisely investigated. A quantitative phase analysis by addition-subtraction method is also presented.

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Basic theory for the determination of stress intensity factor K_I by using the transmitted and the reflected techniques of caustics is described. Fundamental experimental apparatus of this method is shown and moreover some technical points which should be taken into consideration in the experiment are shown. Not only the laser light but also the white light can be used as a light source in the experiment, but sufficiently small size of point light source should be employed for the case of white light. It is pointed out that there occurs the effect of the size r0 of initial curve on K_I and a larger value of r0 than a definite one should be employed. Finally, some examples of application of this technique on various problems at our laboratory are shown. Multiplication technique of the caustic image is illustrated. When this technique is applied to the stress-frozen model in photoelasticity, there appears very different caustic patterns from those of usual one. As an example of application on the dynamic fracture problem, analysis of fracture behavior of ceramic materials under dynamic loading at high temperatures is described.

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Optical methods in experimental stress analysis, such as photoelasticity, moire interferometry, speckle interferometry and holographic interferometry, are very valuable in areas where other methods of analysis are not available or impractical. Though optical methods have many advantages, these optical methods are not so widely used. One of these reasons is that currently there are no standards which cover procedures, materials and equipments for any of optical methods. In order to standardize the optical methods in stress and strain analysis, TWA26 in VAMAS is in active and the standardization of full-field optical stress and strain measurement division has been established in JSEM. The present paper describes the current activities of the standardization of full-field optical methods in VAMAS TWA26, ASTM and JSEM.

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Thermal deformations of two electronic devices, QFP (Quad Flat Package), MCM (Multi chip Module), were measured by moire interferometry. A thermal loading was conducted by cooling the devices from an elevated temperature 100°C to room temperature 25°C. Moiré fringes were obtained on the cross sections of the devices to clarify the effect of the CTE (Coefficient of Thermal Expansion) mismatch of the micro components, such as silicon, metal and resin. The experiments were also made using QFP mounted on the PCB (Printed Circuit Board) to examine the influence of the PCB. FEA (Finite Element Analysis) was also performed to simulate the thermal deformations of the devices.

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A new approach to simultaneous measurement of two different displacement fields by two-directional integrated phase-shifting for moire interferometry is proposed in order to enable the analysis of time-varying problems. Two moire fringe patterns for both of two displacement components produced simultaneously by four-beam interference are recorded as a single image. Then, the phase distributions representing both displacements are separated and obtained from a series of 12 images by adopting simultaneous phase-shifting for both directions. An example problem of rigid body rotation with carrier fringes is demonstrated by use of the proposed method and the effectiveness is shown. It is emphasized that measurement and subsequent analysis can be carried out in real-time since the phase-shifting is performed without stopping and images are recorded successively in the proposed method.

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Grating projection methods have been often used for non-contacting shape measurement. An image of equal-height contours of an object can be obtained in real-time using moire topography. We have developed the phase-shifting scanning moire method for real-time shape measurement with high resolution. But there is a problem that the measuring error becomes larger when the object is moving faster because several images are captured with shifting the grating phase. In this paper, we propose a phase-shifting scanning moire method using a DMD (Digital Micro-mirror Device), which can obtain an image of equal-height contours within a frame time. The direction of a ray reflected at each mirror of a DMD can be selected quickly. For this purpose, we developed a DMD reflection-type CCD camera called as ‘DMD camera’. The camera works as a camera in which each pixel has a shutter. The system and experimental results are shown to confirm the algorithm to obtain a contour image using the DMD camera.

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Almost all of fatigue crack growth in the stmcture occurs under the mode I loading. However in some structures, the fatigue may occur not only under the pure mode I condition but also in the shear and torsion conditions. Under such conditions, the mixed mode fatigue crack growth may occur. In this paper, mode II+III fatigue test is conducted using a single-axis testing machine. After the test, the fracture surface is observed using SEM and the characteristic feature of the mixed mode fatigue surface is observed. The contact between fatigue crack surfaces could be avoided. The crack growth direction is compared with that predicted by Erdogan-Sih critedon and the maximum shear stress criterion. The maximum shear stress criterion predicts the fatigue crack growth direction very well. The three-dimensional FEM analysis is carried out and stress intensity factors, K_II and K_III, are evaluated. The crack growth rate is evaluated and is compared with that of mode I condition. It is found that the mixed mode fatigue crack growth rate is nearly same with that of mode I fatigue.

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