In this paper, first, the concept of hybrid method is presented. On the basis of this concept, various hybrid experimental methods are classified into five categories: (i) hybrid experimental-numerical method, (ii) hybrid numerical-experimental method, (iii) hybrid anal ytical-experimental method, (iv) hybrid experimentalanalytical method, and (v) hybrid experimental-experimental method. Among them, the focus is put in the hybrid experimental-numerical method, which hybridizes an experimental method and a numerical method. The hybrid experimental-numerical method can achieve a new ability that cannot be obtained by the experimental method alone. The effectiveness and usefulness of various hybrid experiment-numerical methods are explained by using the results obtained by our recent studies. Especially, the power was demonstrated for the developments of intelligent hybrid measurement methods and dynamic fracture-path prediction methods.

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Recent speckle photography and application are reviewed. Topics include the laser speckle photography, whitelight speckle photography and electronic speckle photography. These recent applications involve the crack-tip deformation fields, the determination of surface strains and displacements, hybrid experimental method, large-object deformation, and the measurement of three-dimensional deformation fields. Image processing of a speckle pattern progressed quickly with rapid development of a computer and a CCD camera last decade. Therefore, it is expected that the applicable field of speckle photography spreads further.

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Strain measurement by using optical fiber as a sensor is briefly reviewed. The methods of interferometric behaviour of light, bending loss and connecting loss of optical fiber, optical Bragg grating and BOTDR are explained. The applications of each method are also shown.

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Maxillo-facial and oral structures are complex organs which endure enormous stresses. Developing a better understanding of and thereby learning to control excessive forces in maxillofacial and oral structures through research using experimental mechanics techniques is considered to be an important task in dental clinical pathology today. Furthermore, the 21st century will see a progressive aging of society and with it the increased use of partial prostheses in the elderly with alveolar defectS in their remaining teeth In this context, the significance of experimental mechanics in developing new guidelines for mandibular distal extension prosthesis design will be examined through a discussion of a quasi-three dimensional photoelastic stress analysis of intcnal stresses that occur in the abutment teeth with periodontal defects and their surrounding tissues, a situation in which the involvement of excessive forces have been clinically suggested, with consideration for the effect of the axis of rotation in prostheses utilized in such situations.

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Since studies on high-speed photoelasticity focusing on impact problems were performed there has been a lot of researchs, most of which seem to include not only dynamic but also quasi-static stress. Here, as part of basic research on impact problems, experiments have been conducted to investigate the behavior of stress waves in case that impact pulse loads are applied to test strips with circular holes.
The impact load application device was an airgun using compressed air to performe collisions with high-speed and low-mass objects. A Cranz-Schardin type stroboscopic camera was used to record the dynamic fringe patterns with the airgun.

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We investigated a method to measure cyclic strain without contact using aluminum foil and laser speckle. In this method, a small piece of the foil is pasted on a specimen and the specimen is loaded cyclically. The laser speckle detects surface change of the foil surface caused by fatigue of the foil. This method allows the estimation of cyclic strain occurred in the base specimen by observing change in the speckle pattern on the foil surface. The foil can be used as a kind of strain gauge. When we use this method, it is necessary to evaluate diffused pattern of the laser speckle accurately under different experimental conditions. In this paper, we derived a method for evaluating light intensity distribution of the speckle pattern. First, the light intensity distribution was smoothed by the row pass filtering and an exponential function was used to approximate the distribution. Broadness of the light intensity distribution was evaluated with the half width of the exponential function. It was found that influence by difference of the intensity of the laser light source and f value of the camera lens is very small using the evaluation method derived in this study.

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