The part relies on the experience of the worker in the turning process is abundant. The tendency is in the processing of the center hole. The destruction of the center hole becomes a maximum credible accident. This paper advocates the safety standard concerning the center hole. It is a simulation concerning the center hole by using of experimental mechanics and computational dynamics together. This study is composed by some analysis methods. The method is an isochromatic line, an isoclinic line by the photoelasticity method, two dimension finite element method, a tridimensionality finite element method, and method of caustics. In the photoelasticity method, it was done that the test specimen model by which the real machine parts straight side direction section dimensional standard was copied was done. The test specimen model dimensional standard used by the photoelasticity method was analyzed in two dimension finite element method. The model by which real machine parts was faithfully reproduced was analyzed in the tridimensionality finite element method. In method of caustics, an artificial crack was inserted in the test specimen model.

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Functions of suspension springs for automobiles are to keep maneuverability good and to improve comfortability in riding. Rally cars run winding or rough roads with high speed, which causes sometimes cars jumping. When the car jumps, clearances come out between suspension springs and the seats. Then the springs collide hard with the seats in the car landing, which may break the springs. So a spacer called 'helper spring' is inserted between the suspension spring and the seat, which fills the clearance and absorbs the impact forces from the road (Fig. 1). A rectangular wire helical spring is usually used for the helper spring, as it can deflect to a greater extent than a circular wire spring. Recently a new rectangular wire helical spring is contrived, in which the helper spring (Part A) is connected to the suspension spring (Part C) with a connecting spring (Part B) of a continuously changing the wire cross-section (Fig. 2). Namely the helper spring and the suspension spring are combined in a body. In this study the non-linear spring characteristics and the stresses of the springs are studied theoretically and numerically. Furthermore the Finite Element Analysis and experiments are carried out on some test springs to check whether the theoretical analysis is proper or not.

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The changes on vibration properties were investigated to develop a NDT for FRP in working conditions. Glass/vinylester fabric composites were used for a test specimen and a damage specimen was made by 1-cycle load-unload static tensile tests. Impulse response tests, which are very useful to carry out in working conditions, were performed before and after the static tensile tests in order to estimate changes of the vibration properties of the specimen. It became clear from the comparison of vibration properties before and after the test that vibration properties were changed by the damage (i.e. the decrease of natural frequencies and gains at resonance, and increase of damping ratios). Also, it became clear that the changes of vibration properties clearly occurred with the increase of damage. It was remarked that there was a linear relationship between the changing rate of vibration properties and the increasing rate of transverse cracks. These results showed that there was able to estimate the value of damage from vibration analysis.

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In this paper an elliptical crack parallel to a bimaterial interface is considered. The solution utilizes the body force method and requires Green's functions for perfectly bonded semi-infinite bodies. The formulation leads to a system of hypersingular integral equations whose unknowns are three modes of crack opening displacements. In the numerical calculation, unknown body force densities are approximated by using fundamental density functions and polynomials. The results show that the present method yields smooth variations of stress intensity factors along the crack front accurately. Distributions of stress intensity factors are indicated in tables and figures with varying the shape of crack, distance from the interface, and elastic constants. It is found that the stress intensity factors are mainly controlled by the root area parameter almost independent of the crack shape.

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In order to characterize a geothermal reservoir crack, dynamic response of a reservoir crack with fluid leakage along the crack periphery is studied by using a penny-shaped fluid-filled crack in an elastic medium, i.e. a rock mass. Fracture characterization method is derived from dynamic response of the crack. Peak frequencies derived from our crack model are a function of crack radius, aperture, and so on. We characterize reservoir crack by finding a combination of these parameters which minimize the difference between observed peak frequencies in the real field and calculated peak frequencies. Using this characterization method, we could characterize reservoir crack in Higashi-Hachimantai field. Crack radius is around 40 m and aperture is less than 1 mm. These results well accord with those estimated from the field experiments based on different discipline.

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Nondestructive evaluation of welding residual stresses is required to assess the structural integrity of engineering components. Authors have proposed a new nondestructive evaluation method called "the Bead Flush Method" for welding residual stress evaluation. Up to the present studies, the solution set of eigenstrains in the bead flush method has been determined under the assumption which eigenstrain distributions of the bead and the thickness directions are constant, but in general, except for relatively quite thin plates, this assumption does not come into existent. For wider applicability of the bead flush method, the conventional procedure should be improved. In this study, we propose a new evaluation algorism of welding residual stresses applicable to thicker welded plates. Its main characteristic is to enforce eigenstrain determination process in inverse analysis. To do this, a new eigenstrain function based on welding simulations and the optimization method of its parameters using response surface methodology are proposed. And also its utility is confirmed by simulations of the bead flush method.

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The relationships between tensile strength and microstructural parameters and between fatigue limit and microstructural parameters were investigated for seven tempered-martensitic steels S45C, SMn443, SCr440, SNCM439, SCM440, SUP7 and SUP12. An optical and atomic force microscopy showed that prior-austenitic grain diameter, d_γ, block width, W_blo, and precipitation spacing, λ, were 18μm, 0.7μm and 0.11∼0.24μm, respectively, as microstructural parameters. A nanoindentation showed that HV=100+Hv^*_dls+Hv^*_pre+Hv^*_bou, where Hv is macro-Vickers hardness, and Hv^*_pre and Hv^*_bou are micro-covered Vickers hardness due to dislocation and solid, precipitation and block boundary strengthening. Hv^*_pre and Hv^*_bou were expressed by the microstructural parameters of λ and W_blo. The constant value of 100 is base hardness of the iron. Based on these results, we proposed that tensile strength σ_B and fatigue limit σ_w, were expressed in the followings. σ_B=3.27{100 + Hv^*_dls + 1.02 × 10^-2λ^-1 + 3.67 × 10^-4λ^-1w^-1/2_blo}…………………………………(A-1) σ_w=1 .6{100 + Hv^*_dls + 1.02 × 10^-2λ^-1 + 1.15(3.67 × 10^-4λ^-1w^-1/2_blo)}…………………………(A-2)

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A combined instrument of ultra-micro hardness testing and atomic force microscopy (AFM) was developed. The instrument was able to conduct hardness test by a diamond indenter and to obtain high-resolution AFM images by a Si tip, at the same position of a specimen. Ultra-micro hardness test and AFM observation were carried out for electrolytically polished specimens of tungsten single crystal and low-alloy steels SCM 415 and 440. The SCM 415 and 440 steels were tempered at 600 and 415°C, respectively. The benefit of using a Si tip instead of a diamond indenter for AFM observation is clearly shown by the better profile of the indent mark on the tungsten single crystal and the distinguished image of fine carbides of the steels. The ultra-micro hardness of the steels was influenced by the local microstructures such as the carbide density and the presence of ferritic phase.

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