Shigeru Shida

Strength of ceramic materials containing small flaws

Abstract Ceramic strength values for different flaw sizes, grain sizes and notch radii are analyzed with a grain-fracture model. The critical stress-intensity factor for small flaws is lower than that for large cracks. Therefore, conventional LEFM is not applicable for estimating ceramic component strength. However, the relationships between the ratio of equivalent crack length and mean grain diameter, a e d ,and the ratio of critical stress-intensity factors for short and long cracks, K c K Ic ,are almost identical for various kinds of ceramic materials. This fact is well expressed by the model. Moreover, both the effect of grain diameter on plain specimen strength and that of notch-root radius on the notch-toughness value are explained well with the model utilizing the KIc value of materials.

Buckling Strength Analysis of Large Power Transformer Windings Subjected to Electromagnetic Force Under Short Circuit

The inner winding of a power transformer is subjected to radial electromagnetic forces under short circuit conditions. When these forces exceed a certain limit, transformer windings buckle. This paper deals with the buckling strength analysis of transformer windings, including the evaluation of the bending stiffness of a winding disk (coil) of multiple turn laminated construction, the effect of supporting spacers on the deformation of a winding and the plastic deformation of a winding caused by circumferential stress.

Leakage and breakage estimation based on a net-stress approach for stainless steel pipes with circumferential cracks

Abstract Coolant leakage and breakage external loads for stainless steel pipes with circumferentially part-through cracks are predicted by the mechanical properties of pipe materials. In addition, the predicted loads at leaks and breaks are compared with other net-stress approaches. The plastic limit load criterion, a traditional and convenient method, is found to give an overly conservative estimation for shallow cracks and to be nonconservative for 60–80% wall-thickness cracks.

Consideration of allowable flaw size for pressurized pipes

Abstract Failure strength for circumferentially and axially cracked Type 304 stainless steel pipes is evaluated based on the net-stress approach. Using this approach, allowable flaw sizes for pipes containing circumferential or axial cracks are considered from the leakage and breakage viewpoint.

HISETS: A software system for designing semiconductor device packages

HISETS (Hitachi Semiconductor Thermal Strength Design System), a software system for designing semiconductor device packages was developed. Five programs are linked together to form a unified analysis of six important package design characteristics; (1) Thermal resistance, (2) Thermal deformation, (3) Thermal stress, (4) Heat resistance of chips and substrates, (5) Life of bonding layer, and (6) Change in electrical characteristics due to stress. An appropriate structure can be quickly obtained by simulating the revision of a structure until calculated results satisfy desired specifications.

Analysis of Ductile Fracture Behavior of Type 304 Stainless Steel

This report describes the plastic deformation behavior of notched plates of type 304 stainless steel and the ductile fracture criteria for such plates. Elastic-plastic finite element analyses were carried out to determine the relation between crack opening displacement and applied load. The results of the analyses agreed rather well with those obtained in experiments over a relatively small strain, but there were large differences were apparent between the calculated and experimental values in the large strain in which cracks initiate around notches. A simple equation was proposed to predict the load at the onset of penetration of the part-through notched plates.

Interference of light reflected from a convex face

Interference fringes are produced by a simple method, i.e., irradiating a convex face with coherent light. This method can only be used if the face has a mirror surface and the profile of the convex face is expressed by a mathematical function with a point of inflection. This convex face is generally shaped where a thin plate is deformed by pressure. Interference fringes are made wherever reflected light propagates and is clear even in high fringe order ranges.

Non-contact profile measurement of a reflecting diaphragm surface

Abstract An interference pattern produced by a simple optical set-up irradiating a curved surface with coherent light is presented. The pattern is formed where reflected light beams intersect, even far from the curved surface. This reflected light pattern can be used for measuring curved diaphragm profiles which are expressed by mathematical functions with points of infection.