Heihachi Shimada

Stress dependence of leaky surface wave on PMMA by line-focus-beam acoustic microscope

The authors discuss a line-focus-beam (LFB) acoustic microscope as a system for evaluating local stresses in polymeric materials. The goal of this paper is to reveal the stress-dependence of the velocity of the leaky surface skimming-compressional wave (LSSCW), which is excited by the LFB acoustic microscope and propagates on the boundary of the water/specimen surface.

Application of crack-tip-strain loop to fatigue-crack propagation

AbstractCyclic strain at the tip zone of a fatigue crack could be measured continuously by the fine-grating method. At one cycle of fatigue, the loop between strain at the crack tip and applied load was called by the authors the ‘crack-tip-strain loop’ (CTS loop). The CTS loop, which was thought to imply keys of the crack-growth problems, was applied to the fatigue-crack propagation. ΔKeffT was defined from the stress (or load) range of CTS loop as one corrected parameter of ΔK. Moreover, cyclic crack-tip-strain range,

Fine-grid method for large-strain analysis near a notch Tip

\Delta _{\varepsilon ^{\rm T} }

Influence of breadth in bars with reinforced circular holes under tension

, from the strain range of CTS loop was proposed as one possible parameter for fatigue-crack propagation.

Photoelastic investigation of stresses in composite models with notches and holes

Some fundamental problems on the optical method of caustics, which is used to determine the value of the stress-intensity factor, are studied. The paper shows that the radiusro of the initial curve considerably affects the results and describes a method to eliminate this effect. This method is also applied to the biaxial-stress fracture problem. It is shown that the biaxial stress affects the fracture toughness of thin specimens of Plexiglas sheets and that the fatigue-crack-growth rate is increased due to the compressive stress along the crack line.

Quantitative Measurement of Ultrasonic Wave Stress in a Solid by Stroboscopic Photoelasticity

The purpose of this paper is to develop a technique for a fine-grid method to analyze the large strains in a local region surrounding a notch tip. There is a region surrounding a notch tip where very large displacements take place. In such a region, the assumption of infinitesimal deformation does not apply. In this paper, the Lagrangian description was used as a strain-displacement relation. In-plane components of displacements,u andv were obtained directly from change of location of fine grids. Displacement in the thickness direction,w, was estimated by a relation betweenw and (∂v/∂y), decided in advance. It was confirmed that the fine-grid method described in this paper was very useful in measuring directly and continuously the large strains in a local region surrounding a notch tip.

Embedded fine-grid method applied to three-dimensional stress-intensity-factor analysis

This letter describes the trial and processes of producing sintered Ni−Ti compacts, and the characteristics of the SME of the sintered Ni−Ti materials

MEASUREMENT OF RESIDUAL STRESSES OF THE WELDED CARBON STEEL PLATE BY MAGNETIC METHOD USING CONTACT TYPE SENSOR.

This paper reports stress distributions in epoxy-resin bars with reinforced circular holes under tension. The holes were reinforced by bonding aluminum rings to the bars inside the holes. The stress distributions were determined photoelastically.Various proportions of circular reinforcements and different widths of bars were investigated under pure tension. Stress distributions were determined in the epoxy-resin part of the bar, and the maximum shear stresses were given special attention. The relation between maximum shear stress and the width of the bar was determined, and the ranges for which the theoretical solution for an infinite bar approximates that for a finite bar were defined.