Axial Displacement Measurements Research Articles

A Simple, High Precision Biaxial Extensometer for High Temperature Creep Study

Abstract A biaxial extensometer for high temperature creep study is described. The axial displacement is measured by a linear variable differential transformer, the angular displacement by a rotary variable differential transformer. The possible interference between the axial and angular displacement measurements is minimized by using instrument linear motion ball bushing bearings and case hardened shafts. Examples of applications are given for a constant shear strain rate test and a creep test at 200°C under abrupt changes of stress states performed on a thin-walled tube specimen made of 2618 aluminum alloy.

Estimates of ventilation from body surface measurements in unrestrained subjects.

To make estimates of ventilation from measurements of body surface movements in unrestrained subjects, we measured changes in linear dimensions and cross-sectional areas of the rib cage (RC) and abdomen (AB) of six healthy unrestrained subjects during a variety of maneuvers. RC and AB anteroposterior diameters and abdominal length in the cephalocaudal axis (axial displacement) were measured with magnetometers, and RC and AB cross-sectional areas were measured with a respiratory inductance plethysmograph. Flow was measured at the mouth with a pneumotachograph and integrated electrically to give volume. Volume and body surface measurements were analyzed by multiple linear regression. Addition of the axial measurements to either the anteroposterior dimensions or cross-sectional areas of RC and AB improved estimates of tidal volume in all subjects (P less than 0.01). With measurements of axial displacement and cross-sectional area of the RC and AB, tidal volume could be reliably estimated to within 20% of actual ventilation. We conclude that measurement of axial displacements improves estimates of ventilation in unrestrained subjects.

「弥生」の反応度パルス運転時燃料体の振動特性

For research reactors as well as power reactors, it is important to watch the integrity of core fuel. Specifically, pulse reactor safety needs monitoring of the dynamic behavior of core fuel every time pulsed.In August 1976, University of Tokyo research reactor attained 1GW pulse core. In this pulse operation, the dynamic displacement or vibration of fuel were measured by the Core Displacement Measuring Devices which were positioned at four points of the core, and used for the radial and axial displacement measurement of core fuel. The data shown here presenting some pictures of YAYOI type fuel dynamics seem very interesting and are very useful as safety measures.

Measurements of axial displacements undergone by a diffusing object in speckle photography

The speckles of the image plane of an object are both radially shifted and decorrelated when the object is axially translated through an amount ϵ. We demonstrate that this radial shift, which is related to the position of the pupil of the optical system, disappears when the pupil lies in the back focal plane of the imaging lens. However, if the irradiance of the image plane is twice recorded on a photographic plate which is laterally shifted through ζ H between the exposures, the minimum value of the contrast of the Fourier fringes exhibited by the plate after processing, gives the value of ϵ if ϵ is less than a particular value, ϵ M which will be defined. Also we propose a new speckle measurement method in which the fringes are automatically removed when ϵ is greater than ϵ M. We record the image of the object illuminated in convergent light through an amplitude diffuser placed in the Fourier plane of the object. The mean speckle speckle size of the diffuser is equal to the mean size of the speckles generated by the object in its Fourier plane.