The prism-coupling systems and methods include using a prism-coupling system to collect a 2D digital mode spectrum of an IOX article. The mode line and critical angle positions and orientations are found by performing a weighted fit to mode line and critical angle images and are used to define a compensated mode spectrum. If mode line tilt is found, it is removed from the 2D digital mode spectrum to define the compensated mode spectrum. The compensated mode spectrum is then processed using techniques known in the art to provide a more accurate estimate of stress-related characteristics of the IOX sample versus using the uncompensated mode spectrum. Derivative-based methods of accurately establishing positions of intensity transitions in a mode spectrum of an IOX sample using a derivative spectrum and curve fitting are also disclosed.

The present invention relates to the sector of self-diagnostic composite materials. In particular, the invention presents an agent, which can be cross-linked together with a curing agent in a matrix, e.g. an epoxy resin, and fibres, e.g., carbon fibre, in order to obtain a composite material containing a reporting probe capable of detecting stress, fatigue and microscopic cracks in the material with high spatial resolution and sensitivity.

A stress measurement device for strengthened glass includes a polarization phase difference variable member configured to vary a polarization phase difference of a laser light by one wavelength of the laser light or more; an imaging element configured to image a plurality of times at a predetermined time interval a scattered light emitted according to the laser light with the varied polarization phase difference entering the strengthened glass, and obtain a plurality of images; and an arithmetic unit configured to measure a periodic change in luminance of the scattered light using the plurality of images, calculate a change in a phase of the change in luminance, and calculate a stress distribution in a depth direction from a surface of the strengthened glass based on the change in the phase.

A method for determining residual stress in a selectively hardened parts including an unhardened region adjacent to a hardened region is provided. The method includes obtaining a Barkhausen Noise (BN) value for the unhardened region and selecting a corresponding absolute residual stress value from a correlation between BN values and absolute residual stress values. The selected absolute residual stress value accurately estimates the absolute residual stress in the hardened region of the selectively hardened part. In variations of the method the unhardened region is surrounded by the hardened region, the hardened region is a laser hardened region and the unhardened region is not laser hardened.

A gear positioning device according to an embodiment includes: a chuck configured to hold a gear; a rotation drive mechanism configured to rotationally drive the chuck so that the gear rotates around a predetermined rotation axis; a displacement meter configured to continuously or periodically acquire a measurement value representing a distance between a reference point located outside the gear and an outer peripheral surface of the gear while rotating the gear; and a control device configured to set a part of the outer peripheral surface of the gear as a measurement object on the basis of a rotation angle of the gear, the measurement value, and at least one predetermined reference value and control the rotation drive mechanism so that the measurement object is disposed at a reference position.

This evaluating method is an evaluating method for evaluating an assembly (50) provided with a reinforced member (60) and a reinforcing member (70), and includes: a step of introducing incident light into a first optical fiber (20) extending between a first composite layer and a second composite layer and detecting outgoing light therefrom to measure a first strain distribution, and introducing incident light into a second optical fiber (30) extending between the second composite layer and a third composite layer and detecting outgoing light therefore to measure a second strain distribution; and a step of acquiring the shape of wrinkles at the surface (60s) of the reinforced member (60) from the first strain distribution and the second strain distribution.

Provided are a residual stress estimation method and a residual stress estimation device capable of estimating residual stress suitable for a structure in which inherent strain occupied mainly by plastic strain occurs. A constraint condition is introduced to a distribution function used in the residual stress estimation method based on an inherent strain method, the constraint condition being that a plastic-worked structure does not undergo volume change before and after working. Residual stress or elastic strain is measured from a T piece collected from the structure, and a parameter of the distribution function is optimized so as to approximate the inherent strain at each measurement point obtained from the measured value of the residual stress or elastic strain. An estimated value of the residual stress in the structure is calculated using the obtained parameter.

A method of testing the residual stress around a cold-worked hole in a test material. The test uses two identical eddy current coil pairs, each pair having a driving coil and a pickup coil. One coil pair is placed into the cold-worked hole. The other coil pair is placed into a non-cold worked hole in a reference material. When the coils are activated, and with a properly chosen phase difference between the excitation signal and the output signal, the in-phase component of the output voltage signal can be correlated to residual stress around the cold-worked hole.

A method of testing the residual stress around a cold-worked hole in a test material. The test uses two identical eddy current coil pairs, each pair having a driving coil and a pickup coil. One coil pair is placed into the cold-worked hole. The other coil pair is placed into a non-cold worked hole in a reference material. When the coils are activated, and with a properly chosen phase difference between the excitation signal and the output signal, the in-phase component of the output voltage signal can be correlated to residual stress around the cold-worked hole.

Analysis of residual stress in materials is often done in static conditions in a laboratory. Accurate systems and methods for performing these analyses in a dynamic, non-laboratory environment are notoriously difficult and can be very inaccurate. A method using a portable, field deployable apparatus having greater accuracy than currently available is disclosed whereby accurate and repeatable residual stress analysis may be implemented in non-laboratory environments leading to greatly improved diagnostics, maintenance and life limit prediction. Especially the analysis of a pipe or channel can be facilitated with this invention.