Disclosed are methods that, by not physically touching a material being measured, can measure the material's differential response quite accurately. A collimated light shines on the material under test, is reflected off it, and is then captured by a device that records the position where the reflected light is captured. This process is done both before and after the material is processed in some way (e.g., by applying a coat of paint). The change in position where the reflected light is captured is used in calculating the deflection of the material as induced by the process. This measured induced deflection is then used to accurately determinate the stress introduced into the material by the process. Other characteristics of the material under test, such as aspects of the material composition of a bi-metallic strip, for example, may also be determined from a deflection measurement.

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.

A glass product stress evaluation system is provided. The glass product stress evaluation system includes a background light source to selectively transmit light of different wavelengths and illuminates a glass product. An imaging device is mounted in proximity to the glass product and develops digitally encoded representations of internal annealing stresses formed within the glass product. The imaging device converts the digitally encoded internal stress representations into digital signals. A plurality of optical devices provides a converging view of the glass product. A plurality of filters is mounted in proximity to the plurality of optical devices and selectively transmits light of different wavelengths to the optical devices, thereby transforming detected imaged stresses in the glass product into visible colors. A processing unit receives the digital images from the imaging device and converts the digital images into visible images. The digital images can be classified into annealing grades.

An evaluation method of a silicon wafer allows non-destructive and non-contact inspection of a slip that affects the electrical properties of semiconductor devices, without being subjected to restrictions of the surface condition of silicon wafers or processing contents as much as possible. The evaluation method of a silicon wafer includes a step of section analysis where a surface of a single crystal silicon wafer after thermal processing is divided by equally-spaced lines into sections with an area of 1 mm.sup.2 or more and 25 mm.sup.2 or less and the existence of strain in each of the sections is determined based on a depolarization value of polarized infrared light, and a screening step where the wafer is evaluated as non-defective when the number of adjacent sections being determined to have strain by the section analysis step does not exceed a predetermined threshold value.

A method for measuring a residual stress, including irradiating a cast and forged steel product with X-rays; two-dimensionally detecting intensities of diffracted X-rays originating from the X-rays; and calculating a residual stress based on a diffraction ring formed by an intensity distribution of the diffracted X-rays, wherein the irradiating includes changing a condition for irradiation of the cast and forged steel product with the X-rays, the irradiating is a step of performing the changing each time the cast and forged steel product is irradiated with the X-rays, the calculating is a step of calculating the residual stress each time the cast and forged steel product is irradiated with the X-rays, and the method further includes averaging a plurality of residual stresses calculated in the calculating after the irradiating, the detecting, and the calculating are performed in this order a plurality of times.

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.

An evaluation method of a silicon wafer allows non-destructive and non-contact inspection of a slip that affects the electrical properties of semiconductor devices, without being subjected to restrictions of the surface condition of silicon wafers or processing contents as much as possible. The evaluation method of a silicon wafer includes a step of section analysis where a surface of a single crystal silicon wafer after thermal processing is divided by equally-spaced lines into sections with an area of 1 mm.sup.2 or more and 25 mm.sup.2 or less and the existence of strain in each of the sections is determined based on a depolarization value of polarized infrared light, and a screening step where the wafer is evaluated as non-defective when the number of adjacent sections being determined to have strain by the section analysis step does not exceed a predetermined threshold value.

A system may include a first injection electrode, a second injection electrode, a first sensing coil, and a second sensing coil. The first injection electrode and the second electrode may each be configured to contact a material and conduct an alternating current through a portion of the material. The first sensing coil and a second sensing coil may each be configured to inductively sense a Hall current created by the alternating current and a magnetic field perpendicular to the alternating current. The first sensing coil and the second sensing coil may be coupled in series.

The present disclosure relates to the technical field of non-destructive detecting of residual stress, and in particular to a non-destructive detecting device for component residual stress gradient. the non-destructive detecting device comprises: groups of transmitting transducers and receiving transducers arranged symmetrically to each other, the transmitting transducers closer to the symmetry axis have greater excitation frequencies; an acoustic wedge coupled to the groups of transmitting transducers and receiving transducers, wherein groups of cylindrical transmitting tunnels and receiving tunnels are provided obliquely within the transmitting connection area and the receiving connection area through their top surfaces and toward their bottom surfaces, the transmitting transducers are coupled to the transmitting tunnels in a one-to-one correspondence, the receiving transducers are coupled to the receiving tunnels in a one-to-one correspondence, and the bottom surfaces of the transmitting connection area and the receiving connection area are pressed against the surface of the detected component; and a calculation processing module electrically connected to the transmitting transducers and the receiving transducers. The non-destructive detecting device solves the problem that the residual stress values of components at different penetration depths cannot be detected at the same time.

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.