Abstract: A non-destructive testing device and method is provided wherein a test piece is held in a test stand located in a test enclosure. The test enclosure is evacuated. The test stand and test piece held therein is then vibrated, immediately after which the test piece is irradiated by at least one beam of collimated radiant energy, preferably ultraviolet light, which is scanned over the test piece in a systematic pattern. Measurements of exo-electrons given off by the test piece responsive to the irradiation of the test piece are recorded for correlation with other exo-electron measurements made of the test piece throughout the life of the test piece. For metal test pieces not sensitive to this technique, a selected gas or gases (mixed or in sequence) may be introduced into the evacuated chamber for forming a surface compound of gas and metal on the surfaces of the test piece. The test enclosure is then evacuated and the test piece is vibrated and scanned by radiant energy and measurements taken.

Abstract: A method is disclosed for detecting the onset of cracking in an article subjected to dynamic loading. The article is subjected to a dynamically changing load, and additionally is loaded and vibrated at its natural frequency. The onset of a crack in the article is determined by noting a change in its natural frequency.

Abstract: A torsional vibration monitoring system for monitoring torsional vibration occurring in a rotating shaft system such as in a power generator turbine is disclosed. Torsional vibrations are measured at a small number of measurable positions on the rotating shaft system, and stresses at other arbitrary positions are estimated by linearly decomposing the torsional vibrations. The fatigue life expenditure on the rotating shaft system is obtained and monitored on the basis of the estimation obtained by the linear decomposition of the torsional vibration. For a huge vibration such as caused by thunder which may produce stresses on the rotating shaft system and which can not be estimated by the linear decomposition thereof, the torsional vibration monitoring apparatus may be provided with means to produce data which may be used in other analysis, by recording real torsional vibrations caused thereby.

Abstract: A method of detecting very small structural flaws at loads below those which cause the flaws to propagate is disclosed. Certain phenomena and relationships of fracture mechanics are utilized in conjunction with the generation, detection and interpretation of thermal emission signals indicative of plastic deformation of the tested material.

Abstract: A data acquisition system utilizing a microcomputer and incorporating a plurality of monitors each adapted to produce an electrical signal indicative of a physical condition of apparatus to be monitored. The electrical signals are fed via multiplexing equipment and analog-to-digital converters into the microcomputer which is equipped with print-out means. The system is such that the level of any one or all of the signals from the respective monitors can be printed out as well as a change in the condition of any signal. Means are incorporated into the computer for calculating and printing the trend (i.e., the slope of a plot of signal amplitude versus time) of a succession of stored signals from any monitor which would indicate a probable malfunction of a device being monitored and the probable time to failure. In the case where the signals from the monitors comprise vibration signals, the system performs an automatic frequency spectrum analysis whenever a probable or actual malfunction is detected.

Abstract: An improved holographic recording instrument for recording on a holographic recording medium two successive holograms of the structure under differing stress conditions to produce a holographic interferogram containing information defining a deformation fringe pattern representing the deformations in the structure resulting from the change in stress conditions. A holographic recording unit for the instrument and for general holographic recording use.