Abstract: A method for non-invasively monitoring a pressure of a compressed gas inside a closed container includes: forming a magnetic circuit through a portion of the outside wall of the container; detecting magnetic flux amplitude changes in the magnetic circuit created by a transient stress in the outside wall of the container; producing data representing the magnetic flux amplitude changes; and monitoring pressure changes from a nominal pressure by evaluating the data representing the magnetic flux amplitude changes.

Abstract: A method and apparatus for the inspection of ferromagnetic and non-ferromagnetic pipes, tubes or other cylindrical shell structures utilizing the magnetostrictive effect to detect defects such as corrosion pits, wall thinning, and cracks within the structure under evaluation. The apparatus and method constitute an active testing application, wherein 1) a transmitting coil element generates a mechanical pulse within a cylindrical shell structure through the magnetostrictive effect and a second coil detects reflected mechanical waves within the pipe, this by the inverse magnetostrictive effect, or 2) a single sensor functions as both transmitter and detector. The present invention also anticipates a passive monitoring application with a detection coil that continuously monitors ferromagnetic or non-ferromagnetic tubes, pipes, etc.

Abstract: A method and apparatus for the nondestructive evaluation of ferromagnetic and non-ferromagnetic materials, particularly wire ropes, cables, and strands, and pipes utilizing the magnetostrictive effect for measuring minute variations in magnetic fields and characterizing these minute variations as indicative of the acoustic/ultrasonic behavior of fractures, cracks, and other anomalies within a substance under evaluation. The apparatus and method contemplate both an active testing application, wherein a transmitting sensor generates an acoustic/ultrasonic pulse within a material through the magnetostrictive effect and a second receiving sensor detects reflected acoustic/ultrasonic waves within the material, again by the inverse magnetostrictive effect. The advantages of utilizing magnetostrictive sensors as opposed to well known piezoelectric sensors lies in the ability to generate and detect acoustic/ultrasonic waves without a direct physical or acoustical contact to the material.

Abstract: A method and apparatus for the nondestructive evaluation of ferromagnetic and non-ferromagnetic materials, particularly wire ropes, cables, and strands, and pipes utilizing the magnetostrictive effect for measuring minute variations in magnetic fields and characterizing these minute variations as indicative of the acoustic/ultrasonic behavior of fractures, cracks, and other anomalies within a substance under evaluation. The apparatus and method contemplate both an active testing application, wherein a transmitting sensor generates an acoustic/ultrasonic pulse within a material through the magnetostrictive effect and a second receiving sensor detects reflected acoustic/ultrasonic waves within the material, again by the inverse magnetostrictive effect. The advantages of utilizing magnetostrictive sensors as opposed to well known piezoelectric sensors lies in the ability to generate and detect acoustic/ultrasonic waves without a direct physical or acoustical contact to the material.

Abstract: A method for rapidly detecting and locating reinforcing steel corrosion in concrete structures using non-linear harmonic and intermodulated frequencies of electromagnetic signals. The method comprises transmitting either a single primary frequency or two primary frequencies into the concrete structure in the general direction of the reinforcing steel. The reflected/generated signal, which is composed of the primary frequencies and of various harmonics and intermodulation components, is received, filtered, and amplified. A third order harmonic frequency is isolated with a band pass filter, is amplified, and is compared with the amplitudes of the primary frequencies. Intermodulation frequencies, primarily the combination of the primary of a frequency and the second harmonic of a second frequency, or the primary of a second frequency and the second harmonic of a first frequency, are isolated by appropriate band pass filter, are amplified, and are compared with the primary frequency or frequencies.

Abstract: A non-destructive method for evaluating ropes, cables, and strands for flaws and tension is shown. The method permits detecting flaws by recognizing certain vibrational wave amplitude and distribution patterns resulting from striking a test subject with a transverse force. Tension on a test subject is calculated by measuring propagation velocity of the vibrational waves through the test subject. An apparatus is provided which produces vibrational waves in a test subject, measures the amplitude and time distribution of the waves, and displays the measurements for analysis.

Abstract: A method of monitoring the cylinder wall wear using ultrasonic phase comparison techniques is disclosed. The method comprises the steps of introducing ultrasonic waves in a cylinder wall so that the waves travel through the cylinder wall. A change in the traveling time of the ultrasonic waves traveling through the cylinder wall due to cylinder wall wear is determined. The amount of wear of the cylinder wall is calculated by multiplying the velocity of the ultrasonic waves in the cylinder wall by the traveling time change due to cylinder wall wear. The traveling time change due to cylinder wall wear is obtained by determining the actual change in travel time by a phase comparison of the traveling ultrasonic waves and adjusting the actual change in travel time to compensate for any change due to temperature variation of the cylinder wall. With this method, small changes in traveling time on the order of 10.sup.-11 second can be determined so that thickness changes due to wear on the order of 5.times.10.sup.

Abstract: This disclosure relates to a nondestructive method of measuring stress in a ferromagnetic structural material. One method involves the measurement of the change in ultrasonic velocity induced by an externally applied magnetic field; the method enables nondestructively determining the magnitude, the direction, and the sign (i.e., tensile or compressive) of a stress in a ferromagnetic material. The magnetically induced velocity change of an ultrasonic wave is caused by the magnetoelastic coupling in the ferromagnetic material. This magnetically induced velocity change is characteristically dependent on the magnitude and the sign of the stress and also on the relative orientation of the stress, the magnetic field, and the polarization and propagation direction of the ultrasonic wave. The dependence of magnetically induced velocity changes can be utilized for nondestructive stress measurements. In one version, for measuring bulk stresses, either a longitudinal ultrasonic wave or a shear ultrasonic wave is used.