Abstract: The invention is a method of and apparatus for characterizing the amplitudes of a sequence of reflected pulses R.sub.1, R.sub.2, and R.sub.3 by converting them into corresponding electrical signals E.sub.1, E.sub.2, and E.sub.3 and thereafter exponentially adjusting the amplitudes of the respective signals E.sub.1, E.sub.2, and E.sub.3 to substantially the same value during each sequence thereby restoring the reflected pulses R.sub.1, R.sub.2, and R.sub.3 to their initial reflection values by means of timing means 12 and 13, an exponential generator 17 and a time gain compensator 18. Envelope and baseline reject circuits 23 and 24 respectively permit the display and accurate location of the time spaced sequence of electric signals having substantially the same amplitude on a measurement scale on a suitable video display or oscilloscope 14.

Abstract: A method and apparatus for testing steel components for temper embrittlement uses magneto-acoustic emission to nondestructively evaluate the component. Acoustic emission signals occur more frequently at higher levels in embrittled components. A pair of electromagnets are used to create magnetic induction in the test component. Magneto-acoustic emission signals may be generated by applying an AC current to the electromagnets. The acoustic emission signals are analyzed to provide a comparison between a component known to be unembrittled and a test component. Magnetic remanence is determined by applying a DC current to the electromagnets, then turning the magnets off and observing the residual magnetic induction.

Abstract: An ultrasonic apparatus determines crack opening load by placing a transmit transducer on one side of the crack and a receive transducer on the opposite side of the crack. An acoustic signal passing through a region of the crack is mechanically rectified to produce a second harmonic of an input signal. A harmonic output signal of the receive transducer is converted into an electrical signal and the peak harmonic amplitude is determined while increasing a tension load on the specimen. The peak harmonic amplitude indicates crack opening load.

Abstract: Ultrasonic radio frequency toneburst are launched into a sample of material tested. The amplitude of the tone-bursts and the slope of the resulting static displacement pulses are measured. These measurement are used to calculate the nonlinearities of the material.

Abstract: A broadband megahertz range electrostatic acoustic transducer for use in a liquid environment. A liquid-tight enclosure 11 which includes a metallic conducting membrane 18 as part of its outside surface has a means 19 inside the liquid-tight enclosure for applying a tension to the membrane and for mounting an electrode 23 such that the flat end of the electrode is approximately parallel to the membrane. The invention includes structure and a method for ensuring that the membrane 18 and the flat end of the electrode 23 are exactly parallel and a fixed predetermined distance from each other.