| 摘要 |
1,104,875. Ultrasonic flaw detectors. DR. J. U. H. KRAUTKRAMER GESELLSCHAFT FUR ELEKTROPHYSIK. 24 May, 1966 [18 Oct., 1965], No. 23169/66. Heading H4D. In a method of ultrasonic pulse-echo flaw testing a measure of the departure of the configuration of a flaw from a smooth, plane shape is derived as the ratio of the amplitudes of the electrical pulse outputs of two amplifiers of identical gain but different bandwidths each having as input the electrical pulse corresponding to an ultrasonic echo pulse. The invention utilizes the fact that an amplifier of large bandwidth has a shorter rise and decay time than one of narrower band-width so that echo pulses due to smooth plane flaws, which closely resemble the transmitted pulses, i.e. narrow pulses, produce output pulses of lower amplitude from the amplifier of narrower band-width than from the larger band-width amplifier whereas echoes due to fissured &c. flaws have flattened wave fronts and are transmitted through the amplifier of narrower band-width with less amplitude attenuation than are the narrow pulses. Thus, when the amplifier of larger band-width is arranged to produce pulses of equal amplitude for both broad and narrow input pulses the ratio between such amplitude and that of the output pulses from the narrow band amplifier gives a measure of the departure of the flaw from a smooth plane configuration. In carrying out the invention the received echoes may be supplied to the two amplifiers either sequentially (Fig. 1, not shown) or simultaneously (Fig. 4, not shown) rectifier means being incorporated in the amplifier or in associated display means which, in the case of the Fig. 1, arrangement, may comprise an oscilloscope and/or a gated peak voltage indicator-the display means being connected to the amplifiers in correspondence with the sequential inputs whilst, in the Fig. 4 arrangement, the display device may be an electromechanical, or equivalent electronic quotient meter yielding the required ratio directly on a measuring instrument. The input voltages to the display devices may be recorded. |
