Bar material ultrasonic linear array imaging detection method based on Fermat's principle

Abstract

The invention provides a bar material ultrasonic linear array imaging detection method based on a Fermat's principle. The bar material ultrasonic linear array imaging detection method comprises the following steps: utilizing a phased array and a wedge for coupling a bar material by a linear array; setting a bar material size in ultrasonic simulation software; setting the linear array and a signal source according to an actual linear array parameter and an A scanning signal; carrying out electronic scanning to obtainscanning signal of each array; calculating acoustic wave propagation time of each array element according to the Fermat's principle, so as to calculate delaying time; overlapping the delayed A scanning signals in sequence to form an A scanning signal with a deflection and focusing effect; carrying out B scanning imaging on the stacked A scanning signals according to a propagation path; and judging defects and other structure positions according to a maximum value position of an amplitude of each imaging point after imaging. According to the bar material ultrasonic linear array imaging detection method provided by the invention, the disadvantages of an ultrasonic direction contact method of small-diameter bar materials and longitudinal wave detection carried out by a water immersion method can be overcome; and the bar material ultrasonic linear array imaging detection method has good popularization and application prospects.

Description

technical field [0001] The invention relates to the field of non-destructive testing of small-diameter bar material phased array ultrasonic longitudinal wave imaging, and more specifically relates to a method for bar material ultrasonic longitudinal wave imaging detection based on the Fermat principle and using a phased array ultrasonic linear array. Background technique [0002] Small-diameter bars are important raw materials for aerospace key components, important connecting structural bolts, wind tunnel balances, high-pressure joints, valves, and other components. Direct contact methods and water immersion methods are usually used for ultrasonic longitudinal wave nondestructive testing. Schematic diagram of longitudinal wave detection of small-diameter bars by ordinary straight probe direct contact method, as shown in figure 1 shown. Due to the small radius of curvature of small-diameter rods, if ordinary straight probes are used to detect radially incident longitudinal ...

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Problems solved by technology

If the position of the probe is slightly deviated, the sound beam will be deflected and scattered in the bar, the signal-to-noise ratio will be reduced, and even the echo signal cannot be received

Due to the above reasons, it is extremely difficult to use the ordinary straight probe direct contact method to conduct longitudinal wave detection of small diameter bars.

Although the water immersion ultrasonic method overcomes the shortcomings of the straight probe direct contact method, such as poor coupling, large detection blind area, more clutter, and low signal-to-noise ratio, but water immersion ultrasonic often requires a larger water tank and an automatic control system to operate the probe and workpiece (rolling). bar for B-scan imaging), such as figure 2 As shown, it is not conducive to on-site detection, and the length and size of the detected rods are also limited, and the rods will be corroded to a certain extent if they are immersed in water for a long time.

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