Abstract: The invention discloses an ultrasonic dual-wave reliability measurement method for a bolt stress. A first ultrasonic dual-wave transducer is configured to transmit and receive an ultrasonic transverse wave or an ultrasonic longitudinal wave, a second ultrasonic dual-wave transducer is configured to receive the ultrasonic transverse wave or the ultrasonic longitudinal wave, and the transverse wave or longitudinal wave generated by the first ultrasonic dual-wave transducer is propagated in a measured bolt. If a difference between TOF for which the first ultrasonic dual-wave transducer receives the echo signal and double of TOF for which the second ultrasonic dual-wave transducer receives the echo signal in a same mode is not greater than a quarter of one transmission period T, the measured TOF satisfies verification requirements. Reliability of time-of-flight data of the ultrasonic wave can be verified, and various measurement errors can be prevented.

Abstract: An electromagnetic ultrasonic double-wave transducer includes a shell (1), and a permanent magnet assembly, a coil (4), a shielding layer (5), and a wire (6) which are provided in said shell (1); said coil (4) is fixed on the bottom of said shell (1) and is located below said permanent magnet assembly; said shielding layer (5) is arranged between said permanent magnet assembly and said coil (4); one end of said wire (6) is connected to said coil (4) while the other end thereof is connected to the power supply and signal plug (7); said permanent magnet assembly includes a third permanent magnet (12) and a fourth permanent magnet (13); the upper end faces of said third permanent magnet (12) and said fourth permanent magnet (13) realize magnetic circuit closing by means of a magnetic circuit closing element (8).

Abstract: An electromagnetic ultrasonic double wave transducer, comprising a shell (1), and a permanent magnet assembly, a coil (4), a shielding layer (5), and a wire (6) which are provided in the shell (1). The permanent magnet assembly comprises a first permanent magnet (2) and a second permanent magnet (3) sleeved on the first permanent magnet (2). The magnetizing directions of the first permanent magnet (2) and the second permanent magnet (3) are perpendicular to the bottom of the shell (1), and the magnetic field directions of the first permanent magnet (2) and the second permanent magnet (3) are opposite. A non-conducting non-magnetic bushing material (9) is provided between the first permanent magnet (2) and the second permanent magnet (3), and upper end faces of the first permanent magnet (2) and the second permanent magnet (3) realize magnetic circuit closing by means of a magnetic circuit closing element (8).

Abstract: An air-coupled ultrasonic interferometric method is disclosed. An air-coupled ultrasonic transducer, as a probe, is placed directly facing the surface of a workpiece, and an ultrasonic wave is reflected back and forth between the ultrasonic transducer and the surface of the workpiece; the phase difference of the first echo reflected from the surface of the workpiece and reaching the air-coupled ultrasonic transducer is measured; based on the change of the ultrasonic frequency and wavelength, the measured distance is transformed into the rate of change of the acoustic phase with respect to the acoustic angular frequency, wherein the change in the acoustic angular frequency is a product obtained by multiplying 2? by the difference between the highest frequency F2 and the lowest frequency F1 within the bandwidth fB of the air-coupled ultrasonic transducer.

Abstract: An air-coupled ultrasonic interferometric method is disclosed. An air-coupled ultrasonic transducer, as a probe, is placed directly facing the surface of a workpiece, and an ultrasonic wave is reflected back and forth between the ultrasonic transducer and the surface of the workpiece; the phase difference of the first echo reflected from the surface of the workpiece and reaching the air-coupled ultrasonic transducer is measured; based on the change of the ultrasonic frequency and wavelength, the measured distance is transformed into the rate of change of the acoustic phase with respect to the acoustic angular frequency, wherein the change in the acoustic angular frequency is a product obtained by multiplying 2? by the difference between the highest frequency F2 and the lowest frequency F1 within the bandwidth fB of the air-coupled ultrasonic transducer.

Abstract: An electromagnetic ultrasonic double wave transducer, comprising a shell (1), and a permanent magnet assembly, a coil (4), a shielding layer (5), and a wire (6) which are provided in the shell (1). The permanent magnet assembly comprises a first permanent magnet (2) and a second permanent magnet (3) sleeved on the first permanent magnet (2). The magnetizing directions of the first permanent magnet (2) and the second permanent magnet (3) are perpendicular to the bottom of the shell (1), and the magnetic field directions of the first permanent magnet (2) and the second permanent magnet (3) are opposite. A non-conducting non-magnetic bushing material (9) is provided between the first permanent magnet (2) and the second permanent magnet (3), and upper end faces of the first permanent magnet (2) and the second permanent magnet (3) realize magnetic circuit closing by means of a magnetic circuit closing element (8).