We propose and demonstrate an approach for 10 kHz to 34 MHz ultrasound detection based on a dual-core As2Se3-PMMA taper. We fabricate dual-core As2Se3-PMMA tapers with a Young’s modulus 24 times smaller than that of silica fibers, which enhances the acoustic response. Dual-core As2Se3-PMMA fiber tapers show high sensitivities to both shear and longitudinal waves due to the dual-core structure, low Young’s modulus, submicrometer dimension of the core, and the high-contrast interference pattern by the even and odd modes. A dual-core As2Se3-PMMA taper with a core diameter of 0.6 µm detects acoustic waves in the frequency range from 10 kHz to 34 MHz, which are excited by three piezoelectric transducers with optimal operating frequencies of 100 kHz, 3.65 MHz, and 6.8 MHz, respectively.
An ultrasonic Rayleigh wave transducer was designed for nondestructive pressure measurement in vessels. Using polyimide resin as the wedge material, the Rayleigh wave transducer had two piezoelectric elements which were placed in the same wedge with a certain distance. Variations in pressure and temperature of vessels can affect the velocity of ultrasonic waves, which will affect variations in time delay in receiving of the same Rayleigh wave with the two piezoelectric elements of the designed transducer. Based on the acoustoelasticity principle and considered the effect of temperature, a practical correlation model between the time delay and both the pressure and temperature of vessels was developed. Using an air vessel as a specimen, Rayleigh wave transducers were arranged in the axial direction of the vessel. The results of temperature experiments show that effect of changes in temperature on time delay agree with the theoretical results. With the calculation temperature compensation in pressure experiment, the relationship between the variations in the time delay caused by changes of pressure and the pressure is established. The pressure measurement results show that the measurement model is effective and the maximum absolute error is 0.09 MPa, which could be acceptable in engineering application.
The magnetic flux leakage (MFL) testing, as a modern nondestructive testing technology, requires fast and accurate signal progressing methods. A practical signal progressing method for MFL testing was presented, especially for tank floor MFL testing. According to the FFT result of the original signal, a difference amplifier and a low-pass filter were designed in the hardware signal progressing. In the digital signal progressing, a numerical differential progress and an IIR band-pass filter were adopted. Experimental results show that the presented method could effectively eliminate noise. Defect depth measuring results show that, for the 8 mm thickness specimen, the maximum absolute error of depth is 0.23 mm, which means 2.8 % of the 8 mm thickness.
The public reporting burden for this collection of information is estimated to average 1 hour per response, including the time for reviewing instructions, searching existing data sources, gathering and maintaining the data needed, and completing and reviewing the collection of information. Send comments regarding this burden estimate or any other aspect of this collection of information, including suggestions for reducing the burden, to the Department of Defense, Executive Service Directorate (0704-0188). Respondents should be aware that notwithstanding any other provision of law. no person shall be subject to any penalty for failing to comply with a collection of information if it does not display a currently valid OMB control number.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.