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Ultrasonic directivity at different frequencies: (a) the ultrasonic directional angle at different frequencies; (b) the curve of directional angle with change in frequencies.
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Knowing propagating properties of an ultrasonic wave can enhance the non-destructive testing techniques in alloy materials field, such as the electromagnetic acoustic transducer techniques, and the piezoelectric ultrasonic transducer techniques. When temperature is taken into consideration, the ultrasonic propagating attenuation become very complex...
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Adhesive bonded structures are gaining attention in engineering and research communities due to their advantages over conventional joining methods. Non-destructive testing and health monitoring of adhesive bonded structures are challenges requiring focused research. Piezoelectric transducers are used for the actuation and sensing purposes in struct...
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... However, the attenuation factor used in the previous calculation was measured at room temperature. As Wu et al. reports, ultrasonic waves experience greater amounts of attenuation at higher temperatures 60 . As the solid surrounding the melt pool experiences high temperatures, and due to thermal accumulation at higher layers, the decrease in intensity is likely greater than what is predicted by Eq. 4. Since a wave's intensity is proportional to the energy it carries, less energy is transferred into the melt pool during the deposition of higher layers. ...
The presence of defects, such as pores, in materials processed using additive manufacturing represents a challenge during the manufacturing of many engineering components. Recently, ultrasonic vibration-assisted (UV-A) directed energy deposition (DED) has been shown to reduce porosity, promote grain refinement, and enhance mechanical performance in metal components. Whereas it is evident that the formation of such microstructural features is affected by the melt pool behavior, the specific mechanisms by which ultrasonic vibration (UV) influences the melt pool remain elusive. In the present investigation, UV was applied in situ to DED of 316L stainless steel single tracks and bulk parts. For the first time, high-speed video imaging and thermal imaging were implemented in situ to quantitatively correlate the application of UV to melt pool evolution in DED. Extensive imaging data were coupled with in-depth microstructural characterization to develop a statistically robust dataset describing the observed phenomena. Our findings show that UV increases the melt pool peak temperature and dimensions, while improving the wettability of injected particles with the melt pool surface and reducing particle residence time. Near the substrate, we observe that UV results in a 92% decrease in porosity, and a 54% decrease in dendritic arm spacing. The effect of UV on the melt pool is caused by the combined mechanisms of acoustic cavitation, ultrasound absorption, and acoustic streaming. Through in situ imaging we demonstrate quantitatively that these phenomena, acting simultaneously, effectively diminish with increasing build height and size due to acoustic attenuation, consequently decreasing the positive effect of implementing UV-A DED. Thus, this research provides valuable insight into the value of in situ imaging, as well as the effects of UV on DED melt pool dynamics, the stochastic interactions between the melt pool and incoming powder particles, and the limitations of build geometry on the UV-A DED technique.
... Also, the uniform heat transfer and diffusion of the ultrasonic bath allow to modify the freezing points improving the preservation of the microstructure of the plant and even animal cell (if they were matrices or meat waste), thus opening better and faster cryopreservation points of the solids or extracts subjected to ultrasound [45]. On the contrary, there is also evidence that once the ultrasound-treated food matrices or wastes are thawed, they will thaw rapidly, preserving most of the physical and chemical characteristics, if the ultrasonic treatment times to which the microstructure is subjected are respected [42]. Cell softening is another effect on the structure of the material under ultrasonic effect [41]. ...
Ultrasound technology use is a promising strategy for the exploitation of food waste by inducing structural changes on food matrices, favoring their decomposition. In this chapter we will be describing selected experimental methodologies that allow us to prove the influence of ultrasound on the waste decomposition, inducing its reduction and revaluation as a substrate to other applications. The conditions and recommendations of proposed method are also described. Our work aims to encourage the reader about the advantages of using ultrasound to minimize environmental and economic impact generated by food waste.
... Treiber et al. [22] explored the influence of reflection of the coupling layer on the ultrasonic attenuation coefficient, and demonstrated that reflection attenuation plays a dominant role in ultrasonic energy attenuation. Wu et al. [23] modeled the effect of temperature variation on the magnitude of ultrasonic attenuation of an aluminum alloy. Results indicated that ultrasonic energy attenuation was significantly affected by temperature. ...
... Because of the relevance and promising application of the results, numerous studies have been and continue to be conducted widely in this direction. Examples are given in Ross (1982); Damjanovic (1998); Roussy andPearce (1995 1998); Issadore et al. (2009); Andrés (2014); Kyncl et al. (2014); Mazouzi-Sennour and Henry (2014); Wu et al. (2018). The physical laws that explain the relationship between the effects and the reasons that caused them are known. ...
This paper proposes a mathematical model that can be used to quantify the effects of a polarized electric field on the mechanical properties of a polar dielectric in the framework of mechanics of deformable solids. The physical essence of the phenomenon is known. However, its direct use in practical calculations may cause difficulties due to the complexity of the composition and structure of materials used in the design and manufacture of specific products whose operation regimes are based on polarization effects. A continuum description of the polarization phenomenon makes it possible to circumvent these difficulties.
The basis of the generalized model is a micropolar linearly elastic medium. The generalization consists in taking into account the initial stress state of the material, as well as cross effects under the mutual influence of translational and rotational deformations, the possibility to calculate the characteristics of micropolar material properties based on a special nonlocal model of micropolar media with internal nonlocal potential interactions. It takes into account translational and rotational potential interactions of particles of a continuous medium at finite distances. The kinematic characteristics of the material are the same as those used by the traditional model of a micropolar elastic medium ‐ the gradients of translational displacements of the medium's particles, their rotations independent of the medium's rotation and rotations of the particles relative to the medium. Generalized forces performing work on these generalized displacements are volumetrically and surface‐distributed forces and moments. To determine the values of the parameters of the interparticle potentials of the nonlocal model, a method is proposed using data from experiments to determine the material constants of isotropic linearly elastic materials and the dispersion law for plane acoustic waves of high frequency. The paper considers and quantifies the effects of anisotropy in an initially isotropic material, as well as anharmonic effects that cause dielectric heating by a periodically changing polarizing field. The results are compared qualitatively and quantitatively with known experimental data and physical notions of the phenomena in question.
... With the development of EMAT testing technology, high-temperature EMAT testing technology is also becoming more mature. Wu et al. [22] proposed a model to calculate the ultrasonic attenuation caused by temperature changes and tested 7050 aluminum alloy at high temperatures. When the temperature increased from 20°C to 480°C, the ultrasonic energy attenuated 32.31%. ...
... As the temperature increases, the equivalent impedance of the MLC increases, and the excitation current decreases, leading to a decline in the input voltage of the preampli er. The attenuation of ultrasonic waves is greatly affected by temperatures, and there exists a signi cant attenuation of ultrasonic waves with the increasing temperature [22]. Therefore, the ultrasonic wave amplitude obtained by CFM and VFM shows a decreasing trend. ...
A field-circuit coupled finite element (FE) model of an angled vertical shear vertical wave (SV wave) electromagnetic acoustic transducer (EMAT) was established to investigate influencing factors of angled SV wave EMAT in high-temperature aluminum alloy detection. The FE model also considered equivalent circuits of the EMAT excitation and reception. Based on the FE model, we investigated the effect of temperature on the excitation current from the EMAT excitation equivalent circuit, EMAT generation efficiency, ultrasonic propagation and acoustic radiation field, EMAT reception efficiency, and output gain of the EMAT reception equivalent circuit. Subsequently, the influence of temperature on the detected ultrasonic wave signal was analyzed with a constant frequency method (CFM) of 2 MHz and variable frequency method (VFM) and verified by the experimental measurement with the aluminum alloy with temperatures ranging from 20°C to 440°C. The results show that for non-ferromagnetic metal materials such as aluminum alloy, the main reason for the declining ultrasonic amplitude at high temperatures is that the ultrasonic attenuation coefficient increases with the increasing temperature, followed by the power changing characteristics of the EMAT excitation and reception circuit with the rising temperature. When the temperature rises, the equivalent resistance of the excitation coil increases, the current of the equivalent excitation circuit and the input voltage of the preamplifier from the reception equivalent circuit decline, and the output gain decreases. With the increase in temperature, the experimental amplitude of the angled SV wave shows a downward trend. When the temperature is 440 ℃, the amplitude of the angled SV wave with VFM is 42.85% higher than that with CFM, and the SNR is enhanced by 4.9 dB. The application of VFM to detect high-temperature aluminum alloy can significantly increase the ultrasonic signal amplitude and improve the SNR of ultrasonic waves.
