المؤلفون: Yihui Zhu, Wei Wu, Yang Song, Zhuangqing Fan, WeiLong Niu, Zhaoyu Wang, Yaoke Wen, Cheng Xu, Min Xia

المصدر: Journal of Materials Research and Technology, Vol 31, Iss , Pp 1483-1506 (2024)

مصطلحات موضوعية: Ceramics/UHMWPE laminate composite, Bulge hyperbolic profile, Blunt trauma assessment, Ballistic impact wave propagation, Energy transformation, Mining engineering. Metallurgy, TN1-997

الوصف: With increasing local conflicts worldwide, studying the impact response of body armor is crucial for enhancing soldier survival rates. However, there is still insufficient understanding of the back bulge expansion patterns, the impact waves transmission features, and blunt injury assessing method of body armor. To investigate these problems deeply, the three-dimensional digital image correlation method and numerical models were employed to reveal the ballistic response mechanism of ceramic/ultra-high-molecular-weight polyethylene (UHMWPE) composite body armor impacted by 7.62 mm rifle bullet. This study built theoretical function for the bulge expansion, revealed the wave transmission mechanism and fractures in both materials and their interaction. Firstly, the experiment revealed that the back-face bulge transverse expansion velocity exhibits a double exponential decrease. Secondly, the contour of back-face bulges consistently demonstrated excellent hyperbolic characteristics at various moments. Thirdly, the average Viscous Criterion (VC) and Blunt Criterion (BC) values were 5.37 and 0.95, corresponding to Abbreviated Injury Scale (AIS) values of 6 and 4. Fourthly, the simulation revealed that the ceramics transverse and radial cracks seems primarily induced by shear stress xy; ceramics conical cracks occurring at the boundaries of equivalent stress seems primarily induced by stress in x and y directions. Fifthly, numerical results revealed that the velocity of compression waves within the laminate increases over time in the impact direction and consistent with ceramic velocity impacted on the laminate. These findings lead to experimental and theoretical advances in the impact response mechanism of composite body armor and provide index for improving the protective performance.

وصف الملف: electronic resource

العلاقة: http://www.sciencedirect.com/science/article/pii/S2238785424014121Test; https://doaj.org/toc/2238-7854Test

الوصول الحر: https://doaj.org/article/4c7db1e4b91648ff973b82963da44a00Test

المؤلفون: Shuaiyang Fu, Haibo Li, Liwang Liu, Di Wu, Ben Wang

المصدر: Journal of Rock Mechanics and Geotechnical Engineering, Vol 16, Iss 4, Pp 1231-1244 (2024)

مصطلحات موضوعية: Stochastic joints, Intrinsic cohesive zone model, Uniaxial compressive strength (UCS), Wave propagation, Fabric tensor, Engineering geology. Rock mechanics. Soil mechanics. Underground construction, TA703-712

الوصف: The mechanical characteristics and acoustic behavior of rock masses are greatly influenced by stochastic joints. In this study, numerical models of rock masses incorporating intermittent joints with different numbers and dip angles were produced using the finite element method (FEM) with the intrinsic cohesive zone model (ICZM). Then, the uniaxial compressive and wave propagation simulations were performed. The results indicate that the joint number and dip angle can affect the mechanical and acoustic properties of the models. The uniaxial compressive strength (UCS) and wave velocity of rock masses decrease monotonically as the joint number increases. However, the wave velocity grows monotonically as the joint dip angle increases. When the joint dip angle is 45°–60°, the UCS of the rock mass is lower than that of other dip angles. The wave velocity parallel to the joints is greater than that perpendicular to the joints. When the dip angle of joints remains unchanged, the UCS and wave velocity are positively related. When the joint dip angle increases, the variation amplitude of the UCS regarding the wave velocity increases. To reveal the effect of the joint distribution on the velocity, a theoretical model was also proposed. According to the theoretical wave velocity, the change in wave velocity of models with various joint numbers and dip angles was consistent with the simulation results. Furthermore, a theoretical indicator (i.e. fabric tensor) was adopted to analyze the variation of the wave velocity and UCS.

وصف الملف: electronic resource

العلاقة: http://www.sciencedirect.com/science/article/pii/S1674775523002354Test; https://doaj.org/toc/1674-7755Test

الوصول الحر: https://doaj.org/article/face773321e64f49872bb5c93c402bdfTest

المؤلفون: Zahra S. Hafed, S.M. Abo-Dahab, A.M. Abd-Alla, Sameh E. Ahmed, M. Daher Albalwi, Mohammed A. Aiyashi

المصدر: Ain Shams Engineering Journal, Vol 15, Iss 6, Pp 102745- (2024)

مصطلحات موضوعية: Poroelastic, Magnetic field, Wave propagation, Natural frequency, Rotation, Engineering (General). Civil engineering (General), TA1-2040

الوصف: This research delves into the propagation of radial free harmonic waves in a poroelastic cylinder, conceptualized as a magnetically and rotationaly influenced hollow structure. The primary aim is to elucidate the magnetic field's and rotation impact on the vibrational behavior of such systems. The investigative method encompasses the resolution of motion equations, formulated as partial differential equations, through the application of Lame's potential theory. This analytical process is augmented by the implementation of fitting boundary conditions, culminating in the derivation of a comprehensive expression for the complex dispersion equation, predicated on the premise that the wavenumber embodies a complex entity. The precision of the model is corroborated through a comparative analysis with established literature, underpinned by an exploration of diverse scenarios. The research employed MATLAB for both numerical and graphical assessments, focusing on the dispersion and displacement attributes. Dispersion relations within the poroelastic medium were computed, considering varied magnitudes of magnetic field intensity, rotation and angular velocities. The outcomes are articulated through complex-valued dispersion relations, transcendental formulations, and numerical resolutions employing MATLAB's bisection technique. These insights hold substantial significance for the theoretical advancement in orthopedic research, particularly concerning cylindrical poroelastic media. This study deduces that the radial vibrational patterns and the corresponding frequency equation within a poroelastic medium are profoundly modified by the magnetic field's interference and rotation. This study formulate a novel governing equation for a poroelastic medium, highlighting the significance of radial vibrations and investigating the impact of magnetic field and rotation.

وصف الملف: electronic resource

العلاقة: http://www.sciencedirect.com/science/article/pii/S2090447924001205Test; https://doaj.org/toc/2090-4479Test

الوصول الحر: https://doaj.org/article/74c6e3b2f121473fa615b94111e78ec9Test

المؤلفون: Nidhal Ben Khedher, Nouman Ijaz, Mohamed Medani, Kamal Barghout, Nidal Abu-Libdeh

المصدر: Case Studies in Thermal Engineering, Vol 57, Iss , Pp 104317- (2024)

مصطلحات موضوعية: Tetra-hybrid nanofluid, Casson fluid model, Helmholtz double layer, Sophisticated wave propagation, Magnetic field-modulated hemodynamics, Phototherapy-enhanced immunomodulation, Engineering (General). Civil engineering (General), TA1-2040

الوصف: Background: This study explores the use of tetra-hybrid nanoparticles consisting of gold, silver, alumina, and titania nanocomposites dispersed in a non-Newtonian Casson fluid modelled as blood. The motivation lies in harnessing the synergistic optical, electrical, thermal, and physicochemical properties of the multimodal nanoscale assembly to advance electrokinetic pumping processes. Objectives: The study aims to computationally investigate the complex transport assisted by tailored gold, silver, alumina, and titania dioxide nanoparticles in the tetra-hybrid nanofluid, with potential applications in targeted drug delivery, hyperthermia cancer treatment, Lab-on-Chip devices, and miniaturized biosensors. Methodology: The constructed streaming flow model examines the cumulative influence of viscous heating, Joule heating, conductive thermal, and external laser irradiation. Current simulations examine Casson flows with the integrated nanoparticles by modelling two- and three-dimensional conduits subject to transverse magnetohydrodynamics and localized laser irradiation. Key findings: The solutions provide mathematical predictions and physical insights into the fully coupled velocity, temperature, concentration, and pressure gradient contours. Additional plots examining dimensionless analytes against pertinent profiles, combined with streamlined visualization, further elucidate the multifaceted transport and complex trapping patterns stemming from non-Newtonian rheology. Applications/implications: This multiscale examination reveals performance improvements realizable by leveraging biocompatible tetra-hybrid nanocomposites in electrokinetic flows vital for next-generation biomedical technologies.

وصف الملف: electronic resource

العلاقة: http://www.sciencedirect.com/science/article/pii/S2214157X24003484Test; https://doaj.org/toc/2214-157XTest

الوصول الحر: https://doaj.org/article/1c4b959e3d48487f88070a04ddde898bTest

المؤلفون: Minghai Yan, Wei Wang, Shixiang Tian, Jie Liu, Zebiao Jiang, Zhangyin Dai

المصدر: Case Studies in Thermal Engineering, Vol 57, Iss , Pp 104318- (2024)

مصطلحات موضوعية: High-pressure hydrogen leakage, Ignition time, Explosion gas cloud evolution, Deflagration and detonation, Shock wave propagation, Engineering (General). Civil engineering (General), TA1-2040

الوصف: Hydrogen is an efficient, clean, and renewable energy source. When determining a place for hydrogen energy storage and injection into vehicles, the main safety concern of hydrogen refueling stations is high-pressure hydrogen leakage. In this paper, the CFD method is used to study the effect of different ignition times on the explosion and shock wave propagation of high-pressure hydrogen gas leakage, analyze the distribution of flammable gas clouds, and evaluate the impact of combustion flames, temperature, and explosion-induced overpressure on refueling stations. The results show that the concentration of gas clouds ranges from 0 to 80% (volume concentration). Explosion and combustion phenomena occur at different ignition times during the high-pressure hydrogen gas leakage stage, with a maximum pressure of 2.6 bar and a high temperature of 1500–2400 K. After a high-pressure hydrogen leak, ignition can occur only as an explosive phenomenon. This generates a pressure of up to 3.1 bar and a short-lived high temperature. The pressure increases with the length of the leak, and the hazardous area varies depending on the time of ignition. This paper provides theoretical support for safety issues related to high-pressure hydrogen leakage in refueling stations.

وصف الملف: electronic resource

العلاقة: http://www.sciencedirect.com/science/article/pii/S2214157X24003496Test; https://doaj.org/toc/2214-157XTest

الوصول الحر: https://doaj.org/article/1d2841294d514a6ab8f57f359ab3d5cfTest

المؤلفون: Jiaji Chen, Xuanbo Miao, Hongbin Ma, Jonathan B. Hopkins, Guoliang Huang

المصدر: Materials & Design, Vol 244, Iss , Pp 113093- (2024)

مصطلحات موضوعية: Intelligent metamaterial, Deformation and morphing control, Wave propagation, Physical neural network, Materials of engineering and construction. Mechanics of materials, TA401-492

الوصف: The exploration of intelligent machines has recently spurred the development of physical neural networks, a class of intelligent metamaterials capable of learning, whether in silico or in situ, from observed data. In this study, we introduce a back-propagation framework for lattice-based mechanical neural networks (MNNs) to achieve prescribed static and dynamic performance. This approach leverages the steady states of nodes for back-propagation, efficiently updating the learning degrees of freedom without prior knowledge of input loading. One-dimensional MNNs, trained with back-propagation in silico, can exhibit the desired behaviors on demand function as intelligent mechanical machines. The framework is then employed for the precise morphing control of the two-dimensional MNNs subjected to different static loads. Moreover, the intelligent MNNs are trained to execute classical machine learning tasks such as regression to tackle various deformation control tasks. Finally, the disordered MNNs are constructed and trained to demonstrate pre-programmed wave bandgap control ability, illustrating the versatility of the proposed approach as a platform for physical learning. Our approach presents an efficient pathway for the design of intelligent mechanical metamaterials for a wide range of static and dynamic target functionalities, positioning them as powerful engines for physical learning.

وصف الملف: electronic resource

العلاقة: http://www.sciencedirect.com/science/article/pii/S0264127524004672Test; https://doaj.org/toc/0264-1275Test

الوصول الحر: https://doaj.org/article/bdb5cacf4d7142fab2ff4443f8a32064Test

المؤلفون: Yuvaraj George, Abhishek Sarkar, Arshad Javed

المصدر: e-Prime: Advances in Electrical Engineering, Electronics and Energy, Vol 7, Iss , Pp 100484- (2024)

مصطلحات موضوعية: Ultrasound sensors, Ultrasound calibration, Acoustic Instrumentation, Physical aspects of ultrasonic wave propagation, Non-linear ultrasonics, Electrical engineering. Electronics. Nuclear engineering, TK1-9971

الوصف: This article presents experimental methods and analytics for developing statistical models for ultrasonic sensors to improve reliability, repeatability, and signal-to-noise ratio (SNR) in static environments. The experiments use commercial piezoelectric ceramic transducers and over 4100 calibrated readings for three specimens of different materials. Using commercial piezoelectric ceramic transducers, the spatial-temporal approach considers range, environmental factors, material characteristics, and their interactions. A true value approach is used to formulate the error as a function of the distance measured in the time-of-flight (ToF) method at zero azimuth angular directivity. The three statistical models, linear temperature, averaged linear regression, and averaged cubic regression models, are formulated and validated. The most influential parameters in the calibrating distance with an acoustic sensor are the range, coupled effect of temperature, and material characteristics, followed by temperature. The linear model increases the SNR within 0–40 cm from ±20 dB to ≈80 dB, and the cubic model increases the repeatability of the measurement by reducing the absolute error for the entire range of sensors from ±3 cm to less than −1 cm.

وصف الملف: electronic resource

العلاقة: http://www.sciencedirect.com/science/article/pii/S2772671124000664Test; https://doaj.org/toc/2772-6711Test

الوصول الحر: https://doaj.org/article/63a42889199642da87389723938edbc5Test

المؤلفون: M. Ashik Iqbal, M. Mamun Miah, H. M. Shahadat Ali, Nur Hasan Mahmud Shahen, Ahmed Deifalla

المصدر: Partial Differential Equations in Applied Mathematics, Vol 9, Iss , Pp 100597- (2024)

مصطلحات موضوعية: The (G′/G′+G+A)-expansion method, Wave propagation, Nonlinear PDEs, The fractional order (4+1)-dimensional Fokas equation, The fractional order (2+1)-dimensional breaking soliton equation, The soliton solutions, Applied mathematics. Quantitative methods, T57-57.97

الوصف: The motive of this research work is to unravel the mysteries of nature through fractional-order partial differential equations (PDEs). Here, we focus on two important fractional order nonlinear PDEs, namely the fractional order (4+1)-dimensional Fokas equation, which is used to give the model of many physical phenomena and dynamical processes, and the other one is the fractional order (2+1)-dimensional breaking soliton equation which is used to analyze the nonlinear problems like optical fiber communications, ocean engineering, etc. Recently, it has been an essential topic to extract the new soliton solutions which are used to investigate the hidden physical conditions of the nonlinear fractional PDEs. So, it is essential to solve those nonlinear fractional PDEs which have a physical impact in the fields of science and modern engineering. In our investigation, we attempt to provide nonlinear wave propagation patterns and investigate the equations, as mentioned earlier, through a computational method. A computing operating software called Mathematica has been applied to get a clear visualization of our gained outcomes, and we ascertain such types of shapes as the bell shape soliton, the anti-bell shape soliton, the singular bell shape soliton, the periodic solution, and the singular periodic solution. Our obtained results can keep an indispensable role in explaining various physical phenomena of nature shortly, and the applied method is the very cogent, efficient, and interesting to extract such types of solutions. Since we extract abundant solutions of these models, so we hope that this article is the best applications of mention method.

وصف الملف: electronic resource

العلاقة: http://www.sciencedirect.com/science/article/pii/S2666818123001109Test; https://doaj.org/toc/2666-8181Test

الوصول الحر: https://doaj.org/article/8867eba86b3c4d19917ba85bd891ad38Test

المؤلفون: Moinul Haq, Adnan Khan, Tabassum Naqvi, Mohammad Yusuf, Hesam Kamyab, Shreeshivadasan Chelliapan

المصدر: Ain Shams Engineering Journal, Vol 15, Iss 3, Pp 102457- (2024)

مصطلحات موضوعية: Structural health monitoring (SHM), Electro-mechanical impedance (EMI) technique, Wave propagation (WP) technique, Piezo sensors, Finite element (FE) modelling, Reusable smart bolt, Engineering (General). Civil engineering (General), TA1-2040

الوصف: The strength of concrete after its casting increases with time up to a certain limit due to continuous hydration reactions in the cement matrix. To measure the rate of strength development and ultimate capacity of concrete, a novel health monitoring method using Reusable smart bolt (RSB) piezoelectric sensor is proposed in the present paper. The smart piezoelectric Lead zirconate titanate (PZT) patch-based Electro-mechanical impedance (EMI) and Wave propagation (WP) techniques are utilised for accessing the health of concrete at 1, 3, 5, 7, 14, 21 & 28 days of concrete hydration. Firstly, the PZT patch-based sensing capabilities are validated with the experimental results from literature by modelling concrete cube for EMI and beam for WP results. Then, a total of 31 finite element models of concrete cubes having different RSB configurations were taken into consideration for sensor design and optimization. In EMI technique, the shifting of conductance signatures and relative resonance frequency are measured, whereas in WP technique, the shift of P-wave velocity peaks between actuator and sensor is estimated for all the models. The sensitivity of outputs is measured by plotting statistical Root mean square deviation (RMSD) index which proven the efficacy of employing RSB sensors for monitoring concrete strength-development during early-hydration ages with good correlations. Overall, the EMI-identified RMSD plotted for conductance shows 327 % more sensitivity than WP-identified relative change of P-wave velocity in monitoring concrete strength development using RSB sensors.

وصف الملف: electronic resource

العلاقة: http://www.sciencedirect.com/science/article/pii/S2090447923003465Test; https://doaj.org/toc/2090-4479Test

الوصول الحر: https://doaj.org/article/fb123a0b485149c2b79d45f2763b7e1bTest

المؤلفون: Vassily Mikhaltsevitch, Maxim Lebedev, Roman Pevzner, Alexey Yurikov, Konstantin Tertyshnikov

المصدر: Journal of Rock Mechanics and Geotechnical Engineering, Vol 15, Iss 9, Pp 2330-2338 (2023)

مصطلحات موضوعية: Elasticity and anelasticity, Acoustic properties, Fourier analysis, Wave propagation, Engineering geology. Rock mechanics. Soil mechanics. Underground construction, TA703-712

الوصف: In recent decades, low-frequency (LF) experiments based on the forced-oscillation (FO) method have become common practice in many rock physics laboratories for measuring the elastic and anelastic properties of rocks. However, the use of the electronic displacement sensors in traditional acquisition systems of FO devices such as conventional capacitive transducers or strain gauges seriously limits both the efficiency and productivity of LF measurements, and, due to the limited contact area of the displacement sensors with a sample under test, increases the requirements for sample homogeneity. In this paper, we present the first results obtained in the development of a new laboratory method elaborated to measure the elastic properties of solids. The method is a further development of the FO method where traditional data acquisition is replaced by acquisition based on fiber-optic distributed acoustic sensing (DAS) technology. The new method was tested in a laboratory study using two FO setups designed for measurements under uniaxial and confining pressures. The study was carried out on a sample made from polymethyl methacrylate (PMMA) and an aluminium standard, first under uniaxial pressure at FO frequencies of 1, 10, 30, 60 and 100 Hz, and then under confining pressure at an FO frequency of 1 Hz. Both uniaxial and confining pressures were equal to 10 MPa, and the strain in the PMMA sample in all measurements did not exceed 4 × 10-8. The performance of DAS acquisition was compared with the measurements conducted at a strain of 1 × 10-6 using the traditional FO method based on the use of semiconductor strain gauges and the ultrasonic method. The results of the DAS measurements are in good agreement with the FO measurements carried out using semiconductor strain gauges and with the literature data.

وصف الملف: electronic resource

العلاقة: http://www.sciencedirect.com/science/article/pii/S1674775523001464Test; https://doaj.org/toc/1674-7755Test

الوصول الحر: https://doaj.org/article/ed16a4df6e234d4aa6a6ad8dd77f8dcaTest