Articles de revues : « Plate-like structure »

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Ručevskis, Sandris, et Andris Chate. « DAMAGE IDENTIFICATION IN A PLATE-LIKE STRUCTURE USING MODAL DATA ». Aviation 17, n^o 2 (1 juillet 2013) : 45–51. http://dx.doi.org/10.3846/16487788.2013.805863.

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In this paper, an on-going research effort aimed at detecting and localising damage in plate-like structures by using mode shape curvature–based damage detection algorithms is described. Two alternative damage indexes are examined. The first one uses exclusively mode shape curvature data from the damaged structure. This method was originally developed for beam-like structures. In this paper, the method is generalised to plate-like structures that are characterised by two-dimensional mode shape curvature. To examine limitations of the method, several sets of simulated data are applied and damage detection results are compared to the damage identification method that requires mode shape information from both the undamaged and the damaged states of the structure. The modal frequencies and the corresponding mode shapes for the first 15 modes of a plate are obtained via finite element models. Simulated test cases include damage of various levels of severity. In order to ascertain the sensitivity of the proposed method to noisy experimental data, numerical mode shapes are corrupted with different levels of random noise.

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Griso, Georges, Larysa Khilkova, Julia Orlik et Olena Sivak. « Homogenization of Perforated Elastic Structures ». Journal of Elasticity 141, n^o 2 (5 juin 2020) : 181–225. http://dx.doi.org/10.1007/s10659-020-09781-w.

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Abstract The paper is dedicated to the asymptotic behavior of $\varepsilon$ ε -periodically perforated elastic (3-dimensional, plate-like or beam-like) structures as $\varepsilon \to 0$ ε → 0 . In case of plate-like or beam-like structures the asymptotic reduction of dimension from $3D$ 3 D to $2D$ 2 D or $1D$ 1 D respectively takes place. An example of the structure under consideration can be obtained by a periodic repetition of an elementary “flattened” ball or cylinder for plate-like or beam-like structures in such a way that the contact surface between two neighboring balls/cylinders has a non-zero measure. Since the domain occupied by the structure might have a non-Lipschitz boundary, the classical homogenization approach based on the extension cannot be used. Therefore, for obtaining Korn’s inequalities, which are used for the derivation of a priori estimates, we use the approach based on interpolation. In case of plate-like and beam-like structures the proof of Korn’s inequalities is based on the displacement decomposition for a plate or a beam, respectively. In order to pass to the limit as $\varepsilon \to 0$ ε → 0 we use the periodic unfolding method.

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JOVANOVIĆ, DRAGANA J., IVANA LJ VALIDŽIĆ, MIODRAG MITRIĆ et JOVAN M. NEDELJKOVIĆ. « Crystal structure studies on plate/shelf like disodium ditungstate ». Bulletin of Materials Science 36, n^o 1 (février 2013) : 149–52. http://dx.doi.org/10.1007/s12034-013-0419-6.

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Zhou, Kemin, et Xia Li. « Optimization of Grillage-like Continuum by Triangle Plate Element ». Open Civil Engineering Journal 6, n^o 1 (6 mars 2012) : 8–14. http://dx.doi.org/10.2174/1874149501206010008.

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The volume of grillages with stress constraints is minimized. An optimal beams system or plate with reinforced ribs is obtained to present the optimal structure. A grillage-like continuum material model is adapted. Structure is analyzed by finite element method with triangle plate elements. The geometric matrix of triangle plate element in explicit formulation about area coordinates is presented. The stiffness matrix of grillage-like continuum material model is derived. The material distribution field in design domain is optimized by fully-stressed criterion. The densities and orientations of the beam or reinforced ribs at nodes in grillages are taken as design variables. The densities and orientations vary in design domain continuously. The optimal distribution fields of bend moments, flexure displacement and material are obtained simultaneously. Subsequently the discrete structures are founded based on the optimal material distribution fields. The performances of different elements are compared. The optimization procedure is accomplished by computer program automatically.

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Obara, Paulina, et Justyna Tomasik. « Parametric Analysis of Tensegrity Plate-Like Structures : Part 2—Quantitative Analysis ». Applied Sciences 11, n^o 2 (10 janvier 2021) : 602. http://dx.doi.org/10.3390/app11020602.

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The study includes a parametric analysis of a group of tensegrity plate-like structures built with modified Quartex modules. The quantitative assessment, including the calculation of the structure’s response to constant loads, was carried out. A static parametric analysis was performed, with particular emphasis on the influence of the initial prestress level on the displacements, the effort, and the stiffness of the structure. A geometrical non-linear model was used in the analysis. A reliable assessment required introducing a parameter for determining the influence of the initial prestress level on the overall stiffness of the structure at a given load. The stiffness of the structure was found to depend not only on the geometry and material properties, but also on the initial prestress level and external load. The results show that the effect of the initial prestress on the overall stiffness of the structure is greater with less load and that the effect of load is most significant with low pre-stressing forces. The analysis demonstrates that the control of static parameters is possible only when infinitesimal mechanisms occur in the structure.

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Obara, Paulina, et Justyna Tomasik. « Parametric Analysis of Tensegrity Plate-Like Structures : Part 2—Quantitative Analysis ». Applied Sciences 11, n^o 2 (10 janvier 2021) : 602. http://dx.doi.org/10.3390/app11020602.

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The study includes a parametric analysis of a group of tensegrity plate-like structures built with modified Quartex modules. The quantitative assessment, including the calculation of the structure’s response to constant loads, was carried out. A static parametric analysis was performed, with particular emphasis on the influence of the initial prestress level on the displacements, the effort, and the stiffness of the structure. A geometrical non-linear model was used in the analysis. A reliable assessment required introducing a parameter for determining the influence of the initial prestress level on the overall stiffness of the structure at a given load. The stiffness of the structure was found to depend not only on the geometry and material properties, but also on the initial prestress level and external load. The results show that the effect of the initial prestress on the overall stiffness of the structure is greater with less load and that the effect of load is most significant with low pre-stressing forces. The analysis demonstrates that the control of static parameters is possible only when infinitesimal mechanisms occur in the structure.

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Chen, Kuan-Ting, Jun-Wei Huang, Wei-Ting Lin, Tsung-Yuan Kuo, Chi-Sheng Chien, Ching-Ping Chang et Yung-Ding Lin. « Effects of Micro-Arc Oxidation Discharge Parameters on Formation and Biomedical Properties of Hydroxyapatite-Containing Flower-Like Structure Coatings ». Materials 16, n^o 1 (21 décembre 2022) : 57. http://dx.doi.org/10.3390/ma16010057.

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The micro-arc oxidation (MAO) process was used to prepare hydroxyapatite-containing flower-like structure coatings on commercially pure titanium substrates with various values of the applied voltage (330, 390, 450 V), applied current (0.4, 0.5, 0.6 A), and duration time (1, 3, 5 min). It was found that the surface morphology of the coatings was determined primarily by the applied voltage. A voltage of 330 V yielded a flower-like/plate-like structure, while voltages of 390 V and 450 V produced a flower-like structure and a porous morphology, respectively. The applied current and duration time mainly affected the coating formation speed and petal size of the flower-like structures, respectively. The coatings prepared using voltages of 330 V and 390 V (0.6 A, 5 min) both contained Ti, TiO2-A (anatase), TiO2-R (rutile), DCPD (CaHPO4·2H2O, calcium hydrogen phosphate), and hydroxyapatite (HA).However, the latter coating contained less DCPD and had a higher HA/DCPD ratio and a Ca/P ratio closer to the ideal value of HA. The coating prepared with a voltage of 450 V consisted mainly of Ti, TiO2-A, TiO2-R, and CaTiO3.For the coatings prepared with a voltage of 390 V, the flower-like structures consisted mainly of HA-containing compounds. DCPD plate-like structures were observed either between the HA-containing flower-like structures (330 V samples) or within the flower-like structures themselves (390 V samples). The coating surfaces with flower-like/plate-like or flower-like structures had a greater roughness, which increased their hydrophilicity and resulted in superior bioactivity (SBF immersion) and biocompatibility (MG-63 cell culture). The optimal biomedical performance was found in the 390 V coating due to its flower-like structure and high HA/DCPD ratio.

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Obara, Paulina, et Justyna Tomasik. « Parametric Analysis of Tensegrity Plate-Like Structures : Part 1—Qualitative Analysis ». Applied Sciences 10, n^o 20 (11 octobre 2020) : 7042. http://dx.doi.org/10.3390/app10207042.

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The study includes parametric analysis of special spatial rod grids called tensegrity plate-like structures. Tensegrity structures consist of only compression and tension components arranged in a system, whose unique mechanical and mathematical properties distinguish them from conventional cable–strut frameworks. Complete analysis of tensegrity structures is a two-stage process. The first stage includes the identification of self-stress states and infinitesimal mechanisms (qualitative analysis). The second stage focuses on the behaviour of tensegrities under external loads (quantitative analysis). In the paper, a qualitative analysis of tensegrity plate-like structures built with modified Quartex modules was conducted. Starting from a single-module structure, more complex cases were sequentially analysed. The different ways of plate support were considered. To carry out a qualitative assessment, a spectral analysis of the truss matrices and singular value decomposition of the compatibility matrix were used. The characteristic features of tensegrity structures were identified. On this basis, the plates were classified into one of the four groups defined in the paper, i.e., ideal tensegrity, “pure” tensegrity and structures with tensegrity features of class 1 or class 2. This classification is important due to different behaviours of the structure under external actions. The qualitative analysis carried out in the paper is the basis for a quantitative analysis.

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Huynh, Thanh-Canh, So-Young Lee, Ngoc-Loi Dang et Jeong-Tae Kim. « Sensing Region Characteristics of Smart Piezoelectric Interface for Damage Monitoring in Plate-Like Structures ». Sensors 19, n^o 6 (19 mars 2019) : 1377. http://dx.doi.org/10.3390/s19061377.

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For impedance-based damage detection practices, the sensing range of piezoelectric devices is an important parameter that should be determined before real implementations. This study presents numerical and experimental analyses for characterizing the sensing region of a smart PZT (lead–zirconate–titanate) interface for damage monitoring in plate-like structures. First, a finite element (FE) model of the PZT interface mounted on a plate structure is established. The impedance responses of the PZT interface are numerically simulated under different damage locations inflicted in the plate domain. The impedance features are extracted from the impedance signatures to analyze the sensing distance and the damage detectability of the PZT interface. Next, the splice plate of a bolted connection is selected as a practical plate-like structure for the experimental examination of the PZT interface’s sensing region on a limited plate domain. The damage sensitivity behavior of the PZT interface is analyzed with respect to the damage location on the splice plate. An FE analysis of the corresponding PZT interface-splice plate system is also conducted to support the experimental results.

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Yang, Jongmin, Yujia Chen, Jun-Duo Zhang, Wei-Xi Huang et Hyung Jin Sung. « A self-propelled flexible plate with a keel-like structure ». Physics of Fluids 33, n^o 3 (1 mars 2021) : 031902. http://dx.doi.org/10.1063/5.0041316.

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Xu, L., Y. Wang, Y. Cai, Z. Wu et W. Peng. « Determination of impact events on a plate-like composite structure ». Aeronautical Journal 120, n^o 1228 (11 mai 2016) : 984–1004. http://dx.doi.org/10.1017/aer.2016.36.

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ABSTRACTComposite materials have been increasingly used in aircraft structures. However, these composite structures are susceptible to damage from external low-velocity impacts. In this paper, an impact identification algorithm is proposed to estimate the impact location and force time history simultaneously. A localisation method based on basis vectors is proposed, and the impact force time history is reconstructed by simplified transfer functions. The basis vector stands for the relationship between the impact location and the sensor signals, and the transfer function shows the relationship of the sensor signal and the force time history. An experiment is conducted on a flat glass fibre-epoxy matrix composite plate to verify the developed algorithm using only four sensors. The soft impactor and hard impactor are two typical impactors for impact events; therefore, the impact experiment is performed by the rubber and the steel impactors, respectively. The experimental results indicate that the proposed algorithm is feasible for the identification of impact events on plate-like composite structures.

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Navabian, N., M. Bozorgnasab, R. Taghipour et O. Yazdanpanah. « Damage identification in plate-like structure using mode shape derivatives ». Archive of Applied Mechanics 86, n^o 5 (29 septembre 2015) : 819–30. http://dx.doi.org/10.1007/s00419-015-1064-x.

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Samet, Ahmed, Yi Hui, Mohamed Amine Ben Souf, Olivier Bareille, Mohamed Ichchou, Tahar Fakhfakh et Mohamed Haddar. « Experimental investigation of damage detection in plate-like structure using combined energetic approaches ». Proceedings of the Institution of Mechanical Engineers, Part C : Journal of Mechanical Engineering Science 233, n^o 4 (14 mai 2018) : 1193–203. http://dx.doi.org/10.1177/0954406218771102.

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In this paper, an experimental investigation of damage detection in plate-like structure using energetics approaches is presented. Two energetics approaches are developed to localize the damage in structure at low-, medium-, and high-frequency range. The first one is the inverse simplified energy method, which is used for the identification of the excitation source and the detection of damage in medium and high frequencies. The second one is the curvature method, which is used for the damage detection in the low and medium frequencies. The main novelty of this paper is to combine these energetics approaches in order to localize the damage in all frequency bands. Experimental examples with different characteristics of plate were performed for the validation purpose. Results show that the presented methods can detect precisely the defects location in plate-like structures.

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Kodera, Takayuki, Fuminari Isobe et Takashi Ogihara. « Preparation and Electrochemical Properties of LiMnPO₄ Nanoparticles by Polyol Method ». Key Engineering Materials 566 (juillet 2013) : 95–98. http://dx.doi.org/10.4028/www.scientific.net/kem.566.95.

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Plate-like LiMnPO4particles were prepared by polyol method. The chemical and physical properties of plate-like LiMnPO4particles were characterized by XRD and SEM. The thickness of plate-like LiMnPO4particles was approximately 35 nm. XRD pattern of plate-like LiMnPO4was good agreement with orthorhombic olivine structure. The first discharge capacity of C/LiMnPO4cathode was approximately 95 mAh/g. 99.9 % of initial discharge capacity was maintained after 100 cycles.

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Li, Z. G., R. L. Harlow, K. H. Gardner, L. Liang, D. L. Dorset et J. M. Zou. « Plate and needle-like crystal structure determination by combining electron and synchrotron diffraction ». Proceedings, annual meeting, Electron Microscopy Society of America 53 (13 août 1995) : 152–53. http://dx.doi.org/10.1017/s0424820100137136.

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In recent years, significant progress in determining light-element crystal structures using electron diffraction has been made to meet the increasing needs from the material science community. The set of techniques for carrying out electron crystallography, including sample preparation, data collection and recording, diffraction micrograph digitization, and confirmation by direct phasing methods and structure refinements, have being developed. However, only a very limited number of structures have been determinated by electron crystallography because of a number of severe problems and difficulties. Meanwhile, the progress in determining crystal structures using x-ray diffraction has been rapidly increasing, particularly because of the more extensive use of powerful synchrotron diffraction techniques. In this case, the minimum crystal size required for a single-crystal study has decreased from 100 microns to about 10 microns. Even so, many new materials can only be obtained in microcrystalline form with crystallite sizes well below one micron. In this submicron regime, ab initio structure solutions from synchrotron powder-diffraction patterns have proven to be quite powerful.

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Muro, Satoru, Wachirawit Sirirat, Daisuke Ban, Yuichi Nagakawa et Keiichi Akita. « What comprises the plate-like structure between the pancreatic head and the celiac trunk and superior mesenteric artery ? A proposal for the term “P–A ligament” based on anatomical findings ». Anatomical Science International 96, n^o 3 (8 janvier 2021) : 370–77. http://dx.doi.org/10.1007/s12565-020-00597-1.

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AbstractA plate-like structure is located posterior to the portal vein system, between the pancreatic head and roots and/or branches of two major arteries of the aorta: the celiac trunk and superior mesenteric artery. We aimed to clarify the distribution and components of this plate-like structure. Macroscopic examination of the upper abdomen and histological examination of the plate-like structure were performed on 26 cadavers. The plate-like structure is connected to major arteries (aorta, celiac trunk, superior mesenteric artery) and the pancreatic head; it contains abundant fibrous bundles comprising nerves, vessels, collagen fibers, and adipose tissue. Furthermore, it consists of three partly overlapping fibrous components: rich fibrous bundles (superior mesenteric artery plexus) fused to the uncinate process of the pancreas; fibrous bundles arising from the right celiac ganglion and celiac trunk that spread radially to the dorsal side of the pancreatic head and superior mesenteric artery plexus; and fibrous bundles, accompanied by the inferior pancreaticoduodenal artery, entering the pancreatic head. The plate-like structure is the pancreas–major arteries (aorta, celiac trunk, superior mesenteric artery) ligament (P–A ligament). The term “P–A ligament” may be clinically useful and can facilitate comprehensive understanding of the anatomy surrounding the pancreatic head and provide an anatomical basis for further pancreatic surgery studies.

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Abdal-hay, Abdalla, H. Fouad, Basheer A. ALshammari et Khalil Abdelrazek Khalil. « Biosynthesis of Bonelike Apatite 2D Nanoplate Structures Using Fenugreek Seed Extract ». Nanomaterials 10, n^o 5 (9 mai 2020) : 919. http://dx.doi.org/10.3390/nano10050919.

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An innovative, biomimetic, green synthesis approach was exploited for the synthesis of humane and environmental friendly nanomaterials for biomedical applications. Ultrafine bonelike apatite (BAp) 2D plate-like structures were prepared using fenugreek seed extract during the biosynthesis wet-chemical precipitation route. The chemical analysis, morphology and structure of the prepared 2D nanoplates were characterized by inductively coupled plasma atomic emission spectroscopy (ICP-OES), electron microscopy (SEM and TEM), X-ray diffraction (XRD) and Fourier transform infrared (FTIR) spectroscopy. A 2D plate-like nanostructure of BAp with an average width (length) of 12.67 ± 2 nm and thickness of 3.8 ± 1.2 nm was obtained. BAp 2D crystals were tuned by interaction with the fenugreek organic molecules during the fabrication process. In addition to Ca and P ions, bone mineral sources such as K, Mg, Na, SO4 and CO3 ions were incorporated into BAp nanoplates using fenugreek seed extract. The overall organic molecule concentration in the reaction process increased the effectiveness of hydroxyl groups as nucleation sites for BAp crystals. Accordingly, the size of the biosynthesized BAp plate-like structure was reduced to its lowest value. Biosynthesis BAp 2D plate-like nanocrystals showed good viability and higher growth of MC3T3 osteoblast-like structures than that of the control sample. BAp 2D nanoplates prepared by a facile, ecofriendly and cost-effective approach could be considered a favorable osteoconductive inorganic biomaterial for bone regeneration applications.

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Obara, Paulina, et Justyna Tomasik. « Active Control of Stiffness of Tensegrity Plate-like Structures Built with Simplex Modules ». Materials 14, n^o 24 (20 décembre 2021) : 7888. http://dx.doi.org/10.3390/ma14247888.

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The aim of this study is to prove that it is possible to control the static behavior of tensegrity plate-like structures. This possibility is very important, particularly in the case of deployable structures. Here, we analyze the impact the support conditions of the structure have on the existence of specific characteristics, such as self-stress states and infinitesimal mechanisms, and, consequently, on the active control. Plates built with Simplex modules are considered. Firstly, the presence of the specific characteristics is examined, and a classification is carried out. Next, the influence of the level of self-stress state on the behavior of structures is analyzed. A geometrically non-linear model, implemented in an original program, written in the Mathematica environment, is used. The results confirm the feasibility of the active control of stiffness of tensegrity plate-like structures characterized by the presence of infinitesimal mechanisms. In the case when mechanisms do not exist, structures are insensitive to the initial prestress level. It is possible to control the occurrence of mechanisms by changing the support conditions of the structure. Based on the obtained results, tensegrity is very promising structural concept, applicable in many areas, when conventional solutions are insufficient.

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Marjanović, Miroslav, Marija Nefovska-Danilović et Emilija Damnjanović. « Framework for Dynamic-Stiffness-Based Free Vibration Analysis of Plate-Like Structures ». Shock and Vibration 2019 (28 janvier 2019) : 1–15. http://dx.doi.org/10.1155/2019/1369235.

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A framework for free vibration analysis of plate-like structures is presented in the paper. Based on the previously formulated dynamic stiffness elements, FREEVIB object-oriented software in Python environment has been created. Software design and structure as well as a wide range of possible structural problems that could be analyzed using the FREEVIB are presented. Through several illustrative examples including free vibration analysis of stepped, stiffened and folded plate structures, implying isotropic or orthotropic material formulations, the efficiency and accuracy of the FREEVIB is demonstrated. The possibilities of further extensions and improvements of the software are discussed.

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Hayashi, Takahiro. « High-speed non-contact defect imaging for a plate-like structure ». NDT & ; E International 85 (janvier 2017) : 53–62. http://dx.doi.org/10.1016/j.ndteint.2016.10.009.

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Fujimori, Tomoyuki, et Hiromasa Suzuki. « 3310 Contouring Medial Surface from CT Data of Plate-like Structure ». Proceedings of Design & ; Systems Conference 2005.15 (2005) : 524–25. http://dx.doi.org/10.1299/jsmedsd.2005.15.524.

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Hou, Xiao Long, Jun Tong Huang, Zhi Hui Hu, Zhi Jun Feng, Meng Zhang, Ming Qiang Liu et Xi Bao Li. « Molten Salt Synthesis and Formation Mechanism of Plate-Like MgAl₂O₄ Spinel ». Solid State Phenomena 281 (août 2018) : 278–84. http://dx.doi.org/10.4028/www.scientific.net/ssp.281.278.

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Plate-like Magnesium Aluminum spinel (MgAl2O4) with octahedral structure was synthesized using Al2O3plate-like particles and MgO powders as raw materials in the molten salt of LiCl, KCl or NaCl, respectively. The Results indicated that the molten salts accelerated MA formation, and LiCl was more effective than KCl and NaCl, which may be attributed to the higher solubility of MgO in the former than in the latter two. The outline shape of MA spinel product phase was the same as that of original plate-like Al2O3particles. The growth mechanism of plate-like MgAl2O4spinel particles with octahedral structure should be governed by “template formation mechanism” accompanied with “dissolution-precipitation mechanism”.

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Yang, Chun Hui, Zhong Qing Su, Lin Ye, Ye Lu et Michael Bannister. « Propagation Characteristics of Lamb Waves in Stringer-Stiffened Panels ». Key Engineering Materials 334-335 (mars 2007) : 637–40. http://dx.doi.org/10.4028/www.scientific.net/kem.334-335.637.

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Stringer-stiffened plate-like structure is a typical engineering structure and its structural integrity is critical. A guided Lamb wave-based damage identification scheme and an online structural health monitoring (SHM) system with an integrated PZT-sensor network were developed. In the previous studies, the specimens were relatively simple. In this paper, the abovementioned method was extended to the stiffened plate-like structure—a flat plate reinforced by stringer. FE dynamic simulation was applied to investigate the Lamb wave propagation characteristics due to the existence of stringer with the consideration of its material and geometric configurations.

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Schorr, Melanie, Pouneh K. Fazeli, Katherine N. Bachmann, Alexander T. Faje, Erinne Meenaghan, Allison Kimball, Vibha Singhal et al. « Differences in Trabecular Plate and Rod Structure in Premenopausal Women Across the Weight Spectrum ». Journal of Clinical Endocrinology & ; Metabolism 104, n^o 10 (20 juin 2019) : 4501–10. http://dx.doi.org/10.1210/jc.2019-00843.

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AbstractContextPremenopausal women with anorexia nervosa (AN) and obesity (OB) have elevated fracture risk. More plate-like and axially aligned trabecular bone, assessed by individual trabeculae segmentation (ITS), is associated with higher estimated bone strength. Trabecular plate and rod structure has not been reported across the weight spectrum.ObjectiveTo investigate trabecular plate and rod structure in premenopausal women.DesignCross-sectional study.SettingClinical research center.ParticipantsA total of 105 women age 21 to 46 years: (i) women with AN (n = 46), (ii) eumenorrheic lean healthy controls (HCs) (n = 29), and (iii) eumenorrheic women with OB (n = 30).MeasuresTrabecular microarchitecture by ITS.ResultsMean age (±SD) was similar (28.9 ± 6.3 years) and body mass index differed (16.7 ± 1.8 vs 22.6 ± 1.4 vs 35.1 ± 3.3 kg/m2; P < 0.0001) across groups. Bone was less plate-like and axially aligned in AN (P ≤ 0.01) and did not differ between OB and HC. After controlling for weight, plate and axial bone volume fraction and plate number density were lower in OB vs HC; some were lower in OB than AN (P < 0.05). The relationship between weight and plate variables was quadratic (R = 0.39 to 0.70; P ≤ 0.0006) (i.e., positive associations were attenuated at high weight). Appendicular lean mass and IGF-1 levels were positively associated with plate variables (R = 0.27 to 0.67; P < 0.05). Amenorrhea was associated with lower radial plate variables than eumenorrhea in AN (P < 0.05).ConclusionsIn women with AN, trabecular bone is less plate-like. In women with OB, trabecular plates do not adapt to high weight. This is relevant because trabecular plates are associated with greater estimated bone strength. Higher muscle mass and IGF-1 levels may mitigate some of the adverse effects of low weight or excess adiposity on bone.

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Ohashi, Takahiro, Kenta Wakiyama, Hamed Mofidi Tabatabaei et Tadashi Nishihara. « Alleviation of Stress Concentration with Rivet-Like Joints Fabricated by Friction-Stir Forming ». Key Engineering Materials 858 (août 2020) : 33–38. http://dx.doi.org/10.4028/www.scientific.net/kem.858.33.

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In this paper, the authors propose a design for the mechanical joining of dissimilar materials by employing rivet-like structures fabricated by friction-stir forming (FSF) considering the stress concentration on the joined material. The authors have utilized the FSF approach to generate rivet-like joints as follows. First, a substrate material (an aluminum alloy plate) was placed on a joined dissimilar-material plate containing prepared holes, i.e., a steel plate. Afterwards, these materials were placed on a die containing the cavity to fabricate the head of the rivet-like structure. FSF was then conducted to form the stems and heads of the rivet-like structure from the substrate material. Unlike conventional riveting, fastener was not considered necessary for the process; therefore, choosing different diameters of the prepared holes with multiple joints for the optimization of their structural design was easier. It is known that two auxiliary holes neighboring a main hole on either side reduce the stress concentration on the rim of the main hole. In this study, the authors applied the “round-hole-array design” on rivet-like joints fabricated by FSF. The authors examined the design of two smaller prepared holes with a commercial Finite element analysis (FEA) software for the rivet-like joint containing a 4 mm-diameter hole on a joined plate. To prove this, a 3 mm-thick A5083P-O aluminum alloy plate and a 0.7 mm-thick and 20 mm-wide SPCE steel plate was joined with the suggested design, and the strength and fracture of the joints were investigated using the tensile shear test. As a result, all joints were destroyed by the facture of the prepared holes, and it was confirmed that their strength was improved by the round-hole-array design.

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Karthick, Subramani, et Prosun Kumar Datta. « Dynamic Instability Characteristics of Thin Plate Like Beam with Internal Damage Subjected to Follower Load ». International Journal of Structural Stability and Dynamics 15, n^o 03 (8 mars 2015) : 1450048. http://dx.doi.org/10.1142/s0219455414500485.

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This study investigates the vibration, buckling and dynamic instability characteristics of damaged cross-ply and angle-ply laminated plate like beam under follower loading using the finite element approach. The damage is anisotropic in nature and parametrically incorporated into the composite using the concept of reduction in stiffness. It has been observed that damage shows a strong orthogonality and in general deteriorates the vibration and buckling characteristics. For follower type of loading, analysis is carried out on plate like beam structure to obtain the flutter characteristics. The effects of damage and its location on flutter characteristics are studied. The desirable position of damage on the plate like beam structure based on different stability behavior is discussed. The results show that flutter is observed as primary modes of instability when damaged plate like beam is subjected to follower loads. The behavior of flutter characteristics for different damaged parameters is discussed.

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Le, Thanh-Cao, Duc-Duy Ho, Thanh-Canh Huynh et Van-Sy Bach. « Crack Detection in Plate-Like Structures Using Modal Strain Energy Method considering Various Boundary Conditions ». Shock and Vibration 2021 (28 mai 2021) : 1–17. http://dx.doi.org/10.1155/2021/9963135.

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Among vibration-based damage detection methods, one of the effective approaches for damage localization is the modal strain energy method. In this paper, the modal strain energy method is developed for damage detection in plate-like structures with various boundary conditions. Firstly, the theory of the modal strain energy method is briefly outlined. In order to overcome the limitation of measuring points, a central difference method is newly employed to compute the partial differential terms in the modal strain energy formula. Finite element analysis is conducted on an aluminum thin plate to obtain the mode shapes before and after the occurrence of damage. Feasibility of the proposed method is verified by investigating plates with different types of boundary conditions. A damage index is presented to identify the location and extent of crack in the plate-like structures. The analytical results show that the proposed method accurately identifies the crack in the plate structure with various types of boundary conditions by using appropriate mode shapes and damage threshold.

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Ohashi, Takahiro, Hamed Mofidi Tabatabaei et Tadashi Nishihara. « Fastenerless-Riveting Utilizing Friction Stir Forming for Dissimilar Materials Joining ». Key Engineering Materials 751 (août 2017) : 186–91. http://dx.doi.org/10.4028/www.scientific.net/kem.751.186.

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This paper proposes a new joining approach for dissimilar materials, called ‘the fastenerless-riveting,’ employing the friction stir forming (FSF). The FSF is a friction stir process invented by Nishihara in 2002. In FSF, a substrate material was put on a die firstly. Next, friction stirring was conducted on the back surface of the material. The material then deformed and precisely filled the cavity of the die due to high pressure and heat caused by the friction stirring. The authors utilized the FSF approach to generate rivet like joints as followings. First, a substrate which is capable for friction stirring, i.e. an aluminum alloy plate, was put on a dissimilar material plate having holes, i.e. a steel plate. The authors call the former ‘the host member,’ the latter ‘a joined member.’ These members were put on a die having the cavity to fabricate the head of the rivet-like structure. Then FSF was conducted to form the stems and heads of the structure. Joint members are able to be stacked within the forming limit. In the study, the authors firstly conducted the proof of the concept (PoC) tests to generate rivet-like structure between steel and aluminum alloy plate and between CFRP and aluminum alloy plate, then investigated the forming conditions, i.e. tool feed rate, tool pass and the corresponding results, including the volume of the generated stem and head of the individual rivet-like structure. 3mm-thick A5083P-O aluminum alloy plates was utilized as the host member, and a 0.7mm-thick SPCE steel plate and a 0.8mm-thick CFRP plate as the joined members.

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Lee, Chang Gil, Eun Seok Shin, Hyun Uk Kim et Seung Hee Park. « Visualization of Structural Defects Based on Ultrasonic Wave Propagation Imaging Technique Using Pulsed Laser System ». Applied Mechanics and Materials 281 (janvier 2013) : 620–23. http://dx.doi.org/10.4028/www.scientific.net/amm.281.620.

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In this study, structural defects are visualized and localized based on a noncontact nondestructive testing (NDT) method which utilizes an ND: YAG pulsed laser system. The ND: YAG pulsed laser is used to generate Lamb waves of a plate-like structure and to scan specific area of the target structure for the visualization of the structure. Wave responses are measured using only single piezoelectric sensor. The measured responses are analyzed using 3 dimensional Fourier transform. The damage-sensitive features are extracted by wave-number filtering based on the 3D FT. Then, flaw imaging technique of a plate-like structure is conducted using the damage-sensitive features. Finally, the plate with a notch is investigated to verify the effectiveness and the robustness of the proposed NDT approach.

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Wu, Wenwei, Xuewen Yin, Hui Li et Kuikui Zhong. « Power flow analysis of built-up plate structures using the dynamic stiffness method ». Journal of Vibration and Control 24, n^o 13 (27 février 2017) : 2815–31. http://dx.doi.org/10.1177/1077546317695132.

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The dynamic stiffness method (DSM) in our recent paper, which can consider both in-plane and out-of-plane vibrations simultaneously, is formulated to investigate the power flow characteristics of built-up plate structures. Prior to power flow analysis, comprehensive validation works on our DSM are performed so as to better exhibit its numerical capabilities. Power input and power transmission within a two-plate structure are then analyzed by following the context of in-plane and out-of-plane vibrations. In addition, three vibration transmission paths within a multiple plate structure are characterized in terms of power flow densities, which can provide better physical insights in vibration transmission within complex plate structures. Compared to power flow analysis based on the well-known reception/mobility method, our approach is strongly recommended for the dynamics of built-up structures since it can assemble the overall stiffness matrix in a straightforward manner like that in the conventional finite element technique.

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Mendes, Sebastian, et Liling Cao. « Analysis Method for Reinforcing Circular Openings in Isotropic Homogeneous Plate-Like Structures Subjected to Blast Loading ». Advances in Civil Engineering 2018 (5 septembre 2018) : 1–21. http://dx.doi.org/10.1155/2018/4071732.

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An analysis method is formulated to predict the peak bending stress concentrations around a small circular opening in an idealized isotropic homogeneous, linear elastic-perfectly plastic plate-like structure subjected to uniform blast loading. The method allows for the determination of corresponding concentrated bending moments adjacent to the opening for the design of reinforcement that can prevent the formation of localized plasticity around the opening during a blast event. The rapid formation and growth of localized plasticity around the opening can lead to a drastic reduction of the plate-like structure’s local and global stability, which could result in catastrophic failure of the structure and destruction of the entity it is protecting. A set of elemental formulas is derived considering one-way and two-way rectangular plate-like structures containing a single small circular opening located where flexure predominates. The derived formulas are applicable for elastic global response to blast loading. Abaqus was employed to conduct numerical verification of the derived formulas considering various design parameters including material properties, plate dimensions, position of opening, and explosive charge size. The formulas demonstrate a good correlation with FEA albeit with a conservative inclination. The derived formulas are intended to be used in tandem with dynamic SDOF analysis of a blast load-structure system for ease of design. Overall, the proposed method has the potential to be applicable for many typical conditions that may be encountered during design.

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Wang, Jingdou, W. Steve Shepard, Keith A. Williams et Christy B. Gattis. « Active vibration control of a plate-like structure with discontinuous boundary conditions ». Smart Materials and Structures 15, n^o 3 (25 avril 2006) : N51—N60. http://dx.doi.org/10.1088/0964-1726/15/3/n01.

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HAYASHI, Takahiro. « Defect Imaging Technique for Plate-like Structure using Laser-Induced Guided Wave ». Journal of The Institute of Electrical Engineers of Japan 139, n^o 5 (1 mai 2019) : 288–91. http://dx.doi.org/10.1541/ieejjournal.139.288.

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Majewska, K., S. Opoka, P. Kudela et W. Ostachowicz. « Novel FBG rosette for determining impact location in thin plate-like structure ». Journal of Physics : Conference Series 628 (9 juillet 2015) : 012118. http://dx.doi.org/10.1088/1742-6596/628/1/012118.

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Liu, Xinglong, Chengxu Zhou et Zhongwei Jiang. « Damage localization in plate-like structure using built-in PZT sensor network ». Smart Structures and Systems 9, n^o 1 (25 janvier 2012) : 21–33. http://dx.doi.org/10.12989/sss.2012.9.1.021.

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Lowenstam, H. A., et S. Weiner. « Phosphatic shell plate of the barnacle Ibla (Cirripedia) : a bone-like structure. » Proceedings of the National Academy of Sciences 89, n^o 22 (15 novembre 1992) : 10573–77. http://dx.doi.org/10.1073/pnas.89.22.10573.

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Lee, Changgil, et Seunghee Park. « Flaw Imaging Technique for Plate-Like Structures Using Scanning Laser Source Actuation ». Shock and Vibration 2014 (2014) : 1–14. http://dx.doi.org/10.1155/2014/725030.

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Recently, the longitudinal, shear, and surface waves have been very widely used as ultrasonic wave-based exploration methods to identify internal defects of host structures. In this context, a noncontact nondestructive testing (NDT) method is proposed to detect the damage of plate-like structures and to identify the location of the damage. To achieve this goal, a scanning laser source actuation technique is utilized to generate a guided wave and scans a specific area to find damage location more precisely. The ND:YAG pulsed laser is used to generate Lamb wave and a piezoelectric sensor is installed to measure the structural responses. The measured responses are analyzed using 3-dimensional Fourier transformation (3D FT). The damage-sensitive features are extracted by wavenumber filtering based on the 3D FT. Then, flaw imaging techniques of a plate-like structure are conducted using the damage-sensitive features. Finally, the plates with notches are investigated to verify the effectiveness and the robustness of the proposed NDT approach.

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Rucevskis, Sandris, Pavel Akishin et Andris Chate. « Numerical and Experimental Study on the Application of Mode Shape Curvature for Damage Detection in Plate-Like Structures ». Solid State Phenomena 220-221 (janvier 2015) : 264–70. http://dx.doi.org/10.4028/www.scientific.net/ssp.220-221.264.

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The paper describes on-going research effort at detecting and localizing damage in plate-like structures using mode shape curvature based damage detection algorithm. The proposed damage index uses data on exclusively mode shape curvature from the damaged structure. This method was originally developed for beam-like structures. The article generalizes the method of plate-like structures characterized by two-dimensional mode shape curvature. To examine limitations of the method, several sets of simulated data are applied and the obtained results of the numerical detection of damage are validated by comparing them with the findings of the case of the experimental test. The simulated test cases include the damage of various levels of severity. In order to ascertain the sensitivity of the proposed method for noisy experimental data, numerical mode shapes are corrupted with different levels of random noise. Modal frequencies and corresponding mode shapes of an aluminium plate containing mill-cut damage are obtained via finite element models for numerical simulations and by using a scanning laser vibrometer (SLV) for the experimental study.

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Huang, Chuang, Hong Shui Wang, Hai Long Liu, Chun Yong Liang, Bao Fa Li, Bao E. Li, Chang Yi Li et Shi Min Liu. « The Controllable Growth of Stereo Reticular Hydroxyapatite Structure on Femtosecond Lasers Micro-Patterned Titanium Surface ». Journal of Biomimetics, Biomaterials and Biomedical Engineering 25 (octobre 2015) : 90–97. http://dx.doi.org/10.4028/www.scientific.net/jbbbe.25.90.

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The controllable deposition of hydroxyapatite (HA) on femtosecond lasers micro-patterned Titanium (Ti) plates was studied in simulated body fluid (SBF). Energy Dispersive Spectrometer analysis and X-ray Diffraction (XRD) analysis show that the hydroxyapatite deposites on the pattened titanium surface in 1.5 SBF and SEM studies show three growth modes of HA (homogeneous hydroxyapatite layer, needle-like structure, and plate-like structure) deposited at different spots of the Ti plate surface. This stereo reticular structure of hydroxyapatite could be regarded as promising candidate material for metal implantation.

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Samuels, A. L., T. H. Giddings et L. A. Staehelin. « Cytokinesis in tobacco BY-2 and root tip cells : a new model of cell plate formation in higher plants. » Journal of Cell Biology 130, n^o 6 (15 septembre 1995) : 1345–57. http://dx.doi.org/10.1083/jcb.130.6.1345.

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Cell plate formation in tobacco root tips and synchronized dividing suspension cultured tobacco BY-2 cells was examined using cryofixation and immunocytochemical methods. Due to the much improved preservation of the cells, many new structural intermediates have been resolved, which has led to a new model of cell plate formation in higher plants. Our electron micrographs demonstrate that cell plate formation consists of the following stages: (1) the arrival of Golgi-derived vesicles in the equatorial plane, (2) the formation of thin (20 +/- 6 nm) tubes that grow out of individual vesicles and fuse with others giving rise to a continuous, interwoven, tubulo-vesicular network, (3) the consolidation of the tubulo-vesicular network into an interwoven smooth tubular network rich in callose and then into a fenestrated plate-like structure, (4) the formation of hundreds of finger-like projections at the margins of the cell plate that fuse with the parent cell membrane, and (5) cell plate maturation that includes closing of the plate fenestrae and cellulose synthesis. Although this is a temporal chain of events, a developing cell plate may be simultaneously involved in all of these stages because cell plate formation starts in the cell center and then progresses centrifugally towards the cell periphery. The "leading edge" of the expanding cell plate is associated with the phragmoplast microtubule domain that becomes concentrically displaced during this process. Thus, cell plate formation can be summarized into two phases: first the formation of a membrane network in association with the phragmoplast microtubule domain; second, cell wall assembly within this network after displacement of the microtubules. The phragmoplast microtubules end in a filamentous matrix that encompasses the delicate tubulo-vesicular networks but not the tubular networks and fenestrated plates. Clathrin-coated buds/vesicles and multivesicular bodies are also typical features of the network stages of cell plate formation, suggesting that excess membrane material may be recycled in a selective manner. Immunolabeling data indicate that callose is the predominant lumenal component of forming cell plates and that it forms a coat-like structure on the membrane surface. We postulate that callose both helps to mechanically stabilize the early delicate membrane networks of forming cell plates, and to create a spreading force that widens the tubules and converts them into plate-like structures. Cellulose is first detected in the late smooth tubular network stage and its appearance seems to coincide with the flattening and stiffening of the cell plate.

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Portman, R. W., E. L. LeCluyse et W. L. Dentler. « Development of microtubule capping structures in ciliated epithelial cells ». Journal of Cell Science 87, n^o 1 (1 février 1987) : 85–94. http://dx.doi.org/10.1242/jcs.87.1.85.

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Although capping structures are present at the tips of microtubules in both growing cilia and mature cilia, previous work has not determined the time of cap formation. The results reported here reveal that the large caps of mature palate cilia appear in cilia with lengths as short as 1.75 micron. In the growing palate cilium, a disk-shaped plate is formed at the tip during the first micron of growth. As the cilium elongates to 1.5-2.0 microns, a small plate forms underneath the disk-shaped plate that gives an asymmetrical appearance to the whole cap structure. The structure of the cap is complete in cilia longer than 2.0 microns. The hair-like structures that form the extraciliary crown appear on the membrane at the ciliary tip at the same time as the mature cap is forming. The formation of a cap structure is discussed in relation to microtubule assembly during ciliogenesis.

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Tedja, Michael, Anastasia Prisilla, Carolina Carolina, Dimas E. J. Wiharyanto et Johnsen Susiyo. « Perbandingan Metode Konstruksi Plat Lantai Sistem Double Wire Mesh Dengan Sistem Half Slab ». ComTech : Computer, Mathematics and Engineering Applications 4, n^o 2 (1 décembre 2013) : 888. http://dx.doi.org/10.21512/comtech.v4i2.2527.

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Floor plate is a structure on two-story buildings or more. Like other structures, floor plate also develops over time. Demands a shorter time jobs at a cheaper cost are some reasons for structures development of house construction. Floor plate can be constructed with two different way: conventional which uses double wire meshand modern uses half slab. The purpose of this study is to determine which floor plate construction methods of double wire mesh and half slab is more efficient in terms of cost and time. The study is conducted using survey, comparative analysis and literature study. The results of this study indicate that both methods have advantages and disadvantages. Double wire mesh method takes cheaper construction costs while half slab method takes faster construction time.

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Randiligama, H. M. S. P., M. M. M. G. P. G. Mantilaka et T. C. Palihawadana. « Urea-Assisted Synthesis of Nanospherical and Plate-Like Magnesium Oxides for Efficient Removal of Reactive Dye Wastes ». Journal of Nanomaterials 2020 (16 décembre 2020) : 1–10. http://dx.doi.org/10.1155/2020/6189061.

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Nanospherical and plate-like magnesium oxide has been successfully synthesized by urea precipitation method for the first time. A magnesium oxide precursor was prepared by heating MgCl2 solution with urea for 12 hours at 90°C. Then the calcined precursor was analysed by Scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectroscopy, thermogravimetric analysis (TGA), and high-resolution transmission electron microscopy (HR-TEM). In the presence of the nonionic surfactant Triton X-100 in the system, the reaction yielded in nanospheres of MgO contrast to the plate-like MgO in the absence of the surfactant. The precursor and the calcined product appeared in similar morphologies under SEM in both cases with a slight reduction of size upon calcination. The final product was confirmed as MgO using XRD and FT-IR spectroscopic methods. In TGA, both samples showed similar mass loss values upon elimination of adsorbed water molecules and decomposition of the precursor into MgO; however, the nanospherical MgO sample showed an additional weight loss due to elimination of the associated surfactant molecules. The efficiency of removing reactive dye wastes was quantified by UV-visible spectroscopy using reactive yellow dye. Plate-like MgO showed a porous structure under HR-TEM analysis in the dye adsorption study, and both plate-like and nanospherical MgO showed good dye adsorption capability. MgO nanospheres showed higher capacity of dye adsorption compared to plate-like MgO, explained by its higher surface are-to-volume ratio, while the plate-like MgO also performed well due to having a nanoporous structure. These nanomaterials will offer high potential in purifying waste water and as well in recovering expensive dye products.

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Liu, Chang, Lei Zhao, Xue-Wei Li et Ji-Huan He. « Hierarchical structure of nanofibers by bubbfil spinning ». Thermal Science 19, n^o 4 (2015) : 1445–46. http://dx.doi.org/10.2298/tsci1504445l.

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A polymer bubble is easy to be broken under a small external force, various different fragments are formed, which can be produced to different morphologies of products including nanofibers and plate-like strip. Polyvinyl-alcohol/honey solution is used in the experiment to show hierarchical structure by the bubbfil spinning.

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Yang, Yahui, Guanhua Jin et Hang Li. « Photoelectrochemical Properties and Photocatalytic Activity of Fluorine-Doped Plate-Like WO3 from Hydrothermal Radio-Frequency (RF) Sputtered Tungsten Thin Films ». Nano 12, n^o 04 (avril 2017) : 1750041. http://dx.doi.org/10.1142/s1793292017500412.

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Fluorine-doped tungsten oxide (WO3) plate-like films were synthesized by hydrothermal radio-frequency (RF) sputtered tungsten (W) thin films in HF solution. The crystal structure, composition and morphology of nitrogen fluorine (F) doped WO3 were characterized by scanning electron microscope (SEM), X-ray diffractometer (XRD), X-ray photoelectron spectroscopy (XPS), and UV-Vis diffuse reflectance spectra (DRS) techniques. The results indicate that fluorine can be doped successfully into WO3 plate-like films by hydrothermal synthesis in hydrofluoric acid (HF) solution. The F-doped WO3 samples show stronger absorption in the UV-Vis range and a red shift in the band gap transition. Incident photon to current efficiency (IPCE) measurements carried out on photoelectrochemical cell with F-doped WO3 plate-like films as anodes demonstrate a significant increase of photoresponse in the visible region compared with undoped WO3. The photocatalytic activity under visible light irradiation for newly synthesized F-doped WO3 plate-like films was investigated by degradation of methyl orange. The photocatalytic activity of F-doped WO3 plate-like films was 3-fold enhancement compared with pure WO3 samples.

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Lu, Meijuan, Jun Wang, Xiaogang Su, Qilei Wu, Tingyu Yan et Xiaoxiao Zhang. « Fabrication, structure, and microwave absorbing properties of plate-like BaFe12O19@ZnFe2O4/MWCNTs nanocomposites ». Materials Letters 253 (octobre 2019) : 46–49. http://dx.doi.org/10.1016/j.matlet.2019.06.012.

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Ding, Zheyu, Hongbai Bai, Yiwan Wu, Zhiying Ren et Yichuan Shao. « A Constitutive Model of Plate-Like Entangled Metallic Wire Material in Wide Temperature Range ». Materials 12, n^o 16 (9 août 2019) : 2538. http://dx.doi.org/10.3390/ma12162538.

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Entangled metallic wire material (EMWM) is a kind of porous damping material. To promote the engineering application of EMWM, it is necessary to establish the constitutive model of EMWM to estimate its mechanical properties. In this paper, a series of quasi-static compression experiments for plate-like EMWM specimens made of austenitic stainless steel wire (06Cr19Ni10) with different densities were carried out in the temperature range of 20–500 °C. It was found that the stiffness of the plate-like EMWM would increase with the increases in the ambient temperature. The non-linear characteristics of the force–displacement curve of the plate-like EMWM would be weakened. Taking the spatial structural characteristics of the plate-like EMWM and the influence of the thermal expansion of the structure into account, a new constitutive model for plate-like EMWM was presented by the combination of the Johnson–Cook model and the Sherwood–Frost constitutive framework model. The accuracy of the model was verified by the experimental data under different temperatures. The results show that the calculated results of the model are consistent with the experimental results. This model can provide an effective theoretical basis for predicting the mechanical properties of plate-like EMWM and guiding its design.

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Wang, Wei Yuan, Yuan Yuan Li et Hai Sheng Shu. « Sound Insulation Property of Bionic Thin-Walled Stiffened Plate Based on Plants Venations Growth Mechanism ». Journal of Biomimetics, Biomaterials and Biomedical Engineering 20 (juin 2014) : 35–44. http://dx.doi.org/10.4028/www.scientific.net/jbbbe.20.35.

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The leaf can be seen as shin plate structures with stiffener(vein) and the venation distributions are closed related to the external environment load. Leaf venation growing algorithm (VGA) is the abstract description of vein growing process and reflects an ideological of learning from nature. This article concerns the sound insulation property of thin-walled stiffened plates. Numerical method is used to analyze three types of plants: non-stiffened plate, traditional stiffened plate and VGA stiffened plate. The VGA stiffened plate optimized by leaf venations growth algorithm method can reflect the influence of venations layout structure on the noise reduction performance of forest belts. The computational model of sound transmission through a stiffened plate excited by a harmonic oblique incident plane wave and mounted in an infinite baffle using the coupled finite element/boundary element approach is presented. The proposed model also takes the acoustic fluid- structure coupling into account. The results show that the sound transmission losses are closely dependent on the natural frequency. The sound transmission losses of bionic thin-walled stiffened plate are 0.17-2.45dB more than that of traditional stiffened plate in the range of 900-2000Hz. It indicated that the layout of stiffeners is an influence factor for noise reduction for plate structures, just like that of vein layout for tree belts. There is a certain merit to use the method of bionic plant leaves for acoustic optimization.

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Cheng, Li Qian, Mei Feng et Kai Chen. « Topochemical Synthesis of High-Aspect-Ratio Lead-Free (K, Na)NbO₃ Plate-Like Structures ». Solid State Phenomena 281 (août 2018) : 622–27. http://dx.doi.org/10.4028/www.scientific.net/ssp.281.622.

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Single crystalline lead-free (K, Na)NbO3 (KNN) nanostructures have attracted much attention for the high piezoelectricity and environmental compatibility. Especially, the plate-like KNN structures are supposed to be utilized in the synthesis of textured KNN-based ceramics. The KNN plate-like templates were prepared by a two-step molten salt reaction. The layered-perovskite Bi2.5Na3.5Nb5O18 (BNN5) was first prepared by using Bi2O3, Nb2O5, Na2CO3, NaCl as raw materials. The BNN5 precursors possess high aspect ratio with an average size of 15 - 20 μm in width and 0.5 - 1 μm in thickness. Then Bi element in the BNN5 was replaced by Na/K through topochemical reaction, and KNN plate-like products which have anisotropic crystal structure were fabricated. It should be emphasized that piezoresponse force microscopy (PFM) was used to confirm three-dimensional (3-D) morphology, while piezoelectric properties of single crystalline KNN platelets were acquired simultaneously. The as-synthesized KNN structures are expected to play an important role in the study of textured KNN ceramics. Meanwhile, the methodology investigated in this paper can also be applied for further fundamental studies on KNN system as well as other lead-free piezoelectric materials.

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Li, Weibin, Mingxi Deng et Younho Cho. « Cumulative Second Harmonic Generation of Ultrasonic Guided Waves Propagation in Tube-Like Structure ». Journal of Computational Acoustics 24, n^o 03 (30 août 2016) : 1650011. http://dx.doi.org/10.1142/s0218396x16500119.

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Second harmonic generation of ultrasonic waves propagating in unbounded media and plate-like structure has been vigorously studied for tracking material nonlinearity, however, second harmonic guided wave propagation in tube-like structures is rarely studied. Considering that second harmonics can provide sensitive information for structural health condition, this paper aims to study the second harmonic generation of guided waves in metallic tube-like structures with weakly nonlinearity. Perturbation method and modal analysis approach are used to analyze the acoustic field of second harmonic solutions. The conditions for generating second harmonics with cumulative effect are provided in present investigation. Flexible polyvinylidene fluoride comb transducers are used to measure fundamental wave modes and second harmonic ones. The work experimentally verifies that the second harmonics of guided waves in pipe have a cumulative effect with propagation distance. The proposed procedure of this work can be applied to detect material nonlinearity due to damage mechanism in tube-like structure.

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