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Vibrations of a square plate with periodically changing parameters are considered. The averaged fourth-order partial differential equation for plate deflection w is presented. Solution of the problem is obtained with the approxima...
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Vibrations of a square plate with periodically changing parameters are considered. The averaged fourth-order partial differential equation for plate deflection w is presented. Solution of the problem is obtained with the approximate theory. The approximate results are presented by analytical formulas. Asymptotic averaging (implemented in Wolfram Mathematica) and the finite element method (ANSYS) are used to determine the values of eigenfrequencies. Numerical and asymptotic results are compared.
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This paper investigates an inverse technique for the identification of orthotropic elastic constants from measured plate natural frequencies. In general, the accuracy of the identified parameters depends on the method of estimatio...
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This paper investigates an inverse technique for the identification of orthotropic elastic constants from measured plate natural frequencies. In general, the accuracy of the identified parameters depends on the method of estimation, modelling errors and measurement errors. The paper addresses the parameter uncertainty due to errors in the measurements. Based on assumptions of the measurement errors, second-order statistics of parameters are approximated by linearization schemes. The main focus is on the possibility of designing the experiment to minimize the uncertainty of the estimated parameters. The uncertainty of each estimate as function of the experimental design variables is investigated. Also the overall optimality of the experimental design defined as the hypervolume of the confidence region is considered. The results show that not all parameters are estimated with a sufficient precision in the general case, but by carefully designing the experiment, the parameter uncertainties can be greatly reduced. Both thin and thick-plates are considered with focus on single-layer plates, but the results for laminated plates are also discussed. (C) 1998 Elsevier Science Ltd. [References: 20]
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Does the size of a plate influence the serving of all items equally, or does it influence the serving of some foods - such as meat versus vegetables - differently? To examine this question, we used the new method of plate mapping,...
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Does the size of a plate influence the serving of all items equally, or does it influence the serving of some foods - such as meat versus vegetables - differently? To examine this question, we used the new method of plate mapping, where people drew a meal on a paper plate to examine sensitivity to small versus large three-compartment divided plates in portion size and meal composition in a sample of 109 university students. The total drawn meal area was 37% bigger on large plates than small plates, which showed that the portion of plate coverage did not differ by plate size. Men and women drew bigger vegetable portions and men drew bigger meat portions on large plates when compared to small plates. These results suggest that men and women are differentially sensitive to plate size for overall meal size and for meal composition. Implications for decreasing portion size and improving meal balance are that plate size may influence portion size and change the proportions of foods served.
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The problem of bending vibration of a polar-orthotropic non-homogeneous elastic plate on an elastic foundation is considered, and the invariance of the problem-equation under an inversion transformation with respect to a circle is...
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The problem of bending vibration of a polar-orthotropic non-homogeneous elastic plate on an elastic foundation is considered, and the invariance of the problem-equation under an inversion transformation with respect to a circle is proved. As a corollary, the optimization problem (the ''best'' position of the point mass or point support, which optimizes the plate fundamental frequency) is considered and certain geometrical inequalities, which reduce the optimization domain, are proved. Computational time economy generated by the inequalities for the optimization problem is illustrated with numerical examples: (a) the ''best'' position of the point mass on segment and ring-sector plates; (b) the ''best'' radius of the ring support for annular plates. Some other corollaries from the problem-equation inversion invariance are given. (C) 1997 Academic Press Limited. [References: 29]
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This paper is concerned with the bending of sectorial and annular sectorial thick plates with the radial edges simply supported. The Reissner plate theory has been adopted to cater for the effect of transverse shear deformation. I...
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This paper is concerned with the bending of sectorial and annular sectorial thick plates with the radial edges simply supported. The Reissner plate theory has been adopted to cater for the effect of transverse shear deformation. In solving the aforementioned plate problems, we derive the relationships between the bending solutions of the Reissner plate theory and the classical thin plate theory. The relationships enable one to deduce the bending solutions of the Reissner plate theory using the corresponding classical thin plate results, which can be determined readily or are already available in the literature. Several sectorial plate problems are solved, and the Reissner plate results are checked against existing numerical results as well as results obtained using other higher-order plate theories.
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This article deals with the linear static and buckling analysis of an asymmetric square sandwich plate with orthotropic stiffness properties in the face layers. Two analytical formulations related to thin and thick face layers, re...
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This article deals with the linear static and buckling analysis of an asymmetric square sandwich plate with orthotropic stiffness properties in the face layers. Two analytical formulations related to thin and thick face layers, respectively, have been taken from (Zenkert, D. (1995). An Introduction to Sandwich Construction, Chameleon Press Ltd, London, UK (ISBN 0 947817 77 8)), slightly modified to account for unequal faces, orthotropic properties in the face layers, and individual Poisson's ratios, and applied to square sandwich plates of 1 m lateral dimension and a variety of different face layer thickness. All cases assume simply supported edges. The obtained deflections and buckling loads are compared with the results of a 3D analysis (Meyer-Piening, H.-R. (2004). Application of the Elasticity Solution to Linear Sandwich Beam, Plate and Shell Analyses, J. of Sandwich Structures & Materials, 6(4): 295-312) and of finite element calculations. The objectives of this study are to gain insight into the limits of validity of the published formulas in view of unequal thick face layers and or thotropic properties. The obtained results are meant to serve as a benchmark for further studies.
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摘要 :AbstractNew designs of cover plates and grinding plates for a universal grinding machine are developed. These designs greatly expand the functional capabilities of the machine. The plates are durable and their operating costs are ...
展开AbstractNew designs of cover plates and grinding plates for a universal grinding machine are developed. These designs greatly expand the functional capabilities of the machine. The plates are durable and their operating costs are low.]]>
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This paper deals with the bending and vibration analyses of damaged moderately thick slabs strengthened with externally bonded carbon fiber-reinforced polymer (CFRP) sheets. In the analytical formulation, the two adherends and the...
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This paper deals with the bending and vibration analyses of damaged moderately thick slabs strengthened with externally bonded carbon fiber-reinforced polymer (CFRP) sheets. In the analytical formulation, the two adherends and the adhesive layer are all modeled as shear deformable plates using the first order shear deformation plate theory. The anisotropic damage model is adopted to describe the damage extent of the reinforced concrete (RC) slabs. The total potential energy of a locally damaged slab strengthened with an externally bonded sheet is derived. Trigonometric series are used to present the shape functions of strengthened slabs and Rayleigh-Ritz method is employed to determine the deflections and stresses in the case of bending analysis, and natural frequencies in the case of linear eigenvalue problems of vibration. Several test problems are examined to demonstrate the accuracy and effectiveness of the proposed method. Numerical results are presented that relate to the performance of damaged RC slabs bonded with CFRP sheets, in which a damaged RC slab strengthened by a thin steel sheet is treated as a comparator. The effects of damage extent and the effects of the bonded sheet on the bending and vibration characteristics of damaged RC slabs are also studied.
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Purpse Osteosynthesis plate removal is one of the most commonly performed procedures in orthopaedic surgery. Due to technological advances and the quality of increasing osteosynthesis material, more and more locked plates have bee...
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Purpse Osteosynthesis plate removal is one of the most commonly performed procedures in orthopaedic surgery. Due to technological advances and the quality of increasing osteosynthesis material, more and more locked plates have been implanted over the last 20 years. The aim of this study was to determine whether the complication rate during plate removal differs between conventional and locked plates.
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The astronomical events registered in photographic plates are unique. A remarkable interest in using old plates in many areas of the current astronomical research is widely recognized by the IAU. There are almost ten thousand plat...
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The astronomical events registered in photographic plates are unique. A remarkable interest in using old plates in many areas of the current astronomical research is widely recognized by the IAU. There are almost ten thousand plates in several collections at the Córdoba Observatory and most of them are nearly one century old. This photographic material is difficult to handle in order to get the information stored in it. The goal of this project is to make a digital archive of images of these collections. In this first survey plates are being scanned with a standard commercial transparency scanner. These low spatial resolution, low digital resolution and low signal-to-noise ratio images are intended for facilitating handling and visual inspection. However, one arc-second positions can be obtained. Photometric quality has not been yet determined. Otherwise high quality digital images can be acquired with a microdenstitometer based on a scientific grade CCD whose implementation is at its final stage. The possibility of using a better-performance scanner is being evaluated. It is planned to permit the access to low-resolution images via internet. High-resolution images of selected zones will be available upon request. At this first stage, collections totally digitized at low resolution are: Carte du Ciel and Small Magellanic Cloud Zones. Gaviola's Eta Carinae Spectra and Pulkovo Zones are still in process.
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