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Deflection (engineering)

About: Deflection (engineering) is a research topic. Over the lifetime, 30862 publications have been published within this topic receiving 298849 citations.


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TL;DR: In this paper, the von Karman non-linear plate theory has been used to model the deformation of a thin initially flat plate, and the sensitivity of the deflection to the physically induced nonlinearities at moderate strains is significant.
Abstract: Static deflection as well as free and forced large-amplitude vibrations of thin rectangular rubber plates under uniformly distributed pressure are investigated. Both physical, through a neo-Hookean constitutive law to describe the non-linear elastic deformation of the material, and geometrical non-linearities are accounted for. The deflections of a thin initially flat plate are described by the von Karman non-linear plate theory. A method for building a local model, which approximates the plate behavior around a deformed configuration, is proposed. This local model takes the form of a system of ordinary differential equations with quadratic and cubic non-linearities. The corresponding results are compared to the exact solution and are found to be accurate. Two models reflecting both physical and geometrical non-linearities and geometrical non-linearities only are compared. It is found that the sensitivity of the deflection to the physically induced non-linearities at moderate strains is significant.

68 citations

Journal ArticleDOI
TL;DR: In this article, the dynamic response of a functionally graded carbon nanotube reinforced composite (FG-CNTRC) cylindrical panel subjected to moving load on the panel surface is investigated.
Abstract: Present study deals with the dynamic response of a functionally graded carbon nanotube reinforced composite (FG-CNTRC) cylindrical panel subjected to moving load on the panel surface. Panel is formulated within the framework of first order shear deformation shell theory. Formulation is restricted to be geometrically linear. Distribution of CNTs across the panel thickness is considered to be uniform or functionally graded. Effective properties of the composite media are estimated using a refined rule of mixtures approach with introduction of efficiency parameters. The matrix representation of dynamic equations is obtained according to the Ritz method whose orthogonal shape functions are obtained according to the Gram-Schmidt process. The resulting dynamic equations are traced in time following the Newmark time marching scheme. Parametric studies are given to explore the characteristics of CNTs as reinforcements and influences of boundary conditions. It is shown that, increasing the volume fraction of CNT as reinforcements decreases the dynamic response of the panel. Furthermore, in comparison to other patterns of CNT dispersion, in FG-X pattern of CNT distribution, panel becomes more stiff and dynamic deflection decreases.

68 citations

Journal ArticleDOI
TL;DR: In this article, a functionally graded rotating disk with axisymmetric bending and steady-state thermal loading is studied, where the material properties of the disk are assumed to be graded in the direction of the thickness by a power law distribution of volume fractions of the constituents.
Abstract: A functionally graded (FG) rotating disk with axisymmetric bending and steady-state thermal loading is studied. The material properties of the disk are assumed to be graded in the direction of the thickness by a power law distribution of volume fractions of the constituents. First-order shear deformation Mindlin plate and von Karman theories are employed. New set of equilibrium equations with small and large deflections are developed. Using small deflection theory an exact solution for displacement field is given. Solutions are obtained in series form in case of large deflection. Mechanical responses are compared small deflection versus large deflection as well as homogeneous versus FG disks. It is observed that for particular values of the grading index n of material properties mechanical responses in FG disk can be smaller than in a homogeneous disk. It is seen that given the non-dimensional maximum vertical displacement wmax/h close to 0.4 for a homogeneous (full-ceramic in this study) disk greater errors in the mechanical responses for FG disks would be introduced if one uses small deflection theory.

68 citations

Journal ArticleDOI
TL;DR: In this article, a mixed static and dynamic optimization of four-parameter functionally graded material (FGM) doubly curved shells and panels is presented, where particle swarm optimization, Monte Carlo and genetic algorithm approaches are applied to define the optimum volume fraction profile for optimizing the first natural frequency and the maximum static deflection of the considered shell structure.
Abstract: This study deals with a mixed static and dynamic optimization of four-parameter functionally graded material (FGM) doubly curved shells and panels. The two constituent functionally graded shell consists of ceramic and metal, and the volume fraction profile of each lamina varies through the thickness of the shell according to a generalized power-law distribution. The Generalized Differential Quadrature (GDQ) method is applied to determine the static and dynamic responses for various FGM shell and panel structures. The mechanical model is based on the so-called First-order Shear Deformation Theory (FSDT). Three different optimization schemes and methodologies are implemented. The Particle Swarm Optimization, Monte Carlo and Genetic Algorithm approaches have been applied to define the optimum volume fraction profile for optimizing the first natural frequency and the maximum static deflection of the considered shell structure. The optimization aim is in fact to reach the frequency and the static deflection targets defined by the designer of the structure: the complete four-dimensional search space is considered for the optimization process. The optimized material profile obtained with the three methodologies is presented as a result of the optimization problem solved for each shell or panel structure.

68 citations

Journal Article
TL;DR: A semi-mechanistic, semi-empirical analysis technique has been developed in South Africa in terms of which deflection bowl parameters, measured with the FWD, are used in a relative benchmarking methodology in conjunction with standardised visual survey methodology to give guidance on individual layer strengths and pinpoint rehabilitation needs.
Abstract: The falling weight deflectometer (FWD) is used worldwide as an established, valuable, nondestructive road testing device for pavement structural analyses. The FWD is used mostly for rehabilitation project level design investigations and for pavement management system (PMS) monitoring on a network basis. In project level investigations, design charts based on both empirical relations and mechanistic or theoretically based approaches are often used to provide structural evaluations and rehabilitation options. The full mechanistic approach normally uses multi-layer linear elastic theory and back-calculation procedures that have come under scrutiny owing to the inaccuracy of results. A semi-mechanistic, semi-empirical analysis technique has been developed in South Africa in terms of which deflection bowl parameters, measured with the FWD, are used in a relative benchmarking methodology in conjunction with standardised visual survey methodology to give guidance on individual layer strengths and pinpoint rehabilitation needs. This benchmark methodology enables the determination of the relative structural condition of the pavement over length and in depth without the requirement for detailed as-built data. A further correlation study with calculated surface moduli and deflection bowl parameters is presented here for granular base pavements, which can enhance benchmarking methodology.

68 citations


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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
202247
20211,006
20201,140
20191,262
20181,195
20171,215