Effect of Poisson's ratio on the fundamental frequency of transverse vibration and buckling load of circular plates with variable profile

1996 ◽  
Vol 47 (3) ◽  
pp. 263-273 ◽  
Author(s):  
P.A.A. Laura ◽  
V. Sonzogni ◽  
E. Romanelli
Author(s):  
Teik-Cheng Lim

This paper evaluates the elastic stability and vibration characteristics of circular plates made from auxetic materials. By solving the general solutions for buckling and vibration of circular plates under various boundary conditions, the critical buckling load factors and fundamental frequencies of circular plates, within the scope of the first axisymmetric modes, were obtained for the entire range of Poisson's ratio for isotropic solids, i.e., from −1 to 0.5. Results for elastic stability reveal that as the Poisson's ratio of the plate becomes more negative, the critical bucking load gradually reduces. In the case of vibration, the decrease in Poisson's ratio not only decreases the fundamental frequency, but the decrease becomes very rapid as the Poisson's ratio approaches its lower limit. For both buckling and vibration, the plate's Poisson's ratio has no effect if the edge is fully clamped. The results obtained herein suggest that auxetic materials can be employed for attaining static and dynamic properties which are not common in plates made from conventional materials. Based on the exact results, empirical models were generated for design purposes so that both the critical buckling load factors and the frequency parameters can be conveniently obtained without calculating the Bessel functions.


2012 ◽  
Vol 29 (1) ◽  
pp. 121-133 ◽  
Author(s):  
T.-C. Lim

AbstractThis paper investigates the suitability of auxetic materials for load-bearing circular plates. It is herein shown that the optimal Poisson's ratio for minimizing the bending stresses is strongly dependent on the final deformed shape, load distribution, and the type of edge supports. Specifically, the use of auxetic material for circular plates is recommended when (a) the plate is bent into a spherical or spherical-like cap, (b) a point load is applied to the center of the plate regardless of the edge conditions, and (c) a uniform load is applied on a simply-supported plate. However, auxetic materials are disadvantaged when a flat plate is to be bent into a saddle-like shell. The optimal Poisson's ratios concept recommended in this paper is useful for providing an added design consideration. In most cases, the use of auxetic materials for laterally loaded circular plates is more advantageous compared to the use of materials with conventional Poisson's ratio, with other factors fixed. This is achieved through materials-based stress re-distribution in addition to the common practices of dimensioning-based stress redistribution and materials strengthening.


Author(s):  
Mohammed Sobhy

As a new model, functionally graded piezoelectric (FGP) sandwich plate with negative Poisson’s ratio honeycomb core (auxetic core) is considered in this paper. Buckling analysis of the FGP sandwich plate is investigated based on a novel four-unknown shear deformation plate theory. The electrical and mechanical properties of the face layers are continuously varied through the thickness of the layers. This variation is achieved using a power law distribution in terms of the constituents volume fraction. The core layer composed of hexagonal honeycomb cells with negative Poisson’s ratio was made of a metallic material. The sandwich plate is exposed to uniaxial or biaxial compressive loads as well as electric voltage. Five stability differential equations are established based on the principle of virtual work including mechanical and electric loads. The obtained buckling load is compared with that available in the literature. Impacts of various parameters like the power law index, load parameter, external applied voltage, core thickness, boundary conditions and plate geometry on the buckling load of the smart composite plates with auxetic core are investigated. From the numerical results, one can find that the increase of electric voltage and core thickness decreases the buckling load.


2022 ◽  
Author(s):  
Matheus Brendon Francisco ◽  
João Luiz Junho Pereira ◽  
Lucas Antonio de Oliveira ◽  
Sebastião Da Cunha ◽  
Guilherme Ferreira Gomes

Abstract The optimization of five different responses of an auxetic model was considered: mass; critical buckling load under compression effort; natural frequency; Poisson’s ratio; and failure load. The Response Surface Methodology was applied, and a new meta-heuristic of optimization called the Multi-Objective Lichtenberg Algorithm was used to find the optimized configuration of the model. It was possible to increase the failure load by 26,75% in compression performance optimization. Furthermore, in the optimization of modal performance, it was possible to increase the natural frequency by 37.43%. Finally, all 5 responses analyzed simultaneously were optimized. In this case, it was possible to increase the critical buckling load by 42.55%, the failure load by 28.70% and reduce the mass and Poisson’s ratio by 15.97% and 11%, respectively. This paper shows something unprecedented in the literature to date when evaluating in a multi-objective optimization problem, the compression and modal performance of an auxetic reentrant model.


1974 ◽  
Vol 41 (2) ◽  
pp. 521-523 ◽  
Author(s):  
R. Schmidt

This Note develops a new perturbation method for the analysis of circular plates and membranes with finite axisymmetric deflections. The perturbation parameter involves Poisson’s ratio. Two equations of the resulting infinite system of linearized differential equations are identical with Berger’s equations.


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