Collapse mechanisms of sandwich beams with composite faces and a foam core, loaded in three-point bending. Part I: analytical models and minimum weight design

This paper attempts to investigate the flutter characteristic of sandwich panel composed of laminated facesheets and a functionally graded foam core. The macroscopic properties of the foam core change continuously along this direction parallel to the facesheet lamina. The model used in the study is a simple sandwich panel-wing clamped at the root, with three simple types of grading strategies for FGM core: (1) linear grading strategy in the chord-wise direction, (2) linear grading strategy in the span-wise direction, and (3) bilinear grading of properties of foam core across the panel. The results show that use of FGM core has the potential to increase the flutter speed of the sandwich panel. Finally, a minimum weight design of composite sandwich panel with lamination parameters of facesheet and density distribution of foam core as design variables is conducted using particle swarm optimization (PSO).

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A Comparison of the Structural Response of Clamped and Simply Supported Sandwich Beams With Aluminium Faces and a Metal Foam Core

Journal of Applied Mechanics ◽

10.1115/1.1875432 ◽

2004 ◽

Vol 72 (3) ◽

pp. 408-417 ◽

Cited By ~ 45

Author(s):

V. L. Tagarielli ◽

N. A. Fleck

Keyword(s):

Metal Foam ◽

Minimum Weight ◽

Sandwich Beam ◽

Limit Load ◽

Analytical Models ◽

Collapse Mechanism ◽

Foam Core ◽

Sandwich Beams ◽

Polymer Foam ◽

The Face

Plastic collapse modes for clamped sandwich beams have been investigated experimentally and theoretically for the case of aluminium face sheets and a metal foam core. Three initial collapse mechanisms have been identified and explored with the aid of a collapse mechanism map. It is shown that the effect of clamped boundary conditions is to drive the deformation mechanism towards plastic stretching of the face sheets. Consequently, the ultimate strength and level of energy absorption of the sandwich beam are set by the face sheet ductility. Limit load analyses have been performed and simple analytical models have been developed in order to predict the postyield response of the sandwich beams; these predictions are validated by both experiments and finite elements simulations. It is shown experimentally that the ductility of aluminium face sheets is enhanced when the faces are bonded to a metal foam core. Finally, minimum weight configurations for clamped aluminium sandwich beams are obtained using the analytical formulas for sandwich strength, and the optimal designs are compared with those for sandwich beams with composite faces and a polymer foam core.

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The Failure Behavior of Geometrically Asymmetric Metal Foam Core Sandwich Beams Under Three-Point Bending

Journal of Applied Mechanics ◽

10.1115/1.4027200 ◽

2014 ◽

Vol 81 (7) ◽

Cited By ~ 17

Author(s):

Jianxun Zhang ◽

Qinghua Qin ◽

Weilong Ai ◽

Huimin Li ◽

T. J. Wang

Keyword(s):

Failure Mechanism ◽

Failure Modes ◽

Metal Foam ◽

Minimum Weight ◽

Failure Behavior ◽

Foam Core ◽

Sandwich Beams ◽

Three Point Bending ◽

Initial Failure ◽

Core Height

The failure behavior of geometrically asymmetric sandwich beams with a metal foam core is analytically and experimentally investigated. New initial failure modes of the asymmetric sandwich beams are observed under three-point bending, i.e., face yield, face wrinkling, core shear A, core shear AB, core shear A-AB, and indentation. It is shown that the initial failure modes of sandwich beams depend on the span of the beam, the thicknesses of top and bottom face sheets, core height and material properties. We derived the analytical formulae for the initial failure loads and then constructed the initial failure mechanism maps for the geometrically asymmetric sandwich beams. It is shown that the analytically predicted initial failure mechanism maps are in good agreement with the experimental results, which are clearly different from the symmetric sandwich beams. As a preliminary application, the minimum weight designs are presented for asymmetric metal sandwich beams.

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