Failure modes of composite sandwich beams

E. Gdoutos; I.M. Daniel

doi:10.2298/tam0803105g

Failure modes of composite sandwich beams

Theoretical and Applied Mechanics ◽

10.2298/tam0803105g ◽

2008 ◽

Vol 35 (1-3) ◽

pp. 105-118 ◽

Cited By ~ 22

Author(s):

E. Gdoutos ◽

I.M. Daniel

Keyword(s):

Failure Modes ◽

Failure Behavior ◽

Foam Core ◽

Sandwich Beams ◽

Composite Sandwich ◽

Four Point Bending ◽

Constituent Material ◽

Closed Cell ◽

Failure Envelopes ◽

Geometrical Dimensions

A thorough investigation of failure behavior of composite sandwich beams under three-and four-point bending was undertaken. The beams were made of unidirectional carbon/epoxy facings and a PVC closed-cell foam core. The constituent materials were fully characterized and in the case of the foam core, failure envelopes were developed for general two-dimensional states of stress. Various failure modes including facing wrinkling, indentation failure and core failure were observed and compared with analytical predictions. The initiation, propagation and interaction of failure modes depend on the type of loading, constituent material properties and geometrical dimensions.

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Failure of Composite Sandwich Beams

Advanced Composites Letters ◽

10.1177/096369350201100301 ◽

2002 ◽

Vol 11 (3) ◽

pp. 096369350201100 ◽

Cited By ~ 6

Author(s):

I. M. Daniel ◽

E. E. Gdoutos ◽

K.-A. Wang

Keyword(s):

Failure Modes ◽

Foam Core ◽

Sandwich Beams ◽

Composite Sandwich ◽

Four Point Bending ◽

Constituent Material ◽

Closed Cell ◽

Failure Envelopes ◽

Geometrical Dimensions ◽

Cell Foam

A thorough investigation of failure behaviour of composite sandwich beams under three- and four-point bending was undertaken. The beams were made of unidirectional carbon/epoxy facings and a PVC closed-cell foam core. The constituent materials were fully characterised and in the case of the foam core, failure envelopes were developed for general two-dimensional states of stress. Various failure modes including facing wrinkling, indentation failure and core failure were observed and compared with analytical predictions. The initiation, propagation and interaction of failure modes depend on the type of loading, constituent material properties and geometrical dimensions.

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Load and Geometry Effect on Failure Mode Initiation of Composite Sandwich Beams

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.3-4.173 ◽

2006 ◽

Vol 3-4 ◽

pp. 173-178

Author(s):

E.E. Gdoutos ◽

M.S. Konsta-Gdoutos

Keyword(s):

Failure Mode ◽

Failure Modes ◽

Shear Failure ◽

Sandwich Beams ◽

Compressive Failure ◽

Honeycomb Core ◽

Composite Sandwich ◽

Failure Mode Transition ◽

Aluminum Honeycomb ◽

Geometrical Dimensions

Facing compressive failure, facing wrinkling and core shear failure are the most commonly encountered failure modes in sandwich beams with facings made of composite materials. The occurrence and sequence of these failure modes depends on the geometrical dimensions, the form of loading and type of support of the beam. In this paper the above three failure modes in sandwich beams with facings made of carbon/epoxy composites and cores made of aluminum honeycomb and two types of foam have been investigated. Two types of beams, the simply supported and the cantilever have been considered. Loading included concentrated and uniform. It was found that in beams with foam core facing wrinkling and core shear failure occur, whereas in beams with honeycomb core facing compressive failure and core shear crimping take place. Results were obtained for the dependence of failure mode on the geometry of the beam and the type of loading. The critical beam spans for failure mode transition from core shear to wrinkling failure were established. It was found that initiation of a particular failure mode depends on the properties of the facing and core materials, the geometrical configuration and loading of composite sandwich beams.

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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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Carbon Foam Core Composite Sandwich Beams: Flexure Response

Journal of Composite Materials ◽

10.1177/0021998305048740 ◽

2005 ◽

Vol 39 (12) ◽

pp. 1067-1080 ◽

Cited By ~ 10

Author(s):

M. D. Sarzynski ◽

O. O. Ochoa

Keyword(s):

Carbon Foam ◽

Foam Core ◽

Sandwich Beams ◽

Composite Sandwich

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An Investigation on Mechanical Behavior of Tooth-Plate-Glass-Fiber Hybrid Sandwich Beams

Advances in Polymer Technology ◽

10.1155/2020/6346471 ◽

2020 ◽

Vol 2020 ◽

pp. 1-11

Author(s):

Honglei Xie ◽

Li Wan ◽

Bo Wang ◽

Haiping Pei ◽

Weiqing Liu ◽

...

Keyword(s):

Glass Fiber ◽

Failure Modes ◽

Bending Strength ◽

Fibrous Composite ◽

Strain Energy Release ◽

Metal Plate ◽

Plate Glass ◽

Foam Core ◽

Sandwich Beams ◽

Tooth Plate

Tooth-plate-glass-fiber hybrid sandwich (TFS) is a type of sandwich composites fabricated by vacuum-assisted resin infusion process, in which glass fiber facesheets reinforced by metal plate are connected to foam core through tooth nails. Bending properties and interlaminar properties of TFS beams with various foam densities were investigated by flexural tests and DCB (double cantilever beam) tests. The test results showed that by increasing the foam core density from 35 kg/m3 to 150 kg/m3, the peak strength of TFS beams significantly increased by 168% to 258% compared with similar sandwich beams with fibrous composite facesheets. With the change of foam density and span length, the main failure modes are core shear and facesheet indentation beneath the loading roller. The interlaminar strain energy release rates of TFS specimens also increased by increasing the density of the foam. In addition, an analytical model was used to predict the ultimate bending strength of TFS beams, which were in good accordance with the experimental results.

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Mechanical Behavior of Sandwich Panels with Hybrid PU Foam Core

Advances in Civil Engineering ◽

10.1155/2020/2908054 ◽

2020 ◽

Vol 2020 ◽

pp. 1-8

Author(s):

Xudong Zhao ◽

Li Tan ◽

Fubin Zhang

Keyword(s):

Failure Modes ◽

Peak Load ◽

Hard Core ◽

Experimental Results ◽

Control Panel ◽

Foam Core ◽

Initial Stiffness ◽

Composite Sandwich ◽

Pu Foam ◽

Compression Area

The traditional composite sandwich structures have disadvantages of low shear modulus and large deformation when used in civil engineering applications. To overcome these problems, this paper proposed a novel composite sandwich panel with upper and lower GFRP skins and a hybrid polyurethane (PU) foam core (GHP panels). The hybrid core is composed of different densities (150, 250, and 350 kg/m3) of the foam core which is divided functionally by horizontal GFRP ribs. The hard core is placed in the compression area to resist compressive strength and improve the stiffness of the composite sandwich structure, while the soft core is placed in the tension area. Six GHP panels were tested loaded in 4-point bending to study the effect of horizontal ribs and hybrid core configurations on the stiffness, strength, and failure modes of GHP panels. Experimental results show that compared to the control panel, a maximum of 54.6% and 50% increase in the strength and bending stiffness can be achieved, respectively. GHP panels with the hybrid PU foam core show obvious secondary stiffness. Finally, analytical methods were proposed to predict the initial stiffness and peak load of the GHP panels, and the results agree well with experimental results.

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