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

2014 ◽  
Vol 81 (7) ◽  
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.

OPTIMAL DESIGN OF SANDWICH BEAMS WITH LIGHTWEIGHT CORES IN THREE-POINT BENDING

2012 ◽  
Vol 04 (03) ◽  
pp. 1250033 ◽  
Author(s):  
LI-MING CHEN ◽  
MING-JI CHEN ◽  
YONG-MAO PEI ◽  
YI-HUI ZHANG ◽  
DAI-NING FANG
Keyword(s):  
Metal Foam ◽  
Minimum Weight ◽  
Weight Ratio ◽  
Optimization Process ◽  
Stiffness Index ◽  
Sandwich Beams ◽  
Bending Performance ◽  
Three Point Bending ◽  
Composite Sandwich ◽  
Mode Of Failure

Being widely used in engineering, the optimization of sandwich beams to achieve greater stiffness-to-weight ratio is of great research interest. In this paper, the optimization process was carried to obtain minimum weight designs in three-point bending based on prescribed stiffness index. Results indicate that honeycomb-cored sandwich beams possess smaller minimum weight index in comparison with metal foam-cored beams. In addition, failure mechanisms of the optimized designs were also investigated to reveal that the sandwich-cored beams were more prone to face wrinkling than metal foam-cored beams. In the optimization process, five different core topologies and four different parent materials were investigated under a given load index. It was found for low prescribed load values where bending is dominant, unidirectional lattice composite sandwich beams bear loads more efficiently than steel cored beams. However, the primary mode of failure for high prescribed load index is core shear, thus implying no significant advantage in lattice composite sandwich beams over other materials. Comparing the different materials, that laminate lattice composite sandwich beams possess the best bending performance for varying levels of prescribed load index, making it suitable for applications in the aerospace field.

Three-point bending deflection and failure mechanism map of sandwich beams with second-order hierarchical corrugated truss core

2016 ◽  
Vol 19 (1) ◽  
pp. 83-107 ◽  
Author(s):  
Gang Li ◽  
Yaochu Fang ◽  
Peng Hao ◽  
Zhaokai Li
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Failure Mechanism ◽  
Failure Modes ◽  
Second Order ◽  
Sandwich Beams ◽  
Plastic Yielding ◽  
Element Analysis ◽  
Three Point Bending ◽  
Truss Core

For sandwich beams with second-order hierarchical corrugated truss core under three-point bending, a correction factor of shear deflection was firstly proposed to improve the prediction accuracy of the bending analysis, which was verified by finite element analysis and compared with the original formula. Then, the failure modes of the sandwich beam under bending were analyzed, including four competing modes of the large struts (i.e. plastic yielding, buckling, wrinkling of facesheet, shear buckling) and two competing modes of the small struts (i.e. plastic yielding, buckling). Subsequently, the analytical expressions of critical load for each failure mode were derived. On this basis, the failure mechanism maps were constructed. Finally, several typical points from the map were selected and verified by finite element analysis, and a good agreement of predicted failure modes was observed.

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

2004 ◽  
Vol 72 (3) ◽  
pp. 408-417 ◽  
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.

scholarly journals Failure modes of composite sandwich beams

2008 ◽  
Vol 35 (1-3) ◽  
pp. 105-118 ◽  
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.

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

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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