Stability of the face layer of sandwich beams with sub-interface damage in the foam core

2007 ◽  
Vol 78 (4) ◽  
pp. 507-518 ◽  
Author(s):  
Vitaly Koissin ◽  
Vitaly Skvortsov ◽  
Andrey Shipsha
Keyword(s):  
Foam Core ◽  
Sandwich Beams ◽  
Face Layer ◽  
Interface Damage ◽  
The Face

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.

Carbon Foam Core Composite Sandwich Beams: Flexure Response

2005 ◽  
Vol 39 (12) ◽  
pp. 1067-1080 ◽  
Author(s):  
M. D. Sarzynski ◽  
O. O. Ochoa
Keyword(s):  
Carbon Foam ◽  
Foam Core ◽  
Sandwich Beams ◽  
Composite Sandwich

Creep Responses of Smart Sandwich Composites at Multiple Length Scales: Experiments and Modeling

2010 ◽  
Vol 133 (1) ◽  
Author(s):  
Anaïs Farrugia ◽  
Charles Winkelmann ◽  
Valeria La Saponara ◽  
Jeong Sik Kim ◽  
Anastasia H. Muliana
Keyword(s):  
Creep Behavior ◽  
Composite Structures ◽  
Effective Properties ◽  
Micromechanical Model ◽  
Foam Core ◽  
Sandwich Beams ◽  
Fiber Reinforced ◽  
Polymer Foam ◽  
Creep Tests ◽  
Unique Challenge

In service, composite structures present the unique challenge of damage detection and repair. Piezoelectric ceramic, such as lead zirconate titanate (PZT), is often used for detecting damage in composites. This paper investigates the effect of embedded PZT crystals on the overall creep behavior of sandwich beams comprising of glass fiber reinforced polymer laminated skins and polymer foam core, which could potentially be used as a damage-detecting smart structure. Uniaxial quasi-static and creep tests were performed on the glass/epoxy laminated composites having several fiber orientations, 0 deg, 45 deg, and 90 deg, to calibrate the elastic and viscoelastic properties of the fibers and matrix. Three-point bending creep tests at elevated temperature (80°C) were then carried out for a number of control sandwich beams (no PZT crystal) and conditioned sandwich beams (with PZT crystals embedded in the center of one facesheet). Lateral deflection of the sandwich beams was monitored for more than 60 h. The model presented in this paper is composed by two parts: (a) a simplified micromechanical model of unidirectional fiber reinforced composites used to obtain effective properties and overall creep response of the laminated skins and (b) a finite element method to simulate the overall creep behavior of the sandwich beams with embedded PZT crystals. The simplified micromechanical model is implemented in the material integration points within the laminated skin elements. Fibers are modeled as linear elastic, while a linearized viscoelastic material model is used for the epoxy matrix and foam core. Numerical results on the creep deflection of the smart sandwich beams show good correlations with the experimental creep deflection at 80°C, thus proving that this model, although currently based on material properties reported at room temperature, is promising to obtain a reasonable prediction for the creep of a smart sandwich structure at high temperatures.

Experimental investigations on the sandwich composite beams and panels with elastomeric foam core

2017 ◽  
Vol 21 (3) ◽  
pp. 865-894 ◽  
Author(s):  
AR Nazari ◽  
H Hosseini-Toudeshky ◽  
MZ Kabir
Keyword(s):  
Carrying Capacity ◽  
Sandwich Structures ◽  
Failure Mechanisms ◽  
Composite Beams ◽  
Core Material ◽  
Foam Core ◽  
Sandwich Beams ◽  
Load Carrying Capacity ◽  
The Core ◽  
Load Carrying

In this paper, the load-carrying capacity and failure mechanisms of sandwich beams and panels with elastomeric foam core and composite laminate face sheets are investigated. For this purpose, the flexural behavior of laminated composite beams and panels (applied as face sheets) is firstly investigated under three-point bending and central concentrated loads, respectively. Then, the same examination is conducted for the sandwich beams and panels, in which the proposed elastomeric foam is utilized as the core material. It is shown that the failure mechanisms which are associated to the core in the sandwich structures with crushable foams are not considered in the examined sandwich structures. The collapse of the sandwich specimens, examined here, is observed due to the failure of the skins in some steps. By multi-step collapse of these specimens via separately failure of the top and bottom skins, a considerable amount of energy is absorbed between these steps. Due to non-brittle behavior of the core material under loading, a large compression resistance is observed after failure of the top skin which led to the recovery of the load-carrying capacity in the sandwich beams. A similar behavior for the sandwich panels led to the increase of the ultimate strength after appearance of the failure lines on the top skin. The general outcomes of this investigation promise a good influence for the application of elastomeric foam as core material for sandwich structures.

Design and Characterization of Small-Scale Sandwich Beams Fabricated by Photolithography and Electrodeposition

2000 ◽  
Author(s):  
Yuki Sugimura
Keyword(s):  
Aspect Ratio ◽  
High Aspect Ratio ◽  
Sandwich Beam ◽  
Beam Theory ◽  
Shear Stiffness ◽  
Open Architecture ◽  
Small Scale ◽  
Sandwich Beams ◽  
The Face ◽  
Micrometer Size

Abstract Small-scale sandwich beams with core structures having cell diameters and wall widths on the order of 500 μm and 100 μm, respectively, have been produced through fabrication methods that combine photolithography and electrodeposition. Two core configurations have been examined: 1) regular hexagonal honeycomb and 2) high-aspect ratio hexagonal shells having an open architecture. The bending response of the sandwich beams has been examined and compared with the beam theory predictions. Shear stiffness of the honeycomb core was considerably high and therefore the bending behavior was dominated by the face sheets. The bending of the sandwich specimens with the hexagonal shells, on the other hand, was largely dependent on the core. The sandwich beam dimensions investigated in this study have not been optimized for weight minimization and structural efficiency. Further advances in fabrication methods to produce micrometer-size features and high-aspect ratio cores will enable realization of structurally efficient, lightweight sandwich beams and panels that can be used as multifunctional components in small-scale devices.

Buckling and Postbuckling of Sandwich Beams With Delaminated Faces Based on Higher Order Core Theory

1999 ◽  
Author(s):  
R. F. Li ◽  
Y. Frostig ◽  
G. A. Kardomateas
Keyword(s):  
Nonlinear Distortion ◽  
Variational Principles ◽  
Vertical Direction ◽  
Initial Imperfection ◽  
Order Theory ◽  
Sandwich Beams ◽  
Postbuckling Behavior ◽  
The Core ◽  
Core Theory ◽  
The Face

Abstract Delaminations within the face sheets are often observed when a sandwich structure is exposed to impact loads. The buckling and postbuckling behavior of sandwich beams with delaminated faces is investigated in this work. The governing nonlinear equations, boundary conditions, and continuity conditions are formulated through variational principles. The beam construction consists of upper and lower, metallic or composite laminated symmetric skins, and a soft core of a foam or low strength honeycomb type. A high order theory is used for the core that accounts for the nonlinear distortion of the plane of section of the core and the compressibility in the vertical direction. The delamination considered is an interface crack, in which the substrate includes the transversely flexible core. The case of a debond at one of the skin-core interfaces is also included. The effects of the delamination length and location on the overall and local behavior are examined with an arbitrary initial imperfection.

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.

Finite Elements for Curved Sandwich Beams

1977 ◽  
Vol 28 (2) ◽  
pp. 123-141 ◽  
Author(s):  
P J Holt ◽  
J P H Webber
Keyword(s):  
Finite Elements ◽  
Stiffness Matrix ◽  
Test Cases ◽  
Sandwich Beams ◽  
Honeycomb Core ◽  
The Core ◽  
The Face ◽  
Core Thickness ◽  
Displacement Approach ◽  
Circular Sandwich Ring

SummaryThe formulation of curved finite elements to represent a two-dimensional circular sandwich ring with honeycomb core and laminated faces is investigated. Assumed stress hybrid and equilibrium methods are found to be easier to employ in this case than the displacement approach. Using these methods, an element stiffness matrix is developed. The approximations of membrane faces and an infinite core normal stiffness are then used to develop simpler elements. Test cases show that these assumptions may become invalid, but that they are adequate for most practical cases where the core thickness to radius ratio and the face thickness to core thickness ratio are both low.

scholarly journals Graded open-cell aluminium foam core sandwich beams

2005 ◽  
Vol 404 (1-2) ◽  
pp. 9-18 ◽  
Author(s):  
Arnaud Pollien ◽  
Yves Conde ◽  
Laurent Pambaguian ◽  
Andreas Mortensen
Keyword(s):  
Aluminium Foam ◽  
Foam Core ◽  
Sandwich Beams ◽  
Open Cell

Failure of sandwich beams consisting of alumina face sheet and aluminum foam core in bending

2005 ◽  
Vol 409 (1-2) ◽  
pp. 292-301 ◽  
Author(s):  
Kapil Mohan ◽  
Yip Tick Hon ◽  
Sridhar Idapalapati ◽  
Hong Pheow Seow
Keyword(s):  
Aluminum Foam ◽  
Face Sheet ◽  
Foam Core ◽  
Sandwich Beams
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