scholarly journals Towards an Understanding of the Effect of Adding a Foam Core on the Blast Performance of Glass Fibre Reinforced Epoxy Laminate Panels

Materials ◽  
2021 ◽  
Vol 14 (23) ◽  
pp. 7118
Author(s):  
Sherlyn Gabriel ◽  
Christopher J. von Klemperer ◽  
Steeve Chung Kim Yuen ◽  
Genevieve S. Langdon
Keyword(s):  
Glass Fibre ◽  
Failure Modes ◽  
Sandwich Panels ◽  
Stress Wave Propagation ◽  
Foam Core ◽  
Multilayered Structures ◽  
Peak Displacement ◽  
Transient Behaviour ◽  
Blast Response ◽  
Wide Range

This paper presents insights into the blast response of sandwich panels with lightweight foam cores and asymmetric (different thicknesses) glass fibre epoxy face sheets. Viscously damped elastic vibrations were observed in the laminates (no core), while the transient response of the sandwich panels was more complex, especially after the peak displacement was observed. The post-peak residual oscillations in the sandwich panels were larger and did not decay as significantly with time when compared to the equivalent mass laminate panel test. Delamination was the predominant mode of failure on the thinner facesheet side of the sandwich panel, whereas cracking and matrix failure were more prominent on the thicker side (which was exposed to the blast). The type of constituent materials used and testing conditions, including the clamping method, influenced the resulting failure modes observed. A probable sequence of damage in the sandwich panels was proposed, based on the transient displacement measurements, a post-test failure analysis, and consideration of the stress wave propagation through the multilayered, multimaterial structure. This work demonstrates the need for detailed understanding of the transient behaviour of multilayered structures with significant elastic energy capacity and a wide range of possible damage mechanisms. The work should prove valuable to structural engineers and designers considering the deployment of foam-core sandwich panels or fibre reinforced polymer laminates in applications when air-blast loading may pose a credible threat.

Laser Forming of Metal Foam Sandwich Panels: Effect of Panel Manufacturing Method

2019 ◽  
Vol 141 (5) ◽  
Author(s):  
Tizian Bucher ◽  
Min Zhang ◽  
Chang Jun Chen ◽  
Ravi Verma ◽  
Wayne Li ◽  
...  
Keyword(s):  
Metal Foam ◽  
Numerical Models ◽  
Sandwich Panels ◽  
Weight Ratio ◽  
Industrial Applications ◽  
Laser Forming ◽  
Process Conditions ◽  
Foam Core ◽  
Wide Range ◽  
The Impact

Sandwich panels with metal foam cores have a tremendous potential in various industrial applications due to their outstanding strength-to-weight ratio, stiffness, and shock absorption capacity. A recent study paved the road toward a more economical implementation of sandwich panels, by showing that the material can be successfully bent up to large angles using laser forming. The study also developed a fundamental understanding of the underlying bending mechanisms and established accurate numerical models. In this study, these efforts were carried further, and the impact of the foam core structure, the facesheet and foam core compositions, and the adhesion method on the bending efficiency and the bending limit was investigated. These factors were studied individually and collectively by comparing two fundamentally different sandwich panel types. Thermally induced stresses at the facesheet/core interface were thoroughly considered. Numerical modeling was carried out under different levels of geometric accuracy to complement bending experiments under a wide range of process conditions. Interactions between panel properties and process conditions were demonstrated and discussed.

STRUCTURAL RESPONSE OF ALUMINIUM FOAM HYBRID SANDWICH PANELS UNDER THREE-POINT BENDING LOADING

2009 ◽  
Vol 23 (06n07) ◽  
pp. 1733-1738 ◽  
Author(s):  
KAVEH R. KABIR ◽  
TANIA VODENITCHAROVA ◽  
MARK HOFFMAN
Keyword(s):  
Failure Modes ◽  
Bending Strength ◽  
Sandwich Panels ◽  
Structural Response ◽  
Foam Core ◽  
Three Point Bending ◽  
Closed Cell ◽  
Core Thickness ◽  
Bending Loading ◽  
Foam Thickness

The present study focuses on the structural response of sandwich panels consisting of a commercial closed-cell foam core and thin aluminium sheet skins under static three-point bending loading. Panels of different thicknesses and span lengths were tested, and the influence of the foam density, core thickness and skin type on the response was revealed. The failure modes in bending were greatly dependent on the span length but independent on the foam thickness. For short spans, the deformed shape at failure was asymmetric, as opposed to a symmetric mode for long spans. The density and thickness of the foam core, the presence of reinforcing face sheets and the beam span determined the failure load and bending strength of the sandwich panels.

Flexural response of carbon fiber reinforced aluminum foam sandwich

2017 ◽  
Vol 52 (14) ◽  
pp. 1887-1897 ◽  
Author(s):  
Chang Yan ◽  
Xuding Song ◽  
Hui Zhu ◽  
Chuanhe Jing ◽  
Shuo Feng
Keyword(s):  
Carbon Fiber ◽  
Energy Absorption ◽  
Aluminum Foam ◽  
Failure Modes ◽  
Peak Load ◽  
Sandwich Panels ◽  
Foam Core ◽  
Carbon Fiber Fabric ◽  
Final Failure ◽  
Fiber Fabric

Sandwich panels with carbon fiber fabric/epoxy resin face-sheet and aluminum foam core have a potential application value in the engineering field. To study the bending mechanical properties of the reinforced sandwich structure, three-point bending test was conducted by using WDW-T100 electronic universal tensile testing machine. The relation between load and displacement of the aluminum foam sandwich was obtained. Deformations and failure modes of the specimens were recorded. Scanning electron microscopy was used to observe the failure mechanism. Results showed that when aluminum foam was reinforced by carbon fiber fabric as face-sheet, its flexural load-carrying capacity and energy absorption ability improved significantly. Foam core density and number of carbon fiber plies had serious impacts on the peak load value and energy absorption value of the composite structure. It was suggested that aluminum foam core sandwich structure with low foam core density of 0.49 g/cm3 and 5 plies of carbon fiber fabric had the highest energy absorption ability and medium load-carrying ability. Failure modes analysis showed that shear failure leaded to the final failure of sandwich panels with medium peak load and interface de-bonding leaded to the final failure of sandwich panels with high peak load.

Dynamic pulse buckling and failure analysis of the single curved composite sandwich panel using the core high-order theory

2020 ◽  
Vol 234 (10) ◽  
pp. 1990-2011
Author(s):  
Seyed Ali Ahmadi ◽  
Mohammad Hadi Pashaei ◽  
Ramazan-Ali Jafari-Talookolaei
Keyword(s):  
Sandwich Panel ◽  
Failure Modes ◽  
Viscoelastic Model ◽  
Sandwich Panels ◽  
High Order ◽  
Foam Core ◽  
Composite Sandwich ◽  
The Core ◽  
Pulse Buckling ◽  
Dynamic Pulse

The current study aims to investigate the facesheet dynamic pulse buckling of simply supported, cylindrical composite sandwich panels using the Budiansky–Roth buckling criterion. The foam core has been modeled with isotropic elastic-perfectly plastic properties and various failure modes of the sandwich panel like facesheet fracture, foam shear fracture, and foam yield are investigated. The extended high-order sandwich panel core theory was used to model the compressibility of the core. To study the mechanical properties of the viscoelastic foam core, the Kelvin–Voigt linear viscoelastic model was applied. The transient responses and stress components obtained from the present method are compared with finite element solutions using commercial software ANSYS and those reported in the literature. Accordingly, reasonable agreement is observed. It was shown that the pulse local buckling strength of the panel increases with a decrease in the panel radius or an increase in the thickness of the panel, and facesheet fracture is considered more a likely failure mode of these sandwich panels.

Laser Forming of Metal Foam Sandwich Panels: Effect of Panel Manufacturing Method

2019 ◽  
Author(s):  
Tizian Bucher ◽  
Min Zhang ◽  
Chang Jun Chen ◽  
Ravi Verma ◽  
Wayne Li ◽  
...  
Keyword(s):  
Metal Foam ◽  
Numerical Models ◽  
Sandwich Panels ◽  
Weight Ratio ◽  
Industrial Applications ◽  
Laser Forming ◽  
Process Conditions ◽  
Foam Core ◽  
Wide Range ◽  
The Impact

Abstract Sandwich panels with metal foam cores have a tremendous potential in various industrial applications due to their outstanding strength-to-weight ratio, stiffness, and shock absorption capacity. A recent study paved the road towards a more economical implementation of sandwich panels, by showing that the material can be successfully bent up to large angles using laser forming. The study also developed a fundamental understanding of the underlying bending mechanisms and established accurate numerical models. In this study, these efforts were carried further, and the impact of the foam core structure, the facesheet and foam core compositions, as well as the adhesion method on the bending efficiency and bending limit was investigated. These factors were studied individually and collectively by comparing two fundamentally different sandwich panel types. Thermally-induced stresses at the facesheet/core interface were thoroughly considered. Numerical modeling was carried out under different levels of geometric accuracy, to complement bending experiments under a wide range of process conditions. Interactions between panel properties and process conditions were demonstrated and discussed.

scholarly journals Vertically-aligned short E-glass fibre core sandwich composite: Production and evaluation

2021 ◽  
pp. 109963622199388
Author(s):  
Robbie White ◽  
Venkata R Machavaram ◽  
Benjamin A Fernando ◽  
Mark A Paget ◽  
Ashwini Prasad ◽  
...  
Keyword(s):  
Compressive Strength ◽  
Glass Fibre ◽  
Failure Modes ◽  
Fibre Composite ◽  
Sandwich Panels ◽  
Sandwich Composite ◽  
Fibre Bundles ◽  
The Core ◽  
Vertically Aligned ◽  
Honeycomb Cores

This paper reports on the production and evaluation of a new class of “Z-axis” composite sandwich panel where the core consists of a dense array of vertically-aligned, 3 mm long E-glass fibre composite “beams”. The E-glass fibre bundles were aligned using electrostatic charging. A procedure was developed to retain the orientation of the short-fibre bundles whilst they were impregnated and cured with an epoxy/amine resin system. The skins were manufactured from 4-ply carbon/epoxy prepregs with a layup sequence of (0,90)s. The out-of-plane compressive strength of these Z-axis composites was found to be 25.2 and 15.2 times greater than equivalent sandwich panels made with Nomex® and aluminium honeycomb cores respectively. Their compressive strength was found to increase in proportion to the density of the core. Buckling and fracture of the vertically-aligned Z-axis composite were the predominant failure modes observed. The shear and flexural properties of the Z-axis composites were comparable to equivalent honeycomb sandwich panels manufactured from Nomex® and aluminium honeycomb cores.

Stress Attenuation Mechanism of Foam Core Sandwich Panels Subjected to Close-Range Blast Loading

2014 ◽  
Vol 945-949 ◽  
pp. 561-566
Author(s):  
Zhi Qiang Fan ◽  
Hong Hao Ma ◽  
Zhao Wu Shen ◽  
Mou Jin Lin
Keyword(s):  
Failure Modes ◽  
Wave Attenuation ◽  
Sandwich Panels ◽  
Blast Loading ◽  
Peripheral Region ◽  
Face Sheet ◽  
Front Face ◽  
Foam Core ◽  
Attenuation Mechanism ◽  
Close Range

A series of experiments have been conducted to investigate the stress wave attenuation mechanism and the response of sandwich panels made of steel face sheets with foam cores under blast loading in close range. Quantitative results including shock wave pressure and face sheet deflection were obtained and the deformation/failure modes of specimens were identified and discussed systematically. Results show that the face sheet deflection was reduced by adopting a higher density core, however, performance of sandwich panels in blast wave attenuation degrade. Cell collapse type of the central region of the foam core is dominated by brittle crushing under close-range blasting loading. All front face sheets produce localized failure at the focal area and global deformation in the peripheral region.

Elastic and viscoelastic behaviour of sandwich panels with glass-fibre reinforced polymer faces and polyethylene terephthalate foam core

2016 ◽  
Vol 20 (4) ◽  
pp. 399-424 ◽  
Author(s):  
Mário Garrido ◽  
João R Correia
Keyword(s):  
Polyethylene Terephthalate ◽  
Glass Fibre ◽  
Creep Behaviour ◽  
Sandwich Panels ◽  
Full Scale ◽  
Foam Core ◽  
Reinforced Polymer ◽  
Glass Fibre Reinforced Polymer ◽  
Fibre Reinforced Polymer ◽  
Glass Fibre Reinforced

This paper presents experimental and analytical investigations about the elastic and viscoelastic (creep) behaviour of sandwich panels made of glass-fibre reinforced polymer faces and a polyethylene terephthalate foam core, produced by vacuum infusion for civil engineering structural applications. First, the elastic response of the panels’ constituent materials (glass-fibre reinforced polymer and polyethylene terephthalate) in tension, compression and shear was experimentally assessed; shear tests on the foam were carried out using a novel test method, the diagonal tension shear test. The creep behaviour in shear of the polyethylene terephthalate foam was evaluated for different load levels. The effective flexural properties of the full-scale sandwich panels as well as their flexural behaviour up to failure were experimentally assessed. Flexural creep and subsequent recovery experiments were also conducted for different load levels, to characterise the viscoelastic behaviour of the full-scale sandwich panels. Creep deformations of the polyethylene terephthalate foam and of the sandwich panels were found to be significantly lower than those corresponding to polyurethane foam and balsa wood reported in the literature; unrecoverable viscoelastic deformations were observed in the full-scale panels. In the analytical study, the creep response of the panels was modelled using Findley’s power law and the composite creep modelling approach. The composite creep modelling predictions were reasonably accurate and allowed assessing the relative contributions of bending and shear deformations to the total sandwich panel creep deflections.

scholarly journals UV Nanoimprint Lithography: Geometrical Impact on Filling Properties of Nanoscale Patterns

Nanomaterials ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 822
Author(s):  
Christine Thanner ◽  
Martin Eibelhuber
Keyword(s):  
Layer Thickness ◽  
Process Parameters ◽  
Nanoimprint Lithography ◽  
Failure Modes ◽  
Production Method ◽  
Efficient Production ◽  
Comprehensive Overview ◽  
Replication Method ◽  
Wide Range ◽  
Pattern Size

Ultraviolet (UV) Nanoimprint Lithography (NIL) is a replication method that is well known for its capability to address a wide range of pattern sizes and shapes. It has proven to be an efficient production method for patterning resist layers with features ranging from a few hundred micrometers and down to the nanometer range. Best results can be achieved if the fundamental behavior of the imprint resist and the pattern filling are considered by the equipment and process parameters. In particular, the material properties and pattern size and shape play a crucial role. For capillary force-driven filling behavior it is important to understand the influencing parameters and respective failure modes in order to optimize the processes for reliable full wafer manufacturing. In this work, the nanoimprint results obtained for different pattern geometries are compared with respect to pattern quality and residual layer thickness: The comprehensive overview of the relevant process parameters is helpful for setting up NIL processes for different nanostructures with minimum layer thickness.

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