Metal Foam Sandwich Panels Research Articles

Low velocity impact penetration response of foam core sandwich panels with face sheets

Foam aluminum sandwich panels have potential applications in many fields because of their excellent performance. This study aims to explore the low velocity penetration dynamic response of foam sandwich panels. Based on the experimental results, a three-stage penetration model is established. Based on the principle of energy conservation, minimum potential energy and accumulating damage theory, the load and displacement time history, energy absorption and initial failure mode of the sandwich panel during penetration are predicted theoretically. The theoretical prediction results are compared with the experimental results, showing that the predicted failure load and deformation are within 10% of the experimental data. This paper provides an analytical method for studying the deformation failure mode and energy absorption mechanism of metal foam sandwich panels, which is helpful to improve the efficiency of metal foam sandwich panels in design.

3D Laser Forming of Metal Foam Sandwich Panels

Abstract Metal foam sandwich panels have been the subject of many concept studies, due to their exceptional stiffness, light weight, and crash absorption capacity. Yet, the industrial production of the material has been hampered by the fact that it is challenging to bend the material into practical engineering shapes. Only recently, it has been shown that bending of metal foam sandwich panels is possible using lasers. It was also shown that the material can be bent into Euclidean (2D) geometries, and the governing laser-induced bending mechanisms were analyzed. This study was focused on laser forming of metal foam sandwich panels into non-Euclidean (3D) geometries. It was investigated whether the bending mechanisms and process parameters identified for 2D laser forming translate to 3D deformation. Additionally, the impact of the laser scan length was determined by comparing different scan patterns that achieve the same 3D geometries. It was shown that laser forming could induce 3D deformation necessary for both bowl and saddle shapes, the two fundamental non-Euclidean geometries. The amount of laser-induced bending and in-plane strains vary depending on process conditions and the governing bending mechanisms. Lastly, the laser scan length was shown to become more important for metal foam sandwich panels, where the panel thickness tends to be large.

Laser forming of sandwich panels with metal foam cores

Over the past decade, laser forming has been effectively used to bend various metal foams, opening the possibility of applying these unique materials in new engineering applications. The purpose of the study was to extend laser forming to bend sandwich panels consisting of metallic facesheets joined to a metal foam core. Metal foam sandwich panels combine the excellent shock-absorption properties and low weight of metal foam with the wear resistance and strength of metallic facesheets, making them desirable for many applications in fields such as aerospace, the automotive industry, and solar power plants. To better understand the bending behavior of metal foam sandwich panels, as well as the impact of laser forming on the material properties, the fundamental mechanisms that govern bending deformation during laser forming were analyzed. It was found that the well-established bending mechanisms that separately govern solid metal and metal foam laser forming still apply to sandwich panel laser forming. However, two mechanisms operate in tandem, and a separate mechanism is responsible for the deformation of the solid facesheet and the foam core. From the bending mechanism analysis, it was concluded on the maximum achievable bending angle and the overall efficiency of the laser forming process at different process conditions. Throughout the analysis, experimental results were complemented by numerical simulations that were obtained using two finite element models that followed different geometrical approaches.

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

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.

Laser Forming of Sandwich Panels With Metal Foam Cores

Over the past decade, laser forming has been effectively used to bend various metal foams, opening the possibility of applying these unique materials in new engineering applications. The purpose of the study was to extend laser forming to bend sandwich panels consisting of metallic facesheets joined to a metal foam core. Metal foam sandwich panels combine the excellent shock-absorption properties and low weight of metal foam with the wear resistance and strength of metallic facesheets, making them desirable for many applications in fields such as aerospace, the automotive industry, and solar power plants. To better understand the bending behavior of metal foam sandwich panels, as well as the impact of laser forming on the material properties, the fundamental mechanisms that govern bending deformation during laser forming were analyzed. It was found that the well-established bending mechanisms that separately govern solid metal and metal foam laser forming still apply to sandwich panel laser forming. However, two mechanisms operate in tandem, and a separate mechanism is responsible for the deformation of the solid facesheet and the foam core. From the bending mechanism analysis, it was concluded on the maximum achievable bending angle and the overall efficiency of the laser forming process at different process conditions. Throughout the analysis, experimental results were complemented by numerical simulations that were obtained using two finite element models that followed different geometrical approaches.

Manufacturing of aluminum foam sandwich panels: comparison of a novel method with two different conventional methods

In this study, a novel method for manufacturing metal foam sandwich panels via self-propagating high temperature synthesis (SHS) has been introduced. In this method, a powder mixture of metallic aluminum and copper oxide was placed in core—sheet interface, and then sandwich panel was heated under static pressure. During heating, SHS reaction (3CuO + 2Al = + 3Cu, ΔH < 0) occurred in the interface. The generated heat from this exothermic reaction caused sheets to join the core by melting the interface and nearby. In order to evaluate the shear strength of the interface, the shear test was applied to the manufactured sandwich panels and its results were compared with sandwich panels, which were produced by diffusion and adhesive bonding processes. Furthermore, by the aid of energy dispersive spectrometer and X-ray diffraction analyses, the formation of copper in the core—sheet interface and its diffusion into the sheets and the core were investigated. The results showed that metal foam sandwich panels produced by using SHS method have higher joint strength than those produced by diffusion and adhesive bonding processes, and the maximum shear strength of the interface was achieved in shorter heating time. Significantly, this innovating method for manufacturing metal foam sandwich panels can be applied as a proper and alternative method.

A novel method for manufacturing of aluminum foam sandwich panels

AbstractIn this study, a novel method for manufacturing aluminum foam sandwich (AFS) panels via self‐propagating high temperature synthesis (SHS) has been introduced and investigated. In this method, a powder mixture of metallic aluminum and copper oxide was placed in core–sheet interface. Sandwich panel was then heated under static pressure. During heating, SHS reaction (3CuO + 2Al = Al2O3 + 3Cu, ΔH < 0) occurred in the interface. The generated heat from this exothermic reaction caused sheets to join the core by melting the interface and nearby. In order to evaluate the shear strength of the interface, the shear test was applied on manufactured sandwich panels, and its results were compared with those obtained from testing the sandwich panels which were produced by diffusion bonding process. Furthermore, by the aid of energy dispersive spectrometer (EDS) and X‐ray diffraction (XRD) analyses, the formation of copper in the core–sheet interface and its diffusion into the sheets and the core were investigated. In addition, by plotting the hardness values of the panels' sheets across distance, it was found that the generated heat of the exothermic reaction caused a local melting of the panel sheets and the core. These results approved that core to sheet joining in metal foam sandwich panels took place because of the SHS reaction. Significantly, this new method could be applied as a proper and alternative method for production of AFS panels. Copyright © 2010 John Wiley & Sons, Ltd.

Response of Actively Cooled Metal Foam Sandwich Panels Exposed to Thermal Loading

Experimental and analytical results for the thermomechanical response of actively cooled metal foam sandwich panels are presented. With a favorable strength-to-weight ratio and a high specific internal surface area, sandwich panels with metal foam cores are proposed for actively cooled load-bearing components in aerospace thermal protection system applications. First, inconel foam sandwich panels are subjected, via experimental means, to through-the-thickness thermal gradients, defined by fixed temperature conditions on opposite face sheets. With clamped boundary conditions, provided through a test fixture designed to minimize the common conflict of thermal and mechanical boundary conditions in experimental apparatus, the metal foam sandwich panels exhibit out-of-plane bending deformation. The thermomechanical deformation within the panel is then mitigated through active cooling, achieved by pumping compressed air through the metal foam core. Subsequently, the experimental measurements are used to develop a sequentially coupled thermomechanical finite element model. Central to the numerical characterization of metal foam sandwich panels is an understanding of the response of metal foam under shear loading. The material model for the foam is taken from a series of experimental measurements of the shear response of metal foam, providing density-dependent relationships for material stiffness and strength. The numerical model provides a strain-temperature history for metal foam sandwich panels under through-the-thickness thermal gradients

Convective Heat Transfer in Open Cell Metal Foams

Convective heat transfer in aluminum metal foam sandwich panels is investigated with potential applications to actively cooled thermal protection systems in hypersonic and re-entry vehicles. The size effects of the metal foam core are experimentally investigated and the effects of foam thickness on convective transfer are established. Four metal foam specimens are utilized with a relative density of 0.08 and pore density of 20 pores per inch (ppi) in a range of thickness from 6.4mmto25.4mm, in increments of approximately 6mm. An exact-shape-function finite element model is developed that envisions the foam as randomly oriented cylinders in cross flow with an axially varying coolant temperature field. A fully developed velocity profile is obtained through a semi-empirical, volume-averaged form of the momentum equation for flow through porous media, and used in the numerical analysis. The experimental results show that larger foam thicknesses produce increased heat transfer levels, but that this effect diminishes for thicker foams. The finite element simulations capture the thickness dependence of the heat transfer process and good agreement between experimental and numerical results is obtained for larger foam thicknesses.

Thermal Buckling of Metal Foam Sandwich Panels for Convective Thermal Protection Systems

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Metal foaming by a powder metallurgy method: Production, properties and applications

A method for fabricating metal foams based on the powder metallurgy process is presented. This foaming process allows for the production of complex-shaped foam parts, metal foam sandwich panels and foam filled hollow profiles. A range of alloys can be foamed using this method including aluminum, zinc, tin, lead and steel. The as-produced part has a closed-cell microstructure and a high fraction of porosity (typical range from 40–90% porosity). Selected mechanical properties of metal foams are evaluated, including the loading of foam samples with and without face skins and the axial crushing of tubular structures with foam reinforcement. Potential applications are discussed such as lightweight construction and energy absorption for both military and civilian uses.