Metal Foams for Electromagnetics: Experimental, Numerical and Analytical Characterization

Abstract

Abstract-This work focuses on the use of metal foams, a relatively new class of materials, for high added-value electromagnetic (EM) shields. First, the Shielding Effectiveness (SE) of aluminum foam slabs is experimentally evaluated, showing very good shielding properties. Successively, accurate numerical models of metal foams are proposed and used in a proprietary Variable-Mesh Parallel Finite Difference Time Domain code, in order to characterize the EM properties of slabs of such materials. Afterwards, a third approach is adopted. It consists in the application of the effective medium theories in order to obtain an analytical EM model of the metal foams; this way, their SE can be evaluated with a negligible computational time by using common mathematical tools. Finally, a methodology to design/analyze customized metal foams for EM shield applications is suggested. It takes advantage from the joint use of the numerical and analytical presented approaches, thus allowing a computationally efficient evaluation of SE and other electromagnetic properties of metal foams. Results demonstrate the suitability of metal foam structures for effective EM shielding in many industrial applications, as well as the accuracy of the proposed analytical and numerical approaches.

Electromagnetic Shielding Materials in GHz Range

“…However, the high weight of them limits their use in some applications. Metal foams are currently the focus of much research because of their lightweight, stiffness, strength, and high electrical and thermal conductivity . Metal foams with different specific physical properties can be produced on demand, varying cell topology (open or closed cells), material (aluminium, copper, titanium etc.…”

Investigation of Electromagnetic Shielding for Wire Mesh Composite for Aircraft against Lightning Strike

“…For a given operating wavelength, we measure the effectiveness of wire-mesh screens in blocking electromagnetic waves. When describing it, the wire-mesh composite corresponding sheet-impedance is utilized [29][30][31][32]. When an electromagnetic wave contacts a mesh, it generates a reactive field that is restricted to the region of the mesh surface due to the periodicity of the mesh aperture and the small electrical size of the mesh aperture compared to the wavelength.…”

“…Above equation1 represent the absorption and reflection loss. The parameters R and A are defined as follows by [28][29][30][31]:…”

Specifications for Modelling of the Phenomenon of Compression of Closed-Cell Aluminium Foams with Neural Networks

“…Closed-cell aluminium is a well-known engineering material, mostly used where light-weight applications require satisfactory mechanical properties [ 1 , 2 , 3 ] or energy absorption as a determinant [ 2 , 4 ]. Other properties, which make this material multifunctional, are: sound wave attenuation [ 5 , 6 ], electromagnetic wave absorption [ 7 , 8 ], vibration intimidation [ 9 ], thermal conductivity [ 10 , 11 ], relatively easy shape tailoring [ 12 ] and potential for usage in composites [ 13 , 14 , 15 ]. Examples of the usage of aluminium foams include, among others: the automotive industry, space industry, energy and battery field, military applications and machine construction [ 16 , 17 , 18 , 19 , 20 ].…”

“…Taking into consideration so much engineering and design interest in closed-cell aluminium foams, it is a natural consequence that much scientific attention is drawn to the appropriate description of this material in various aspects. A significant number of works focus on structural characterization, e.g., [ 16 , 29 , 30 , 31 ], property analysis, e.g., [ 1 , 2 , 3 , 4 , 5 , 6 , 7 , 8 , 9 , 10 , 11 , 32 ], manufacturing methods, e.g., [ 12 , 16 , 33 ], experimental investigations, e.g., [ 34 , 35 , 36 , 37 , 38 , 39 ] and modelling. As for modelling, this field is widely researched, and the number of publications about this subject is extensive.…”