Composite Metallic Structures Research Articles

Automated detection and characterization of defects in composite-metal structures by using active infrared thermography

Automated detection and characterization of defects in composite-metal structures by using active infrared thermography

Triple-Band Terahertz Perfect Light Absorber Using the Strong Interaction of Two Metallic Resonators

An approach to realize a multiple-band perfect light absorber is demonstrated using a simple metamaterial design featuring a composite metallic structure consisting of a closed ring and a rectangular patch atop a metallic substrate separated by an insulator. Three narrow-band and discrete resonance peaks with nearly 100% absorption rates are obtained. The first absorption peak is due to the dipole resonance of the closed ring, while the last two absorption peaks are caused by the coupling effect of the closed ring and rectangular patch. The field distribution of the three absorption peaks is given to provide additional evidence. Unlike traditional multiple-band light absorbers that eliminate (or avoid) the interaction between the metallic array structures, our design is based on the mode coupling of the composite structure. This method can obviously reduce the number of metallic resonators, simplify the structure design and reduce fabrication costs.

Mechanical performance of plymetal structures subjected to impact loading

Plymetal is a new type of composite metallic structure based on the concept of plywood created by laser direct metal deposition additive manufacturing technology. Two different metal powders, 316L stainless steel and H13 tool steel, are deposited in alternative parallel rows in each layer in the defined orientations to create a plymetal structure. In this research, the plymetal was manufactured by the POM DMD 505 machine, in which a laser beam melts various metal powders deposited through a coaxial nozzle in a layer-by-layer manner to form a metallic structure. The ballistic performance of plymetal structures was then experimentally studied for high impact applications. Ballistic tests were carried out using a high-pressure gas gun. The plymetal plates of 3-mm-thick were subjected to impact of projectiles at various velocities and the results were compared with test results of stainless steel plates of different thicknesses. Results show that the ballistic resistance of the direct metal deposition generated plymetal structure is better than the ballistic resistance of the stainless steel 316L with the same thickness. Vickers hardness and face deformation characteristics of the plymetal samples and stainless steel samples were also investigated.

Assessment Strategies for Composite-metal Joining Technologies – A Review

Mixed material constructions, especially composite-metal structures, are widely applied in industry. Today many different joining technologies exist. However, the tools are missing that support decision making for the most suitable technology depending on the desired application. Especially small and medium sized enterprises struggle, due to a lack of know-how and their limited innovation budgets. In this review the existing literature about different joining technologies is discussed and evaluated with attention on comparative studies. Based on the described literature a future assessment strategy for enterprises is outlined and a general procedure of data acquisition is presented.

Chiral metamaterials: enhancement and control of optical activity and circular dichroism.

The control of the optical activity and ellipticity of a medium has drawn considerable attention due to the recent developments in metamaterial design techniques and a deeper understanding of the light matter interaction in composite metallic structures. Indeed, recently proposed designs of metaatoms have enabled the realisation of materials with unprecedented chiral optical properties e.g. strong optical activity, broadband optical activity, and nondispersive zero ellipticity. Combining chiral metamaterials with nonlinear materials has opened up new possibilities in the field of nonlinear chirality as well as provided the foundation for switchable chiral devices. Furthermore, chirality together with hyperbolicity can be used to realise new exciting materials such as photonic topological insulators. In this review, we will outline the fundamental principles of chiral metamaterials and report on recent progress in providing the foundations for promising applications of switchable chiral metamaterials.

The development and scalability of a high strength, damage tolerant, hybrid joining scheme for composite–metal structures

Advanced hybrid joints, which incorporate a specially designed array of macro-scale pins that provide mechanical interlocking reinforcement, have been developed in order to address the challenges associated with joining fibre reinforced composites to metals. In the present work, important joint characteristics including strength, mechanical fatigue, damage tolerance and durability have been studied and discussed. The results indicate that with advanced hybrid joints it is possible to achieve the benefits of the respective bonded and bolted systems but with virtually zero net weight gain, or conceivably a weight reduction as the increased performance of the hybrid scheme could facilitate smaller joints. The authors also present initial results from a comprehensive manufacturing and scalability trial, and demonstrate that low-cost, large-scale manufacture of hybrid joints is now feasible.

Multimode magnetic responses in NIR and visible ranges

We demonstrate a nonsymmetrical composite metallic structure with realistic material parameters. This structure can realize double magnetic responses in near-infrared (NIR) range (0.92 mu m) and in visible range (0.61 mu m), which can be attributed to two different modes of magnetic coupling. The difference of the index dependence of two magnetic responses is due to the influence of metal on LC model at optical frequencies. The multimode magnetic responses may provide us a new way to design special nano-optical devices at high frequencies. We also show that magnetic response has larger sensitivity to the local index of dielectric than plasmon resonance and suggest a possible approach in detecting the local index of the dielectric surrounding metamaterials.

Gallium/aluminum nanocomposite material for nonlinear optics and nonlinear plasmonics

We report on a new type of composite metallic structure for nonlinear optics and nonlinear plasmonics, created by grain boundary penetration of gallium into an aluminum film. These composite films form mirrorlike interfaces with silica and show an exceptionally broadband phase-transition-based nonlinear response to optical excitation.

Composite metal etching for submicron integrated circuits

To define metal lines for composite metal structures for integrated circuits with small pitches (<2 /spl mu/m), the etch selectivity and dimensional control must be improved from existing values of /spl sim/1.5:1 and >0.1 /spl mu/m/line, respectively, without leaving metallic residue and without undercutting the masking layer. These goals have been achieved for a layered metal structure of Ti-W/Al-Cu(2%)/Ti-W with an Applied Materials AME 8330 batch system after examining process parameter spaces defined by the following: (i) reactor pressure, (ii) dc bias voltage, and (iii) gas composition for these two films. The selectivity between Al-Cu(2%) and photoresist increases with decreasing dc bias voltage and increasing Cl/sub 2/ content of Cl/sub 2//BCl/sub 3//CHF/sub 3/ gas mixtures. In comparison, the selectivity between Ti-W and photoresist increases only with increasing CF/sub 4/ content of CF/sub 4//Cl/sub 2/ gas mixtures; changes in the other variables examined in this work with Ti-W have no significant effect on selectivity.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>