Aluminum Structures Research Articles

Member capacity of cold-rolled aluminium alloy channel columns – Part II: Numerical investigation and design

The paper first presents the development of detailed finite element (FE) models for investigating the member capacity of cold-rolled aluminium alloy 5052-36 channel columns. The numerical non-linear FE models are developed using the commercial FE software package ABAQUS to simulate laboratory experiments and calibrated against the test results. The experimental program was performed by the authors at the University of Sydney and the detailed test results are fully described in a companion paper. The calibrated numerical FE models with actual mechanical properties and measured geometric imperfections in analyses accurately predict the experimental results and behaviours, including flexural and flexural-torsional buckling as well as local-global interaction buckling failure modes. A parametric study is subsequently performed to extend the data range by varying cross-section dimensions and member lengths. The effects of loading eccentricity positions and initial geometric imperfections are also considered in the parametric study. The experimental and numerical results are compared with design strength predictions from current Australian/New Zealand, American and European specifications for aluminium structures in the companion paper. In this paper, the Direct Strength Method (DSM) for the design of compression members as per the Australian/New Zealand standard AS/NZS 4600 for cold-formed steel structures is adopted for comparison. The DSM design rules for cold-formed steel compression members are found to provide more accurate predictions than those of current specifications for aluminium structures and therefore used to propose improved design equations for cold-rolled aluminium alloy columns. Finally, a reliability analysis is performed to evaluate the safety level of current design specifications and the proposed design rules.

Molecular dynamics study of surface alkalization reaction in high calcium systems

Alkali-activated materials (AAMs) offer significant benefits in the field of civil engineering, thanks to their energy-efficient and environmentally-friendly properties, as well as their exceptional strength and durability. However, the fundamental chemical reaction underlying the use of AAMs has not yet been fully understood. The process of the silicate depolymerization of the supplementary gelling materials is determined by their nano characteristics, which have certain restrictions by using experimental techniques. In this study, we utilized reactive molecular dynamics (MD) simulations to elucidate the chemical events occurring during alkali-activation in different AAMs. The sodium hydroxide (NaOH) solution selectively dissolves the silicon chains, while the aluminum chains remain intact. Furthermore, the laminar structures of silicon and aluminum in metakaolin (MK) crystal are entirely disturbed. However, the disintegration of silicon chains is negligible, and the Slag minerals maintain their layered structure. Calcium ions are crucial in stabilizing the chemical process of alkali activation. Furthermore, this study evaluates the fluctuations in their activity. Gaining insight into the minute details of this reaction provides essential theoretical foundations for developing eco-friendly and high-performing alkali-activated concrete materials.

Monitoring fatigue cracks in riveted plates using a sideband intensity based nonlinear ultrasonic technique

Aluminum structures are routinely used in aircraft due to their lightweight and corrosion resistance properties. Multi-layered aluminum plates are generally joined by rivets forming regions which are prone to fatigue crack formation in an aircraft. Therefore, the detection and monitoring of fatigue cracks at rivet joints in aluminum structures are crucial for ensuring flight safety. In this study, piezoelectric sensors were utilized to generate and detect Lamb waves on aluminum plates with rivet joints to investigate the feasibility of a newly developed Sideband Peak Count (SPC) technique for detecting fatigue cracks around these joints. To overcome the limitations of existing SPC-I (Sideband Peak Count – Index) and SPI (Sideband Peak Intensity) techniques in capturing harmonic and modulating wave frequencies due to material nonlinearity, a comprehensive index, the Sideband Intensity Index (SII) is introduced. Comparative analysis with existing SPC-I and SPI techniques confirm the effectiveness of the SII technique. This investigation shows that the SII technique significantly improves the detection capability of initial fatigue cracks around rivet joints on aluminum plates. This study offers a more efficient method for detecting critical fatigue cracks in rivet joints.

Assessing how metal reef restoration structures shape the functional and taxonomic profile of coral-associated bacterial communities

Significant threats to the long-term persistence of coral reefs have accelerated the adoption of coral propagation and out-planting approaches. However, how materials commonly used for propagation structures could potentially affect coral-associated bacterial communities remains untested. Here, we examined the impact of metal propagation structures on coral-associated bacterial communities. Fragments of the coral species Acropora millepora were grown on aluminium, sand/epoxy-coated steel (Reef Stars), and uncoated steel (rebar) structures. After 6 months, the functional and taxonomic profiles of coral-associated bacterial communities of propagated corals and reef colonies were characterised using amplicon (16S rRNA gene) and shotgun metagenomic sequencing. No differences in the phylogenetic structure or functional profile of coral-associated bacterial communities were observed between propagated corals and reef colonies. However, specific genes and pathways (e.g., lipid, nucleotide, and carbohydrate metabolism) were overrepresented in corals grown on different materials, and different taxa were indicative of the materials. These findings indicate that coral propagation on different materials may lead to differences in the individual bacterial taxa and functional potential of coral-associated bacterial communities, but how these contribute to changed holobiont fitness presents a key question to be addressed.

Experimental and numerical analysis of the behavior of rehabilitated aluminum structures using chopped strand mat GFRP composite patches

PurposeThis paper comprehensively addresses the influence of chopped strand mat glass fiber-reinforced polymer (GFRP) patch configurations such as geometry, dimensions, position and the number of layers of patches, whether a single or double patch is used and how well debonding the area under the patch improves the strength of the cracked aluminum plates with different crack lengths.Design/methodology/approachSingle-edge cracked aluminum specimens of 150 mm in length and 50 mm in width were tested using the tensile test. The cracked aluminum specimens were then repaired using GFRP patches with various configurations. A three-dimensional (3D) finite element method (FEM) was adopted to simulate the repaired cracked aluminum plates using composite patches to obtain the stress intensity factor (SIF). The numerical modeling and validation of ABAQUS software and the contour integral method for SIF calculations provide a valuable tool for further investigation and design optimization.FindingsThe width of the GFRP patches affected the efficiency of the rehabilitated cracked aluminum plate. Increasing patch width WP from 5 mm to 15 mm increases the peak load by 9.7 and 17.5%, respectively, if compared with the specimen without the patch. The efficiency of the GFRP patch in reducing the SIF increased as the number of layers increased, i.e. the maximum load was enhanced by 5%.Originality/valueThis study assessed repairing metallic structures using the chopped strand mat GFRP. Furthermore, it demonstrated the superiority of rectangular patches over semicircular ones, along with the benefit of using double patches for out-of-plane bending prevention and it emphasizes the detrimental effect of defects in the bonding area between the patch and the cracked component. This underlines the importance of proper surface preparation and bonding techniques for successful repair.Graphical abstract

Analysis and Design of High-Rise (G +12) Building Using STAAD Pro

High rise building is the most frequently used word in all most all construction activities especially in rapidly growing cities in terms of development and population. National Building Code (NBC) defines a high-rise as “All buildings 15 m or above in height (a building more than 4 storeys). The employment opportunities and facilities offered by the developing cities makes people to migrate towards urban areas which create the land scarcity for both Industrial and residential occupants. To satisfy the needs considering the future demand of habitable area and efficient use of land without expanding the boundaries of the cities makes people to choose high rise building it also facilitates with stunning views less noise pollution etc. STAAD is a popular structural analysis application known for analysis, diverse applications of use, Interoperability, and time-saving capabilities. STAAD helps structural engineers perform 3D structural Analysis and design for both steel and concrete structures. It ensures on-time and cost-effective Completion of steel, concrete, timber, aluminium, and cold-formed steel structures and designs, Regard less of complexity. We conclude that in this study we consider plot area 70 m x 24 m of g+12 Building consisting of 72 flats located kesarapalli near vijayawada Located in zone 3. we are going to analyse the high rise building for shear force and bending moments and design of critical sections of slab staircase footing by considering various loads such as with and without wind load, imposed load, dead loads. Key Word: High rise building, wind load, STAAD pro.

Optimizing the Design Structure of Recycled Aluminum Pressing Machine using the Finite Element Method

Optimizing the Design Structure of Recycled Aluminum Pressing Machine using the Finite Element Method

Design, Additive Manufacturing, and Electromagnetic Characterization of Alumina Cellular Structures for Waveguide Antenna

In this work, a design and additive manufacturing approach is successfully implemented to print via digital‐light‐processing cubic cellular alumina structures for antenna waveguides. Cellular structures’ porosity is varied during the design phase and different dielectrics are finally produced and inserted in antenna waveguides with the aim of decreasing the cutoff frequency in the range from 1 to 10 GHz. In parallel, the electromagnetic behavior of the cellular alumina structures into the antenna waveguide as the structure porosity varies is simulated. Printed samples are then tested in a laboratory setup. In the results obtained, it is shown that the antenna cutoff frequency increases as the porosity of the alumina cellular structures increases, also evidencing a linear correlation between their average dielectric constant and porosity. In this study, it is demonstrated that the dimensional accuracy achieved after the sintering process is essential because even a small (1%) deviation of the sintered sample size from the nominal ones, due to nonlinear shrinkage, highly affects their cutoff frequencies.

Alloying synergistic flame retardant effect on PA6 by polyimide containing alkyl hypophosphate structure

A novel flame retardant − bismaleimide polyalkyl phosphinate aluminium (BPPA), containing both imide and phosphinate structures, was designed and synthesized to investigate the intramolecular synergistic flame retardant effect between imide and phosphinate structures and alloying effect of the imide structure with PA6. Based on the flame retardant and mechanical properties of BPPA/PA6 composites, the alloying flame retardant effect of BPPA on PA6 was systematically investigated. The PA6 material had almost no char after burning; however, BPPA can produce a large amount of residue and form a dense char layer during combustion of PA6 matrix, effectively reducing the heat release, while BPPA also improved the mechanical properties of PA6 composites through the alloying effect. The peak heat release rate (pk-HRR) decreased by 55.8 %, and the residue yield increased by 9.2 wt% for 20BPPA/PA6, compared with the PA6. After compounding aluminum diethylphosphinate (ADP) and BPPA, the flame retardancy of the composites can be further improved. The LOI value of the 8ADP/6BPPA/PA6 was increased to 29.8 % and passed the test of UL94 V-0 level. Its pk-HRR and residue yield were similar to that of the 14BPPA/PA6, which indicated that the compounding system of ADP and BPPA can provide excellent charring properties and gas-phase flame retardancy of PA6. Meanwhile, the alloying BPPA with PA6 not only reduced the effect on the tensile strength of ADP on PA6, but also improved the breaking elongation of the composite. In conclusion, it provides a new direction for developing high-performance halogen-free flame retardant polyamides.

Structure and dynamical properties during solidification of liquid aluminum induced by cooling and compression

Abstract The structural transformation from a liquid to a crystalline solid is an important subject in condensed matter physics and materials science. In the present study, firstprinciples molecular dynamics calculations were performed to investigate the structure and properties of aluminum during the solidification which was induced by cooling and compression. During both the cooling and compression processes, it was found that the icosahedral short-range order was initially enhanced and then began to decay, the face-centered cubic short-range order eventually became dominant before it transformed to a crystalline solid.

Vibrational and thermal properties of amorphous alumina from first principles

Amorphous alumina is employed ubiquitously as a high-dielectric-constant material in electronics, and its thermal-transport properties are of key relevance for heat management in electronic chips and devices. Experiments show that the thermal conductivity of alumina depends significantly on the synthesis process, indicating the need for a theoretical study to elucidate the atomistic origin of these variations. Here we employ first-principles simulations to characterize the atomistic structure, vibrational properties, and thermal conductivity of alumina at densities ranging from 2.28 to 3.49 g/cm3. Moreover, using a machine-learned interatomic potential trained on first-principles data, we investigate how system size affects predictions of the thermal conductivity, showing that simulations containing 120 atoms can already reproduce the bulk limit of the conductivity. Finally, relying on the recently developed Wigner formulation of thermal transport, we shed light on the interplay between atomistic topological disorder and anharmonicity in the context of heat conduction, showing that the former dominates over the latter in determining the conductivity of alumina. Published by the American Physical Society 2024

Effect of Al-Si and Al-Mg filler wires on microstructure and mechanical properties of bead-on-plate weld on AA6061-T6 using CMT welding

In recent times, cold metal transfer (CMT) welding has become a popular choice to weld large structures of aluminium and its alloys as it provides good quality weld beads with lesser heat input. The welded joint of AA6061-T6 achieved through CMT welding provides the desired characteristics and better mechanical performance than other fusion welding methods. In the present work, bead-on-plate experimentation has been performed on an AA6061-T6 plate with two different filler wires ER4043 and ER5356 using two combinations of welding speed and current, keeping the gas flow rate constant throughout the experiment in CMT welding. Optical micrograph and X-ray diffraction analysis have been studied from which it has been observed that bead welded with ER5356 exhibits more fine equiaxed grain structure in the fusion zone and columnar-dendritic fragmentation in HAZ than beads welded with ER4043 due to the presence of higher amount of Mg2Si. X-ray diffraction reveals the presence of different phases with silicon found exclusively in specimens welded with ER4043. Porosity, dilution, microhardness and tensile strength have been examined over the weld bead and a comparison has been done between the filler wires at the same welding parameters. Porosity levels have notably elevated, measuring 53.69% and 55.71% higher in specimens welded with ER4043 filler than ER5356. Similarly, the dilution level is 33.33% and 17.51% higher in specimens welded with ER4043 filler than ER5356. Conversely, specimens welded with ER5356 filler exhibited a 4.02% and 20.37% increase in microhardness and a 3.42% and 8.82% improvement in tensile strength as compared to ER4043.

Demonstration of the Fabrication of a Large-Scale Aluminum Structure by Wire-Arc Directed Energy Deposition Using a Novel Aluminum Alloy

Demonstration of the Fabrication of a Large-Scale Aluminum Structure by Wire-Arc Directed Energy Deposition Using a Novel Aluminum Alloy

Optical and Electrochemical Properties of a Nanostructured ZnO Thin Layer Deposited on a Nanoporous Alumina Structure via Atomic Layer Deposition.

This study explores the optical and electrochemical properties of a ZnO coating layer deposited on a nanoporous alumina structure (NPAS) for potential multifunctional applications. The NPAS, synthesized through an electrochemical anodization process, displays well-defined nanochannels with a high aspect ratio (~3000). The ZnO coating, achieved via atomic layer deposition, enables the tuning of the pore diameter and porosity of the NPAS, thereby influencing both the optical and electrochemical interfacial properties. A comprehensive characterization using photoluminescence, spectroscopy ellipsometry and impedance spectroscopy (with the sample in contact with NaCl solutions) provides insights into optical and electrochemical parameters, including the refractive index, absorption coefficient, and electrolyte-ZnO/NPAS interface processes. This research demonstrates potential for tailoring the optical and interfacial properties of nanoporous structures by selecting appropriate coating materials, thus opening avenues for their utilization in various technological applications.

Modelling of closed-cell aluminum foam using Weaire–Phelan unit cells

AbstractDesign and testing of real materials is a costly process and usually requires some specific equipment. To alleviate this task numerical methods can be leveraged. In this work we show possible modelling technique for closed-cell material structure using Weaire–Phelan unit cells. As an example existing aluminum structures were used and modelled parametrically, allowing to establish different geometrical models for different applications. Numerical simulations for compression was also done on the developed models to reveal the material response. The influence on the cell wall thickness and the friction between the material and the compression plate was investigated. It was found that the friction coefficient has no significant effect on the material response, except in the case where bonded connection was assumed. It was also demonstrated that material response and the porosity controlled by cell wall thickness have an approximately linear relationship with each other. This method proved to be a flexible and alternative solution of real laboratory tests and targeted to reduce costs of material design.

Underwater implosion behavior of 3D-printed polymer structures

This study experimentally investigates the failure behavior of 3D-printed polymer tubes during underwater implosion. Implosion is a prevalent failure mechanism in the underwater domain, and the adaptation of new technology, such as 3D printing, allows for the rapid manufacturing of pressure vessels with complex geometries. This study analyzes the failure performance of 3D-printed polymer structures to aid the future development of 3D-printed pressure vessels. The 3D-printed tube specimens analyzed were fabricated using digital light synthesis (DLS) technology and included four different case geometries. The geometries consist of three cylindrical shells of varying diameter and thickness and one double hull structure with a cylindrical gyroid core filler. These specimens were submerged in a pressure vessel and subjected to increasing hydrostatic pressure until implosion failure occurred. High-speed photography and Digital Image Correlation (DIC) were employed to capture the collapse event to obtain full-field displacements. Local dynamic pressure histories during failure were recorded using piezoelectric transducers. The findings highlight that the 3D-printed polymers underwent significant deformation and failed at localized points due to material failure. The fracture of the specimens during failure introduced inconsistencies in pressure and impulse data due to the chaotic nature of the failure. Notably, the energy flow analysis revealed that the proportion of energy released via the pressure pulse was lower than in traditional aluminum structures. These findings contribute to our understanding of the behavior of 3D-printed polymers under hydrostatic pressure conditions.

Numerical investigation of hypervelocity impact simulation with FEM/SPH formulation for space structures

This paper investigates the response of aluminum structures to hypervelocity impact (HVI) and the formation of debris clouds using the Adaptive Finite Element (FEM)/Smoothed Particle Hydrodynamics (SPH) method. The main objective is to accurately replicate the response of curved thin plates to various HVIs and to characterize the resulting debris cloud shapes., for representative of shielding structures against Micrometeoroids and Orbital Debris (MMOD). In particular, the effects of different solid element formulations on the adaptive method are investigated. Experimental data from the literature is used to validate the proposed model, which is then applied to a curved thin plate subjected to varying impact angles. The findings highlight the significant influence of solid element formulation on the effectiveness of the adaptive method. Moreover, a direct correlation is observed between the impact angle and the produced debris cloud shape. These results contribute to the current knowledge on HVI responses and provide valuable insights for predicting and analyzing debris cloud formation in relation to aluminum structures.

Structural and mechanical optimization of porous alumina structures fabricated by carbon sacrificial template

The Taguchi method is used to optimize the manufacture of porous alumina made through reactive spark plasma sintering and carbon sacrificial template. The goal is to design a new versatile procedure that allows the fabrication of porous alumina with tailored physical properties. The structural and mechanical properties taken as target parameters were the subtle combination of porosity and Young’s modulus of the human cortical bone: typical pore size ¿100μm, and Young’s modulus in the range of 3–30 GPa. The input factors of the Taguchi method are wt.% of carbon, sintering time, calcination heating rate, and final heat treatment. Hg porosimetry, electron microscopy, uniaxial compression and computer aided tomography were used for the characterization of the porosity, pore size distribution, pore interconnectivity, and Young’s modulus. Finally, according to the conclusions of the Taguchi analysis, the parameters of the process were changed for the fabrication of the new samples with optimized properties. Highly porous structures with 90% interconnectivity, Young modulus of 5.5 ± 1.1 GPa, and compression strength of 49 ± 20 MPa, were obtained, successfully emulating the targeted properties.

Performance of flat-plate aluminum structures subjected to in-contact underwater explosions

This work investigates the effects of in-contact Underwater Explosion (UNDEX) on flat plates of various thicknesses. The interaction between generated bubbles and the plates is also studied. High-speed photography paired with digital image correlation (DIC) was used to capture full-field displacements, velocities, and strains on the plates during loading. Shockwave pressure was also recorded using pressure transducers strategically positioned in the water. The results show that, in the absence of rupture, thicker plates experience less deformation and allow the bubble to grow to a larger volume than the thinner plates, albeit smaller than that of a free field bubble. Bubbles generated in the vicinity of thicker plates also retain more energy. Contrary to cases of free field or near explosions which feature spherical and drifting bubbles, here the bubble assumes an ellipsoidal shape and attaches itself to the plate where it is confined to a more rapid cycle of collapse and regrowth before fully dissipating. When plate rupture does occur, it is immediate and is due to the initial shock. This structural failure drastically alters the behavior of the bubble.

Bipolar Current Collectors of Cu/polymer/Al Composite for Anode‐Free Batteries

AbstractThe all‐in‐one design of cathode and anode is a promising strategy to improve energy density and assembly efficiency for lithium batteries. However, it is an important prerequisite to combine negative and positive current collectors in a single sheet. Here, an asymmetric structure of bipolar composite current collector (BCCC), thin copper (Cu) and aluminum (Al) metal layers respectively deposited on each side of a thin polyethylene terephthalate (PET) polymer substrate is developed. Unlike conventional metal foils, the electronically insulative polymer blocks electron transfer between the cathode and anode coated on each side of BCCC. Buckling‐based mechanics measurement and molecular simulation are conducted to quantitatively evaluate the interfacial strength of metal/polymer, which is enhanced by introducing an intermediate chromium (Cr) layer. For applications in anode‐free wound batteries, the integrated sheet of separator/cathode/BCCC can simplify the alignment of the electrodes during the winding process. Without special surface and electrolyte optimizations, a higher Coulombic efficiency (99.1%) and larger capacity retention (50.0%) are achieved after 100 cycles in the LiNi0.8Co0.1Mn0.1O2 anode‐free battery than the battery using Cu foils.