Porous Aluminum Alloy Research Articles

Sound absorption performance of micro-perforated plate sandwich structure based on triply periodic minimal surface

The sandwich structure based on Triply periodic minimal surface (TPMS) is a lightweight and high-strength multifunctional composite material that combines the versatility of heat exchange, impact resistance, and energy absorption, and has been widely used in various fields such as aviation and aerospace. However, its sound absorption performance has not meant fully studied. In this paper, a Micro-perforated plate Diamond sandwich structure (MPP-DSS) was designed based on TPMS method, which was composed of aluminum alloy solid panel, aluminum alloy macroscopically ordered porous Diamond structure and aluminum alloy micro-perforated plate. The acoustic absorption performance in low and medium frequency band was studied by impedance tube method. The results show that MPP-DSS has higher absorption coefficient and bandwidth than traditional perforated plate structure with the same structural parameters. Increasing the thickness of micro-perforated plate can improve the sound absorption capacity of MPP-DSS in the low frequency range, but the width of the sound absorption band will be narrowed accordingly. Different from the resonant sound absorption mechanism of the traditional perforated plate structure, the sound absorption mechanism of MPP-DSS is the combined effect of resonant sound absorption and friction loss sound absorption. This study broadens the versatility of the TPMS structure and can serve as a reference for the design of integrated load-bearing and sound-absorbing structures.

Design and Applications of Additively Manufactured Porous Aluminum Alloys

Design and Applications of Additively Manufactured Porous Aluminum Alloys

Evaluation of the Elastic Modulus and Plateau Stress of a 2D Porous Aluminum Alloy Based on a Convolutional Neural Network

Porous metals are a new ultra-light material with high specific stiffness, specific strength, and good energy absorption properties. The elastic modulus and plateau stress of porous metals are essential parameters. There have been many studies on the effects of the matrix material, porosity, and pore size on the elastic modulus and plateau stress of porous metals, but few studies can be found on the impact of pore arrangement. The pore arrangement of porous metals cannot be quantitatively described, and the design space of a porous metal structure under the same porosity is vast. With the powerful learning and prediction ability of neural networks, the influence of pore arrangement can be better understood. In this paper, a convolutional neural network was used to explore the impact of pore arrangement on both the elastic modulus and plateau stress of a porous aluminum alloy. Firstly, a finite element method was used to simulate the compression of a porous aluminum alloy to obtain a training sample library. Secondly, a convolutional neural network was built to positively predict the elastic modulus and plateau stress of the porous aluminum alloy. Partial samples were used to select the best training model from five convolutional neural network candidates. Dropout, Batch Normalization, and L2 regularization methods were used to alleviate the over-fitting phenomenon in training. All data in the database were then trained and predicted, and the predicted goodness of fit of the elastic modulus and plateau stress were 0.8785 and 0.5922, respectively. A search method based on the convolutional neural network was then used to iteratively search the database. Under the condition of using a small amount of data, the pore structure with the best elastic modulus and plateau stress in the database could be determined, and the inverse design of a structure with high elastic modulus and plateau stress could be realized.

О применении высокопористых алюминиевых сплавов и сотовых конструкций в посадочных устройствах космических аппаратов

The paper presents results of studying mechanical properties and shock-absorbing characteristics of the highly porous aluminum alloys and aluminum alloy cellular structures with the initial average density from 190 to 2250 kg/m3. The study is based on data from foreign publications and experimental results obtained by the authors. Diagrams of deformation are provided illustrating characteristic stages of the deformation process and compaction of the highly porous alloys and cellular structures made of the aluminum alloys. Highly porous alloys are identified, which deformation is close to the idealized. Based on the analysis of experimental data, presence of two groups of materials is shown: the first with deformation diagram without hardening at the compaction stage and the second with hardening. Basics for calculating specific and effective impact absorption energy are provided. Analogue shock absorbers are shown for characteristic stages of the deformation diagrams. Introduction of the effective impact absorption energy is proposed as a criterion to compare the shock absorbers with each other. The results obtained could be used in the development of the single shock absorbers.

A review of the compressive properties of closed-cell aluminum metal foams

Materials scientists and engineers have been trying to create porous metals and metal foams for many years. Naturally occurring porous materials such as bone, coral, cork, balsa wood, etc., are responsible for initiating research in the area of producing porous metals and metal foams. Metal foam is a cellular structure made up of a solid metal-containing a large volume fraction of gas-filled pores. These pores can either be sealed (closed-cell foam), or they can be an interconnected network (open-cell foam). The closed-cell foam is referred to as metal foams, while the open-cell foam is referred to simply as porous metal. Some of the key properties of the metal foam are, ultra-light material (75–95% of the volume consists of void spaces), very high porosity, and high compression strengths combined with good energy absorption characteristics. This paper provides a comprehensive review of mechanical characterizations of closed-cell aluminum metal foams (CCAFs) or porous aluminum alloys, the trends in their mechanical behavior specifically their compressive performance. The significant factors influencing this behavior are intricately studied in light of the available literature. The aim of this work is to facilitate a channelized development over the past few decades in the field of mechanical behavior of CCAF that may be of help to the researchers, academicians, and industries for the critical understanding of the failure criteria and mechanical properties of closed-cell aluminum metal foams.

Mechanical properties of a new kind of porous aluminum alloy composite from ceramic hollow spheres with high strength

A new kind of porous 6061 aluminum alloy composite material was successfully fabricated using self-made high-strength silicon-containing ceramic hollow spheres as reinforcement. For comparison, another composite with commercial alumina hollow spheres was produced. All of these porous composite materials were produced by sintering at 650 ℃ for 2 h. Their microstructures display that the aluminum alloy reacts with the self-made ceramic hollow spheres, forming a thin transition layer containing MgO and Al2O3. Moreover, it was analyzed that the influence of the different classes of ceramic hollow spheres on the properties of porous composites, including the compressive strength, specific strength and energy absorption performance. The results indicate that the self-made silicon-containing ceramic hollow sphere can help to hinder the plastic deformation of the aluminum alloy metal matrix, which makes the sample display a short yield platform where the stress remains relatively stable. As a comparison, there is no yield platform where the stress remains relatively stable in the sample with commercial alumina hollow spheres under compression. Due to the formed transition layer, the sample with the self-made ceramic hollow sphere has a significantly higher compressive strength, specific strength and energy absorption performance. Compared with the porous magnesium alloy composite, the compressive behavior of porous composite is subject to that of the metal matrix to a great extent, and the content of Mg in the matrix determines the resultants and the level of the interface reaction. In addition, the compressive strength, specific strength, and energy absorption capacity of the porous aluminum alloy composite are all significantly higher than those of the porous magnesium alloy composite.

Production of high thermal conducting aluminum-graphite
 composite materials by the press-squeeze method utilizing porous graphite preforms and aluminum alloys

Consideration is given to the technological process of producing high thermal conducting
 aluminum-graphite composite materials by press-squeeze method utilizing porous graphite preforms and aluminum alloys. It is shown that the rate of press-squeeze process, aluminum alloy
 composition provide dense, defect-free and non-porous thermal interface between graphite and matrix alloy, it is noted the absence of crystal inclusions of third phases, such as SiC, Al4C3.
 An example of evaluation of thermal conductivity of the sample of composite material is given with consideration of graphite particles orientation and matrix-filler thermal interface heat
 conductivity.

Microstructure and compressive properties of Al‐Si10‐Mg lattice structures manufactured using selective laser melting

AbstractIn this study, the aluminum alloy lattice structure was processed using selective laser melting, and the compressive behaviour was studied. When the porous aluminum alloy was compressed along the building direction, the compressive stress initially increased, followed by a decrease, and then another increase. The aluminum alloy lattice structure mainly underwent the stages of elasticity, shearing, collapse, and then densification in the course of the compression process; the fracture primarily occurred at the joints of the pillars and the support plates. Moreover, the fractures of the aluminum alloy lattice structure, as prepared by selective laser melting, exhibited dimples of different sizes and shapes. The silicon content at the bottom of such a dimple was higher than that at the edges. When the stress level reached its limit and was insufficient to coordinate the plastic deformation of the two phases (α‐aluminum / silicon interface), micro‐pores formed at the interface (the dimples resulted from the breakage of numerous micro‐pores after aggregation), which caused the silicon content at the bottom of the dimple to be higher than that at the edge.

ПЕРСПЕКТИВА ПРИМЕНЕНИЯ ПЕНОАЛЮМИНИЯ ДЛЯ ИЗДЕЛИЙ АВИАКОСМИЧЕСКОЙ ТЕХНИКИ (обзор)

Provides an overview of methods for producing porous aluminum, its properties, advantages and disadvantages, and considers the use of aluminum foamed materials in the aerospace and mechanical engineering industries. It has been established that the mechanical properties of foam aluminum depend on the size and location of the pores, as well as on the method of its production; carrying out the process of modeling the deformation of samples with different pore diameters and the type of porous structure will make it possible to control the mechanical properties of a porous aluminum alloy.

Using highly porous aluminum alloys and honeycomb structures in spacecraft landing gear

Highly porous aluminum alloys and honeycomb structures may be utilized as single-use shock absorbers in landing gear and other elements of spacecraft thus ensuring safety of the landing process. This paper presents the results of studies that make it possible to estimate mechanical properties and shock-absorbing characteristics of highly porous aluminum alloys and honeycomb aluminum alloy structures, the initial average densities of said alloys and structures ranging from 330 to 2250 kg/m³. We list analogs that correspond with different stages found on stress-strain curves of highly porous aluminum alloys and honeycomb structures. The paper also provides the foundations of calculating the specific and effective energies of shock absorption.

Uniaxial compression model for a metal-matrix/hollow-microsphere composite synthesized by pressure infiltration

A new calculation technique is proposed for determining the deformation-strength characteristics of composites made of a porous metal matrix and hollow spherical inclusions. It is based on a three-phase micromechanical model of a dispersion-filled composite with taking into account the presence of an interfacial layer. For validation/exemplification purposes, this method is used to describe the initial pressing stage of a porous aluminum alloy containing hollow glass microspheres; the simulated mechanical characteristics and axial stress peak of the target composite are compared with experimental data and the results by a simplified alternative model. Additionally, the developed method is able to provide acceptable prediction accuracy for the elastic moduli of the composite and the peak axial stress. The proposed methodology is capable of predicting not only the elastic parameters but also strength characteristics of heterogeneous materials under consideration, which is demonstrated using three composites synthesized by pressure infiltration technology.

Design, FEM Analysis and Compression Tests on Energy-Absorbing Property of Disordered Cellular Solids Developed by 3D-Voronoi Division

Lightweight cellular solids have been used as an energy-absorbing material for automotive and aerospace applications. Additive manufacturing is a useful process for the design and manufacture of cellular solids. The present study focuses on the relationship between the energy-absorbing property and the cell structure of additively manufactured porous aluminum alloys. Disordered cell structures with different regularity are designed by the technique of 3D-Voronoi division. Open-cell structures with a porosity of 90% and a strut diameter of 1 mm are generated using commercial 3D CAD software. Explicit FEM analysis including a Johnson-Cook failure model successfully simulates the compressive stress-strain curves of disordered porous aluminum alloys. Experimental results of compression tests were in good qualitative agreement with the FEM analysis. The ordered cell structure with high regularity is disadvantageous for energy-absorbing applications because of the formation of a macroscopic shear band. A slightly low cell regularity in a additively manufactured cellular solid is effective for increasing energy absorption.

Fabrication of Porous Aluminum Alloy by Precursor Method Using Vertical Type Twin-Roll Casting

Fabrication of Porous Aluminum Alloy by Precursor Method Using Vertical Type Twin-Roll Casting

Study on the influence of porous material on underwater vehicle's hydrodynamic characteristics

As humans accelerate the pace of marine development, autonomous underwater vehicles (AUVs) are increasingly attracting worldwide attention. Due to the limitations of carrying energy and battery technology, AUV's endurance is nonideal. Therefore, designers usually make AUVs more streamlined to reduce drag. Here we show that when a layer of porous material is attached to an AUV's surface, the AUV's drag changes significantly. In this paper, simulations of the basic body of a REMUS100 and SUBOFF submarine model were carried out under multiple conditions. It is found that the drag increases as the porous viscosity coefficient or the thickness of the porous material increases. When REMUS100 and SUBOFF models are attached to the porous material with suitable porous viscosity coefficient, their drag becomes smaller. Boundary layer theory is also used to explain and analyze the phenomenon of the proportional increase of viscous pressure drag when using porous material, which is verified by vertical plate numerical simulations. Finally, we tested the mechanical properties of porous nickel and aluminum alloy 6061, and found that the porous material does have an effect of drag reduction, and can reduce the fluctuation range of the drag during the movement.

Corrosion Monitoring Method of Porous Aluminum Alloy Plate Hole Edges Based on Piezoelectric Sensors.

Corrosion damage to the aircraft structure can significantly reduce the safety performance and endanger flight safety. Especially when the corrosion occurs in a stress concentration region, such as hole edges, it can easily threaten the entire structure. In this paper, an on-line imaging qualitative monitoring algorithm based on piezoelectric sensors is proposed for detecting hole edge corrosion damage of porous aluminum alloy structures. The normalized amplitude is used to characterize the correlation between the initial Lamb wave signal and the damage signal, which is as an image reconstruction parameter in the algebraic iterative probability reconstruction algorithm. Moreover, a homogenization algorithm is proposed to process the reconstruction results. The experimental results of single hole and double hole corrosion for porous aluminum alloy plate show that the method can effectively achieve the location and quantification of corrosion damage to one and two holes of the porous structure.

Effects of CeO2 on the microstructure and properties of 2A12 porous aluminum

The micron porous aluminum has received considerable attention in various domains, and the research of rare earths for the synthesis of materials with improved mechanical performance. In the present work, 2A12 aluminum alloys with different porosities were successfully prepared by cold pressing-vacuum sintering-dissolution process (SDP) with the CeO2 additive, and the CeO2 content effect on the microstructure and mechanical properties of the porous aluminum alloys were investigated. The results show that the open-cell porous aluminum with uniform holes can be obtained by SDP. CeO2 addition affects the microstructure of porous aluminum alloys and results in the formation of Al11Ce3 phase in specimens, which can enhance mechanical properties of the alloys. With increasing content of CeO2, all the specimens have a trend of increasing first and then decreasing, and when the CeO2 content equal to 0.2 wt%, the tensile and compression strengths of porous aluminum with different porosities achieved the maximum value.

Improvement of Strength and Energy Absorption Properties of Porous Aluminum Alloy with Aligned Unidirectional Pores Using Equal-Channel Angular Extrusion

Porous aluminum alloy with aligned unidirectional pores was fabricated by dipping A1050 tubes into A6061 semi-solid slurry. The porous aluminum alloy was processed through Equal-channel Angular Extrusion (ECAE) while preventing cracking and maintaining both the pore size and porosity by setting the insert material and loading back pressure. The specific compressive yield strength of the sample aged after 13 passes of ECAE was approximately 2.5 times higher than that of the solid-solutionized sample without ECAE. Both the energy absorption EV and energy absorption efficiency ηV after four passes of ECAE were approximately 1.2 times higher than that of the solid-solutionized sample without ECAE. The specific yield strength was improved via work hardening and precipitation following dynamic aging during ECAE. EV was improved by the application of high compressive stress at the beginning of the compression owing to work hardening via ECAE. ηV was improved by a steep increase of stress at low compressive strain and by a gradual increase of stress in the range up to 50 pct of compressive strain. The gradual increase of stress was caused by continuous shear fracture in the metallic part, which was due to the high dislocation density and existence of unidirectional pores parallel to the compressive direction in the structure.

Mechanical Properties of Functionally Graded Porous Aluminum Consisting of Pure Aluminum and Al-Mg-Si Aluminum Alloy

Porous aluminum can potentially satisfy both the lightweight and high-energy-absorption properties required for automotive components. In this study, functionally graded porous aluminum consisting of pure aluminum and Al-Mg-Si A6061 aluminum alloy was fabricated by a sintering and dissolution process. It was found that functionally graded porous aluminum with the same pore structures but different types of aluminum alloy can be fabricated. By performing compression tests on the fabricated functionally graded porous aluminum, it was found that its stress-strain curve initially exhibited a relatively low plateau stress similar to that of uniform porous pure aluminum. Thereafter, the stress-strain curves exhibited a relatively high plateau stress similar to that of the uniform porous A6061 aluminum alloy. Namely, it was found that the compression properties of porous aluminum can be adjusted and optimized by selecting the appropriate type of aluminum alloy.

The impact of defect morphology, defect size, and SDAS on the HCF response of A356-T6 alloy

This paper aims to investigate the influence of defect morphology, defect size, and SDAS on the fatigue behavior of A356-T6 aluminum alloy. A 3D finite element analysis for specimens containing different pore morphologies—(i) spherical pore, (ii) elliptical pore, and (iii) complex pore—was implemented. The Chaboche kinematic hardening model embedded in Abaqus is used to characterize the material response during cyclic loading. Kitagawa diagrams for defective A356-T6 are simulated using the defect stress gradient (DSG) approach. A good agreement is found between experimental and numerical results for predicting fatigue limit in the case of spherical defects. The impact of defect morphology on the fatigue resistance is clearly demonstrated. This paper shows that aluminum fatigue resistance is strongly dependent on the defect size, SDAS, and the defect morphology. Therefore, a mathematical model that takes into account the impact of these three parameters is developed using response surface (RS) approach to predict fatigue limit of porous aluminum alloy. Moreover, the effects of defect morphology, defect size, and SDAS on fatigue response and their interactions under fully reserved tensile loading are investigated.

Anti-icing and anticontamination properties of coatings induced by surface structure

The development of the first model coatings with innovative surface structures, anti-icing, and anticontamination properties could be implemented in the EU-project CleanSky. A porous aluminum alloy structure created by anodization was filled with fluid silicon oil polydimethylsiloxane. At the surface, the silicon oil was modified with vacuum ultraviolet-light to form a thin and solid hydrophobic layer. For further investigations, laser-structured metal surfaces were copied and reproduced with a coating and afterward filled with fluoro-modified oils. Additionally, aluminum alloy AA2024 samples were pickled and treated with hot water to create micro- and nanostructures at the surface. These samples were also filled with different fluoro-modified and nonmodified oils. After application, the surface properties were analyzed with special tests for functionality regarding anti-ice and anticontamination properties.