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Investigating the mechanical properties of complex, porous microstructures by assessing model representative volumes is an established method of determining materials properties across a range of length scales. An understanding of how behavior evolves with length scale is essential for evaluating the material's suitability for certain applications where the interaction volume is so small that the mechanical response originates from individual features rather than a set of features. Here, we apply the Kentucky Random Structure Toolkit (KRaSTk) to metallic foams, which are crucial to many emerging applications, among them shielding against hypervelocity impacts caused by micrometeoroids and orbital debris (MMOD). The variability of properties at feature-scale and mesoscale lengths originating from the inherently random microstructure makes developing predictive models challenging. It also hinders the optimization of components fabricated with such foams, an especially serious problem for spacecraft design where the benefit–cost–mass optimization is overshadowed by the catastrophic results of component failure. To address this problem, we compute the critical transition between the feature-scale, where mechanical properties are determined by individual features, and the mesoscale, where behavior is determined by ensembles of features. At the mesoscale, we compute distributions of properties—with respect to both expectation value and standard variability—that are consistent and predictable. A universal transition is found to occur when the side length of a cubic sample volume is ~10× greater than the characteristic length. Comparing KRaSTk-computed converged stiffness distributions with experimental measurements of a commercial metallic foam found an excellent agreement for both expectation value and standard variability at all reduced densities. Lastly, we observe that the diameter of a representative MMOD strike is ~30× shorter than the feature-scale to mesoscale transition for the foam at any reduced density, strongly implying that individual features will determine response to hypervelocity impacts, rather than bulk, or even mesoscale, structure. [ABSTRACT FROM AUTHOR]

Aluminium foam offers an exceptional strength-to-weight ratio and energy absorption capacity, but variations in the cell structure hinder its performance and limit industrial applications. The addition (ex situ) or formation (in situ) of specific particles during the processing of metal foams stabilizes the foam by restricting the cell coalescence and liquid drainage during foaming. In this study, we investigated the potential of in situ formed Al3Zr particles to enhance the stability and properties of AA6061 closed-cell foams. The microstructure analysis revealed the presence of Al3Zr particle clusters along the plateau borders, inhibiting cell coalescence and wall thinning. Consequently, the composite foams exhibited a 37 pct increase in plateau stress and a 56 pct increase in energy absorption capacity, with a 78.5 pct mean energy absorption efficiency compared with base AA6061 foams. The coefficient of thermal expansion mismatch of particles with the matrix is the primary strengthening mechanism, leading to a 12.9 pct improvement in the yield strength of the composite. The mesoscale ex situ compression test showed a brittle failure mode with premature cell fracture due to the formation of microcells and secondary phases within the cell edge region. The fractography revealed a mixed mode of ductile and brittle failure with debonding of the secondary phase network and fracture of in situ Al3Zr particles. [ABSTRACT FROM AUTHOR]

A promising alternative to established methods for solar hydrogen generation is direct water splitting via thermochemical two-step redox cycling, which has the potential for highly attractive solar-to-fuel efficiencies. This paper presents results of a 250-kW prototype fixed-bed reactor, utilizing a hemispherical-shaped porous metal foam absorber. A complex multi-physical simulation model has been developed with fine local resolution of the size of thin slices of absorber blocks. The focus of this paper is on local energy flow analysis of hot spots, characteristic behavior of absorber temperature distribution in case of nonuniform irradiation and resulting influence on efficiency. Further, balancing effects of surface temperature inhomogeneities are analyzed by varying thermal conductivity of reactor materials, thereby reducing both surface and radial temperature differences: increasing the conductivity of the used tape material by a factor of 5 (or 20) the overall plant efficiency can be substantially improved by roughly 50% or 100%, respectively. • Solar thermochemical splitting of water for efficient hydrogen generation. • 3D energy flow analysis of a large scale fixed-bed prototype reactor. • System analysis regarding the impact of inhomogeneous irradiation and hot spots. • Determination of significant efficiency improvement by enhanced thermal balancing. [ABSTRACT FROM AUTHOR]

Aluminum metal foam, distinguished by its lightweight nature, exceptional strength-to-weight ratio, and distinctive cellular structure, has emerged as a highly promising material with extensive applications across diverse industries. Various fabrication techniques, including the sintering and dissolution process (SDP) and powder metallurgy, have been explored to produce metal foams. However, challenges persist in achieving uniform pore sizes and distributions, especially at temperatures surpassing the base material's melting point. To overcome this hurdle, simultaneous loading and heating during fabrication have been proposed, with spark plasma sintering (SPS) emerging as a viable solution. This study delves into the manufacturing of aluminum metal foam utilizing NaCl space holders via SPS, investigating variations in space holder volume to analyze pore morphology and porosity. Additionally, the mechanical properties of the resulting foams are examined, providing valuable insights into the potential of SPS for crafting aluminum metal open foams with tailored properties. Porosity analysis, conducted through X-ray micro CT, reveals porosity ranging from 55 to 70% in metal foams with NaCl space holder volume fractions of 60 to 80%. Notably, a maximum energy absorption capacity of 23 MJ/mm3 is achieved in a metal foam with 57% porosity. S1 (40% NaCl) had lower porosity, smaller pore sizes, and thicker pore walls, buckling in the middle with minimal pore collapsibility and crack initiation at the edges. In contrast, the sample with more than 40% NaCl had higher porosity and thinner pore walls, resulting in greater collapse and energy absorption. [ABSTRACT FROM AUTHOR]

Salt hydrates, like the sodium acetate trihydrate (SAT), possess a remarkable ability to store copious amounts of thermal energy, thanks to their ingenious utilization of a high latent heat of fusion. This unique property makes them a compelling choice for various energy storage applications. In this study, aluminum and copper foams with pore sizes of 40, 80, and 110 pores per inch (PPI) coated with disodium hydrogen phosphate dodecahydrate were prepared, and their effects on the SAT solidification temperature, latent heat of fusion, and thermal conductivity were investigated. The samples' thermal conductivity was measured using the guarded heat flow method. Thermal properties, including latent heat of fusion and supercooling were measured using the T-History method. The results showed that the metal foam matrix is an effective method of enhancing the thermal conductivity of SAT while occupying a small volume of the composite. The copper foam with a PPI of 80 was able to increase the effective thermal conductivity to 2.62 W/(m·K), an increase of 388.15% compared to pure SAT while occupying approximately 6.5% of the composite volume. The T-History results showed a solidification temperature of 57.52 °C along with a super cooling of 3.28 °C for the same sample set. Furthermore, it was also found that copper samples significantly outperformed the aluminum ones, despite the higher porosity. [ABSTRACT FROM AUTHOR]

Metal foams are highly useful in industries because of their lightweight, energy and vibration absorption properties. This study investigated the propagation of torsional waves in an elastic layer over a fluid-saturated fractured poroelastic half-space with a metal foam coated layer. It is assumed that the interfaces are in sliding contact with two different sliding parameters. The coated layer is closed-cell aluminium foam. We use the separation variable technique and the Bessel function to solve the equation of motion in different layers. The displacement components are written in terms of the second kind Whittaker functions. Using an asymptotic formulation of the Whittaker function and appropriate boundary conditions, the dispersion equation is derived in terms of the determinant. The control of the vibration due to the metal foam-coated layer is one of the important goals of this study. Also, numerical and graphical analyses have been done with the help of Mathematica software to see the effect of different parameters on torsional wave propagation. It is found that the presence of coated metal foam layer decreases the phase velocity of the torsional wave propagation. The work may be helpful in the seismology, automobile, and aerospace industries. [ABSTRACT FROM AUTHOR]

Metallic foams are unique engineering materials with large pore volumes and an interconnected solid-metal structures. Lightweight, high-energy absorbing capacity and low thermal conductivities are some of the distinctive characteristics of metal foam that make them the preferred choice for many structural and functional applications. Although prevalent since 1940, the commercialization of metal foams has not achieved their full potential owing to large-scale production and near-net shaping limitations. In addition to technical challenges, mass production is hindered by to high manufacturing costs compared to those of ceramic and polymer foams. Depending on the pore structure, viz. open or closed, metal foams can be multifunctional, making them suitable for several conventional and niche applications. This review details the prevailing methods for fabricating closed metal foams, as well as their advantages and limitations. Apart from established methods such as gas injection and powder compaction, other emerging unconventional techniques for making metals, alloys and intermetallic foams are also discussed. The parameters that control the physical characteristics, such as the pore size and cell structure of the foam, are also explained. The standard characterization methods used to estimate various physical, mechanical, and thermal properties were reviewed. Applications and recent developments in closed foam research are presented here. [ABSTRACT FROM AUTHOR]

In this study, nanofluids were produced from CuO nanoparticles decorated with Ag atoms at different mass concentrations, and their cooling performance was examined in a channel containing metal foam heat sinks (MFHS) with pore densities of 10 and 40 pore per inch (PPI). CuO-H2O/2% Polyethylene Imine (PEI) nanofluid with a concentration of 0.1% by mass was used. The surfaces of the CuO nanoparticles were decorated with Ag at mass concentrations of 0.03%, 0.05%, and 0.1%. Experiments were performed for volumetric flow rates varying from 17.6 L/h to 76.5 L/h in laminar conditions, and the heat fluxes applied to the bottom of the channel were chosen in the range of 3267 W/m2-5400 W/m2. The base fluid (BF)-empty surface case was used as the reference for all measurements. In the findings of experiments conducted on the base surface, it was found that decorating CuO nanoparticles with 0.03% and 0.05% Ag atoms effectively lowers the surface temperatures compared to the BF. On the contrary, an increase in surface temperatures was detected when 0.1% Ag atoms were used. Passing a 0.1% CuO-0.05% Ag/2% PEI-H2O (NF3) nanofluid through 40 PPI MFHS’ achieved the highest improvement in mean surface temperatures, with a 37.4% increase compared to using the BF on the empty surface. [ABSTRACT FROM AUTHOR]

This study modeled and analyzed the thermomechanical buckling behavior of smart magneto-electro-elastic (MEE) sandwich nanoplates using nonlocal elasticity, strain gradient elasticity, and higher-order plate theory. The sandwich nanoplate consists of ceramic and metal functional graded foam structure in the core layer and is composed of magneto-strictive and electro-elastic materials in the surface layers. Due to the functionally graded feature in the core layer, pure metal/metal foam, pure ceramic/ceramic foam, and metal + ceramic foam structures are modeled. The foam structure can be distributed uniformly and symmetrically throughout the thickness of the core layer. The effects of nonlocal elasticity, strain gradient elasticity, foam distribution, and foam void ratio of the core layer on the thermomechanical buckling behavior of the smart sandwich nanoplate have been examined in a broad framework. Additionally, the effects of electro-elastic and magneto-strictive material characteristics of smart surface plates on thermomechanical buckling response were examined according to the applied external electric and magnetic potential intensities. It is observed that the foam structure and foam void fraction ratio in the core layer are effective on the thermomechanical buckling behavior of the smart sandwich nanoplate. Moreover, it is concluded that the applied external electric and magnetic potential can change the thermomechanical buckling behavior of the sandwich nanoplate. [ABSTRACT FROM AUTHOR]

The performance of latent heat thermal energy storage (LHTES) systems can be significantly enhanced by improving the thermal properties of phase change materials (PCMs). Today, these systems serve as a sustainable energy resource and find applications in various sectors, including energy conservation in buildings, household hot water systems, air conditioning units, peak load reduction, waste heat recovery, and biomedical applications. This paper investigates the effects of fins and metal foam on the melting and solidification rates of PCM within a spherical latent heat thermal energy storage unit (LHTESU). To assess the impact of fin geometry on energy storage efficiency, three types of fins were tested: fins with a constant length, fins with a variable length, and curved-shaped fins. Additionally, three different porosity levels of metal foam were considered. A finless reservoir filled with PCM was used as a baseline and benchmark to evaluate the performance enhancements provided by the different fin and metal foam configurations. The results indicated that utilizing seven fixed-length fins with a thickness of 1 mm represents the most effective configuration for increasing melting and solidification rates among the constant volume fraction cases, leading to reductions in melting and solidification times by 58.76% and 72.66%, respectively. Furthermore, incorporating metal foam significantly improved the phase change rate of the PCM, achieving reductions in melting time by 89.11% and solidification time by 94.96% when 85% porosity was used. These results highlight the potential of advanced fin designs and porous media in significantly enhancing the thermal energy storage efficiency, offering promising insights for future sustainable energy technologies. [ABSTRACT FROM AUTHOR]

The high-speed trains traveling at 400 km/h will generate severe alternating pressure and potential sonic boom when passing through tunnels. This paper proposed foam metal hoods (FMH) to mitigate the pressure waves induced by trains traversing tunnels. 1:20 scaled moving-model experiments were conducted to investigate the mitigation mechanisms of FMH on micro-pressure waves (MPW), residual pressure, and aerodynamic loads on the train and tunnel. The impact of FMH's installation position and length on MPW and residual pressure were discussed. The results indicate that the entrance FMH can weaken the expansion wave generated by the tail train entering the tunnel, thereby reducing the pressure amplitude on the train surface and tunnel wall. FMH can reduce the reflection intensity of pressure waves, effectively lowering the root mean square (RMS) of residual pressure. Installing FMH at both ends can reduce the RMS of residual pressure in the middle of the tunnel by 25%. The exit FMH enables the initial wavefront to gradually release pressure outward, thereby reducing MPW intensity. The radiation range of the MPW iso-surface is narrowed by energy consumption as the wavefront passes through the porous structures. The mitigation ratio of MPW intensifies as the length of the exit FMH increases. Using a 4-m-long exit FMH can decrease the MPW amplitude by 83.2% at 20 m from the FMH exit. The FMH facilitates a low-noise environment near tunnel portals, reducing the aerodynamic loads on the tunnel structures, and mitigating the train aerodynamic loads. [ABSTRACT FROM AUTHOR]

Here, the thermal characteristics of open-cell metal foam (OCMF) integrated stainless steel (SS) foil are investigated experimentally during air jet impingement using circular and elliptical nozzles. The aspect ratio (AR) of the elliptical nozzle is varied from 2 to 4, the Reynolds number (Re) is varied within 5000 - 25,000 and the impinging distance (z/d) is varied within 3–7 during tests. Thin foil thermal imaging infrared thermography has been utilized to record the temperature, and the measured temperature data is used to estimate the performance parameters. The thermal performance is evaluated based on the local, average, and stagnation Nusselt number (Nu) for different configurations. The integration of OCMF with SS foil has been found to significantly enhance heat transfer at the stagnation point in different nozzle configurations. At a Reynolds number (Re) of 5000, the percentage increase in stagnation Nu with foam compared to when there is no foam is found to be 80%, 46%, 38%, and 24% for nozzles with AR of 1, 2, 3, and 4, respectively. The local (0 ≤ x/d ≤2) and average values of Nu for lower impinging distance (z/d ≤5) are found to be higher for the elliptical nozzles, while for z/d ˃ 5, the circular nozzle is found to exhibit better performance. The peak average Nu with nozzle AR = 4 at Re = 25000 is found to be higher than nozzle AR of 3, 2, and 1 by 6.75%, 8.72%, and 23.44%, respectively. Additionally, for the same Re, the peak average Nu of nozzles with AR = 4, AR = 3, and AR = 2 is higher than the circular nozzle by 23.44%, 15.62%, and 13.54%, respectively. New correlations based on experimental results are proposed to determine the local and average Nusselt number as a function of various operating parameters. [ABSTRACT FROM AUTHOR]

Graphene platelets (GPLs)-reinforced metal foam structures enhance the mechanical properties while maintaining the lightweight characteristics of metal foams. Further bonding piezoelectric actuator and sensor layers on the surfaces of GPLs-reinforced metal foam beams enables active vibration control, greatly expanding their applications in the aerospace industry. For the first time, this paper investigates the vibration characteristics and active vibration control of GPLs-reinforced metal foam beams with surface-bonded piezoelectric layers. The constant velocity feedback scheme is used to design the closed-loop controller including piezoelectric actuators and sensors. The effects of the GPLs on the linear and nonlinear free vibrations of the beams are numerically studied. The Newmark-β method combined with Newton's iteration technique is used to calculate the nonlinear responses of the beams under different load forms including harmonic loads, impact loads, and moving loads. Additionally, special attention is given to the vibration reduction performance of the velocity feedback control on the responses of the beam. [ABSTRACT FROM AUTHOR]

The enhancement of the thermal performance of heat exchangers has a great importance to the researchers. This is because improving the performance will lead to increasing the efficiency of the application where the heat exchangers are used. In this study, the thermal and hydraulic performance of a double heat exchanger with open-cell copper foam baffles inside was investigated numerically and experimentally with water as operating fluid. The numerical simulation was conducted using ANSYS FLUENT 2020 R2 to simulate the water flow and temperature distribution in the heat exchanger at different configurations. These configurations included the completely and partially filled with metal foam with different foam properties such as pore density, baffle angle, and baffle thickness. The experimental work included the designing and building of the test rig and obtaining the temperature recordings which were used for comparison purposes. Results were obtained for temperature contours, velocity streamlines, Nusselt numbers, effectiveness, pressure drops, and friction factors at variable baffles angles (β = 60°, 120°, 180°), variable baffles thickness (t =10, 20, 30mm), and variables pore density (PPI=10, 20, 30, 40, 50PPI). They showed that as the volume of metal foam increases, the heat transfer rate (Qave) and the pressure drop (Δp) increases. In addition, the performance of the heat exchanger with a partially filled core was better than that in the completely filled case. On the other hand, when the metal foam volume decreases, the pressure drop decreases. Furthermore, it was observed that the heat transfer rate increases with the increase in pore density. Experimental results showed an enhancement in heat transfer rate in a double-pipe heat exchanger by 32.4% at 40PPI and β=180°. There was also an enhancement in the Nusselt number value (Nuave) by 117% due to the use of copper foam baffles. [ABSTRACT FROM AUTHOR]

A thorough numerical investigation was carried out to examine the heat transfer characteristics within a rectangular channel integrated with metal foam blocks for solar air heating applications. The study employed numerical simulations using the extended Darcy–Forchheimer model with the assumption that there exist local thermal nonequilibrium conditions within the porous foam region. Four configurations, denoted as P–A, P–P, A–P, and A–A, were explored based on the presence or absence of foam blocks relative to the heated section. The study meticulously analyzed the influence of key parameters, such as the number of foam blocks (N = 1–5), permeability (quantified by pore density, ω=10‐30 PPI $\omega =10 \mbox{-} 30\unicode{x0200A}\mathrm{PPI}$), and Reynolds number (Re=4000‐16,000 ${Re}=4000 \mbox{-} 16,000$), on the thermohydraulic performance. The results were promising, indicating a significant increase in the average Nusselt number (Nu ${Nu}$) with the inclusion of foam blocks, albeit accompanied by an undesirable increase in the friction factor. Among the various configurations, the P–A arrangement, where porous blocks are situated at the entrance of the heating channel, exhibited superior thermal performance. Furthermore, the optimal heat transmission rate was attained with a single porous block (N = 1) in the P–A configuration, at a Reynolds number of 16,000 and high permeability (ω=10 PPI $\omega =10\unicode{x0200A}\mathrm{PPI}$). Conversely, the maximum friction factor was observed with five porous blocks (N = 5) in the A–P configuration, at a Reynolds number of 4000 and low permeability (ω=30 PPI $\omega =30\unicode{x0200A}\mathrm{PPI}$). The exhaustive analysis of thermohydraulic performance was evaluated using the performance evaluation criterion (PEC), which optimizes the trade‐off between increased heat transfer rate and consequent pressure loss. The P–A arrangement, particularly with higher permeability and a minimal number of porous blocks, demonstrated the highest PEC value of 2.71, representing a significant 171% improvement compared with an empty channel. This study underscores the effectiveness of strategically placing and optimizing metal foam blocks to improve the thermal performance of heat exchanger systems. [ABSTRACT FROM AUTHOR]

This paper investigates the vibration and buckling analysis of porous metal foam thin-walled box beams. These beams exhibit a unique structural configuration with symmetrical and asymmetrical porosity distributions along their wall thickness, thereby altering the effective mechanical properties. The first-order shear deformable beam theory is employed and the governing equations are derived using the Hamilton's principle. Numerical results are presented for porous metal foam thin-walled box beams under simply-supported, clamped–clamped and clamped-free boundary conditions. The effects of various porosity parameters, length-to-side and side-to-wall-thickness ratios on the beams' performance are also examined. A comprehensive comparison between the porous metal foam thin-walled box beams and their counterparts in the form of equivalent homogeneous are presented. [ABSTRACT FROM AUTHOR]

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Copyright of Journal of Engineering (17264073) is the property of Republic of Iraq Ministry of Higher Education & Scientific Research (MOHESR) and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

To overcome the disadvantage of difficult recovery of powder catalysts and improve catalyst utilization, the selection of foam metal substrates as supports can reduce the difficulty of material recovery and effectively inhibit the leaching of metal ions. Herein, CoMnNi-layered double hydroxide (LDH) derived from Co-Mn ZIF was immobilized onto nickel foam (NF) through in situ synthesis. The results of XRD and SEM analyses of the samples indicated that the LDH was successfully grown on the nickel foam matrix, and the material could maintain its original morphology to the maximum extent after loading. By comparing the XPS of the material before and after the reaction, it was confirmed that the surface hydroxyl group and C=O of the material were involved in the activation of peroxymonosulfate (PMS). The results of the quenching reaction showed that SO4•− and 1O2 are the main active substances in the oxidation of enrofloxacin (ENR). When the dosage of NF@CoMnNi-LDH was 0.4 g/L, the pH of the solution was 6.82, and when the dosage of PMS was 2.0 mM, the degradation rate of ENR reached 82.6% within 30 min. This research offers novel insights into the degradation of antibiotics from water using a monolithic catalyst supported by metal foam. [ABSTRACT FROM AUTHOR]

We study shock recompression of the metal spall fracture region using macroscopic simulations in a wide range of initial parameters. Recompression states are mainly analyzed based on different simulation methods. First, we employ an empirical numerical treatment within the fracture post-processing model, resulting in a good agreement with experimental data of porous metals. To further validate its applicability, we carry out direct simulations that distinguish various initial fractured states, and we find that the influence of an initial fractured state on the recompression state is remarkable, especially the temperature. By comparing recompression states calculated by two different simulation methods, it reveals that empirical-treatment-based simulations actually describe fragment-state recompression. The present study shows that empirical-treatment-based simulations are physically capable of describing the shock recompression of fractured metals, which might be potentially used to investigate detonation-driven experiments with more complicated physical scenarios. [ABSTRACT FROM AUTHOR]

In this research, it is tried to study the effect of the external electric voltage on the vibrational behavior of a smart sandwich plate made of graphene oxide-strengthened metal foam nanocomposite core and two piezoelectric face sheets for the first time. The sandwich plate is modeled utilizing first-order shear deformation theory. The effective material properties of the core layer are estimated with the aim of the blend of Halpin-Tsai micromechanical model and rule of the mixture while considering different graded graphene oxide distribution patterns. Additionally, various porosity distributions are regarded in the metal matrix of the core layer. The partial differential equations of motion are derived using Hamilton's principle and the derived governing equations are solved through Navier's solution. To perform an accurate verification, the obtained results are compared with different literature investigations. Afterward, the influence of various important variants including external electric voltage, aspect ratio of plate, core to face sheet thickness ratio, different porosity distribution patterns, porosity coefficient, nanofillers weight fraction, and various distribution patterns of graphene oxides on the dimensionless frequency of smart sandwich plate in the framework of a group of tables and figures. [ABSTRACT FROM AUTHOR]

A hybrid sandwich panel with lightweight core composed of corrugated core and metallic foam were designed. The dynamic responses of this hybrid sandwich panels were numerically investigated under combined loading of blast and fragments by LS-DYNA software. To simulate this loading condition, the TNT charge was used to drive prefabricated fragments. The developed numerical approach was validated by using the existing experimental results. The effects of foam layer location, foam density, back plate configuration and stand-off distance on the dynamic response were systematically analyzed. The results indicate that the hybrid sandwich panels with corrugated and foam separation demonstrate higher protective capability. Compared with the foam-filled corrugated sandwich panels, the energy absorption is increased by up to 16.3%. Increasing the foam density can enhance the impact resistance of the structure under combined loading of blast and fragments. The back plate with composite plate has better anti-fragmentation ability than the steel plate. [ABSTRACT FROM AUTHOR]

Metallic foams have become a cutting-edge solution for many thermal management problems. These are of interest by thermal research community because of the cellular structure and have gas-filled pores inside a metal matrix. Due to the uniqueness in their structure, they exhibit good performance in boiling heat transfer because of the properties such as higher specific surface area, large number of nucleation sites, wettability characteristics, and capillary action. The boiling heat transfer over metal foam is a complex phenomenon, greatly affected by the thickness, porosity, and pores per inch (PPI) of metal foam along with the thermo-physical properties of the foam and boiling liquid. By thoroughly examining recent research investigations, the paper explains the impact of open-cell metal foams on pool boiling of different liquids such as water, refrigerants, organic liquids, and dielectric liquids. This paper reviews the complexity and various influencing factors involved in flow boiling through metal foam in tubes. It also highlights findings that show metal foam significantly enhances jet impingement boiling heat transfer. Moreover, the discussion on gradient metal foams, offering insights into their potential to enhance boiling heat transfer. The comprehensive review also encompasses numerical modeling studies, such as the lattice Boltzmann method, contributing to a deeper understanding of the intricate flow and heat transfer characteristics within channels filled with metal foam. [ABSTRACT FROM AUTHOR]

Composite metal foams (CMF) are renowned for their high strength‐to‐density ratio, high stiffness, and energy absorption capabilities. Homogenized finite element models of CMF have been numerically solved to understand the mechanical behavior of the material under a variety of external loading conditions. This work aims to pioneer a comprehensive finite element model for steel–steel composite metal foam by incorporating the interactions between embedded stainless‐steel hollow spheres with entrapped air inside stainless‐steel matrix. The material behavior of hollow spheres, surrounding matrix, and air are modeled using Johnson–Cook (JC) plasticity, Deshpande–Fleck (D–F) foam, and linear polynomial equation of state in LS DYNA. Further, the finite element model utilizes a combination of Lagrangian solid elements and meshfree smooth particles hydrodynamics with appropriate contacts to effectively model the interaction of entrapped air within stainless‐steel hollow spheres with surrounding metallic spheres and matrix. The strain rate and the crosshead velocity of 65 s−1 and 2.4765 m s−1 are used for quasistatic compression analysis. Finally, the results obtained from the computational model are compared and validated using previously reported experimental quasistatic compression data. The numerical model corroborates stress–strain response of CMF with 5.6% error for plateau stresses average within 25% and 30% strain. [ABSTRACT FROM AUTHOR]

The difficult determination of morphological properties in metal foams stands behind the reasons why metal foams are not widely used in industry, since quality control of the batches produced is limited to destructive methods. To approach this challenge, a new method of analysis of morphological properties based on 2D X‐Ray radiograms and the employment of a new Convolutional Neural Network architecture is proposed. The training of this model is based on a combined approach of simulating simplified foams as pretraining data and the acquisition of real experimental data, extracted from X‐Ray computer tomographies. The network is trained successfully with 41 foams to obtain predictions for cell size distribution between 0.3 and 5 mm, as well as sphericities in ranges from 0.4 to 1. In addition, tests are carried out to get an insight into the robustness of the model when confronted with similar data that are not included in the training process. It is found that the effectiveness of the neural network increases with a larger number of cells in the observed volume where above 500 cells per volume 92.5% of sphericity predictions and 99.4% of cell size predictions passed the Kolmogorov‐Smirnov test. [ABSTRACT FROM AUTHOR]

Metal foams are an interesting class of bio‐inspired materials for lightweight construction and energy absorption. Commonly, aluminum (Al) foams are used. However, the mechanical properties have been improved by coating pure Al foams with a nanocrystalline nickel (Ni) coating resulting in Ni/Al hybrid foams. Herein, the meso‐mechanical deformation mechanisms in Al foams and the changes in the mechanisms in Ni/Al hybrid foams are studied using time‐lapse micro‐computed tomography measurements in comparison between numerical modeling using voxel finite element models and evaluation of displacement fields using 3D optical flow. This gives never‐seen insights into the highly localized 3D deformation mechanisms within the entire volume of the foams and not only on the surfaces as given by conventional digital image correlation methods. Displacements calculated by the 3D optical flow algorithm demonstrate its possibility to reveal a significant concentration of plastic deformation, particularly evident when deformation occurs within a distinct, slightly inclined band in the central region. Common numerical simulations using standard plasticity models do not accurately capture this localized deformation, underscoring the need to integrate damage and softening models into the simulation. [ABSTRACT FROM AUTHOR]

Metal foams are characterized by low weight, high resource efficiency, high relative stiffness, and exceptional energy absorption capacity under compressive load. Nickel/polyurethane (Ni/PU) hybrid foams consist of an open‐cell polyurethane foam coated with a layer of nickel produced by electrochemical deposition. The coating of the PU foams takes place in a flow reactor, in which the electrolyte is pumped through the foam at a defined flow velocity. The macromechanical properties of foam‐like structures depend on the structure of the skeleton, the inherent material properties and, in the case of Ni/PU hybrid foams, the properties of the electrochemically generated nickel layer. To influence their mechanical properties, the Ni/PU hybrid foams are subjected to heat treatment. In the given experimental setup, the parameters flow velocity, temperature, and duration of the heat treatment are each investigated at two different levels. Thus, interactions between the initial microstructure and the type of heat treatment are evaluated by means of X‐ray diffraction (XRD) and electron backscatter diffraction (EBSD) measurements. Interactions between initial mechanical properties and heat treatment are investigated by uniaxial compression tests and superimposed compression‐torsion tests. The knowledge gained is used to control the macromechanical properties of the hybrid foam. [ABSTRACT FROM AUTHOR]

Novel cellular materials promise a combination of high strength and low specific weight for sustainable and energy‐efficient material design. Inhomogeneities of the materials, such as varying coating thickness, are inherent to the production process but require advanced characterization in order to better understand mechanical properties. Herein, global and local acoustic analysis for nondestructive characterization of local coating thickness on an open‐porous hybrid metal foam system is studied. Experiments and numerical simulations are carried out to evaluate vibration behavior stimulated by a low‐energy impact. The novelty of the work is the use of local excitation and analysis of decay times to determine coating thickness gradients. This qualitative measurement can inform and speed up the material development process due to its simplicity, speed, and low cost. Furthermore, it provides a basis for quality control when scaling up the technology of metal hybrid foams for industrial applications. [ABSTRACT FROM AUTHOR]

An analysis is done in this research on the dynamical behavior of thick sandwich plates subjected to a moving load. The considered sandwich plate is composed of a porous aluminum core augmented with graphene platelets (GPLs) and titanium alloy face sheets. The core of sandwich plate is identified as a porosity-dependent composite and consists of six layers with each of them having different values of porosity. The time-dependent equations of motion are established for the sandwich plate by implementing the principle of virtual work. The governing equations are numerically solved for different boundary conditions utilizing the Ritz technique. The Newmark time marching scheme is also applied to obtain the temporal evaluation of displacement field in the plate volume. The verification example demonstrates the effectiveness and accuracy of the applied formulation. Novel numerical examples are presented to study the influences of porosity distribution pattern and its coefficient on the dynamic characteristics of the sandwich plate. Also, the effects of graphene’s weight fraction, plate’s geometric parameters and its boundary conditions are examined. [ABSTRACT FROM AUTHOR]

The temperature distribution has a significant influence on the performance and lifespan of proton exchange membrane fuel cell (PEMFC) stacks. However, analyzing the temperature distribution of large PEMFC stacks is challenging and has been rarely conducted. In this study, a simplified model of a large PEMFC stack is developed using computational fluid dynamics (CFD) methods, which includes 300 cells and 60 cooling plates. The influence of cooling parameters, including configurations, dimension and flow rate, is discussed. The study indicates that U-type stack exhibits better temperature uniformity than Z-type stack. Increasing the coolant flow rate can effectively reduce the stack temperature. The study proposes a modified cooling design, which effectively reduces the heat accumulation at the end of the stack. Lastly, a comparison between traditional serpentine channels and porous foam metal flow fields reveals that the porous foam metal flow field exhibits superior thermal management characteristics. The results can offer insights for thermal management of large-scale PEMFC stacks. • A simplified model of water-cooled large-scale PEMFC stack with 300 single cells is established. • The effects of cooling parameters, including configurations, dimension and flow rate, are discussed. • U-type stack exhibits better temperature uniformity than Z-type stack. • The modified cooling design with one cooling plate at both ends can reduce the heat accumulation at the end of the stack. [ABSTRACT FROM AUTHOR]

AZ31 magnesium alloys stand out as a pivotal alternative for orthopedic applications owing to their inherent attributes of biocompatibility, biodegradability, favorable mechanical properties, and the facilitation of bone regeneration. The Mg AZ31 foams serve as temporary implants thanks to its bioabsorbability, offering the advantage of obviating the need for additional surgical interventions and minimizing associated ailments and discomfort. However, addressing the intrinsic corrosion rate of magnesium is imperative. To mitigate corrosion, surface activation techniques, specifically alkaline activation and hydrofluoric activation, are applied to treat the surfaces of AZ31 alloys. Subsequently, these treated alloys, configured as scaffolds, undergo coating with varying concentrations of collagen solutions (0%, 16%, and 64% w/w). The corrosion rate is then assessed through the hydrogen evolution method within a simulated physiological environment (simulated body fluid [SBF]). The analysis of results employs quantitative techniques, such as atomic absorption (AA) spectroscopy and qualitative methods, including electron microscopy with atomic analysis. The outcomes reveal the successful consolidation of the collagen coating, identification of corrosion byproducts, a notable reduction in corrosion rate, and additional indicators providing evidence of potential bone tissue regeneration. [ABSTRACT FROM AUTHOR]

The effect of the metal foam thickness on the conduction and convection heat transfer for a metal foam flat plate impinged by a circular air jet is investigated. The IR thermography and thin-metal foil technique are used for the measurement of local heat transfer. An open-cell aluminum metal foam is used for the metal foam flat plate. A 3D-printed resin foam and detached metal foam flat plate are used for the appreciation of the conduction and convection heat transfer. The varying parameters are the thickness of the foam, Reynolds number, and the nozzle exit to plate distance. The presence of the metal foam offers a conduction effect. This predominates over the attenuation in the convective heat transfer by foam due to additional hydraulic resistance. The additional hydraulic resistance offered by the porous foam increases with the increase in the foam thickness. The heat transfer of a porous foamed flat plate decreases with the increase in the foam thickness. The local Nusselt number of the resin foam and detached foam flat plate is almost the same. The conduction effect and attenuation in the convection heat transfer of a metal foam flat plate are quantified by attenuation and enhancement factors. The overall augmentation offered by 4, 8, and 12 mm thick metal foam flat plates is 1.71, 1.42, and 1.43 times compared to the smooth flat plate case, respectively. Hence, it is advisable to use a metal foam flat plate with 4-mm-thick metal foam under circular air jet impingement. [ABSTRACT FROM AUTHOR]

The liquid metal dealloying (LMD) process enables the fabrication of porous metals with various chemical compositions. Despite its advantages, LMD still faces key challenges such as maintaining the high‐temperature molten metal bath for a prolonged time, avoiding the use of toxic etchants, and so on. To overcome these challenges, the study develops a water‐leachable and oxidation‐resistant alloy melt (AM) in Ca‐Mg binary system. Specifically, Ca72Mg28 eutectic AM is designed, which exhibits higher oxidation resistance and lower melting temperature compared to pure Mg, allowing LMD to be conducted in atmospheric conditions as well as temperatures >200 K lower. The AM also enables an innovative process to fabricate Ti foams with a hexagonal faceted surface structure by carefully manipulating the etching rate during the water etching process. This approach allows for the creation of foam with a surface area over 13% larger than that of foams with smooth surfaces via normal acid etching, potentially enhancing efficiency in applications such as electrodes for electrochemical systems or biomedical materials where increased cell adhesion can be beneficial. This study paves the way for efficiently manipulating the LMD process to fabricate metal foams with customized compositions and enhanced surface properties. [ABSTRACT FROM AUTHOR]

The triply periodic minimal surface (TPMS) is receiving much interest among researchers. The advantage of using this TPMS structure is the ability to design a structure based on engineering need. In the present context, experimental measurement was conducted and compared with numerical models using a foam porous medium and TPMS porous structure, leading to an accurate calibration of the model. A porous medium, metal foam, was heated experimentally at the bottom, and forced convection was investigated for different heating conditions. Then, the porous foam was replaced with a TPMS, and the experiment was repeated under similar conditions. The experimental data were compared with the numerical model using COMSOL software. Besides the model's accuracy, the TPMS showed a uniform heating condition contrary to the metal foam case. At a later stage, the numerical model was used to investigate the importance of flow direction (two flow directions) in cooling hot surfaces. The first flow was parallel to the hot surface, and the second perpendicular to the hot surface. The TPMS structure was located on the top of the hot surface and acted as a fin in both cases. The Nusselt number exceeded 80 in the presence of the TPMS. As the porosity of the TPMS decreases below 0.7, a more considerable pressure drop is observed. The performance evaluation criterion was found to be greater than 70 when the porosity of the TPMS structure was 0.8. [ABSTRACT FROM AUTHOR]

This study delves into the dynamic characteristics of intelligent arches composed of metal foams, augmented with piezoelectric nanocomposite actuators. These arches are represented within the polar coordinate system, utilizing a higher-order shear and normal deformation theory that eliminates the need for shear correction factors. The structural properties exhibit thickness-dependent variations following predetermined functions. The model operates within a thermal environment and is supported by a Winkler–Pasternak elastic substrate. Hamilton's principle is employed to derive the equations governing the structure's motion. In solving these equations for a scenario with simply supported ends, Fourier series functions are employed as an analytical method. The outcomes are cross-verified against previously published studies with simpler configurations. The investigation explores the impacts of various critical parameters on the dynamic response of the structure. Findings reveal that an increase in pores within the metal foam core decreases the frequency, whereas an increase in the volume fraction of carbon nanotubes has the opposite effect. The primary objective of this study is to design and fabricate more efficient smart structures, through a comprehensive understanding and optimization of the behavior of metal foam arches when integrated with piezoelectric components. [ABSTRACT FROM AUTHOR]

The existing study examines the moisture-dependent vibrational behavior of a metal foam spherical panel that is positioned between two composite layers reinforced with graphene platelets (GPL). The Kerr foundation, a three-parameter elastic foundation, supports the model. Based on specified functionalities, the pores’ arrangement and the GPL dispersion throughout the core and face sheets, respectively, are taken into consideration. The Halpin–Tsai and extended rule of mixture micromechanical models are utilized to ascertain the face sheets’ effective hygromechanical property values. After the motion equations are determined, the frequencies are extracted using the analytical technique, which is particularly effective for shells with simply supported edges. The impacts of various influences on the natural frequencies are considered and addressed over the course of the inquiry. It is shown that natural frequencies drop with increasing porosity coefficient. Furthermore, a small amount of GPL is shown to have a strong reinforcing effect on the stiffness of the structure, hence enhancing natural frequencies. The outcomes of this investigation can be beneficial to a variety of industries such as aerospace, automotive, marine, and civil engineering, where spherical shells are commonly employed. Furthermore, the outcomes might function as a standard for subsequent research. These results not only advance the understanding of moisture effects on composite structures but also provide a foundation for future research aimed at optimizing material properties for specific applications. Additionally, this study offers practical insights for the design and manufacturing of more resilient and efficient spherical components in real-life engineering scenarios. [ABSTRACT FROM AUTHOR]

Metal hydride is a type of solid hydrogen storage material that offers excellent hydrogen absorption and desorption reaction properties. However, there is a strong thermal effect during the reaction process when the materials are applied in reactors. Thus, effective thermal management techniques are crucial for promoting efficient reactions. Prior studies on the subject have shown that phase change materials can be coupled with metal hydride reactors to transfer the reaction heat. To further enhance the transfer of heat and reaction efficiency of the metal hydride reactors based on phase change materials, this study explored heat transfer enhancement methods on the phase change materials side, including adding heat transfer fins and discussing the fin parameters and composite foam metal. The findings of the study showed that in comparison to the reactor without fins, the absorption rate of adding 10 sets of fins can increase by 28%, and as the number of fins increased to 14, this value could increase to 39.4%. The use of Y-shaped fins did not substantially improve the reaction rate, mainly due to the sufficient number of straight fins, and the heat transfer area reaching the limit of the fin enhanced the process of heat transport. Thus, the improved method of using copper foam is further considered. Compared with the reactor with and without fins, the absorption rate of the copper foam coupled reactor is increased by 23.4% and 61.3%, respectively. • The fins on the PCM side can enhance the performance of MH reactors. • The shape and quantity of fins have limited performance enhancement effect. • Foam metal can significantly break the upper performance limit of fins. • MH reactor based on PCM composite copper foam shows excellent performance. [ABSTRACT FROM AUTHOR]

Graphite composite bipolar plate (BP) have limited conductivity, which makes them less than ideal for extensive application in proton exchange membrane fuel cell (PEMFC). In traditional graphite composite BP, the construction process of the conductive network is entirely random. To enhance conductivity, it is typically necessary to increase the content of conductive fillers or incorporate high aspect ratio carbon nanomaterials to optimize the density of the conductive network. In this work, we manufactured a highly conductive composite bipolar plate with synergistic conductive networks of graphite and metal foam (MF). With a synergistic conductive network, the ASR of CuG80-20ppi decreased to 7.7 mΩ cm2. Additionally, thermal conductivity increased to 24.76 W/(m·K), and in-plane conductivity reached 294.1 S/cm at 80 wt% mass fractions of conductive filler, using 20 ppi copper foam as the metallic conductive network. CuG80-20ppi exhibited a flexural strength of 52.2 MPa. G80 and CuG80-20ppi have the 80 wt% conductive filler and are molded into BP with parallel flow fields. CuG80-20ppi enhances the current density of PEMFC by 0.132 W/cm2 and reduces the ohmic impedance by 5.25%. Therefore, the findings of this study offer valuable insights for the enhancement of composite BP conductivity, while simultaneously ensuring the stability and continuity of the synergistic conductive network. A novel approach is presented to enhance the electrical conductivity of graphite composite bipolar plate (BP) for proton exchange membrane fuel cells (PEMFCs). By embedding metal foam as a supplementary conductive network within the graphite matrix, a synergistic conductive architecture is achieved. This innovation significantly reduces the area specific resistance (ASR) to 7.7 mΩ cm2 and boosts thermal conductivity to 24.76 W/(m·K). The resulting CuG80-20ppi BP, with 80 wt% conductive filler, exhibits improved mechanical strength and conductivity, contributing to a 0.132 W/cm2 increase in PEMFC current density and a 5.25% reduction in ohmic impedance. This work highlights the potential of metal foam integration to enhance BP conductivity and PEMFC performance. • A novel synergistic conductive network is introduced to develop bipolar plates. • This conductive network is constructed from graphite and metal foam. • It can achieve rapid and regular electronic transfer by metal and graphite. • Bipolar plate was optimized for brittleness by incorporating metal foam. • PEMFCs with this novel bipolar plate reduces Ohmic polarization by 5.25%. [ABSTRACT FROM AUTHOR]

Using metal foam as a flow field structure is an attractive route to improve the performance of open-cathode PEMFC. Metal foam has shown great potential in improving the uniformity of reactants, but optimized structure parameters that can more effectively transfer gas and remove excess water are needed. Here we experimentally investigate the effect of metal foam structure parameters on cell performance using polarization curves, power density curves, and electrochemical impedance spectrum (EIS) measurements. By optimizing the pore density, thickness, and compression ratio of the metal foam, the performance of the fuel cell is improved by 49.8%, 42.1%, and 7.3%, respectively. The optimum structure value of metal foam is the pore density of 40 PPI, the thickness of 2.4 mm, and the compression ratio of 4:2.4. In this configuration, the cell could achieve a maximum power density of 0.485 W cm−2. The findings of this work are beneficial for the application of metal foams in open-cathode PEMFC. [ABSTRACT FROM AUTHOR]

Tissue regeneration can be achieved by providing endogenous cells with a biomaterial scaffold that supports their adhesion and proliferation, as well as the synthesis and deposition of an extracellular matrix (ECM). In this work, silk fibroin protein foams were formed by lyophilization to generate tissue engineering scaffolds. Three types of medically relevant nanoparticles (NPs) (iron oxide, gold and silver) were added to this biomaterial to assess the ability of silk foams to be functionalized with these NPs. The structural and mechanical properties of the foams with and without the NPs were suitable for tissue support. The in vitro cytocompatibility of the scaffolds was confirmed according to the ISO 10993 guidelines. The biocompatibility of the scaffolds was investigated by assessing inflammation and endogenous cell colonization in a mouse subcutaneous model These in vivo experiments demonstrated a loss of acute inflammation and the absence of chronic inflammation in the grafted animals. The obtained results show that silk foams are good candidates for supporting soft tissue regeneration with the additional possibility of functionalization with NPs. [ABSTRACT FROM AUTHOR]

The results of the first stage of work aimed at improving a hybrid drive system in which the combustion engine is supported by a pneumatic–hydraulic motor are presented. The purpose of the described work was to show that a heat exchanger with a design adapted to the operating conditions of a pneumatic–hydraulic motor would allow sufficient air heating at the expense of waste heat from the combustion engine, thus increasing the efficiency of the drive system. It was assumed that the key component of the heat exchanger would be copper foam in order to increase the heat exchange surface. A prototype modular heat exchanger was designed and tested. An open-cell copper foam with a porosity of 0.9 and a pore density of 40PPI was placed in the heat exchanger. Experimental and numerical air heating studies were carried out under various heat exchanger operating conditions. The tests were conducted at initial air temperatures of −123 °C, −71 °C, and 22 °C and air pressures of 2.5 × 106 and 7.0 × 106 Pa. The air mass flux was in the range of 3.6–1644 kg/(m2s). It was found that the tested heat exchanger allows a reduction in air consumption in the drive system of 11% to 58% and increases the efficiency of the air expansion system by 16% to 30%. The maximum efficiency of the heat exchanger is 96%. The results of the work carried out will help to improve the pneumatic–hydraulic drive systems of work machines and vehicles. [ABSTRACT FROM AUTHOR]

The synthesis of nanoporous gold (np‐Au) through the conventional method of dealloying a more reactive element from AuTherma alloys has been extensively studied and applied in various fields, particularly catalysis. Herein, a novel approach to creating droplet‐like np‐Au through the selective dissolution of Au–Ge eutectic microstructures is explored. This work reveals that adjusting the undercooling of the eutectic melt during solidification allows for the tuning of pore and ligament sizes. It is demonstrated that this undercooling can be modified, either directly or indirectly, by adjusting either the cooling rate or the heterogeneous nucleation site density of the eutectic melt. The findings, aligned with the model based on classical theory for eutectic solidification, elucidate the connection between the tuning of pore and ligament sizes in the eutectic microstructure and the undercooling of the eutectic melt. Importantly, it is established that this phenomenon is applicable across a variety of compositions, including hypereutectic, eutectic, and hypoeutectic. The ability to regulate pore and ligament size in single crystals of np‐Au droplets offers a novel approach to synthesizing catalytic np‐Au crystals with enhanced mechanical and thermal stability compared to conventional methods. [ABSTRACT FROM AUTHOR]

The development of sustainable cooling technologies and increased concern for recycled materials will affect the reduction of greenhouse gas emissions, which primarily originate from the production industry. In this research paper, a twofold contribution to sustainability is made through the efficient application of a workpiece, obtained by recycling waste in the form of metal chips, and the machining of the obtained workpiece by using alternative cooling techniques comparing them to cutting fluids. Minimum quantity lubrication and cold compressed air cooling were selected as two sustainable, alternative cutting environments. Using Taguchi's L9 orthogonal array, the influence of cutting speed, feed rate and cutting environment on drilling thrust force, built-up edge formation and hole deviation was observed. Using the analysis of variance method, feed rate was identified to have the highest influence on the output parameters (31%), followed by cooling and lubrication techniques (18%) and lastly by cutting speed (5%). Based on the grey relation analysis, optimal controllable factors were identified. This analysis indicated that low cutting speeds and feed rates, coupled with the MQL cutting environment, produced the lowest thrust force, deviation of hole and built-up edge formation. [ABSTRACT FROM AUTHOR]

In this work we describe the use of bimetallic silver‐copper macroporous foams for electrochemical nitrate reduction in acidic conditions (pH 2, 0.1 M NaClO4). By carefully selecting the composition of the electrodeposition bath, we have successfully prepared foams with atomic percentage varying from Ag dominant to Cu dominant. Also, we have succeeded to obtain morphologies that vary between the one specific to pure Ag foam to the one specific to pure Cu foam. We have shown that these foams contain a pure silver phase and also a silver‐copper alloy. The electrochemical active surface area of the foams depends both on the morphology as well as on the atomic composition. These materials were used for the first time as catalysts for nitrate electrochemical reaction (NO3RR). Both liquid and gaseous products were quantified with several analytical techniques. It was shown that bimetallic foams present superior faradaic efficiency (FE) towards liquid products in comparisons with pure silver and copper foams, suggesting a synergetic contribution from both metals. The Ag94Cu6 (AgCu10) foam shows a FE as high as 92 % towards liquid products and the lowest FE (3 %) towards the undesired product, i. e. nitrous acid. Also, this material shows a better stability than pure copper materials in the presence of nitrate in acidic conditions. [ABSTRACT FROM AUTHOR]

In order to reduce the weight of integrated metal foam skeleton under the double constraints of target thermal and structural reliability indexes, this work proposes a three-dimensional (3D) thermal-structural reliability-based topology optimization (RBTO) method, in which the position uncertainty of the multi-structural-thermal loads is considered. The double reliability index constraints in RBTO are decoupled to a sequence of deterministic topology optimization (DTO) and inverse reliability assessment equivalently, based on performance measure approach (PMA). The inverse most probable failure points (IMPP) required by decoupling sequence are searched by the method of moving components. And the sensitivity required in skeleton topology update and IMPP searching are both quickly evaluated by complete analytical expressions using the adjoint method. Results show that 10.12–16.06% additional weight is introduced by RBTO compared to DTO when reliability index increases from 2 to 3, and the rod lattice topology obtained by RBTO is more complex than DTO. Furthermore, the plate-rod hybrid lattice topology is obtained when the load density increases under constant total loads. In addition, the uneven distribution of the multi-structural-thermal loads affects the structural and thermal failure positions significantly. More material is located below the higher loads and 3D tree-like topology is generated by RBTO, which is beneficial for force and heat redistributing and transferring uniformly. The above methods and findings have extensive application prospects in topology design of metal foam with efficient heat transfer and load-bearing capacity. [ABSTRACT FROM AUTHOR]