Aluminum Foam Sandwich Panels Research Articles

Comparison between Stiffened Plate and Steel Aluminum Foam Sandwich Panels

Comparison between Stiffened Plate and Steel Aluminum Foam Sandwich Panels

Preparation of interfacial metallurgically-bonded aluminum foam sandwich panels by graphite coating heat transfer technology

Preparation of interfacial metallurgically-bonded aluminum foam sandwich panels by graphite coating heat transfer technology

Effect of Core Density on the Three-Point Bending Performance of Aluminum Foam Sandwich Panels.

Using the powder-metallurgy rolling method, aluminum foam sandwich (AFS) panels with a metallurgical bond between the foam core and the panel can be produced. In this study, by manipulating the foaming temperature and duration, AFS panels were fabricated with varying core densities and thicknesses, all maintaining a panel thickness close to 1 mm. Through the three-point bending test, this research deeply delved into how core density influences the mechanical behaviors of these AFS panels. It became evident that a rise in core density positively affects the bending strength and failure load of the panels but inversely impacts their total energy absorption efficiency. Differing core densities brought about distinct failure patterns: low-density samples primarily showed panel indentation and core shear failures, whereas those of high density demonstrated panel yield and fractures. Furthermore, the research offers predictions on the initial failure loads for different failure modes and introduces a comprehensively designed failure diagram, laying a foundational theory for the production of AFS panels.

Face sheet defects in plastic forming of aluminum foam sandwich panel: theoretical models, numerical and experimental studies

In this paper, the theoretical models of face wrinkling and dimpling defects occurred in the plastic forming of aluminum foam sandwich panel (AFSP) were constructed and the influences of AFSP parameters on defect were investigated to predict and avoid the surface forming defects. The wrinkling and dimpling behaviors of shaped AFSPs were analyzed at different scales first, and the analytical models of critical wrinkling and dimpling stresses of face sheet for the forming of AFSP were developed using energy method and differential equilibrium equation method respectively. Finite element simulations of curved AFSPs forming were performed using macroscopic and mesoscopic AFSP models, and plastic forming experiments of spherical and saddle-shaped AFSPs with different core relative densities were conducted. The surface profiles of simulated parts and the face wrinkles and dimples in experimental parts indicated that the established theoretical models can predict the occurrence of face sheet defects in curved AFSPs forming accurately. Furthermore, the effects of geometric and material parameters of AFSP on face wrinkling suggested that the seriousness of face wrinkling can be reduced by decreasing the thicknesses of face sheet and core, and the wrinkling can be suppressed when the elastic Poisson's ratio of core is close to 0 and 0.5.

Numerical analysis of face sheet/core debonding failure in the plastic forming of aluminum foam sandwich panel

Numerical analysis of face sheet/core debonding failure in the plastic forming of aluminum foam sandwich panel

Prevention of Oil-Immersed Equipment Rupture Due to Arcing Faults Based on Metal Foam

Oil-immersed power equipment, even when equipped with complete relay protection devices, is still exposed to a risk of rupture and explosion. During an internal arcing fault, such equipment will suffer from overpressure before the fault current is interrupted by circuit breakers. In this letter, a novel approach based on metal foam is proposed for preventing oil-filled equipment rupture. Specifically, density-layered aluminum foam sandwich panels are designed for use as sacrificial claddings to promptly mitigate arc-induced overpressure by absorbing energy through deformation. An actual arcing fault test platform with two limited closed tanks was established, and a multicharacteristic measurement system with pressure sensors and laser displacement sensors was used. Field arcing test results under various fault levels demonstrate the effectiveness of the presented method. Furthermore, the detailed morphology of metal foam, observed by a scanning electron microscope (SEM), indicates that the impact energy was partially absorbed through microscopic deformation. The proposed method provides new insight into fast overpressure mitigation and serves as a potential countermeasure to the challenging problem of equipment rupture.

Application of column buckling theory to steel aluminium foam sandwich panels

In steel structures, a lot of attention is paid to lightweight structures, i.e. reduction of dead load without compromising structural safety, integrity and performance. Thanks to modern steel aluminium foam sandwich panel manufacturing technology a new possibility became available for lightweight structural design. Assessment and understanding of the behaviour of this sandwich panel under in-plane compression or flexure is crucial before its application in steel structures. Column buckling theory is considered and applied to the steel aluminium foam sandwich panel to evaluate its behaviour under in-plane compressive load. In this work, various assumptions are made to generalise Euler’s buckling formula. The generalisation requires modification of the buckling stiffness expression to account for sandwich panel composite properties. The modified analytical expression is verified with finite element simulation employing various material models specific to steel face-plates and aluminium foam as well as various geometric imperfections. Based on this study, it can be concluded that Euler’s buckling formula can be successfully modified and used in the prediction of the load-carrying capacity of a sandwich panel.

Evaluating UHMWPE-stuffed aluminium foam sandwich panels for protecting spacecraft against micrometeoroid and orbital debris impact

Robotic spacecraft shielding for protection against micrometeoroid impact is typically provided by existing structural panels, thermal insulation blankets, or reinforced component containers. Here the performance of an open cell aluminium foam core sandwich panel with intermediate ultra-high molecular weight polyethylene (UHMWPE) stuffing under hypervelocity impact of spherical aluminium projectiles was evaluated. Providing comparable structural and thermal performance as honeycomb sandwich panels, foam core sandwich panels have demonstrated improved impact shielding behaviour in existing studies. The inclusion of UHMWPE stuffing is found, through experimental testing and a comprehensive numerical study, to increase the shielding capability of foam core sandwich panels (40–80% increase in critical projectile diameter) for a modest weight penalty (25%). Compared to conventional aluminium honeycomb sandwich panels with equivalent weight, the improvement in shielding performance is >100%.

Microstructural and mechanical characterisation of reinforced aluminium foam sandwich panels made by one-step squeeze casting method

ABSTRACT In just one step, a squeeze casting process was applied to produce aluminium foam sandwich panels. NaCl particles with mean sizes of 4.75 and 6.35 mm were used as space holders in different proportions. In-situ face sheet manufacturing was conducted through previously placed steel meshes in the mould. The effect of NaCl particle sizes and the proportion of each size on porosity, microstructure, and mechanical properties were investigated. Results showed a decline from 59.8% to 43.8% in the porosity amount of samples with increasing the proportion of larger NaCl particles. Accordingly, an increase in compression yield stress (from 3.2 to 6.1 kgf/mm2) and the absorbed energy were observed. Also, at the elevated densities of the sandwich panel core, the plateau stress was enhanced. The presence of Cu, Ni, Fe, and Si elements leads to the formation of brittle intermetallic compounds in the microstructure of cell walls.

Microstructural characteristics and mechanical properties of 7075 aluminum alloy foam sandwich panels fabricated via integrated forming and foaming

A new integrated forming and foaming method based on friction stir welding (FSW) was proposed for foam sandwich panels. The microstructure characteristics of the precursors and foams with different welding parameters were analyzed using optical microscopy and scanning electron microscope (SEM/EDS). The temperature field and flow field of foam precursor joint in FSW were simulated by Fluent CFD software. The microstructural characteristics of foam precursor after hot forming were analyzed using electron backscattered diffraction (EBSD) and transmission electron microscopy (TEM). The effect of foam precursor deformation on foam evolution was also investigated. The results show that the formability of foam precursor is the same as that of rolled plate. Aluminum foam sandwich panel with homogenous pore structure is prepared at 680 °C for 225 s. After hot forming, the equiaxed recrystallized grain is obtained, and the dislocation and the second phase provide reinforcement. In addition, Rgoss{110}〈110〉 texture component strength increases. When the tensile strain is 0.15, smaller and more uniform pores are produced. Numerical simulations show that the peak temperature gradually decreases with the increase of the distance of the stirring head center. In addition, the temperature on the advancing side (AS) is higher than that on the retreating side (RS). When the tool travel speed is 50 mm/min and rotational speed is 2000 r/min, the maximum material flow velocity at the joint section is 184.2 mm/s and the highest concentration of powder tracing particles is 0.0123 kg/m3. It is proved that the integrated forming and foaming method can solve the problem in manufacturing of complex curved AFS components.

Investigation of the Indentation Resistance of Aluminum Foam Sandwich Panels with Metallurgical Bonding Interfaces under Low-Velocity Impact

The impact resistance of aluminum foam sandwich panels (AFS) with metallurgical bonding interfaces prepared by the powder cladding rolling method was investigated. Low-velocity impact tests were conducted by using a drop-weight impact facility to explore the dynamic mechanical behavior, deformation and damage mechanisms, and energy absorption of AFS with metallurgical bonding interfaces. The effects of variation of impact energy, panel thickness, and specimen density on the energy absorption performance of AFS were quantitatively evaluated by energy absorption indicators. The results indicate that the load-displacement curve illustrates prominent three-stage characteristics when the impact energy is 120 J containing the front panel yielding stage, the foam core's compressive and shear failure stage, and the back panel fracture stage. The impact strength of the sandwich structure increases with increasing panel thickness and specimen density. The AFS with metallurgical bonding interfaces presents favorable energy absorption efficiency under low velocity.

Numerical Simulation Analysis on Surface Quality of Aluminum Foam Sandwich Panel in Plastic Forming

The surface quality of an aluminum foam sandwich panel (AFSP) is very important for its appearance and application. This paper mainly studies the surface quality of AFSP after plastic forming. Combined with three-dimensional (3D) scanning technology, the normal deviation between the experimental AFSP and the target surface was obtained, and the surface quality parameters Sq, Sz and dmax were calculated to evaluate surface quality. The AFSP models with cubic-spherical (CS) and tetrakaidecahedral (TKD) as foam structures were established respectively. A series of numerical simulations of multi-point forming (MPF) were then carried out. Equivalent strain and deformation characteristics of spherical and saddle-shaped AFSP were discussed. The main surface defects produced by AFSP in plastic forming, such as surface wrinkle, the local straight face effect and surface dimpling were analyzed. Finally, MPF experiments were carried out, and it was found that the numerical simulation results were significantly corresponded to the experimental AFSP in terms of the degree and distribution of normal deviation and surface quality evaluation parameters. The TKD model was more consistent with the experimental results than the CS model. Moreover, the results show that the surface quality can be improved by thicker face sheets and smaller core cell sizes.

Experimental and numerical study on ballistic resistance of aluminum foam sandwich panel considering porosity and dimensional effect

Sandwich panels have been widely used in various industries due to their high strength and energy absorption capacity. In this study, the ballistic behavior of a sandwich panel comprised of two aluminum face-sheets and an aluminum foam as the sandwich core is studied. The panels are constructed and subjected to the blunt-nosed projectile. The experimental test consists of a sandwich panel with three different ranges of foam densities and two thicknesses for the panels beside hardened steel projectiles. Then, numerical simulations of the projectile perforation in the panels are conducted that are in good agreement with the experiments. The failure mechanism of the sandwich panels is investigated and the role of foam core is discussed. Failure mechanism and the amount of plug depends on foam density and projectile velocity, such that different failure mechanisms such as plugging, petaling, and dishing occurred for the face-sheets. After that, the ballistic limit velocity (VBL) of sandwich panels was calculated via experiments and finite element simulations. The experiments and simulations showed that increasing the density and thickness of the foam core generally leads to an increase in VBL. Finally, we study the panels with the constant mass and (or) constant height with different foam densities and the effect of foam density is investigated in these cases.

Lower Limb Response to Anti-personnel Landmine Blast Explosions: Injury Assessment and Mitigation Strategies

Injuries in lower extremities due to anti-personnel (AP) landmine blasts have been a major cause of amputation in soldiers. Therefore, it is crucial to understand the mechanism of these injuries for designing advanced personnel protective equipment and superior medical interventions. Various attempts have been made to correlate lower limb cadaveric mine blast test data using surrogate models, but till date, no study has been reported to validate it using numerical methods. In this work, a finite element computational framework was developed for landmine blasts using a biofidelic human body lower limb model for validating in situ tibia forces and injury patterns with PMHS (post mortem human subjects) test data. Based on the reliability of the validated numerical analysis model, efforts were made to elucidate landmine blast physics, blast wave intensity for various mine threats, pathophysiology of lower extremity trauma, and effectiveness of various blast mitigation strategies. Numerical simulations were performed to assess the level of protection offered by a standard army combat boot to the lower limb for an M-14 mine blast. Furthermore, for attenuating the load transmission to the lower limb, aluminum foam sandwich panel has been proposed as a potential shoe insert material due to its high-energy absorption capabilities. Compared to the bare foot scenario, aluminum foam shoe insert in double-core configuration was effective in minimizing severity of M-14 mine blast injuries by reducing the peak tibia force by 34% with a significant delay in time of arrival of the peak. Additionally, the proposed mine protective shoe concept offers 25.2% more reduction in peak tibia force compared to the standard military combat boot for a charge triggered by victim’s heel.

Numerical studies on ballistic limit and cellular dispersion of aluminium foam sandwich panel under hypervelocity impact

This study presents the ballistic limit and cellular dispersion analysis for open cell aluminum foam sandwich panel. Systematic simulation of cell-based open-cell aluminum foam sandwich models is completed and a numerical method for determining ballistic limit is developed. The validity of the simulation technique can be verified by comparing the simulated ballistic limits with the experimental results and this approach can be used to get the ballistic limit of foam materials with arbitrary cellular parameters. It is found that the ballistic limit of foam core sandwich exhibits dispersion characteristics. A comparative analysis of protection performance of aluminum foams with different cellular parameter was carried out, and aluminum foam with smaller cell size has better protection performance under the same relative density condition; in addition, the topology of the foam also had a significant influence on the shielding performance.

Quasi-Static Three-Point Bending Behavior of Aluminum Foam Sandwich with CFRP Face-Sheets

Aluminum foam sandwich panels are excellent structure–function integrated materials. With high specific strength, cushioning energy absorption and sound absorption of aluminum foam material, they overcome the disadvantage of the low strength of single aluminum foam materials. In this paper, the response of aluminum sandwich panels comprising aluminum foam cores and carbon fiber reinforced plastic (CFRP) face-sheets was investigated under quasi-static three-point bending, and the effect of core thickness as well as core density on flexural loads and deformation modes was studied. The experimental results show that increasing the thickness and the density of the core materials can increase the flexural load and bending stiffness in the bending process. The aluminum foam sandwich panels mainly include the following deformation modes in the three-point bending process: indentation, core shear, face-sheet fracture and debonding.

Effect of Cu and Sn additions on the cellular structure of Al–Si–Mg alloys foaming at low temperature (≤600 °C)

Low-temperature foaming is essential for the preparation of aluminum foam sandwich (AFS) using the powder metallurgy method . It ensures that the AFS panels, which are made of aluminum alloy plates, are not melted when the core layer is foamed. Therefore, the core material for the AFS should be an alloy with a low melting temperature, and it exhibits a better cellular structure and improved mechanical properties after foaming. In this study, foaming experiments were performed on Al–Si–Mg alloys at low temperature (≤600 °C) and the effect of Cu and Sn addition to the cellular structure of aluminum foams was analyzed. The results show that alloys composed of Al, Mg and Si benefit from the addition of Sn and Cu by reducing the pore size and foaming temperature, respectively. In particular, the observed cellular structure with uniform pore size could be the result of the needle intermetallic phase Al 2 Cu formation in the cell wall. This intermetallic phase possible stabilized the bubble pores when Cu and Sn were added together. However, cracks were detected in the cell wall. They gradually increased and expanded with increasing Si content in the alloy, thus reducing the quasi-static axial compression strength of the aluminum foam. Furthermore, it was more difficult for the foamable precursor to achieve compaction when the Si content was increased to 10 wt%. The findings of the study show that AlMg4Si6Cu4Sn4 has better cellular structure and mechanical properties after foaming at 600 °C for 15 min. • Uniform pore size can be obtained when Cu and Sn were added in Al–Si–Mg alloys. • Al 2 Cu phase with needle-like structure enhanced the stability of the bubble. • Alloy AlMg4Si6Cu4Sn4 can provided the better cellular structure and properties.

Mechanical response of aluminum foam sandwich structure under impact load

This study investigates the mechanical response of aluminum foam sandwich panels, sandwich cylindrical shells, and sandwich shallow shells under impact loads. First, a finite element model of the sandwich panel was established, and an impact load was applied. The numerical results were compared with theoretical and experimental results to verify the model’s effectiveness. Second, the energy absorption efficiency and overall deformation of sandwich panels, sandwich cylindrical shells, and sandwich shallow shells under the same impact load were studied. The research shows that the energy absorption performance of the sandwich shells is better than that of the sandwich panels, and the overall deformation is less than that of the sandwich panels. The effect of increasing panel thickness on the two types of sandwich shell studies is based on this basis. The conclusions describe that increasing the panel thickness will significantly reduce the structure’s energy absorption efficiency and deformation. Finally, the effect of single-and double-layer structure on the impact resistance of sandwich shells was studied when the total thickness of the sandwich structure was unchanged. The results show that compared with the single-layer structure, the energy absorption efficiency, overall deformation, and contact force between the projectile and structure of the double-layer structure will be reduced.

Three-Point Bending Fatigue Behavior of Aluminum Foam Sandwich Panels with Different Density Core Material

The monotonic and fatigue strength of adhesively bonded aluminum foam sandwich panels with different densities of core aluminum foam (0.3 g/cm3, 0.4 g/cm3, 0.6 g/cm3) were investigated in three-point bending tests to study the flexural fatigue behavior of aluminum foam sandwich panels. The force cycle curves, deflection curves, and hysteretic curves are presented to describe the fatigue process of aluminum foam sandwich panels. Their fatigue fracture modes are completely different, the failure modes of the low-density cores (0.3 g/cm3, 0.4 g/cm3) are debonding and face fatigue, whereas the failure mode of the high-density core (0.6 g/cm3) is face fatigue without debonding. The reason is that high-density aluminum foam cores with lower porosity have a larger joining face, which can also provide higher strength and lead to a longer fatigue life.

Prediction and prevention of fracture defect in plastic forming for aluminum foam sandwich panel

In this study, the predicting and avoiding method of core fracture in plastic forming for aluminum foam sandwich panel (AFSP) were investigated. By observing the macroscopic core cracks and microscopic morphology of the fracture surfaces, the core fracture occurred in plastic forming of AFSP can be confirmed as ductile fracture. Five ductile fracture criteria were introduced for predicting the fracture initiation and detailed simulations on plastic forming of AFSP were performed with a mesoscopic 3D Voronoi AFSP model; besides, multi-point forming experiments of cylindrical, spherical, and saddle-shaped AFSPs were carried out. Normalized value I distributions on the cores using different fracture criteria and core cracks found experimentally indicate that Ko fracture criterion is the most suitable to predict the core cracking during curved AFSPs forming. Moreover, on the basis of the core value I distributions obtained using Ko criterion and the experimental panels in the case of different forming step numbers and core relative densities, it is found that the risk of core fracture can be reduced by adopting multi-step forming and increasing the core relative density.