Aluminum Honeycomb Core Research Articles

Hybrid Shielding for Hypervelocity Impact of Orbital Debris on Unmanned Spacecraft

The passive shielding of space craft structures is critical due to the increase in demand for lightweight protection, which is required to counter the damaging effects of micro-meteoroid orbital debris (MMOD) on unmanned spacecraft, which have steeply increased in recent years. Research on hypervelocity impact (HVI) led to the development of shield configurations such as the conventional Whipple shield, which consists of two plates separated by a stand-off distance to allow for the fragmentation and dispersion of the debris from the impact. Variations in the Whipple shield have been proposed, where additional layers are included for increased energy dissipation efficiency. In this work, the authors develop, validate and test a numerical model of an orthogonally loaded hybrid Whipple shield, incorporating an aluminium honeycomb core, orientated with hexagonal tubes perpendicular to the direction of proposed debris travel, to mitigate the well-known channelling effect. The debris threat is an A2024-T3 projectile, impacting the structure at a velocity of 6.5 km/s. The proposed model is validated with experimental observations of the debris spread at half-angle and the efficiency of the proposed topology is assessed against a conventional two-plate A2024-T3 shield. The honeycomb core cell density, its position relative to the point of impact, the thickness of the honeycomb shell, and the material of the honeycomb are thoroughly analysed. A hybrid honeycomb structure concept is proposed, which provides a highly efficient alternative to a standard Whipple shield design, without significantly compromising the weight of the structure. The obtained results clearly show that the hybrid Whipple shield exhibits significantly increased the kinetic energy dissipation of the debris from the impactor and shield front plate, with an increase in the dissipated kinetic energy that can reach 86.8% relative to the conventional shield.

Instantaneous cutting force model considering the material structural characteristics and dynamic variations in the entry and exit angles during end milling of the aluminum honeycomb core

The structural characteristics of the material and dynamic changes in the entry and exit angles are of great significance for the accurate prediction of the cutting force during milling of the aluminum honeycomb core. In this study, an instantaneous cutting force prediction model for the aluminum honeycomb core that comprehensively considers the porous structural characteristics of the material and dynamic changes in the entry and exit angles during the machining process was developed. A unified structural model for an aluminum honeycomb core with a regular hexagonal cell structure and excellent mechanical property was established. Based on the structural characteristics of the aluminum honeycomb core, three types of thin-walled edges were considered, and the dynamic changes in their entry and exit angles were investigated by considering the cutter radius, cutting width, honeycomb core wall thickness, and relative position between the cutter and thin-walled edge. An orthogonal-to-oblique cutting transformation approach that can effectively reflect the cutting characteristics of the material was adopted to calibrate the cutting force coefficients in which cutting experiments using different cutter geometries and parameters were conducted. The aluminum honeycomb core was fixed using green, high-efficiency cryogenic liquid nitrogen. To verify the reliability of the proposed model, a series of milling experiments were carried out and the experimental and simulation results were compared. It was found that the simulated cutting force is highly consistent with the experimental result. The proposed model can accurately predict the peak values of the cutting force in the x, y, and z directions, with an average prediction error of less than 10%.

Failure behavior of sandwich beams with glass fiber-reinforced epoxy/aluminum laminates face-sheets and aluminum honeycomb core under three-point bending

The failure behavior and energy absorption performance of aluminum honeycomb sandwich beams with glass fiber-reinforced epoxy/aluminum laminates (GLARE) face-sheets under three-point bending are experimentally and numerically studied. The experimental specimens consists of 2/1 (2 aluminum sheets and 1 glass fiber/epoxy laminates) GLARE and aluminum honeycomb core. The effects of core height (8 mm, 20 mm, 40 mm) and indenter shape (cylindrical indenter and flat indenter) on bending failure behavior are tested in quasi-static three-point bending. Six sandwich beam specimens (300 mm-long and 40 mm-wide) were prepared. The initial failure modes of GLARE sandwich beams are observed, i.e. core shear and indentation. The numerical model considering geometric nonlinearity is established by ABAQUS/Explicit software and its effectiveness is verified by the experimental results of specimens with the same size and loading conditions. The effects of geometric and material parameters on the load-carrying capacity and energy absorption of the GLARE sandwich beams are discussed in details. It is shown that increasing the face-sheet thickness, honeycomb wall-thickness, the ratio of the core height to span length and the elasticity effect of metal materials or reducing the side length of the honeycomb cell can improve the load-carrying capacity and energy absorption of GLARE sandwich beams. The work can provide the guidance for the design of the GLARE sandwich structure with honeycomb core.

A facile and reliable approach to enhance the energy storage performance of 1-Decanol for sustainable and energy-efficient cold storage system

The energy efficiency of an ice-based cold storage system (CSS) is intensively affected by its supercooling nature, low phase change temperature and probable nucleation behavior. As a result of this, the chiller should be operated at a lower evaporator temperature to freeze the water as well as to achieve better heat transfer performance. By virtue of this, the coefficient of performance of the chiller is significantly reduced, which in turn results in ineffective utilisation of energy sources for CSS. To tackle this issue, the water should be replaced with a suitable alternate PCM, which has no supercooling and high phase change temperature. In this study, 1-Decanol has been identified as a prospective replacement for water, and its energy storage performance has been enhanced in a practically feasible and economically viable way using an aluminium honeycomb core (AHCC). The effect of different sizes (small, medium and large) of AHCC on the charging performance of 1-Decanol has been explored in the spherical capsule (S.C). Further, the effect of adding AHCC, the diameter of S.C and wall temperature on the energy storage performance of 1-Decanol have been explored. It is found that the medium size AHCC is an optimal size for charging and discharging. Also, −3 °C is an optimal wall temperature for charging. The lower diameter S.C delivered better charging and discharging performance for a specified storage volume. For the 1-Decanol + AHCC based CSS, the effective utilisation ratio is remarkably high (10.49 to 14.96), and the reduction in energy storage capacity is only minimal (1.24% to 1.81%). Experimental results prove that upon adding medium size AHCC, the average enhancement in charging rate is 150.32%. Further, the average reduction in charging time is 60.09%, which signifies that chiller operating time and carbon emission can be reduced by 60.09%. The above results prove that the employment of AHCC to enhance the charging performance of 1-Decanol would lay the foundation for establishing energy-efficient and sustainable CSS.

Determining parameters of sandwich composite panels for earth remote sensing satellite bus

The paper discusses the feasibility of replacing conventional sandwich panel with carbon fiber skins and aluminum honeycomb core in the structure of an Earth remote sensing satellite bus. Thermal loading conditions for sun-synchronous orbit were considered and math simulations were run for stress-strain behavior of a satellite bus element built of the proposed versions of sandwich composite panels. Simulations results might be of interest for design of ultra-lightweight structures of the satellite bus, solar arrays and antenna reflector. Key words: Earth remote sensing spacecraft, Sun-synchronous orbit, math simulations, polymer composite materials.

Study of matrix modifications by nano-clay on the mechanical properties of AA3003 honeycomb sandwich panels

Face/core debonding is one of the crucial problems of composite sandwich panels which consist of AA3003 aluminium honeycomb and glass fiber reinforced polymer face sheets. The panel was prepared by a hand-lay process at different nano-clay weight addition of 0%, 2%, 4%, and 6% with the objective of improving face/core adhesion. Interface bonding between face sheets and honeycomb core composite sandwiches and their mechanical behavior were investigated under in-plane compression and bending load. The flexural property of sandwich panels due to the influence of variation in strain rate is further determined. The morphologies of fractured samples were investigated by scanning electron microscope (SEM). The results revealed a significant improvement in mechanical characteristics when nano-clay was loaded to the composites at a concentration from 2 to 4 wt%, and the in-plane compression and flexural failure load values increased by 45% and 81%, respectively, when compared to a pristine sample. It was observed that increasing strain rate led to the increase in failure load of the sandwich panel. SEM images of fractured surfaces showed residual aluminium honeycomb was present in the face sheet, which indicates better adhesion between aluminium honeycomb core and face sheets.

Damping contribution of the glass reinforced aluminum laminates epoxy to the aluminum based-sandwich structures

Despite many potential use of aluminum sandwiches in advanced industries, their poor performance in damping and sound transmission demands new challenges for improvement. This study aims to improve dynamic performance of these sandwiches using hybrid face sheets in the form of Glass Laminate Aluminum Reinforced Epoxy (GLARE). While parameters related to the aluminum honeycomb core were kept constant, the effects of different fiber orientations of the GLARE on the fundamental natural frequency, equivalent flexural modulus, and especially damping values were investigated. The dynamic values of the structures have been measured using a specially designed non-contact vibrating beam test with free-free end conditions. A comparison of the sandwiches with the GLARE and with bare aluminum face sheets has also been made to find out their differences in the dynamic performance. The experimental results were compared to those from a numerical modal analysis via the Altair Hyperworks 2019 Software. The results have shown that the maximum equivalent modulus is obtained from the specimen with the unidirectional (0°) fibers, and the minimum value is from that with the 90° ones. But the opposite is the case if their Specific Damping Capacity values are compared. The values of the specimens with 0°/90° and 0°/45° fibers are on moderate levels. Considerable increments between 54% and 172% are found in the damping values of the specimens with GLAREs, compared to those with the bare aluminum face sheets. The results from the experimental and numerical works have been found in a good agreement.

Manufacturing and characterisation of a new thermal pre-stressed carbon fibre-reinforced lattice core for sandwich panels

Development of high-performance sandwich structures is particularly attractive for aerospace applications, where novel lighter materials and structures are object of extensive research. This work is focused on the design of a new high-performance Carbon FRP core as alternative to traditional periodic prismatic ones. The innovative core is designed as a 2D close-packing pattern of circular cells and manufactured by connecting pre-preg corrugated laminates in specific locations. The corrugated laminates are layered following an asymmetric sequence in order to generate residual thermal stresses within the core to enhance energy absorption and compressive properties. The distribution of the residual thermal stress within the core was numerically studied with a finite element model of the unit cell, in order to prove the positive contribution of the asymmetric layup on the mechanical properties and study the failure mechanisms of the unit-cell. Composite core samples were manufactured, and their mechanical properties were experimentally evaluated through compression, both out-of-plane and in-plane, and beam flexure tests. Results were compared in terms of specific properties with traditional aluminium honeycomb core, showing large increments of specific compressive strength (+84.6%), in-plane compressive modulus (over +500%), Specific Energy Absorption (+145%) and shear (>20%). The FEM model was validated against experimental compressive results, showing an error below 10%. The results show that the core is suitable for applications in novel high-performance sandwich structures, leading to numerous advantages in comparison to traditional cores, such as higher specific properties, manufacturability of complex sandwich structures and higher adhesion and compatibility with CFRP skins.

Damage assessment of sandwich structures with Al/SiC functionally graded plasma sprayed faceplates subjected to single and repeated impacts

Structural response, energy absorption, and damage mechanisms of honeycomb sandwich structures (HSS) subjected to single and repeated impacts were investigated in present work. The HSS was constructed with an Al/SiC functionally graded plasma sprayed (FGPS) face plate and aluminium honeycomb core. Experiments were carried out using single-stage gas gun to study the effect of repeated impacts at a constant impact energy of 260 J. A numerical model based on the piecewise plasticity and Johnson-Cook material models was developed to study the effects of impact energy ranging from 164 J to 754 J. The experimental and numerical results were correlated for the case of 260 J impact, and they show good agreement with regard to dent width, central deflection, core compression, and damage area. The energy absorption of the top faceplate rises as the impact energy increases owing to the local indentation, whereas the energy absorption of the core decreases. Two failure modes were observed in the FGPS coating, namely tensile delamination and shear delamination. The accumulation of damage in the coating of FGPS plate and FGPS HSS were mapped through image processing. Thus the current research provides a detailed understanding of the damage behaviour of HSS under various impact scenarios.

Análisis de placas sándwich con pieles de material compuesto sometidas a impacto oblicuo de alta velocidad

In this work, the oblique impact response of sandwich structures, with carbon/epoxy face-sheets and aluminium honeycomb core, is analysed by implementing a 3D numerical model in Abaqus/Explicit finite element code. The numerical model was validated with data taken from the scientific literature for a normal impact, and numerical results showed good correlation with experimental data. The validated model was used to study the variation of the ballistic limit and the residual velocity with the impact angle of the projectile.  In order to determine the contribution of the core in the impact process, another finite element model was developed, corresponding to that of a laminated spaced plates a distance equivalent to the thickness of the composite sandwich core. It was found that both ballistic limit values ​​and residual velocity are affected by the presence of the core in the sandwich plates and by the obliquity of the impact angle.

Dynamic responses and energy absorption of sandwich panel with aluminium honeycomb core under ice wedge impact

In this paper, the dynamic responses and energy absorption characteristics of aluminium honeycomb sandwich panels (AHSPs) under ice wedge impact are numerically and experimentally investigated. A three-dimensional nonlinear finite element model of AHSP under ice impact is established based on a concrete constitutive ice model in the commercial package ANSYS/LS-DYNA. The impact force-displacement curves and energy absorption properties as well as the crushing process of ice wedge are numerically achieved. In addition, the ice wedge impact tests of AHSPs were conducted by using a horizontal impact experimental apparatus. Furthermore, the effects of impact parameters and structural parameters on the dynamic responses and energy absorption are performed. Results show that the numerical results of ice wedge-AHSP impact dynamic responses are consistent well with the experimental results. The permanent deformation profiles of face sheets are approximately axisymmetric about the vertical and horizontal centerline. The ice impact energy is mainly converted into the plastic deformation energy of AHSP and rebound kinetic energy of ice wedge as well as the fracture energy of ice wedge. With the increase of the impact energy and thickness of face sheets, the energy dissipation ratio of ice broken increases dramatically and the energy dissipation by ice wedge makes an increasingly contribution to the impact energy absorption.

Fabrication of aluminum honeycomb cored carbon fabric/epoxy composite sandwich structures via vacuum assisted resin infusion technique

AbstractA detailed step‐by‐step fabrication procedural document of thin‐walled aluminum honeycomb sandwich composite structures, panels, and specimens using vacuum assisted resin infusion process was delivered in this paper. By and large, honeycomb sandwich structures are made by keeping the honeycomb core in between two face sheets, which are glued with the help of adhesives. In the present fabrication process, aluminum honeycomb core was glued in between the carbon fabric reinforced epoxy composite face sheets through vacuum assisted resin infusion technique. The present paper is aimed at fabricating two configurations of honeycomb sandwich composite panels namely, without considering any filler material inside the honeycomb cell, with considering the filler material inside the honeycomb cell. Plastic pellets made up of poly carbonate were considered as filler material for stiffening the aluminum honeycomb sandwich composite panels.

DETERMINATION OF MECHANICAL PROPERTIES OF COMPOSITE SANDWICH PANEL WITH ALUMINIUM HONEYCOMB CORE

This paper deal with comparison of mechanical properties of composite sandwich panel with aluminium honeycomb core which is determined by experimental measurement, analytic calculation and numerical simulation. The goal was to compared four composite sandwich panels. The composite sandwich panels were made of two different aluminium honeycomb cores with density 32 and 72 kg.m-3 and two different layup of skin with 4 and 5 layers. The comparison was performed on a three-point bend test with support span 400 mm. This paper confirms the possibility of a very precise design of a composite sandwich panel with an aluminium honeycomb core using analytical calculation and numerical simulation.

Influence of geometric parameters on free vibration behavior of an aluminum honeycomb core sandwich beam using experimentally validated finite element models

The hexagonal honeycomb core sandwich panels used in the satellite structure are subjected to severe vibration during launch. Therefore, the amounts of natural frequencies of these panels are of great importance for design engineers. Three-dimensional finite element modeling of the core considering all geometric parameters (i.e., a high-fidelity model) to achieve accurate results is not cost-effective. The honeycomb core is traditionally equivalent to a homogenized continuum core (i.e., a low-fidelity model) using simple analytical relations with ignoring the adhesive layer at the double cell-walls and radius of inclined cell-wall curvature. In this study, analytical formulations are first presented for the prediction of the equivalent elastic properties of a hexagonal aluminum honeycomb with considering all geometric parameters including adhesive layer thickness, cell-wall thickness, inclined cell-wall length, radius of inclined cell-wall curvature at the intersection, internal cell-wall angle, and honeycomb height. Then, two aluminum honeycomb core sandwich beams with free-free boundary conditions are modeled and analyzed in Abaqus finite element software, one with 3D high-fidelity core and the other with 3D low-fidelity core. In order to validate the results of the equivalent model, the modal analysis test was performed and the experimental natural frequencies were compared. The obtained results show a good agreement between the 3D low-fidelity and high-fidelity finite element models and experimental results. In addition, the influence of the above-mentioned geometric parameters has been investigated on the natural frequencies of a sandwich beam. [Formula: see text]

Configuration optimization of the honeycomb core in the latent heat thermal energy storage of a solar air heater: Experimental and numerical study

This article investigates the effect of embedding the aluminum honeycomb structure in latent heat thermal energy storage (LHTES) of a solar air heater (SAH) and proposes an optimal arrangement of the partial honeycomb core. The effect of placing an aluminum honeycomb core in the LHTES of a solar air heater in mass flow rates of 0.02 and 0.04 kg/s is investigated numerically. A finite volume method is utilized to solve the governing equations in the 3D domain. The phase change material's (PCM's) solid–liquid interface and temperature field are solved by the enthalpy-porosity method and validated by experimental results. The honeycomb core embedded in paraffin is simulated as a composite material with effective thermal properties and local thermal equilibrium condition. The effect of the insertion of eight different honeycomb configurations in the latent heat storage is examined, and an optimized arrangement of the honeycomb structure is proposed. The experimental setup of the SAH is designed based on the optimized honeycomb configuration and is built in the laboratory. The performance of SAH and LHTES is analyzed for three cases: (1) in the presence of a honeycomb (case 8), (2) in the absence of a honeycomb (case 1), and (3) the optimized honeycomb structure (case 2). The results indicate that the honeycomb core in LHTES reduces the melting time by over 35%. Case 2 LHTES (honeycomb in 1/3 bottom portion) is suggested as the best honeycomb structure compared with other configurations. This structure is found to increase the energy storage rate by about 50%, while the energy storage density reduces by 2%. As the thermal performance of the SAH grows after the sunset, the warm air production lasts for a longer duration.

Vibro-acoustical responses of a sandwich panel consist of aluminum honeycomb core and fabric-reinforced graphite facings

This research presents a numerical study on vibro-acoustic and sound transmission loss behavior of an aluminum honeycomb core sandwich panel with fabric-reinforced graphite (FRG) composite face sheets. The sandwich theory, which assumes the honeycomb core as an orthotropic structural layer, is applied to investigate the free and forced vibration behavior of the panel. The radiated sound power from the panel is quantified by Rayleigh integral method, and the random diffuse field as an incident sound source is derived based on finite element method with the employment of ACTRAN. A validation between the simulated results and the experimental data published is carried out to demonstrate the accuracy and reliability of the present approach. The comparison between different materials of honeycomb sandwich structures illustrates the advantages of the fabric-reinforced graphite honeycomb sandwich structure over the other types of sandwich structures considered. The effects of different boundary conditions and honeycomb structural geometry properties on the acoustical performance of the stiffness of the FRG panel are also investigated. The approach of the present research provides useful guidance for evaluating and selecting the other honeycomb sandwich panels when the vibratory and acoustic behaviors of the panels are considered.

Carbon fiber reinforced plastics with aluminum honeycomb core design methodology for space and surface mining applications

The space mining market is expected to grow in the future with water, gold, and platinum as just a few of the resources that could be accessible in the Moon or in near-Earth asteroids. To achieve this mining capability, sandwich composites offer an optimum structure for space mining vehicles due to their relatively high strength and stiffness compared to their weight. The challenge of designing such structures is often hampered by the lack of design approaches for practicing engineers in the mining industry usually lacking the composite material expertise or access to significant test capabilities. Expanding the use of sandwich composite materials into this industry requires selection charts that fully define the material system for a design engineer. Currently there is no methodology that systematically allows a design engineer to define a material system that uses carbon fiber reinforced plastics with aluminum honeycomb cores. The purpose of this paper is to introduce novel selection charts that allow an engineer to define the number of plies, stacking sequence, core thickness, and core density of a sandwich composite based off the moment carrying capacity. An example implementation of this approach is conducted using a carbon-fiber/epoxy with an aluminum alloy 5052 core. The selection charts developed with this approach are than validated with experimental analysis in accordance with ASTM D7249 (Standard Test Method for Facing Properties of Sandwich Construction by Long Beam Flexure). Experimental results show strong correlation with the selection charts by predicting the available moment and the mode of failure. Such selection charts will help facilitate wider use of these materials into industries that do not currently use them. Additionally, a novel numerical modeling approach for thick section sandwich composites using 3D finite elements is introduced. This approach shows how sandwich composite facesheets can be modeled with standard 3D elements instead of elements that support layers. Such an approach allows access to a wider variety of elements and is conducive to rapid design iterations when topological changes are occurring such as in a research and development environment. It is shown that numerical results correlate well with experimental data when using a linear-elastic isotropic core model with bilinear isotropic plasticity.

Mechanical response and strength characteristics of aluminum honeycomb sandwich panels for infrastructure engineering

The use of aluminium sandwich panels has been increased in a certain number of engineering applications from infrastructure systems and transportation to aircraft and naval engineering. Due to their structural efficiency these materials are ideal for applications where ratio of strength to weight is of crucial importance. In the current study the investigation of the strength characteristics of aluminium sandwich panels with aluminium honeycomb core and different types of skins is performed using both analytical models and experimental procedures. A series of strength tests such as tension, shear, three point bending and double cantilever beam were conducted on aluminium honeycomb-cored sandwich panel specimens with five different skins in order to examine the mode of failure and the mechanical behaviour of the structural elements. The experimental findings are compared to theoretical values while an attempt for the explanation of the mechanisms leading to failure such as buckling, delamination or debonding between core and skins is performed. The results occurring from the study are very useful for the enhancement of the mechanical behaviour of sandwich constructions, thus more intensive work must be carried out in order to understand the physical mechanisms leading to strength characteristics of sandwich panels.

The self-healing sandwich panel: Production of epoxy based self-healing capsules, self-healable sandwich panel development, and experimental measurement of self-healing performance

In this study, macro-capsules were developed by encapsulating epoxy and hardener agents for macro-level structural healing. Obtained macro-capsules were placed into an aluminum honeycomb core to obtain self-healable sandwich structures. In principle, the aim was to self-repair damaged sandwich structures by breaking the macro-capsules with the resulting leak of healing agents into the cells of the core. The developed sandwich structure was subjected to repetitive quasi-static compression and high strain rate compression impact tests. According to the experimental results, the sandwich structure gained a very effective self-healing facility and maintained this property under multiple repetitive loadings. In addition, the energy absorption capacity of honeycomb aluminum sandwich structures was increased by approximately 80% under both quasi-static and high-speed impact loads.

The effect of carbon nanotubes modified polyurethane adhesive on the impact behavior of sandwich structures

AbstractSandwich panels with aluminum honeycomb cores have emerged as an essential class of lightweight building materials in a wide variety of structural engineering areas, including marine, railway, aerospace, and automotive structures. Although sandwich structures offer remarkable mechanical properties, for instance, high specific strength and stiffness, these structures are open to the damage created by the low‐velocity impact. This study investigates the dynamic behavior of aluminum honeycomb sandwich panels with different core cell sizes based on neat and multi‐walled carbon nanotube (MWCNT) reinforced polyurethane (PU) adhesives that are aimed. The enhancement in impact performance of honeycomb sandwich structures obtained by the inclusion of MWCNTs in the PU adhesive is investigated. The effect of the MWCNT reinforcements on square sandwich panels at 50 J energy level is examined using an instrumented drop tower test setup. After acquiring load–time histories, the numerical integration method is implemented to obtain load–deflection and energy–time curves. Also, energy balance modeling (EBM) is utilized to characterize the effectualness of MWCNT reinforcement to PU adhesive on the impact behavior of sandwich panels. Theoretical EBM is confirmed that absorbed energy in the shear and bending deflections increased as the percentage of MWCNT‐added PU adhesive increases. Understanding the damage event implicated in absorbing and dissipating the impact energy is determined and compared for panels with different cell sizes, including nanoparticles, using the macroscopic optical images and microscopic scanning electron microscopy images of sandwich panels.