Honeycomb Core Sandwich Panels Research Articles

The analysis and prediction of nonlinear damping characteristics of partially filled all-composite honeycomb-core sandwich panels

In this paper, a comprehensive nonlinear damping prediction model of partially filled all-composite honeycomb-core sandwich panels (PF-ALHCSP) is proposed. Based on integrating high-order shear theory and Hamilton's principle, a theoretical model of the structure is established. Then, the energy equations are deduced by the finite element method. Thus, the nonlinear damping is obtained by the introduced complex modulus method. To validate the overall performance of the material and the accuracy of the theoretical model, the corresponding specimens are fabricated and a self-designed vibration testing platform is established. The results indicate that this material exhibits higher damping capacities compared to traditional metals or composite materials. To further enhance the material optimization, in conjunction with the proposed theoretical model, an investigation on the influence of three variables, filler density, honeycomb cell thickness, and panel thickness, on the structural damping characteristics across three different filling ratios is conducted. The proposed novel composite material and nonlinear damping prediction model can be adjusted according to practical applications for structural parameters, meanwhile effectively reducing material replacement frequency. The theoretical model provides a relatively accurate computational method for studying the nonlinear damping characteristics of partially filled foam honeycomb core sandwich structures, offering valuable insights for research in this field.

Nonlinear vibration characteristics of all-composite honeycomb-core sandwich panel: Theoretical and experimental investigation

Nonlinear vibration characteristics of all-composite honeycomb-core sandwich panel: Theoretical and experimental investigation

Enhancing the performance of honeycomb core sandwich panels through friction stir spot welding strategies and fracture of lap shear specimen

The manufacturing of honeycomb core sandwich structures using friction stir spot welding (FSSW) methods as alternatives for adhesive bonded (AB) structures is examined. AB, FSSW with disk insert (FSSW_D), FSSW_D with AB (FSSW_D_AB) are adopted for the purpose. The performance during the lap shear test and the cohesive zone modeling (CZM) in the finite element (FE) simulation served as the foundation for the comparison. A homogenized core and equivalent cohesive layer were used during the numerical simulations of lap-shearing of all joints. Maximum load-carrying capacity improved significantly when the FSSW_D and FSSW_D_AB were used; the improvement ranged from 592% to 878% over AB joints. Peak load was shown to be around 24% higher in FSSW_D_AB in comparison to FSSW_D joints. The peak load-to-weight ratio of the FSSW_D_AB joints was remarkable (542% to 747%). Stiffness measurements were approximately 0.43 kN/mm for FSSW_D and 0.63 kN/mm for FSSW_D_AB joints. Microstructural analysis revealed finer grains with increased rotation speed and distinct fracture modes, with SEM showing improved ductility. The good agreement between the numerical predictions and the experimental results for all types of joints showed the usefulness of the proposed numerical model. Moreover, FE simulations-based stress analyses of the three joints provided crucial results on normal and shear stress distributions enabling the sandwich structures to be tailor-made for their intended applications.

Analysis of vibrational characteristics of all-composite honeycomb core sandwich panels: theoretical and experimental study

Analysis of vibrational characteristics of all-composite honeycomb core sandwich panels: theoretical and experimental study

Failure analysis of additively manufactured AuxHex and hierarchical honeycomb-core sandwich panels subjected to projectile impact

Honeycomb sandwich panels (HSPs) are extensively employed across various industries owing to their outstanding strength and capacity for energy absorption. Despite their widespread use, the potential of additively manufactured (AM) honeycombs in ballistic protection remains relatively unexplored. This study aims to comprehensively assess the energy absorption performance of two distinct HSP configurations, namely AuxHex and Hierarchical, through high-velocity impact tests spanning velocities ranging from 220 to 270 m/s. The high-velocity impact experiments are conducted using a single-stage pneumatic gun, complemented by simulations executed via Abaqus/Explicit. Our findings reveal that the hierarchical HSP demonstrated a notable 9.6 % enhancement in energy absorption compared to panels featuring an AuxHex honeycomb. Interestingly, the hierarchical panels also necessitated 4.8 % more energy for perforation. In terms of failure mechanisms, both sheets of the HSPs experienced ductile shearing, with the formation of characteristic petal-like structures. Concurrently, the honeycomb core underwent fragmentation on the side facing the projectile, while plugs were ejected from the back sheet. Moreover, our analysis indicates that the residual deflection of the back sheet surpassed that of the striking sheet by 15–20 %. This disparity can be attributed to prolonged contact duration and variations in interaction forces between the sheets. Overall, this investigation provides valuable insights into the energy absorption capabilities of AM honeycomb-based HSPs under high-velocity impact conditions, shedding light on their potential for enhanced ballistic protection in various applications.

Adhesion Systems in New Supports for Mural Paintings: Reversibility Tests

ABSTRACT This article presents a study that investigates the utilization of diverse adhesives and intervention layers for affixing new supports to archaeological mural paintings that cannot be preserved in their original state. Depending on artwork characteristics (materiality, dimensions, state of conservation, location), various materials can be employed for attaching new supports, encompassing adhesives and intervention layers. Evaluating and assessing these materials is vital to ensure the stability, reversibility, and notably, the retreatability of the artwork. To this end, we have evaluated three commonly used adhesives and three intervention layers applied to new mural painting supports. We prepared test samples of mural paintings affixed to a new support structure, utilizing an aluminum honeycomb core sandwich panel (Aerolam). Through bibliographic analysis, we identified frequently used adhesives and intervention layers, and conducted an initial assessment of their behavior. Subsequently, following an aging process, we conducted color evaluations and reversibility tests to comprehensively study these materials and facilitate an objective comparison of their properties.

Research on The Damping Characteristics of Partially Filled All-Composite Honeycomb-Core Sandwich Panel

Research on The Damping Characteristics of Partially Filled All-Composite Honeycomb-Core Sandwich Panel

Characterization of the mechanical energy absorption of honeycomb core sandwich panels filled with shear thickening fluid under low speed impact

Characterization of the mechanical energy absorption of honeycomb core sandwich panels filled with shear thickening fluid under low speed impact

Experimental investigation with FE analysis on flexural strength of hexagonal-shaped honeycomb sandwich panel

In this study, a three-point bending test was carried out to determine the mechanical properties of hexagonal-shaped honeycomb core sandwich panels made of jute yarn with two distinct fiber orientations. A custom-made handloom was used to weave the unidirectional jute mat, and hand-layup with the cold press process was applied to fabricate the hexagonal honeycomb sandwich panel. To explore the effectiveness of different natural fibers for producing honeycomb core sandwich panels, a Finite Element Method (FEM) analysis was performed on different natural fibers with different fiber orientations. The resistance to environmental deterioration of bending properties was also investigated. Overall, this work offers perceptive information about the mechanical characteristics of sandwich panels made of jute honeycomb core and their behavior under various climatic circumstances, which may be relevant in a variety of engineering applications. Finally, it is noteworthy that the mechanical properties of jute fibers are anisotropic, which implies that their strength varies with the direction of loading. Sandwich panels with horizontal fiber orientation of hexagonal honeycomb core withstand a 36% higher bending strength than those with vertical fiber orientation.

Ultrasonically welded eco-friendly sandwich panels based on upcycled thermoplastic core: An eco-mechanical characterisation

A structure's sustainability depends not only on its components, but also on the manufacturing process. The adhesive layer mostly increases the structural weight, reducing weight-specific properties, beside hindering its disassembly and sorting at end-of-life. This study investigates an alternative joining method based on ultrasonic welding for upcycled honeycomb core sandwich panels. Thermoplastic composite skins, reinforced with flax or glass fibres, are connected to an upcycled polyethylene core made from disposed bottle caps and tested under quasi-static and dynamic loads. A life cycle assessment evaluates the environmental benefits of skin/core welding compared with adhesive bonding. Welded panels made from similar skins and cores presented similar to higher weight-specific flexural properties of adhesive-bonded structures (up to 45 % increase), while specific energy absorption under impact is increased by up to 23 % with welded joints. Skin/core welding reduces the panel environmental damage by up to 71 %, with an increment of up to 130 % in its eco-mechanical efficiency.

Response of aluminium honeycomb sandwich panels under combined shock and impact loading: Experimental and numerical investigations

The performance of sandwich structures against individual shock loading and fragment impact loading has been extensively examined, but little is known about their performance in the presence of simultaneous shock and impact loading. Based on a recently developed composite projectile to simulate combined shock and single fragment impact loading, the performance of aluminum honeycomb core sandwich panels (HCSPs) against combined loading is methodically examined. The achieved results reveal that the combined loading exhibits a synergistic effect compared to the single loading, i.e., increased damage of the sandwich panel and enhanced perforation resistance of the sandwich panel. After that, a three-dimensional finite element simulation is performed to explore the underlying mechanism of the synergistic effect. Numerical analysis indicates that the increased damage is a result of perforation-induced reduction of load-carrying capacity of sandwich panel, while the enhanced perforation resistance is the result of deflecting-induced perforation time delay of the perforation process. Finally, the parametric investigation of sandwich geometries such as asymmetric face sheets, core density, and core height is comprehensively conducted. The gained results reveal that both performance and synergistic effect due to combined loading are sensitive to these parameters.

Influence of core topology on blast mitigation application of multi-layered honeycomb core sandwich panel

In the past years, the aluminium honeycomb core sandwich panel has emerged as a promising blast mitigation solution owing to its high energy absorbing capacity under impulsive loading. To enhance its performance against the blast load, it is important to understand the mechanical behaviour of honeycomb core sandwich panel with varying core configurations. The present study investigates the difference in load mitigation behaviour of sandwich panel under blast loading with different honeycomb core topologies. Three types of honeycomb core topology i.e., square, circular, and hexagonal are considered in the present study. The performance of the sandwich panels under blast loading is compared for two criteria i.e., constant mass (or aerial density) and constant cell size. The influence of a multi-layered core along with the intermediate sheets on the blast resistance of sandwich panel is further examined under blast load. It is observed that the multi-layered core and intermediate sheets not only strengthen the sandwich panel but also make it significantly stronger under the blast loading in comparison to the single layer sandwich panel. The role of intermediate sheets in energy dissipation is observed to be insignificant in multi-layered sandwich panel for the parameters considered in this investigation. Further, it is observed that the difference in energy dissipated by front face sheet and back face sheet is increased with increase in the number of layers of cores.

Performance evaluation of composite sandwich structures with additively manufactured aluminum honeycomb cores with increased bonding surface area

AbstractModern aerostructures, including wings and fuselages, increasingly feature sandwich structures due to their high‐energy absorption, low weight, and high flexural stiffness. The face sheet of these sandwich structures are typically thin composite laminates with interior honeycombs made of Nomex or aluminum. Standard cores are structurally efficient, but their design cannot be varied throughout the structure. With additive manufacturing (AM) technology, these core geometries can be altered to meet the design requirements that are not met in standard honeycomb cores. This study used a modified aluminum honeycomb core, with increased surface area on the top and bottom, as the core material in sandwich panels. The modified honeycomb core was produced through the laser powder bed fusion method. The behavior of the modified sandwich composite panels was evaluated through three‐point bend, edgewise compression, and impact tests, and their performance was compared to that of a conventional honeycomb core sandwich panel. The three‐point bend test results indicated that the sandwich structure's ultimate shear strength improved by 12.6% with the modified honeycomb core. Additionally, the displacement at the failure of the structure increased by 11%. The edgewise compression tests showed that the ultimate edgewise compressive strength improved by 19.1% when using the modified core. The impact test results revealed that the peak force increased by 8% and the energy‐absorbing capacity of the sandwich structure increased by 20% with the use of the modified honeycomb core.

Fabrication and Experimental Characteristics of Aluminum Honeycomb Core Sandwich Panel Compared with Nomex Honeycomb Sandwich Panel

Fabrication and Experimental Characteristics of Aluminum Honeycomb Core Sandwich Panel Compared with Nomex Honeycomb Sandwich Panel

Dynamic response of honeycomb cored sandwich panels under high velocity impact: A numerical study

To investigate the impact resisting behavior of honeycomb cored sandwich panel under the bullet attacks, birds and debris, computational analysis of ballistic impact tests have been performed. The honeycomb sandwich panel with SS 316L front and back sheets are used owing to its better impact resistance, high ductility and superior strength for impact resisting applications. The Ballistic test simulations under a wide range of 150 to 800 m/s have been carried out on a SS 316L sandwich panel embedded with Aluminum alloy (AA 3003) honeycomb core using ABAQUS/Explicit software. For this, 12 mm thick sandwich panel and three types of bullet profiles namely conical, hemispherical and blunt are considered. The initial and residual velocity obtained from the simulation is used for computing the dynamic energy absorption of the panels. The significance of projectile velocity, nose shape on overall energy absorption capacity of the panel have been thoroughly investigated. The sandwich panel reportedly absorbed 20.6% and 41.2% higher energy when impacted with blunt projectile than those impacted with hemispherical and conical bullets. Moreover, an almost linear increase in the overall energy absorption capacity of the panel have been observed by increasing the striking sheet thickness.

Sound absorption performance of a micro perforated sandwich panel with honeycomb-hierarchical pore structure core

A new micro perforated sandwich panel with honeycomb-hierarchical pore structure core is designed and prepared in this study. Carbonized cotton with hierarchical pore structure is combined with a micro perforated honeycomb core sandwich panel, which enhances the sound-absorbing performance of the structure without significantly increasing its weight. The experiment showed that pure carbonized cotton filling can improve the average sound absorption coefficient (at 125, 250, 500, 1000, 2000, and 4000 Hz) of the structure from 0.220 to 0.558, and hierarchical pore structure can further improve the average sound absorption coefficient to 0.626. Meanwhile, appropriate theoretical and finite element models are established, with 16.8 % and 8.6 % error respectively based on the predicted average sound absorption coefficient relative to experimental results.

The Dynamic Response of AuxHex and Star-Reentrant Honeycomb Cored Sandwich Panels Subject to Blast Loading

The Dynamic Response of AuxHex and Star-Reentrant Honeycomb Cored Sandwich Panels Subject to Blast Loading

INVESTIGATION IN TO THE STATIC AND DYNAMIC PROPERTIES OF LIGHTWEIGHT STRUCTURAL SANDWICH PANEL

Analytical investigations on the static and dynamic behaviour of light weight structural sandwich panels, which are widely employed in maritime, aircraft, transport, and mechanical/civil engineering applications, are provided. These light, thin-walled structures can vibrate ferociously and are sensitive to even the smallest disturbances. So, the main goal of this work is to improve sandwich panels' static and dynamic behaviour by investigating various face sheets and core materials. Studies on carbon-based polymer nanocomposite are currently generating more interest because to its favourable thermal, electric, magnetic, and structural characteristics. In this study, functionally graded carbon nanotube reinforced polymer composite faces with a 3D graphene foam core and functionally graded carbon nanotube reinforced polymer composite faces were all used to make the sandwich panels. Also, the thermal stresses created in this structure when these panels are exposed to a thermal environment have a significant impact on the dynamic behaviour. Hence, the honeycomb core and polymer composite sandwich panels with reinforced FG-CNT face sheets are examined in various thermal environments. This study examines the properties of forced and free vibration to analyse the dynamic behaviour of a structure

Parametric study of re-entrant honeycomb cored auxetic sandwich panel exposed to blast loading

The protection of military vehicles and critical infrastructure against Improvised Explosive Devices (IED) has become a significant challenge due to frequent terrorist attacks. Sandwich panel with periodic lattice structures as a core material has gained the attention of researchers for blast resistant applications because of their lightweight and high energy absorption capability. Auxetic structures are a class of lattice structures that possess a negative Poisson's ratio (NPR) owing to their topology as a consequence that it undergoes lateral contraction upon compression. Due to this lateral contraction, additional material movement takes place in the impact zone offering more resistance to the localized loading. Near field detonation of explosives imposes localized loading on the structures. The sandwich panel with an auxetic mechanism in the core provides maximum resistance at the point of loading by recruiting more material in the impact zone. The purpose of this study is to numerically investigate the performance of re-entrant honeycomb cored sandwich panels (RHSP) subjected to blast loading. It is followed by a parametric study for optimizing the energy absorption by the core and the force transmitted to the protected structure. Effects on the performance of RHSP for the variation in geometrical parameters, charge mass, and the number of core layers are discussed. Effective Poisson's ratio (EPR) is evaluated for quantifying the lateral contraction in the auxetic structure.

Numerical analysis of low-speed impact response of sandwich panels with bio-inspired diagonal-enhanced square honeycomb core

The diagonal-enhanced square grid configuration inspired by glass sponge has great potential in mechanics, with geometries serving as honeycomb cores for sandwich panels, which can improve the structure’s energy absorption capabilities. Modeling the hexagonal honeycomb core (HHC) sandwich panels, a finite element numerical model for low-speed impact of sandwich panels with high accuracy is proposed, and low-speed impact response of bio-inspired diagonal-enhanced square honeycomb core (BSHC) sandwich panels is studied. The impact response of BSHC sandwich panels, Hexagonal honeycomb core (HHC) sandwich panels and ordinary square honeycomb core (OSHC) sandwich panels were studied with the same relative densities and the same face-sheets. BSHC can lead to significantly enhanced the peak loads and stiffness of the sandwich panels. BSHC sandwich panels not only have excellent energy absorption performance, but also outperform HHC sandwich panels in terms of resistance to impact deformation. BSHC can transfer dynamic loads from the front face-sheet to the back face-sheet efficiently without stress concentration in the core itself. A theoretical analysis of the energy absorption capacity of the BSHCs and HHC were performed to illustrate the energy absorption mechanism. In addition, the peak load and contact energy of BSHC sandwich panels and HHC sandwich panels were theoretically predicted under low-speed impact.