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An innovative multi-layer composite explosion containment vessel (CECV) utilizing a sliding steel plate-aluminum honeycomb-fiber cloth sandwich is put forward to improve the anti-explosion capacity of a conventional single-layer explosion containment vessel (SECV). Firstly, a series of experiments and finite element (FE) simulations of internal explosions are implemented to understand the basic anti-explosion characteristics of a SECV and the rationality of the computational models and methods is verified by the comparison between the experimental results and simulation results. Based on this, the CECV is designed in detail and a variety of FE simulations are carried out to investigate effects of the sandwich structure, the explosive quantity and the laying mode of the fiber cloth on anti-explosion performance and dynamic response of the CECV under internal explosions. Simulation results indicate that the end cover is the critical position for both the SECV and CECV. The maximum pressure of the explosion shock wave and the maximum strain of the CECV can be extremely declined compared to those of the SECV. As a result, the explosive quantity the CECV can sustain is up to 20 times of that the SECV can sustain. Besides, as the explosive quantity increases, the internal pressure of the CECV keeps growing and the plastic deformation and failure of the sandwich structure become more and more severe, yielding plastic strain of the CECV in addition to elastic strain. The results also reveal that the laying angles of the fiber cloth's five layers have an impact on the anti-explosion performance of the CECV. For example, the CECV with fiber cloth layered in 0°/45°/90°/45°/0° mode has the optimal anti-capacity, compared to 0°/0°/0°/0°/0° and 0°/30°/60°/30°/0° modes. Overall, owing to remarkable anti-explosion capacity, this CECV can be regarded as a promising candidate for explosion resistance.

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The face–core debonding of sandwich structures under bending will affect the overall load-bearing capacity. Fiber metal laminate (FML) sandwich composite structures with 3D woven hollow integrated core (3D core) were prepared by vacuum resin infusion method and thermal molding process. The flexural behavior of the structures was experimentally studied by a three-point bending test and investigated by evaluation of specific flexural strength, flexural rigidity, and ductility. Numerical simulation finite element models of structures with different cores under three-point bending were calculated by ABAQUS/Explicit. Results showed that plastic rotation of the "8"-shaped fibers in the 3D core was the main reason for the failure modes of asymmetric densification. FML as the faceplate of the 3D core can significantly improve its flexural strength, rigidity, and ductility. [ABSTRACT FROM AUTHOR]

Aluminum honeycomb core (AHC) is extensively applied in aerospace and transportation industries for its exceptional strength-to-weight ratio. However, the unique structure of AHCs limits their manufacture. In this research, the damage mechanism of AHCs is firstly studied with polycrystalline diamond (PCD) circular saw blades to provide high-quality AHCs for wide-format honeycomb composites. The study meticulously examines the various forms of sawing damage incurred by AHCs at different material removal rates (MRR) and categorizes them accordingly. The results show that burrs of AHCs change from tiny blocks to larger strips with the MRR. At high MRR, the predominant failure modes include collapse, deformation, and hot cracking, while at low MRR, AHCs mainly suffer from cracking, micro-collapse, and oxidation by SEM and EDS analysis. A dynamic analytical model of the sawing angle is proposed based on the sawing trajectory to elucidate vibration scratching and burr formation. The effect of the sawing angle is quantified by the deformation displacement and damage area by the optical measurement. The microscopic reciprocating vibration scratching of AHCs is interpreted by the blade's vibration state. The causes of sawing damage at different MRRs are investigated, indicating that at high MRR, the increased impact of the sawtooth leads to severe vibration scratches, collapses, and strip burrs, whereas, at low MRR, the high-frequency scratching of the sawtooth tends to result in tearing and micro-collapses. A comprehensive description of burr formation is presented by a 3D finite element model. Additionally, the cutting heat is the main cause of the oxidation of sawing surfaces by EDS. This systematic investigation analyzes and explores the sawing damage mechanisms of AHCs, offering in-depth insights for optimizing the sawing process to eliminate surface quality problems and improve the sawing efficiency and accuracy of wide-format AHCs. [Display omitted] • Aluminum honeycomb materials can be manufactured by high-speed sawing for obtaining wide-format honeycomb cores. • The damage mechanisms of aluminum honeycomb cores under different material removal rates were finely analyzed and classified. • A dynamic analytical model of sawing angle based on sawing trajectory is proposed. • The sawing burr formation was fully described by 3D finite element modeling. [ABSTRACT FROM AUTHOR]

The honeycomb sandwich structure has been widely used in the field of aerospace owing to extremely high specific strength and specific rigidity. However, the honeycomb core has anisotropic mechanical characteristics and in-plane weak rigidity, which brings new challenges to the cutting process. In this paper, a three-way equivalent heat conduction model including heat conduction and heat convection in the cutting process was established based on the structural characteristics of the honeycomb core. As for the milling cutter combined with the crushing blade and circular blade specified for aluminum honeycomb core, the moving surface heat source of the crushing blade and the moving line heat source of the circular blade during the milling process were proposed. A prediction model of temperature distribution in the milling of aluminum honeycomb core based on the two heat moving sources was established and verified by the milling experiments. Finally, the temperature distribution law and heat affected area of the honeycomb core during the milling process were studied. It was found that the milling temperature of the honeycomb core maintained a high temperature in the contact area, but fell sharply outside the contact area. Moreover, the heat affected area of the milling heat does not exceed three honeycomb cores. [ABSTRACT FROM AUTHOR]

In the end milling of aluminum honeycomb core, the bottom edge of the cutter and the feed direction of the cutter will have a significant impact on the surface machining quality. If the above two factors are neglected in mechanistic modeling, the surface machining quality will be difficult to improve. In this paper, a mechanistic model considering the bottom edge cutting effect and the anisotropic characteristics of the material is firstly proposed to accurately predict cutting forces. Based on the contact relationship between the bottom edge and the honeycomb wall, a cutting force model of the bottom edge is developed, which includes the geometric characteristics of the bottom edge and the thin-walled edge cutting angle. For anisotropic characteristics of the material, a dynamic variation model of the entry and exit angles in any cutting direction is established on the basis of the structural model of the honeycomb core and cutting edge trajectory. The proposed mechanistic model was validated through a series of milling experiments. The results indicate that this model can be used to predict the cutting force of various parts of the cutter (including bottom and flank edges) and any feed direction. [ABSTRACT FROM AUTHOR]

Tension-shear test was carried out on middle temperature self-brazing aluminum honeycomb cores after high temperature aging by micro mechanical test system, and the microstructure and component of the joints were observed and analyzed using scanning electron microscopy and energy dispersive spectroscopy to study the relationship between brazing seam microstructure, component and high temperature aging properties. Results show that the tensile-shear strength of aluminum honeycomb core joints brazed by 1060 aluminum foil and aluminum composite brazing plate after high temperature aging(200℃/12h, 200℃/24h, 200℃/36h) is similar to that of as-welded joints, and the weak part of the joint is the base metal which is near the brazing joint. The observation and analysis of the aluminum honeycomb core microstructure and component show that the component of Zn, Sn at brazing seam is not much affected and no compound phase formed after high temperature aging; therefore, the main reason for good high temperature aging performance of self-brazing aluminum honeycomb core is that no obvious change of brazing seam microstructure and component occurs.

This paper presents an experimental study of the compressive response of hexagonal honeycomb core from the initial elastic regime to a fully crushed state. To understand the crushing mechanism, aluminum honeycomb core was compressed quasi-statically between rigid platens under displacement control. Honeycomb test specimens made of aluminum alloy with different configurations such as cell size, cell number, core density, and specimen size have been tested. During the crushing, the cells buckle elastically and collapse at a higher stress due to inelastic action, after the cells crush by progressive formation of folds on cell walls. The response densifies when folds consume the whole panel height. The peak load recorded during tests corresponded to the buckling of honeycomb cells. The different specimens showed similar load/displacement curves, and the differences observed were only due to the influence of the core density, number of cells, and specimens size on mechanical behavior of hexagonal honeycomb core which has a very important role in the energy absorption capacity. In addition, this study allowed us to build a database of experimental tests for various configurations and allowed us to know the precise energy absorption capacity. [ABSTRACT FROM AUTHOR]

Abstract In this experimental study, high velocity impact behavior of honeycomb sandwich structures with Al6061/B 4 C FGM face plates subjected to 0.30 caliber fragment simulating projectile impact was investigated via a single-stage gas gun. The material composition of the FGM face plates was represented according to a power-law variation through the plate thickness. The specimens were produced for six types of face plates, Al6061 and five different FGM face plates from metal-rich to ceramic-rich composition. Impact test results of the specimens were evaluated in terms of their damage and deformation mechanisms. The test results stated that the material composition variation of the FGM face plates was a highly influential parameter for damage modes, energy absorbing capacity, and impact resistance of the sandwich structure, and the honeycomb core contributed to the energy absorbing capacity of the sandwich structure with the plastic buckling of the cell walls and lateral crushing deformations. [ABSTRACT FROM AUTHOR]

[Display omitted] • A new model for honeycomb cutting is derived based on the mechanical model and analytical analysis. • The interaction state between cutter and honeycomb wall is revealed by modeling the material structure. • The function of entry and exit angles are developed to describe various types of thin-walled edges. • The analytical results are verified by comparison with the experimental data. 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%. [ABSTRACT FROM AUTHOR]

Aluminum honeycomb core is one of the most sought after material for the sandwich panel for light weight applications. While the aluminum face sheet is isotropic, the honeycomb core assumes orthotropic characteristics due to its configuration and strenuous load transfer paths. It is now well established that stiffness, dynamic, and low velocity impact response of the honeycomb core sandwich panel are critically dependent on the elastic constants of the core. An attempt is made to determine the elastic constants of orthotropic core through finite element approach simulating the load transfer and fixity boundary conditions likely to be prevalent in the unit cell of the honeycomb core. The cell wall thickness and the cell shape dictated by plastic bending limitations have also been simulated to determine their influence on the elastic constants. Further, the cell wall thickness and the bend radius have been varied and their influence on orthotropic elastic constants has been determined. The results of the study have been compared with analytical solutions proposed by researchers. The finite element procedure evolved is a simple, efficient, and quick solution methodology to accurately predict elastic constants of honeycomb core depicting the exact cell size and shape. [ABSTRACT FROM AUTHOR]