Honeycomb Thickness Research Articles

Acoustic insulation performance of a honeycomb panel using a transfer matrix method

Honeycomb panels have good mechanical properties and are widely used in various industries because of their high strength-to-weight ratio. However, more research into their acoustic insulation is needed. In this study, a transfer matrix was derived for the acoustic insulation performance prediction of a honeycomb panel. To properly derive the transfer matrix for the model, it should be configured from the relationship between the pressure and particle velocity of the front and rear sections of the honeycomb panel. Each type (fluid, solid, etc.) consisting of a layer was analyzed by a continuous pressure and velocity condition. The numerical results were verified through experimental results using the intensity method. We confirmed that the two results (numerical and experimental result) were in good agreement within approximately 2 dB. Finally, the acoustic insulation performance was studied in relation to the honeycomb thickness, cell size, cell-wall thickness, and cell shape. We observed that smaller cell sizes and thicker cell walls improved the insulation performance. We confirmed that acoustic insulation performance of honeycomb panels can be improved by changing the cell design.

On design of graded honeycomb filler and tubal wall thickness for multiple load cases

Circular tube filled with cellular materials becomes a fairly attractive structural option in energy absorbing devices, such as crash box and front rail in vehicle. This paper introduces a novel configuration, namely double functionally graded (DFG) structure, which comprises of a functionally graded honeycomb filler in a functionally graded thickness (FGT) tube. Based on the validated finite element (FE) models, a comparative study on the DFG tube, single functionally graded (SFG) tube, and traditional uniform honeycomb filled uniform thickness (H-UT) tube were carried out to explore the crashing behaviors of different structures under multiple load cases. It is found that as crushing displacement increases, DFG structure exhibits superior capacity of energy absorption over other configurations and this trend is positively related to the impact angles. In addition, the comparisons of deformation modes and critical crushing angles clearly indicate that the DFG structure is of better and more stable crashing characteristics, being a crashworthy structure. Following the configurational comparison, further parametric studies on the DFG structures were conducted to explore the effects of tubal thickness range and honeycomb thickness range on the crashworthiness. It is found that the tube thickness range is more important to crashworthiness, which provides a basis for structural optimization.

Analytical homogenization for in-plane shear, torsion and transverse shear of honeycomb core with skin and thickness effects

The homogenization of the honeycomb sandwich core enables to obtain an equivalent homogeneous solid and its elastic moduli thus to make numerical modeling very efficient. In the present paper, the in-plane shear, torsion, in plane-shear coupled with torsion and transverse shear are studied with skin effect: the honeycomb core’s deformation is constrained by two fairly rigid skins, so the core’s stiffness is largely increased. An analytic homogenization method, using trigonometric function series is proposed to study the influence of the honeycomb thickness on the elastic properties, and the upper and lower bounds of their equivalent elastic moduli can be given directly by the analytical homogenization models (H-models). A very good agreement has been achieved between numerical results issued from the H-models and 3D FE modeling.

Honeycomb Structures of TiO2-modified Hydroxyapatite Composite for Microbial Filtration Application

Honeycomb structures of TiO2-modified hydroxyapatite composite (HA/TiO2) were fabricated using extrusion technique. The mixture formulations of HA/TiO2 extrusion pastes (S1-S4) were investigated to optimize the process. The filtering effectiveness of the HA/TiO2 honeycombs was evaluated by photocatalytic activity measurement and a bactericidal test. The effects of sintering temperature and honeycomb thickness on photocatalytic and antibacterial activities were additionally studied. The S3 and S4 honeycomb samples, sintered at 650°C, exhibited a similar trend in reducing methylene blue concentration. At 800°C, the S3 honeycomb sample showed a slightly faster reduction in methylene blue concentration compared to the S4 honeycomb. Honeycomb samples of 2 and 5 cm in thickness showed significantly greater photocatalytic activity than that of 1 cm such that methylene blue concentrations rapidly decreased after UV exposure for 24 hours. The S3 and S4 honeycomb samples also exhibited decomposition of both gram-negative E. coli and gram-positive S. aureus. Approximately 50% of gram-positive S. aureus and gramnegative E. coli were decomposed by the honeycombs in the sample-thickness dependent manner after 2 hours of UV exposure. Low survival ratios of bacteria (5% - 10%) were observed after 6 hours of UV exposure and the 2 mm and 5 mm thick honeycomb samples showed the greatest and most similar antibacterial activities.

Honeycomb Structure Design Based on Finite Element Method

The element model of a honeycomb structure is established by using ANSYS software. Then theinfluence of design parameters such as inscribed circle diameter and thicknessof honeycomb on the strength and stiffness of honeycomb structure is explored.Under a given external load condition, the honeycomb structure which satisfies the equivalent stress criteria is got by changing inscribed circle diameter,wall thickness and skin thickness of a standard structure respectively. Comparethe weight of honeycomb structure get from these three methods and generalize a method of honeycomb structure lightweight design which satisfies different requirements.

Scanning and Modeling of Large Thin-Walled Curved Surface Part

The large sandwich structure composed of thin-walled aluminum alloy panels, and variable thickness of honeycomb or Polymethacrylimide (PMI) foam core is usually manufactured by pre-bonded forming process, that is pre-forming panels and sandwich core, and then curing adhesive them to be sandwich structure. Welding process of large thin-walled panel causes the panel surface to be irregular and have greater errors relative to the design surface. Simply CNC machining the sandwich core according to the design surface cannot guarantee an exact match sandwich core consistent with the panels. The actual topography of the panels must be scanned. It is proposed that the use of a new hand-held laser scanner, Handyscan to scan large thin-walled curved surface parts, of Geomagic software to handle the acquired point clouds and construct the surface model.

Design and fabrication of composite smart structures for communication, using structuralresonance of radiated field

In this paper we report the development of a loadbearing outer surface that enhancedantenna performances, and is termed CSS for ‘composite smart structure’. A CSS is amultilayer composite sandwich structure in which antenna layers are embedded. Two typesof CSS are designed. One uses a direct-feeding stacked patch antenna and theother an aperture-coupled patch antenna for electrical performances. The designprocedure is presented including structure design, material selection and design ofantenna elements in order to achieve high electrical and structural performances.Antenna design is processed at a central frequency of 12.2 GHz and a bandwidthover 1 GHz. Honeycomb thickness under the outer facesheet is selected for themost efficient electrical performances. A high gain can be obtained by placing anouter facesheet at a resonance position of the radiated field, which is half thewavelength distance from the spot which the radiation originates from. Measuredelectrical performances show that CSSs have a wide bandwidth over 10% and ahigher gain than the antennas before they are embedded, and no doubt theyhave excellent structural performances due to sandwich effects by compositesand honeycomb cores. With the CSS design concept, antenna efficiency can beimproved with structurally effective materials of high electrical loss. The CSSconcept can be extended to give a useful guide for manufacturers of structural bodypanels as well as antenna designers, promising innovative future communicationtechnology.

Design and Fabrication of Composite Smart Structures with High Electric and Mechanical Performances for Future Mobile Communication

In this paper, we have developed a load-bearing outer skin for antennas, which is termed a composite smart structure (CSS). The CSS is a multilayer composite sandwich structure in which antenna layers are inserted. A direct-feed stacked patch antenna is considered. A design procedure including the structure design, material selection, and design of antenna elements in order to obtain high electric and mechanical performances is presented. An optimized honeycomb thickness is selected for efficient radiation and impedance characteristics. High gain conditions can be obtained by placing the outer facesheet in the resonance position, which is at about a half wavelength distance from the ground plane. The measured electrical performances show that the CSS has a great bandwidth (over 10%) and a higher gain than an antenna without a facesheet and has excellent mechanical performances, owing to the composite laminates and honeycomb cores. The CSS concept can be extended to give a useful guide for manufacturers of structural body panels and for antenna designers.

The use of the impedance method of non-destructive testing on honeycomb structures

The operation of the impedance method of non-destructive inspection on honeycomb structures with carbon fibre reinforced plastic (CFRP) skins has been investigated. The mechanical impedance at positions of skin-core disbonds of different sizes has been compared with that in good areas of panels with 0·5 mm and 1 mm thick skins. It has been shown that when the honeycomb thickness is over 10 mm, the method will detect defects 10 mm in diameter under 0·5 mm thick skins, but that defects 20 mm in diameter are close to the margin of detectability under 1 mm thick skins. However, when the honeycomb thickness is reduced below 10 mm, the reliability of the test is greatly reduced. The tests reported here were carried out with an impedance head, and it has been shown that this transducer is an attractive alternative to the vibrating rod transducer used in commercially available testing instruments, since an absolute value of impedance can readily be obtained, whereas the output of the vibrating rod transducer is a highly non-linear function of impedance so only comparative measurements are produced.

Performance of Honeycomb Solar Collectors : Effects of Thickness, Aspect Ratio and Height of Honeycomb Structure

Experiments have been made to clarify the effects of the thickness, aspect ratio and height of honeycomb structures on the performance of honeycomb solar collectors, and a new model, in which the honeycomb heat capacity and the absorption of the solar irradiation by the honeycomb wall are taken into account, has been proposed to predict the performance. Calculated values by this model agree better with the experimental results than those by a previous model, and the suitable honeycomb thickness, aspect ratio and height are determined by using this model. Furthermore, the performance of the honeycomb collector is compared with those of other types of collectors and the effectiveness of the honeycomb collector is indicated.