Papers by Keyword: Honeycomb

Abstract: There exist some problems in the crash box and anti-collision beam sandwich structure, such as monotone deformation pattern and uneconomical energy absorption performance. In order to raise the deformation capacity and energy absorption performance of sandwich structure, centrosymmetric reentrant honeycomb (CRH) and hexagonal centrosymmetric reentrant honeycomb (HCRH) are proposed based on auxetic reentrant honeycomb (ARH) in this work. Based on HCRH, four kinds of transverse combination structures and two kinds of longitudinal combination structures are obtained. The results of specific energy absorption show that the energy absorption capacity of the angular contact homodromous combination structure (ACOC) is about 3 times that of the other three transverse combination structures. Compared with longitudinal heterodromous combination structure (LHEC), the energy absorption capacity of longitudinal homodromous combination structure (LHOC) is improved by 72.7%.

Abstract: Lightweight panels for indoor constructions are typically made from composite materials with honeycomb and corrugated structures. The reinforcements are used in this study, one is fiberglass and the other is cellulose fiber, which cellulose from recycled paper. Experimental results indicate that the weight of honeycomb paper panel is light, only 13.6% of fiberglass composite and 32.6% of plywood. The presence of honeycomb structure has a significant effect on mechanical behaviors of composite panels. Both flexural and compressive strengths increase by replacing corrugated structure into honeycomb structure. During compression, the compressive strength and modulus of two-layer honeycomb/core panel are higher than those of monolayer honeycomb/core. Particularly, the honeycomb cell-wall thickness has a little effect on the weight, but has an important effect on mechanical properties. These results can be created low cost and lightweight environment-friendly panels by using recycled paper honeycomb structure.

Abstract: This paper deals with a new fabrication technique of carbon fiber-reinforced thermoplastic (CFRTP) honeycomb cores and all-CFRTP honeycomb sandwich panels. The CFRTP core was made of plane woven carbon fiber-reinforced polypropylene prepreg sheets. The stacked CFRTP prepreg sheets were periodically hot-pressed at the node locations, and then expanded to form an all-CFRP honeycomb core. The resultant CFRTP honeycomb cores were glued with the same polypropylene-based plain-woven CFRTP skin plates. The mechanical performance of the all-CFRTP honeycomb sandwich panels was evaluated by flexural tests. The experimental results showed the effectiveness of proposed all-CFRTP sandwich panels.

Abstract: In this paper the influence cell honeycomb geometry on the mechanical behaviour of a composite sandwich plate is analyzed. Three cell geometries (circular, hexagonal and square) are static analysed so that to select the best type of honeycomb that will be used in the manufacturing the sandwich plate core. The main aim is to develop approach models of equivalent orthotropic materials to replace the real model of honeycomb core with their properties so that to quickly calculate the sandwich plate made out of composite when is used a finite element analysis code. Geometry and material properties of the honeycomb are delivered by the material provider. Comparative analysis, by using Finite element analysis is performed for all geometries, in the same boundary conditions. Since in the impact loading of the composite sandwich plate the core is mainly loaded to compression, comparative study of the three cell geometries honeycomb was performed for this type of compressive loading. Since the cell is the basic element of the honeycomb core, the calculus is performed for one unit volume of sandwich, concerning also the part of skins.

Abstract: The axial crushing behavior of commercial metal honeycombs was studied with laying emphasis on the effects of strain rate and geometry on its characteristics as an energy absorber. To investigate the effect of strain rate on the energy absorption capacity, the honeycombs of some metal foil materials were numerically modeled by taking the plastic deformation and failure of adhesively-bonded joint between corrugated sheets and the initial imperfection into consideration. The relationship between the enhancement of mean buckling stress and the strain rate was discussed. Furthermore, A3003 honeycomb model was examined by changing its branch angle from 30° to 180° because the geometrical dispersion will also affect the energy absorption capacity. Typical calculated results under different strain rate and geometric conditions were compared with the corresponding experimental results. It was found that the effect of strain rate on the stress – strain relation of the honeycomb structure is greatly relaxed as compared with that of the material itself. The effects of the boundary condition on the crushing behavior of irregular honeycombs were also discussed.

Abstract: This paper presents a new method based on the split Hopkinson pressure bar (SHPB) to perform impact combined shear-compression test for cellular materials. For this purpose, a bevelled end is cemented to the input bar and the output bar are rotatable to be parallel to the inclined plane of the bevelled end. The system uses the friction between the specimen and the pressure bars to apply the combined shear compression loading on the honeycomb specimen. Such a testing method is validated by the simulation of the whole loading system (split bar + specimen) using ABAQUS code. It shows that this combined shear-compression test provides a quite accurate measurement. Tests on the 5052 aluminium honeycombs are performed. The shear stress-strain behaviour and the compressive behaviour are separated. The experiment result confirms previous testing results and reveals that the shear component will weaken the compressive strength of the honeycomb at high strain rate.

Abstract: The axial crushing behavior of some metal honeycombs, of which materials show different characteristics including the strain rate sensitivity with each other, was studied with varying the branch angle at the node of honeycomb, and the effects of geometry and strain rate on that as an energy absorber were discussed. Honeycomb specimens of different branch angles were made by the corrugation technique, and axial crushing tests were carried out under low-speed and impact loading conditions. Then, the effects of the characteristics of stress – strain relation of the material itself, the branch angle and the strain rate on the stress – strain relation of honeycomb structure and the mean buckling stress were examined. The tendency of deterioration in the plateau load or the mean buckling stress due to the irregularity of branch angle was evaluated with considering the influence of boundary conditions by the aid with the numerical simulation. It was also found that the strain rate dependence of metal honeycomb is greatly relaxed as compared with that of the material itself.

Abstract: In this work the mechanical performance of various sandwich constructions with respect to core material were experimentally evaluated. Sandwich structures were made of glass prepreg and three types of plastic core using vacuum bagging, technology traditionally used for production of parts for transport industry. The aim of this study is to analyze the impact of the core material type and its thickness on bending behavior at different environmental temperatures. Moreover, the effect of core layers compared to one layer core of same thickness was determined. Conducted research provided useful information of bending behavior and showed specific failure modes of individual sandwich constructions.

Abstract: Support structure plays a vital role in Rapid Prototyping system in producing quality and dimensional accurate prints for a product having bridges or overhangs in a Rapid Prototyping product. The paper reports the selection of best support structure for any given model based on build time, material requirement and quality output of the prints. It also discusses the effects of introducing raft layers on a given model. A CAD model in STL (stereo lithography) format is an input to the Rapid Prototyping system. The CAD data is sliced for 3 different support structures by keeping constant printing parameters. Based on the build time, material consumption and part quality obtained, thebest support structure of any given model is experimentally found.

Abstract: Thin-walled honeycombs have been extensively investigated and they are often used as sandwich panels to enhance the energy absorption in many applications including vehicles. In this study, axial compressive tests at three different velocities (3, 30 and 300 mm/min, respectively) by using an MTS machine were conducted with both empty and hybrid aluminium tubes filled with aluminium honeycomb. The aim of this work is to study the contribution of aluminium honeycomb in square hybrid tubes in terms of the deformation mode and energy absorption. Square aluminium tubes made of AA 6060-T5 with two different side lengths, 40 and 50 mm, were used. Two types of honeycombs made of AA 5052 with different cell wall thicknesses were used in this study. The force and displacement of the tubes were recorded during the test. The specific energy absorption (SEA) of honeycomb-filled tubes was compared with the sum of the SEA of an empty tube and honeycomb. It was noticed that the SEA of the hybrid tubes depended on the honeycomb density and the loading velocity within the velocity range studied.