Papers by Keyword: Honeycomb

Abstract: All components of a huge machine tool need to work together perfectly to ensure not only a quality finished product, but operator safety. One of those many components is the material of support panels and moving parts in the machine construction. Mechanical structure of the machine, in most cases does not reach the technical level of regulatory techniques or electric drives and potential increase in dynamics, speed or accuracy of the machines remain unused. Used classic construction materials, steel or light alloy then zoom in to limit their physical capabilities. Designers have machine tools or robots are forced to solve the formidable task in the form of reducing the weight of the moving parts while maintaining or even increasing stiffness with respect to the thermal stability or damping. Laminates are for construction of production machines, robots and manipulators of crucial importance. One big advantage is the high rigidity while maintaining low specific weight. The presented paper is focused on the investigation of composite sandwich construction produced by prepreg technology, which is the suitable production choose for construction of machine tools parts. First of all, the production of sandwich structures with cork core, honeycomb core and foam cores are compared and described. In terms of the production process it is a method very friendly to the environment, since there are no leaks styrene vapours into the air. Since it is important from the perspective of a manufacturer of transport or machine industry manufactured from environmentally friendly materials, so naturally from materials that are from the perspective of safety of passengers (operators of machine tools or robots) at a high level, when any accident was lowest possible hazard due to fire (burn materials used) and terms of the strength of composite materials. This is one of the major scientific articles and to find the most ideal surveyed composite sandwich materials that would be the greatest possible extent fulfils the required properties. In the experimental part of the article are compared and investigated the mechanical characteristics of composite sandwich structures with regard to varying number of layers of predimpregnated skin materials due to the different types of core materials suitable for use in the machine industry. In addition, these characteristics are an important part of the article research because described the influence number of layers to values of the bending stiffness those composite structures.

Abstract: This paper aims at studying the dynamic buckling characteristic of the fiber composite honeycomb under out-of-plane impact load. It was found that: with the increasing of the wall thickness, both the critical buckling load and the critical failure load of the composite honeycomb will decrease gradually. By increasing the wall aspect, the critical buckling load will decrease, while the critical failure load will increase. However, when the aspect reaches to 3.5,both the above two kinds of load are no longer sensitive to the variation of it.

Abstract: The axial crushing behavior of metal honeycomb was studied with laying emphasis on the effects of adhesively-bonded joint and strain rate dependence on its characteristics as an energy absorber. To introduce the influences of the plastic deformation of adhesive layer and the fracture of adhesively-bonded joint, the embedded-process-zone (EPZ) model was used. First, the axial crushing behavior of metal honeycombs (A3003 aluminum alloy and SUS430 stainless steel) was studied with changing the strain rate by low-speed and drop-weight experiments, and then the numerical model of honeycomb, which included EPZ model and the initial imperfection, was investigated by the explicit FEM code LS-DYNA. The mean buckling load calculated with EPZ model becomes smaller than that calculated with the combined model and agrees well with the experimental result. The effect of the strain rate dependence of material on the structure was also studied by the numerical simulation as well as by the experiment. A3003 honeycomb shows no strain rate dependence on the load –displacement relation while SUS430 honeycomb shows significant increase in the mean buckling load.

Abstract: There were built some new original composite sandwich bars with polypropylene honeycomb core and the exterior layers of the bars were made of epoxy resin reinforced with steel wire mesh. For these composite bars, there were determined the stiffness by using two different experimental methods: variant 1- using the Walter-Bai testing machine and variant 2- using the eigenfrequency of the first eigenmode. The errors between these two methods were determined. In the next stage of the paper, some metallic beams, equivalent from the stiffness point of view with the composite ones, were considered. Comparisons between them, from the mass per unit length point of view, were made.

Abstract: The objective of this study is to find the density, stiffness, and strength of truss-wall unit cell models. The diamond-corrugation, triangular-corrugation, and Navtruss-corrugation models are used for the unit cell. The ideal solutions derived for these are based on truss-wall unit cell models and are developed using the GibsonAshby theory. To verify the ideal solutions of the models, the density, strength, and stiffness are simulated using ABAQUS software and compared with the ideal solutions on a log-log scale. The material properties of stainless steel 304 are applied. The diameter is 0.5 mm; the opening width is 0.5 mm; and the corrugation angle is 45°. Consequently, the relative Youngs modulus and relative yield strength of the truss-wall unit models are good matches for the ideal expectations. It may be possible to apply a truss-wall model to diverse fields such as transportation or biomedical applications as one of the open-cell cellular solids.

Abstract: This research paper deals with an investigation of the influence of honeycomb core compression on the mechanical properties of sandwich structures. These structures consist of prepreg facing layers and two different material types of honeycomb and are produced by modified compression molding called Crush-Core technology. Produced structures are mechanically tested in three-point bending test and subjected to low-velocity impact and Charpy impact test.

Abstract: In order to develop the lightweight composite materials, we developed an integrated manufacturing method. The first trial production of the integrated honeycomb plate was fairly rough. This paper focuses on the trial manufacture of bionic honeycomb plates and discusses their mechanical properties. The conclusions were :1) An edge-sealing bionic integrated honeycomb plate has been provided; 2) some specific cases of improving the integrated manufacturing technology have been studied; and 3) the failure strength in the integrated honeycomb plate is significantly higher than that of the honeycomb plate with the adhesive layer.

Abstract: Cavitation noise is the major source of noise in fluid power transmission system. Noise value is the most important index to measure the quality of equipments. So reducing noise is the primary goal. Honeycomb called a natural miracle has unique structure and good acoustic performance. A kind of noise reduction device was presented in this paper based on micropore structure of honeycomb and micro-perforated panel theory. The design idea and design scheme of the device had been discussed. Then simulation of the device had been done in order to optimize the design ,the number and position of cavitation had been assured and the open porosity was selected as a judgment index. The results of simulation indicated the device added to fluid system could reduce cavitation noise effectively. The device was made and added to the water circuits in experiment field. Eliminating interference of environmental noise,the noise of water circuits system used the device was decreased by 3dB or so compared with system without the device.

Abstract: By analyzing advantages and disadvantages of the existing energy absorbers, carbon fiber composite and regular hexagon honeycomb structure were chosen as material and topological structure respectively to make a big-bearing, lightweight energy absorber. Preparation method of carbon fiber composite honeycomb energy absorber was studied, which was applied to manufacture some specimens,and it is feasible because of the specimens good consistency and regularity. Quasi-static compression tests of the specimens were carried out, and then the related parameters of energy-absorbing characteristics were calculated. The results show that the carbon fiber composite honeycomb energy absorber has excellent energy-absorbing characteristics.

Abstract: The effect of low density filler material comprising polyurethane foam on the axial crushing resistance of Nomex honeycomb under quasi-static compression conditions was analyzed. Honeycombs with two different densities, two different heights and similar cell size, along with five different densities of polyurethane foams were used in the research. A total of 14 unfilled Nomex honeycombs, 15 polyurethane foams, and 39 foam-filled Nomex honeycombs were subjected to quasi-static compression loading. The crushing load and capability of foam-filled Nomex honeycomb structure in absorbing the energy were found to increase significantly since the cell walls of honeycomb were strengthened by the foam filler; the walls did not buckle at the very beginning of compression loading. The failure mechanism of the foam-filled honeycomb was analyzed and compared with the unfilled honeycomb.