Light Filler Research Articles

Determination of the stability of a three-layer shell of a traveling wheel with light filler

Purpose. Development of a calculation methodology for three-layer cylindrical shell stability, which will significantly improve the calculation practice for these structures regarding the determination of critical external pressure. Methodology. When determining the critical external pressure, the method of variational calculation using the Euler equation of the mixed variational problem was used. To determine three-layer cylindrical shell stability, the factors of significant influence on its strength and stability were taken into consideration, namely the reduced modulus of a three-layer wall elasticity. Bending stiffness Dh was substituted with flexural stiffness of three-layer shell with account for the shear deformation. Findings. The current situation of the three-layer cylindrical shell stability issue is investigated. Using the variational calculation methods via the Euler equation of the mixed variational problem an equation is composed of equality condition of inner and external force action of an orthotropic structure, which is under the state of neutral equilibrium with radial displacement. The previously obtained equation for radial displacements having been taken and applied to the system potential energy per unit of length equation, an equation for the critical pressure determination is determined. The analytical solution obtained was proposed for the structure of the crane travelling wheel with an elastic insert. Pcr 1267MPa was obtained. The allowable wheel pressure on rail for the crane travelling wheels is adopted to be within 250 MPa, i.e. the available stability margin is nc 1267/250 5.1. As we can see, the stability margin is more than sufficient. Originality. A new methodology for the three-layer cylindrical shell under external pressure calculation is developed. A quantitative assessment of the crane travelling wheel with flexible insert critical pressure is carried out. Practical value. A determination methodology for critical pressure of a three-layer cylindrical structure under external pressure is created.

Application of Artificial Neural Networks to Predict Insulation Properties of Lightweight Concrete

Predicting the properties of concrete before its design and application process allows for refining and optimizing its composition. However, the properties of lightweight concrete are much harder to predict than those of normal weight concrete, especially if the forecast concerns the insulating properties of concrete with artificial lightweight aggregate (LWA). It is possible to use porous aggregates and precisely modify the composition of lightweight concrete (LWC) with specific insulating properties. In this case, it is advisable to determine the parameters of the components and perform preliminary laboratory tests, and then use theoretical methods (e.g., artificial neural networks (ANNs) to predict not only the mechanical properties of lightweight concrete, but also its thermal insulation properties. Fifteen types of lightweight concrete, differing in light filler, were tested. Lightweight aggregates with different grain diameters and lightweight aggregate grains with different porosity were used. For the tests, expanded glass was applied as a filler with very good thermal insulation properties and granulated sintered fly ash, characterized by a relatively low density and high crushing strength in the group of LWAs. The aim of the work is to demonstrate the usefulness of an ANN for the determination of the relationship between the selection of the type and quantity of LWA and porosity, density, compressive strength, and thermal conductivity (TC) of the LWC.

Calculation of three-layer rotation shells for an axisymmetric load in conditions of nonlinear creep

The article is devoted to the calculation of three-layer shells of rotation with a light filler under the creep conditions. Unlike previous works of the authors, the hypotheses of the theory of shallow shells are not used. General geometric and physical equations are presented, as well as a system of resolving equations for axisymmetrically loaded structures. An example of calculating a spherical dome is given. The features of changes in the stress-strain state of the considered structure during creep are revealed.

Gypsum composites with glass granules

The article explored the possibility of reducing the average density of self-reinforced gypsum composites. Gypsum matrix and glass hollow granules leads to the appearance of a synergistic effect. It manifests itself in the formation of a compacted gypsum reinforced matrix, which is filled with microspheres. This provides a modified gypsum stone with high technical indicators. The volume of use of glass hollow granules is increasing every year, including in the construction industry. This material, unique in its properties, provides very high compressive strength, low water absorption, low heat conductivity, high chemical resistance, and radio transparency for its composite materials. The method of obtaining this light filler is a combination of complex physicochemical and hydrodynamic processes that occur during the formation of hollow balls from microparticles of glass melt. Creating effective composites based on glass micro granules as a component in the molding of gypsum products opens up new possibilities for designers and technologists. This will significantly expand their scope.

Effect of expanded polystyrene content and press temperature on the properties of low-density wood particleboard

In this study, three-layer low-density (about 400 kg/m3) particleboards consisting of a mixture of wood particles and expanded polystyrene (EPS) were manufactured. EPS bead was incorporated in the core layer as a light filler. The influence of EPS content (0 %, 2,5 %, 5 %, 7,5 %, 10 %, and 12,5 %) and press temperature (110 °C and 140 °C) on the microstructure, density profile, bending properties, internal bond and thickness swelling of the panels were investigated. Results showed that incorporation of EPS beads filled in the voids between wood particles improved the core layer integrity, and generated a more pronounced density profile. Consequently, the bending properties and internal bond of panels adding EPS were remarkably improved, and the thickness swelling was decreased. However, the variation of the number of EPS from 2,5 % to 12,5 % had no significant effect on the bending properties and thickness swelling. Comparing the two press temperatures, higher temperature (140 °C) was more favourable in control panels without EPS as filler. For panels adding EPS filler, 140 °C had a negative effect on the properties of panels, especially at high EPS contents (10% and 12,5%), attributing to the shrinkage of EPS bead under press temperature that is much higher than its glass transition temperature (104 °C)

Expanded obsidian as a soil aerator, its porosity, physical and mechanical characteristics

Today, the decline in soil fertility progress, therefore, special attention paid to the search for new, including non-traditional sources of raw materials that allow cultivating agricultural crops. It is propose to use expanded obsidian as a soil aerator. Obsidian is a volcanic rock, consisting of volcanic glass in which water content does not exceed 1%. A characteristic feature of this stone is the ability to expand under heat treatment. The expansion of obsidian is possible to implement at temperatures of 1050… 1150 °C. It has been shown that due to obsidian expansion it is possible to obtain a light porous filler with an average density of 200… 350 kg/m3, where the heat treatment of 5… 10 mm grains should be performed under temperatures from 1050 to 1150°C, during 3…5 minutes. The mechanical strength of the expanded obsidian is due to the thickness of the internal partitions of the pores and depends on the total porosity. Increased porosity decreases the strength of the expanded obsidian grains as the internal partitions of the pores become thinner. Relatively high mechanical strength develop grains with less porosity, ie lower coefficient of expansion. At the same time, the nature of the external surface of the grain has a significant influence on the mechanical strength. The melted surface,under other equal conditions provides mechanical strength increase of the expanded obsidian.

Effect of Heavy Filler on Dynamic Mechanical Properties of Polymer Composites

Experimental studies on the effect of frequency and temperature on the dynamic mechanical properties of filled composites are studied poorly and require further research. The purpose of theresearch is to study the effect of heavy fillerbarite (BaSO4), on the dynamic characteristics of a highly filled composite based on butyl rubber, and to compare the efficiency of barite in the composite with similar light filler. The conclusions are made on the basis of a comparative analysis of the temperature-frequency dependences of the loss tangent and the storage modulusat various percentages of filler, obtained by the DMA method. It has been established that while increasing barite concentration the elasticity of the composite material decreases, the glass transition temperature shifts upwards, and the reverse occurs in the zone of highly elastic state of the composite: the higher the barite concentration, the higher the damping properties. The authors provided a rationale that the heavy filler shows the effect only in the highly elastic zone if compared with the light one. The article is of practical value for the development of new vibration insulation materials.

Ecologically closed energymetallurgical technology of powdered iron ore and coal-cleaning wastes processing

The problem of coal-cleaning wastes utilization is actual in many countries of the world. At present in Russia these wastes are used only at 10–15% in different industries, but the potential of their utilization is much wider. Peculiarities of waste-less technology of powdered coal-cleaning wastes gasification in the slag suspended layer considered, resulted in conditional synthesis gas obtaining with simultaneous reducing and isolation of metal from ash and slag. Besides, another result was obtaining a highporous alumina-silicate slag (microspheres), applicable as a light filler for paints and coatings with low heat conductivity, as well as absorbing agent etc. It was shown, that based on the earlier elaborated jet-emulsion facility, a waste-less technology of gasification (processing) of coal and its cleaning wastes can be created resulting in obtaining three liquid products: synthesis gas (or electric power), alumina-silicate micro granules and iron with dissolved in it rare metals. Apart from the wastes of coal-cleaning availability, the presence of powdered iron-containing wastes (dust from gas-cleaning systems, iron ore concentration tails) can increase the efficiency of the technology. The increase will take place due to stable gas-slag emulsion support and the two-phase flow in the connection channels, as well as decrease of gaseous oxygen consumption at the expense of it substitution by oxygen of iron oxides.

Fluoro-Anhydrite Compositions with a Light Filler Based on Expanded Perlite Sand

Fluoro-Anhydrite Compositions with a Light Filler Based on Expanded Perlite Sand

A Survey of Fertility Program Responses of Kentucky Dark Fire-Cured Tobacco (Nicotiana tabacum L.) Yield and Quality for Cigars Manufacture in the Benevento Province (Southern Italy)

Summary Nitrogen (N) fertilization of Kentucky dark fire-cured tobacco can be used to increase weight of high quality cured leaves for cigar manufacture. We conducted field experiments at 11 different locations in the province of Benevento (Southern Italy) where the following four N treatments were compared: 1) unfertilized control (N0); 2) a site-specific N rate, calculated by a N fertilization plan (NFP) based on physical and chemical soil characteristics, which ranged between 113 and 145 kg N ha−1; 3) 200 kg N ha−1 (rate commonly used by farmers, N200); 4) 100 kg N ha−1 (half of the rate commonly used by farmers, N100). Yields of the following five commercial quality categories of cured leaves were measured: i) wrappers, ii) heavy filler (Fh), iii) light filler (Fl), iv) heavy shredded (Sh) and v) light shredded (Sl). Fh cured products of B1, B4, B6 and B10 locations were analyzed for: total alkaloids, reducing sugars, chlorides, total N (Kjeldahl), ammonium-N (NH4-N), nitrate-N (NO3-N), and tobacco specific nitrosamines (TSNA). Color parameters: Lightness (L), Chroma (C) and Hue (H) were determined on five cured leaves / plot of both Fh and Fl types at B1, B2, B3, B6, B8 and B10. A blind evaluation of cured leaves collected across locations was conducted by a panel test who considered the main basic characteristics of cured leaves (stalk position, leaf structure, texture, etc.). The total yield of cured products increased with fertilization across locations, up to NFP treatment, without any statistically significant increase at N200 treatment. Fertilization increased yield of wrappers at B1 up to NFP treatment (113.5 kg N ha−1), without any significant increase at N200 treatment. Yield of light filler product was positively influenced by fertilization up to the maximum dose only in 5 out of 11 locations. Total alkaloids significantly increased with increasing fertilization up to 100 kg N ha−1 without any significant changes at higher N rate. Fertilization hardly increased L and C of Fl leaves, which appeared light-brown but brilliant-colored. There was a reduction in the H value of Fh products which indicated a darker tone of those leaves with respect to Fl. Increasing N rate affected production costs more than revenues. According to agronomic results, in most locations the best results in terms of net revenues were obtained by NFP treatment. Considering that N rates above the NFP would disqualify growers from the economic aids provided by EU agrienvironmental measures, by economic point of view the NFP treatment would be recommended over the current grower standard (N200).

Automobile crashworthiness improvement by energy-absorbing characterisation of aluminium foam porosity

Aluminium foam has been adopted as one of the light filler materials in auto body structural components because of its excellent energy-absorbing ability and lightweight which play a key role in reducing weight and improving safety. This paper combines the porosity of aluminium foam material and the application in car's crashworthy structures to present the energy-absorption behavior and its effect evaluation. First, the paper focuses on the effect of porosity on the energy absorption by experimental study. All the experiments were performed with the specimens subjected to quasi-static axial loadings. As the experimental results, the energy-absorbing properties on porosity are presented, implying that the porosity is a very sensitive factor to energy absorption and the best porosity of aluminium foam in energy-absorption capacity was obtained. A case study on aluminium foam-filled material for automobile front rails was carried out by collision simulations, the improved crashworthiness was verified.

The Preparation and Performance of Gypsum-Based Composites

Gypsum-based composites was produced using gypsum power(cement), PVA, white latex and sawdust via pouring process. The influences of water/ cement ratio, PVA/ cement ratio and glue/ cement ratio on release time, density and impact strength of the gypsum-based composites were investigated through orthogonal experiment. The results showed that PVA strengthened obviously impact strength, and also delayed the s release time of the Gypsum-based composites. Sawdust as light filler reduced the composites density. Low content of white latex is beneficial to increase the impact strength, while high content of white latex is easy to form micelle in the gypsum crystallization process and is enclosed in crystals, which decreases the impact strength of composite materials.

Detection limits of impurities in a light filler in an X-ray fluorescent arrangement with a secondary target

The application of the arrangement with a secondary target for the X-ray fluorescent analysis of microimpurities in water solutions without sample destructions and preliminary sample preparations is considered. The limiting contrast values of fluorescence spectra are estimated, the limits of detecting impurities by the arrangement are theoretically calculated and experimentally measured (Cmin is smaller than 0.5 ppm). The range of chemical elements, which are efficiently excited by the secondary target, is determined by the Cmin criterion.

Influence of hollow glass microspheres on the mechanical and physical properties and cost of particle reinforced polymer composites

The goal of the study was to find a cost-effective composition of a particle reinforced composite that is light in weight but has sufficient mechanical properties. The matrix of the particulate composite is unsaturated polyester resin that is reinforced with alumina trihydrate particles. Part of the alumina trihydrate proportion was replaced with hollow glass microspheres to reduce weight and save costs. In order to find out the influence of the light filler on the physical and mechanical properties of composites, materials with different percentages of the light filler were prepared. Test specimens were cut from moulded sheets that were fabricated with vacuum assisted extruder. Tensile strength, indentation hardness measured with a Barcol impressor, and density were determined. Based on the experimental data a multi-criteria optimization problem was formulated and solved to find the optimal design of the material. Artificial neural networks and a hybrid genetic algorithm were used. The optimal solution is given as a Pareto curve to represent the distinction between the density and selected mechanical properties of the composite material. The composite material filled with 6% hollow glass microspheres showed 3% loss in the tensile strength and 26% loss in the surface hardness compared to the composition without the filler. The weight decreased by 13% compared with the initial composition. The addition of hollow glass microspheres did not lower the net value of the material, it increased 7%.

Dynamics of circular three-layer plates with elastic base under axisymmetric loading

We consider axisymmetric transverse vibrations of a circular three-layer plate with light filler on the elastic base subjected to the action of suddenly applied and pulsed surface loads. The reaction of the base is described by the Winkler model. For the analysis of the kinematics of a sandwich asymmetric over the thickness, we use the hypotheses of broken normal. The analytic solutions are obtained by using a system of Heaviside functions and the Dirac δ-functions. The numerical calculations and comparative analysis of the obtained solutions are performed.

Vibrations of circular sandwich plates connected with an elastic foundation

The results of analyzing axisymmetric forced vibrations of an elastic circular sandwich plate connected with an elastic foundation under different surface loads are presented. The hypotheses of a broken normal are accepted to describe the kinematics of a package that is nonsymmetrical over the thickness. The analytical solutions of a problem for plates with a light filler are obtained and numerical analysis is carried out.

Deformation of a composite plate on an elastic foundation by local loads

Bending of an elastic annular composite plate with a light filler lying on an elastic foundation is considered. The plate is subjected to local loads. To describe the kinematics of the package, asymmetric across its thickness, the hypotheses of broken normal is accepted. The reaction of foundation is described based on the Winkler model. A system of equilibrium equations is constructed, and its exact solution in displacements is found. Numerical solutions for a metal-polymer sandwich plate are presented.

Optimum honeycomb filled crash absorber design

Axial and oblique impact crash tests on empty and honeycomb filled aluminum square tubes have been performed. Furthermore, in order to find more detail about crash process, finite element simulation of the experiments has been performed. In terms of finding more efficient and lighter crash absorber in this research, two steps have been done: First, multidesign optimization (MDO) technique has been applied to maximize the energy absorption and specific energy absorption of square, rectangular and circular tubes. Results of MDO have shown that the circular tubes have the best response. Results of previous works have indicated that filling of tubes with light filler often improve the crashworthiness behavior, and when the density of filler is higher than critical filler density the structure will lose its weight efficiency. Therefore, selection of an appropriate honeycomb density and tube thickness is unavoidable. In the second step, the MDO technique has been used to optimize honeycomb filled aluminum.

Bending of Circular Sandwich Plate on Elastic Foundation

Bending of elastic circular sandwich plate with light filler, which is on an elastic foundation, is considered. To describe the kinematics of plate bending that is nonsymmetric in sandwich thickness, broken normal hypotheses are accepted. The foundation reaction is described by the Winkler model. The load is local symmetrical. A set of equilibrium equations and their exact solution in displacements have been obtained. Numerical results for a metal-polymeric sandwich plate are given.

Local stability “in the large” of the rigid layer of a sandwich plate in compression with bending

Experiments show that at certain geometrical and mechanical parameters of a sandwich plate subjected to compression with bending the loss of stability of its rigid layer occurs through a leap to a nonadjacent form of equilibrium. The current notion about the loss of stability of rigid layers of multilayer systems and calculation schemes correspond only to particular cases of the phenomenon and are true only in the framework of certain physical, mechanical, and geometrical characteristics of structures. The most general and closest to reality is the calculation method which takes into consideration the entire complex of deformations of all elements of a multilayer system. The study includes the experimental and theoretical analysis of the influence of bending rigidity, initial bend, and decisive deformational factors on the value of the critical force in the rigid layer of the plate having a light filler. The position of the local energetic extremum emerging in the process studied and the region where it is necessary to take into account the real character of the loss of stability “in the large” are determined.