Papers by Keyword: Elasticity

Abstract: The article contains the results of studies concerning the effects of selected parameters of the manufacturing process of elastic bellows on their elastic properties and strength. Bellows models were made using additive technology SLS selective laser sintering, in which the material used to construct models was a polyamide PA 2200. Bellows printing process proceeded in a surface parallel to the axis of the bellows and in a surface perpendicular to it. Based on measurements of deformation coefficients of elasticity of bellows were determined, also the measure of the maximum axial force exerted by the bellows while loading the internal pressure was carried out. Comparing the measurement results a significant effect of process parameters on the flexible properties of elastic bellows and their resistance to internal pressure were determined.

Abstract: HVFAC (High Volume Fly Ash Concrete) is an attractive construction material with cost benefit and reduced CO₂ emission. In this paper engineering properties such as compressive and shear strength are evaluated and their characteristics are investigated. For this work HVFAC with FA (Fly Ash) replacement ratio of 35% and 50% are prepared and strength (compressive, shear, and bond) are measured with basic parameters like elasticity and ultimate strain. Test results are compared with conventional predictions from Korea Structural Code and their applicabilities are evaluated. In bond strength and elasticity in HVFAC are evaluated to need reasonable coefficients for HVFAC design.

Abstract: Infrastructure-As-A-Service (IAAS) provides an environmental setup under any type of cloud. In Distributed file system (DFS), nodes are simultaneously serve computing and storage functions; that is parallel Data Processing and storage in cloud. Here, file is considered as a data or load. That file is partitioned into a number of File chunks (FC) allocated in distinct nodes so that Map Reduce tasks can be performed in parallel over the nodes. Files and Nodes can be dynamically created, deleted, and added. This results in load imbalance in a distributed file system; that is, the file chunks are not distributed as uniformly as possible among the Chunk Servers (CS). Emerging distributed file systems in production systems strongly depend on a central node for chunk reallocation or Distributed node to maintain global knowledge of all chunks. This dependence is clearly inadequate in a large-scale, failure-prone environment because the central load balancer is put under considerable workload that is linearly scaled with the system size, it may thus become the performance bottleneck and the single point of failure and memory wastage in distributed nodes. So, we have to enhance the Client side module with server side module to create, delete and update the file chunks in Client Module. And manage the overall private cloud and apply dynamic load balancing algorithm to perform auto scaling options in private cloud. In this project, a fully distributed load rebalancing algorithm is presented to cope with the load imbalance problem.

Abstract: A parametric variational principle is deduced according to the equivalent integral form of all the controlling equations and boundary conditions in elasticity, and by adjusting the parameters, all kinds of variational principles put forward past and some new variational principles can be gained, which means that the method above is more clear in concept, and more concise.

Abstract: The article contains the result of studies on the effects of selected geometrical parameters of elastic bellows on their elastic properties. Bellows models were produced with using additive technology, selective laser sintering SLS, where the material used to build models was polyamide PA 2200. Based on the measurements of elastic deformation coefficients of each models bellows were determined. Comparing the results of the measurements there was found a significant effect of the thickness, number of corrugations and their length on the value of the coefficient of elasticity.

Abstract: This paper presents the results of an experimental investigation on the effects of orientation and grain size on nanoindentation measurements of hardness and modulus of elasticity for three polycrystalline metals: copper, nickel, and iron. Three geometrically different indenter tips were used, and the pile-ups were characterized with a surface probe instrument. The electron backscatter diffraction (EBSD) technique and a scanning electron microscope (SEM) were used to characterize grain orientation and microstructure. It was found that additional contact areas due to pile-ups have a significant effect on determination of mechanical properties by the nanoindenter.

Abstract: Polyurethane foam is widely used in numerous applications. The quasi-static mechanical behaviour of polyurethane foam shows a nonlinear elasticity and a viscoelasticity in large compression deformation. In this paper, the uniaxial compression / decompression tests in three different strain rates are performed. The purpose of this paper is to propose three visco-hyperelastic models and to identify the parameters based on the experimental results. A difference-stress proper identification method is used to obtain the model parameters. The results show that the three models can predict the mechanical behaviour of polyurethane foam very well. Finally, the three models are compared according to the model results.

Abstract: We use quantum-mechanical calculations to study single-crystalline elastic properties of (Ca,Mg)CO₃ crystals with concentrations ranging from calcite CaCO₃ to magnesite MgCO₃. By analyzing results for a dense set of distributions of Ca and Mg atoms within 30-atom supercells, our theoretical study shows that those atomic configurations, that minimize the total energy for a given concentration, are characterized by elastic constants that either increase with the Mg content or remain nearly constants. Employing these ab initio calculated single-crystalline elastic parameters, the polycrystalline elastic properties of (Ca,Mg)CO₃ aggregates are determined using a mean-field self-consistent homogenization method. The computed integral elastic moduli (bulk and shear) show a significant stiffening impact of Mg atoms on calcite crystals. Our analysis also demonstrates that it is not advantageous to use a granular two-phase composite of stoichiometric calcite and magnesite instead of substituting individual Ca and Mg atoms. Such two-phase aggregates are not significantly thermodynamically favorable and do not offer any strong additional stiffening effect.

Abstract: Strength characteristics of an elastic plane weakened by round holes arranged in a quadratic order are considered. The stress concentrations in the three different hole lattices are studied in conditions of the uniaxial tension/compression with different directions (0°÷45°, it is enough, because the lattices are symmetrical). The minimal and maximal concentrations values are calculated; the stress fields are considered in different lattices. It is shown that in the particular conditions of fracture at compression can occur in the inner zone of the material rather than at the hole contours. It is demonstrated that in dense lattices a power-like type of the concentrations dependencies on the structural parameter takes place; the parameter is a ratio of the holes interval to the hole radius. Next, the modes of initiation of fracture in elastic perforated plates (lattices) under external uniaxial compression are considered. Special attention is paid to the internal mode of initiation (i.e., to the case of fracture initiation inside the material, and not on the contours of the holes). The parametric region of the internal mode is studied, it depends on the angle of the applied external loads and the structural lattice parameter; the size of the region (extreme values) is calculated. A particular point of the region is found; it is shown that at this point there are three possibilities of fracture initiation: two positions at the hole contour, and one position inside of material. Keywords: elasticity, perforated plates, lattice of circular holes, fracture initiation, uniaxial compression.

Abstract: There are several methods and equations which are used to evaluate the efficiency of the service vehicle fleet of logistic. The aim of this paper is to introduce a well handle method. The base of this method is the production function and it can define the influence of the parameters. The CP (ceteris paribus) method is used by the examinations. At first we take consideration to the non changed parameters are in the examined range by the examination of the multi parameter production function. The parameter sensitivity analysis is guided back to elasticity analysis where the effects of changes of the ratio of influence is examined to the influential ratios.