Papers by Keyword: Material

Abstract: The presented study demonstrates the possibility of an analytical approach called the multi-optional hybrid-effectiveness functions uncertainty measure conditional optimization doctrine. This method is applied in order to obtain the known, therefore considered proven, solutions by-passing the entirely probabilistic approach. It is made in application to the stochastic process measures determination. Supposedly, the process is developing in the aircraft engine system’s element (the state condition of its material). The solution is found in the framework of the entropy paradigm. It helps assess the newly emerged materials applications rationality and the novelty technologies implementations expediency on condition of the operational options uncertainty.

Abstract: Modern scientific foundation for the unification of methods of control and analysis of structural features and practically important properties of various metallic and non-metallic polymeric, ceramic materials are considered. Within the framework of improving materials' control and analysis methods through taking into account the effects of chemical elemental composition on their structure and properties, a new fundamental approach was developed. This method, unlike others, is applicable to both metals and non-metals, and implies considering the impact of both the composition and the type of chemical bonding on structure and properties of materials. This was done on the basis of a unified multilevel classification of structure of metallic and non-metallic materials, the use of a unified model and system of chemical bonds and compounds, which allowed evaluating the effect of mixed types of chemical bonds on characteristics of their multilevel structure and properties.

Abstract: Material choices for liquid lead bismuth spallation target are some of austenitic stainless steel, ferrite martensitic steel and cold-worked austenitic stainless steel. In order to ensure materials resistance to irradiation and corrosion as well as compatibility with lead bismuth, it is appropriate to lower the incident proton current density and the process temperature, in which temperature range engineering design can control to work, especially in ADS (Accelerator-Driven nuclear transmutation System) concept. The lower limit temperature is determined from the physical melting temperature and the engineering efficiency of the steam generator involved in process control. The material related issues for liquid lead bismuth are mass loss by impinging secondary flow, wettability at the device interface for ultrasonic waves application, detachable control of the slag in the flowing system, stabilized electrical resistance between the material and the liquid lead bismuth interface. Electromagnetic fluid analyses show how flow rate relates electrical resistivity of flow channel material.

Abstract: Lightweight Steel (LWS) systems, made of Cold Formed Steel (CFS) profiles, are widespread in seismic areas and often preferred to traditional systems. Improving structural performances in order to have higher building is now the goal, which could be achieved thanks to the use of steel innovative material. In particular, to increase the seismic performances of CFS buildings, the University of Naples “Federico II”, in cooperation with the Italian company Lamieredil S.p.A., has developed an innovative Lateral Force Resisting System (LFRS). The LFRS mainly consists of CFS frame (studs and tracks) braced by “V” shaped pre-tensioned Ultra High Strength (UHS) steel bars. The bracing was designed to be able to limit global displacement of structure, working as elastic spring, and to dissipate seismic energy by yielding. In order to prove the effectiveness of the new system, an extensive experimental campaign has been conducted. This paper focuses on material and component tests, describing tension tests on traditional materials and UHS steel, creep tests on UHS steel and nut-bar assembly tests.

Abstract: Polymer/composite sheets were developed using sand as the filler, and high-density polyethylene (HDPE), by melting extrusion in a melt blender followed by compression molding. The effects of addition of filler, and the addition of polyethylene grafted maleic anhydride (PE-g-MA) as the compatibilizing agent were investigated by observing the morphology, the mechanical performance as well as the wettability characteristic via contact angle measurements. A decreasing trend was observed with filler addition, both for the Young’s modulus and yield stress values of each of the samples, from 1200.81 MPa and 35.15 MPa at 0 wt% to 1182.33 MPa and 23.11 MPa for the non-compatibilized sheet at 35 wt%, to 629.95 MPa and 9.56 MPa in the case of the compatibilized sheet respectively. However, addition of filler did not significantly affect the surface wetting in any case, thereby promoting good anti-wetting performance for both sets of sheets. As a result, the potential use of such synthetic composite sheets could be considered as a good alternative for applications which require reduced ductility or increased anti-wetting performance.

Abstract: The method to determine thermal fields considering dependence of thermophysical and mechanical properties of coating materials and a base from the temperature, the running of plastic deformations and stresses relaxation at plasma spraying is suggested. The mathematical model of calculation of thermal field with moving boundary considering nonlinear feature of coating growth at layer-by-layer deposition and dependences from thermophysical properties of materials of the system «coating-base» is developed. The model application helps to estimate the effect of the parameters of plasma spraying process on the level of the residual stresses in the increased coatings.

Abstract: Ultracapacitor is a new electrical energy storage device which has high power density than conventional battery and capacitor. It offers high capacitance in small volume compared to conventional capacitors. While selecting ultracapacitors for various applications, parameters like specific resistance, internal capacitance, pulse current, energy density are required to be considered. Amongst these factors, specific capacitance of ultracapacitor depends mainly on parameters of electrode. The present paper is focused on modeling of ultracapacitor based on variations in some of the electrode parameters. The objective of present research work is to apply a statistical method to obtain an electrode material based model for prismatic type ultracapacitor. To have deep insight about the performance through modeling approach, the number of trials have been taken by doing the variations in the electrode materials of ultracapacitor and the quantity of the electrode material loaded on the current collector. The effect of both these variations is studied over the specific capacitance, which is taken as output parameter of model. Developed model is validated at selected values of input parameters.

Abstract: A new characterisation method based on free-bulge tests is proposed to find the characteristic parameters of the strainstress relation in superplastic alloys. The method is applied to experimental tests found in the literature and to new adhoc tests performed on aluminium, magnesium and titanium alloys. The parameters are then compared to independent values obtained from tensile test and computer-aided simulations. The characterisation of the material is evaluated as an apparent viscosity function of the strain-rate and is extracted from the height evolution at the apex dome during the forming process. Results show a good agreement between parameter estimation using this method and independent values. Moreover, this characterisation method exposes the non-newtonian fluid behaviour of these materials during superplastic processes known as shear-thinning or pseudoplasticity.

Abstract: In the present work, in the framework of solving the problem of obtaining a new generation of materials with a set of properties not inherent in traditional metal and non-metal types, the practical necessity of developing a unified approach to designing their structure and properties is substantiated. Within the framework of the paradigm of multi-level structural organization of materials, based on a single model of chemical bonding, a generalization of physicochemical prrinciples was carried out, revealing the unity of nature and the causes of differences in the structure and properties of metallic and non-metallic substances and materials. Through the effects of the ratio of the components of the chemical homo - or heteronuclear interaction of the elements of the fine microstructure of substances and materials on the differences in subsequent levels of the structure (molecular and non-molecular, etc.) and properties (conductor-dielectric, ductile, elastic or fragile and hard, etc.) of metals and nonmetals the practical significance of the scientific approach developed in the work was shown.

Abstract: Fluxing and tinning processes are usually used to improve the adhesion of the Al bearing layer on steel substrate. Commonly after grinding the surface of the steel substrate, it is briefly immersed in flux solution followed by coating steel surface with either pure Sn (in a process known as tinning process) to promote adhesion between the bearing alloys and the steel. The current work is designated to investigate the influence of tinning material for carbon steel substrate using simultaneous fluxing and tinning mixture technique. The influence of three different tinning materials on the interface structure and shear strength of cast Al-Sn bearing alloy/steel bimetal composite is evaluated for compound casting technique. Sn pure, Sn-3Cu alloy and Sn-7.5Sb-3Cu powder alloys mixed individually with flux are used as tinning materials. It was found that using of different tinning materials have a significant effect on the bonding of interface area and the shear strength of interface as well. The shear strength of the bimetal fabricated using tinning mixture contains Sn+3% Cu with flux significantly increases by 59% compared to that fabricated using tinning mixture contains pure Sn. This increment is mainly due to the improvements of the interface bond structure and lower percentage of tin oxides. Such kind of phenomena can be explained in the fact that Cu minimizes the possibility of Sn oxidation during tinning process and during preheating of tinned steel substrate before casting of Al12Sn4Si1Cu bearing alloy as well.