Papers by Keyword: Material Property

Abstract: Various studies have been carried out to understand the properties and the performance of Thermally Stable Diamond Composite (TSDC) when it is used as the rock cutting tools. Existing studies focused on the influences of uncertain TSDC material properties, and randomly varied rock strengths and thickness on the failure probability of cutting tips made of TSDC. It is found that the compressive strength of TSDC cutting tips is much higher than their tensile strength. As a result, the ability of a TSDC cutting tip to bear the resultant force applied along its axis is much greater than its ability to bear the resultant force perpendicular to its axis. However, the resultant angle during rock cutting processes varies greatly. This study focuses on the investigation of the impact of varied resultant force angles on the performance and failure characteristics of TSDC as a rock cutting tip using Monte Carlo simulations. The results show that the varied resultant angle can significantly influence the failure characteristics of the TSDC cutting tip with a fixed attack angle.

Abstract: The accuracy of the simulation results of stamping processes of thin sheet material depends on the correct properties’ specification, namely stamping ability. Experiments have been carried out and the influence of the deformation speed on the hardening exponent during cold sheet metal forming was studied. It was found out, that strain changed 100 times can influence the strain grade of the hardening curve of about 10%. This regularity has been taken into consideration prior to the calculation in any CAE-software for material forming.

Abstract: The three natural rubber compounds of solid tires producing were performed the mechanical property test. The constitutive model of each material tire layer was determined by the curve fitting method of the true stress-strain characteristic results. The Ogden constitutive model was the most suitable material model for all layers of solid tires. It had the precise R² result comprising of 0.990, 0.988 and 0.989 for the internal, middle and tread layer of solid tires, respectively. Subsequently, the material model was implemented for the finite element method (FEM) to test the rubber specimens. The FEM obtained an average error of 7.84%. Finally, the compression load test on solid tires was performed both FEM and physical experiment. The solid tire model with the Ogden constitutive model had a good agreement with the experimental data and obtained an average difference of 2.27 mm for the vertical deformation under compression test.

Abstract: Silicon nitride ceramic balls are successfully applied in advanced bearings. In order to improve the performance and precision for ball bearings, the research about the material properties of Si3N4 ball is shown in this paper. For the Si3N4 ball, the material properties can be described by the following factors: density, hardness, apparent porosity, crushing load and fracture toughness. In this paper, Si3N4 balls from three different manufacturers are tested to reveal the inherent correlations of the material properties, and the correlation coefficients are calculated. The results indicate that with the increasing of ball diameter, its crushing load increases correspondingly. The higher hardness contributes to the lower crushing load of the Si3N4 ball. Apparent porosity has a greater influence on the crushing load than hardness and the density. Hardness has the closest relevance with fracture toughness among the material characteristics, with the increasing of the hardness, the fracture toughness of Si3N4 ball becomes lower.

Abstract: Material play an important role in engineering design and the characterisation of material property has become an essential requirement for their successful application as structural elements. In this paper, the development of material property characterisation method has been presented. Impulsive excitation test has been performed on rectangular bars (medium carbon steel S50C, cast iron FCD 500, stainless steel AISI 304and brass). The transient vibro-acoustic signals generated during the excitation test have been captured using data acquisition system consist of accelerometer-microphone combination. A new method for reducing the noise components from the recorded signals is introduced by an extensive process of a new Z-stem filtering technique. The filtered signals have been analysed using an alternative statistical method known as Integrated Kurtosis-based Algorithm for Z-notch filter (I-kaz^TM) to determine the pattern of the signal and to estimate the significance differences among those materials. The representation of the experimental curves obtained by the determination of I-kaz coefficient, Z^∞ for various impact forces and materials revealed that the results are statistically significant and can be successfully used for determining the correlation between the curves and material property. Implications of this research to material property characterisation will be discussed.

Abstract: High performance concrete (hereafter, HPC) is well known by its high compressive strength, strong resistance to deformation and excellent durability. Whereas, HPC is prone to spall when exposed to high temperatures and it probably results in sharp reduction of the fire resistance and loading capacity of HPC elements and structures. This paper presents a summary of research achievements on fire-resistance behavior of HPC in the past 10 years including the mechanical behavior degradation, analysis of spalling mechanism, effect of various types of fiber and other factors influencing the post-fire properties of HPC material as well as structural behavior of HPC elements. Studies on micro-structure of HPC have been carried out, which will help build a more sophisticated recognition of its performance under high temperatures. In spite of the large number of research results, more improvement on HPC material and HPC structures are still needed because of the devastating consequences caused by strength degradation or spalling-to-collapse. Thus in this paper a new idea of HPC-composite structures is proposed, expected to decrease the probability of spalling.

Abstract: In order to cope with various problems associated with machining of PCD, development of a new PCD possessing excellent tool properties and good machinability at the same time has been demanded. From this point of view, the authors have developed a new PCD, “EC-PCD (Electrically Conductive PCD)”, composed of boron doped diamond particles in place of the standard non-conductive diamond. In this research, investigation into material properties of the newly developed EC-PCD is made. Through the tests, it was found that the boron doped diamond particles (the source material of the new PCD) had an electrical resistivity of 1.6×10^-4Ω·m and the thermal conductivity after sintering was lower than that of the standard PCD. In addition, it was confirmed that the electrical conductivity of the source diamond particles of the EC-PCD had not been lost even under the condition of high temperature and high pressure during the manufacture. As a result of the heat test, EC-PCD’s high resistance to oxidation at high temperatures was confirmed showing no changes in the surface condition even at 675oC while the surface of the S-PCD was largely changed at the same temperature. One of the reasons for this is guessed to be that EC-PCD is hard to react with the cobalt contained as a catalyst metal. Further, it was found in the friction tests using a steel ball that the friction coefficient of the EC-PCD was 50% higher than that of S-PCD at the room temperature though it dropped by 10-30% at the temperature of 80oC.

Abstract: According to the Hypersonic Vehicle harsh environment, impacts of temperature on the mechanical properties for functionally gradient materials are studied. A power-law distribution of material is applied between the two pure materials; a material property model of FGMs is built. Several temperature conditions are set up and the results are obtained in the end through numerical analysis. It can be shown that the material properties of FGMs plate are temperature-dependent and vary along the thickness in terms of volume fractions of constituents.

Abstract: The graduation design of engineering course is an important practice teaching link of the preliminary scientific research trained for students in university, and is also an effective way of high-quality innovative applied talents. In accordance with the requirements of materials science and engineering course, the undergraduate graduation design of the materials professional is implemented. The professional theoretical knowledge applied to practical production and the studies of material properties are emphasized, and combined with scientific research. The students' initiative and creativity is stimulated, and their comprehensive quality is improved by adopting the heuristic teaching. Through a series of graduation design practice, the best way of thinking summed up is that the students' ability is cultivated by the teachers' scientific research project combination of actual production plan of the enterprise for adapting to the needs of society at present.

Abstract: In sodium cooled fast breeder reactors, the high operating temperature necessitates hard facing of grid plate to avoid galling and to reduce the wear loss of the base material . Nickel-base cobalt-free alloy called Colmonoy-5 has been chosen as the hard facing material for the Prototype Fast Breeder Reactor (PFBR) grid plate. The grid plate (GP) which is a critical component made of 316 LN SS that holds the core subassemblies are hard faced, to prevent galling and also to minimize wear caused by subassembly insertion/removal and erosion due to high sodium velocity at 670 K. Thermal cycling of hard faced circular grid plate made by Plasma Transferred Arc Welding (PTAW) generates residual stresses due to differential shrinkage of the molten deposit and difference in coefficients of thermal expansion between the deposit and substrate material. In this project the effect of thermal cycling of a nickel-base hardfacing alloy deposited on an austenitic stainless steel grid plate was studied. Finite element analysis of hard faced circular grid plate is performed for obtaining residual stress which includes elasto-plastic analysis. Coupled thermo-mechanical analysis is done for thermal cycling of hardfaced circular gridplate to quantitatively estimate the residual stress.