Advanced Materials Research Vol. 1064

Abstract: A three dimensional analysis model is developed on the fatigue life prediction of composite laminates based on a progressive damage analysis. This model consists of stress analysis, fatigue failure analysis and material property degradation. Teserpe’s failure criteria is used to fatigue damage analysis. Fiber tensile/compressive breakage, matrix tensile/compressive cracking, matrix/fiber shear failure and tension/compression delamination are considered in fatigue damage analysis. The methodologies of sudden degradation and gradual degradation are both applied in the material property degradation. The stiffness and strength gradual degradation is based on the Shokrieh fatigue model, which is based on fatigue test for unidirectional laminates. In order to consider the scatter of the material in the practical structures, the stiffness and strength of the material are randomly distributed using normal distribution in the numerical model. The progressive fatigue damage model is developed in finite element code ABAQUS through user subroutine UMAT, which can simulate the fatigue damage process. Fatigue life of different ply stacking sequences and geometries composite laminates under different cycle loading are predicted. The predicted fatigue life is in good agreement with the experimental results.

Abstract: Installing viscoelastic dampers on electrical transmission tower will significantly reduce the wind-induced vibration response of electrical transmission tower-line system. On the basis of the concept of strain energy method with the combination of related codes and the theories of calculation for equivalent damping,a mothed is presented which is used to estimate the additional damping of electrical transmission tower-line system with viscoelastic dampers.Through a electrical transmission tower with viscoelastic dampers, based on the formula of strain energy in design code,this paper puts forward a calculation method of equivalent damping ratio based on the concept story of transmission tower,and through finite element model the responses of transmission tower with viscoelastic dampers model and the one with additional damping ratio model were compared.The simulation results show that the calculation method of equivalent damping ratio has high precision,and the errors are less than 5% in multi engineering conditions.

Abstract: A mathematical model to describe the pressure distribution in a thermoset large-sized composite rod as it travels through the pultrusion die is developed on the basis of Darcy’s law. A finite-difference method is employed to solve the governing equations of three-dimensional axis-symmetric cylindrical die geometry. The influence of pre-heating on pressure rise inside a cylindrical die inlet is investigated. The present model may be utilized to obtain the optimal linear taper angle for die inlet and process conditions to achieve maximum possible pressure rise in the die inlet.

Abstract: In this study, the effect of stacking fault energy on the grain size of aluminum, copper, and brass fabricated via accumulative roll bonding (ARB) process was investigated. Evolution of microstructure of the samples was investigated by transmission electron microscopy (TEM). It was found that occurrence of the recrystallization (both continuous and discontinuous) in the copper and brass led to the formation of nanograins with mean size of 80, and 40 nm, respectively; while, the mean grain size of aluminum was 250 nm. Differences in microstructural evolution during processing of aluminum, copper, and brass was related to their stacking fault energies (SFEs). When the SFE decreased, grain refinement occurred more easily and the measured grain size was smaller.

Abstract: The relationship between grindability of blast-hole cuttings, strength parameters and bit wear rate were investigated. In order to achieve this, drill cuttings were collected from twenty blast-holes drilled in a quarry. The samples were tested in the laboratory for Silica content using X-Ray Fluorescence (XRF) spectrometer. Also, the length of button worn on the surface of bit was measured at regular interval with aid of digital vernier caliper on the field as drilling operation progresses to determine wear rate. Sieve analysis was used to determine the size distribution of the blast hole cuttings in the laboratory using sieve shaker while grindability was determined using the ball mill, by grinding for certain number of revolutions. The result obtained show that the weight of drill cuttings retained on 850μm decreases while weight retained on 75μm increases as wear rate increases. Grindability was correlated with wear rate and weight retained at 75μm sieve, the value of multiple coefficients of correlation is 0.126 and 0.064 respectively, this show that there is no relationship between grindability, wear rate and weight of cuttings retained on 75μm. The result of correlation of wear rate and weight retained at 75μm shows that strong relationship exist between them and the value of multiple coefficient of correlation is 0.892.

Abstract: This paper considers an approach to improve durability of broaching tools made of high alloyed powder metallurgical high-speed steels by complex treatment which includes ion nitriding and following deposition of wear-resistant coating (Nb, Ti,Al)N using two-stage vacuum-arc discharge. Broaching tools complex hardening conditions which provide minimal wear rate when machining heat-resistant nickel alloy Inconel 718 used for turbine discs are defined.

Abstract: The article considers new technological principles of designing of vacuum-plasma coatings for ceramics on the basis of Al₂0₃–TiC and Si₃N₄ and the requirements for the following coatings: (Zr, Hf, Cr) N; (Ti, Cr) N; ZrN. Each of these coatings has specific features which can significantly improve working capacity of ceramics in various operation conditions. Technological process and the equipment for deposition of coating on ceramic samples and cutting plates are developed. Undertaken studies of the coatings deposited according to the developed technological principles, show ability to increase considerably beam strength of the samples from oxide-carbide and nitride ceramics. The article shows the possibility to replace grinding operation of details of bearings from tempered steels like ShH15SG type (62 ... 65HRC) to turning by the cutting tools equipped with plates from Al₂0₃-TiC ceramics with a coating (Zr, Hf, Cr)N.

Abstract: The possible technologies of formation of nanostructured surface layers: a method of thermal mass transfer in a high temperature gradient; the combined method, comprising plasma nitriding a cathode in a low pressure and deposition of titanium nitride in a single process cycle; combined method comprising an ionic nitriding and high frequency deposition of chromium carbide by pyrolysis of organic chromium compounds in a glow discharge plasma are considered. The possibility of formation of nanostructured layers is shown. Examples of the practical use of these technologies are given. The tests found that the use of the combined coating nitriding + TiN increases cyclic durability of machinery parts in contact loading conditions and corrosive environments on the two orders, providing a specified level of reliability and combined nitriding + CrC coating on steel С1050 allowed to reach values ​​of the fatigue limit under Impact NaCl 400 MPa.

Abstract: Using the methods of experimental design made ​​the choice determining factors for the calculation of modes magnetron sputtering coating SME steel 321H; received mathematical-statistical model that relates the performance criteria with the main parameters of the process. Studies on developing the technology of magnetron sputtering materials with shape memory TiNi-based study of the structure and formed surface layers showed that the recommended spraying regimes provided obtain a homogeneous quality of the surface layer with a grain size of 15 nm to 50 nm, chemical and phase composition which provides the memory effect.

Abstract: The article describes prospective nanostructured titania coatings modified with functional ceramic nanoparticles and obtained on surface of titanium items. Consistency changes of morphological characteristics and crystalline structure, physico-mechanical properties of experimental titania coatings obtained by the combination of oxidation and surface modification with ceramic nanoparticles during induction heat treatment are defined.