Applied Mechanics and Materials Vols. 84-85

Abstract: This paper is researched on SiO₂-coated Cr₂O₃ for the hydrolysis reaction of tetraethyl orthosilicate. The influences of precursors, solid contents of suspension and Si ratio of water on coated particle surface are investigated. The products are characterized and the conclusion shows that the experimental method is feasible.

Abstract: Polyhedral oligomeric silsesquioxane (POSS) can be used to prepare organic/inorganic hybrid materials. Octaepoxysilsesquioxane (E-POSS) containing eight reactive epoxy groups in a molecule was synthesized through the hydrolysis and condensation reaction of γ-[(2,3)-epoxypropoxy] propyltrimethoxysilicane. In this study, E-POSS was cured with 4,4'-Diaminodiphenylsulfone diamine (DDS) and methylnadic anhydride (MNA) , respectively. The curing reactions for both systems were monitored by Fourier transforms infrared spectroscopy (FT-IR). And the thermal properties of the cured systems were studied by Thermogravimetric analysis (TGA). The disappearance of the epoxy groups showed that either DDS or MNA was able to cure E-POSS into an organic-inorganic hybrid system with excellent thermal stability.

Abstract: In rolling system, there are some drive spindles. While simulating rolling processes, these drive spindles need to be merged into one, and the one merged is described by dynamic model module. According to loading state, the working process of drive spindle is divided into normal stage, critical stage, and over loading stage. The syntony strength of drive spindle is judged with material performance and working frequency.

Abstract: Dissimilar metal of Steel and Magnesium alloy used for friction stir spot welding is studied. Based on using orthogonal test method optimizes the process parameters and gets satisfactory joints , SEM is used to observe the features of joint,XRD is applied to determine the joint phase, and the results show that: the design of rotating tool without pin is reasonable and it can form satisfactory joints without keyhole of spot welding. The performance of spot welding joint depends on the extent of diffusion of Zn and Mg and high weld consistency. There is small existence of intermetallics made of MgZn2,Mg0.97Zn0.03 in welding joint.The properties of joint depends on the intermetallics, Due to this,The microhardness of joint increases gradually from the magnesium side to steel side.

Abstract: Porous UHMWPE were prepared by hot press molding in Metallographic Sample Mounting. The tribological properties of normal UHMWPE and porous UHMWPE were studied under different loads and lubricant on an improved tribological tester. The friction coefficient and wear loss of porous UHMWPE are steady and low under low loads, which attribute to the porous structure and extrusion effect of lubricant in testing. The results also show that the lubricant of BSA is better than that of water by its high viscosity. Among the increasing of loads, friction coefficient and wear loss are enhance rapidly. Serious cutting is the wear mechanism for porous UHMWPE under high loads.

Abstract: When the marine water-lubricated bearings are working in starting or stopping stage, they will be in low speed, heavy load and bad lubrication conditions, which would bring vibration and noise. Therefore, doing research on noise mechanism of rubber material has important theory significance and engineering practical value. This research is mainly based on tribological test of rubber material, and using pulse vibration analysis platform for data acquisition and spectrum analysis of the vibration generated in rubber material tribological test. And the influencing law of load, speed and temperature on noise are discussed. It has been proved that the noise is mainly affected by the speed, temperature and less affected by the load.

Abstract: Rolling bearing is extensively used in various areas including shipbuilding, aircraft, mining, manufacturing, agriculture, etc. The breakdowns of the bearings may do unexpected hazardous to the machinery. Therefore, it is crucial for engineers and researchers to monitor the bearing conditions in time in order to prevent the malfunctions of the plants. Hence the vibration analysis accompanying other condition monitoring methodologies has been successfully used in the field of roller bearings fault diagnosis as well as other key components. The fault diagnosis method of roller bearing using vibration analysis was introduced in this paper. And the development trend of vibration analysis was presented. Meanwhile the main existing problems in fault diagnosis of roller bearing were discussed. It concludes that the integration of vibration analysis and other detection approach can provide effective and reliable fault diagnosis results.

Abstract: Effect of substrate conditions, including material type, thickness and radius of substrate, on residual thermal stresses of plasma spraying Sm₂Zr₂O₇ TBCs was analyzed though finite element method in this paper. The radial and shear stresses of Sm₂Zr₂O₇ decrease with increasing of distance from the center to edge along radius of specimen, and they decrease abruptly at the edge of the specimen, while the axial residal stress increase abruptly at the edge of substrate. All residual stresses increase with increasing of thermal expansion coefficient of substrate. The thickness of substrate has slight effect on the radial residual stress, and axial residual stress and shear stress are almost uneffected by thickness of substrate. The optimum thickness of substrate is 10mm. Radius of substrate have no effect on radial stress when it is greater than 28mm, and radius of substrate has no effect on axial stress and shear stress of Sm₂Zr₂O₇ TBCs.

Abstract: The some five-axis machining center was investigated, and it divided ten subsystems. Based on analysis of fault data, the distribution of fault time submits to Weibull distribution, the distribution function and reliability function of each subsystem were confirmed. The reliability allocation model with the constraints of cost is established based on reliability prediction to get optimal reliability allocation results of the complicated mechano-electronic system. The most growth potential of the reliability of subsystem and growth situation of reliability of each subsystem could be got by using this method. The reliability allocation is an important part of reliability design, because its result influences system design directly. This provides reference for design improving of this series of new products.

Abstract: All electrical motor or generator bearings can potential suffers from electric erosion. Unfortunately, problems can start after just a few months of running a new electric motor or generator. From visual inspection, it was found that the failure happened on the raceway surface in equal spacing. There may be many reasons for this – heavier loading than has been anticipated, inadequate or unsuitable lubrication, careless handling, ineffective sealing, or fits that are too tight, with resultant insufficient internal bearing clearance. Each of these factors produces its own particular type of damage and leaves its own special imprint on the bearing. Consequently, by examining a damaged bearing such as visual inspection, it is possible, in the majority of cases, to form an opinion on the cause of the damage and to take the requisite action to prevent a recurrence.