Decontamination of a Contaminated RCP Shaft Using the SP-HyBRID Process

It is very important to minimize the waste generation for decontamination of the reactor coolant system in a nuclear facility. As an alternative to commercial decontamination technologies, an inorganic acid chemical decontamination (SP-HyBRID) process can be effectively applied to the decontamination because it can significantly reduce the waste generation. In this study, the decontamination of a contaminated reactor coolant pump shaft from a nuclear facility was conducted using the SP-HyBRID process. First, equipment for a mock-up test of the decontamination was prepared. Detailed experimental conditions for the decontamination were determined through the mock-up test. Under the detailed conditions, the contaminated shaft was successfully decontaminated. The dose rate on the shaft surface was greatly reduced from 1400 to 0.9 μSv/h, and the decontamination factor showed a very high value (>1500).

Recent Patent on an Energy Conserved Journal Bearing with the Slippage Sleeve Surface

Background: Energy consumption in mechanical apparatus has become a big problem in modern industry. It is very important to develop energy-conserved rotary machines, which are very promising in the future. Objective: To introduce a patented energy-conserved hydrodynamic journal bearing with low friction where the interfacial slippage is designed on the whole sleeve surface. Methods: The analytical results are presented for the carried load and friction coefficient of the introduced bearing based on the limiting interfacial shear strength model. The performance of the introduced bearing is compared with that of the conventional hydrodynamic journal bearing for the same operating condition. Results: The obtained results show that in the same operating condition, the carried load of the introduced bearing can be 35%~50% times that of the conventional journal bearing, but its friction coefficient on the shaft surface can be 30%~70% times that of the conventional journal bearing, while its friction coefficient on the sleeve surface is considerably lower and can only be 5%~20% times that of the conventional journal bearing. The friction reducing effect of the bearing depends on the eccentricity ratio and the fluid-sleeve surface interfacial shear strength; the lower the latter, the smaller the friction coefficients on both the shaft and sleeve surfaces. Conclusion: The introduced bearing is obviously of low friction and energy-conserved. It has application values especially in the condition of modest eccentricity ratios, where the loss of the loadcarrying capacity of the bearing due to the interfacial slippage is not so large.

Experimental Investigation and Numerical Modelling of a Large Heavily-Loaded Tilting Pad Journal Bearing With Polymer Lined Pads

A large tilting-pad journal bearing (TPJB) with “PEEK” polymer-lined pads was tested over a range of operating conditions representative of those experienced on turbogenerators used in fossil fuel power plants. The 500 mm diameter test-bearing has four offset-pivot pads, ball and socket pivots, load-between-pivot configuration, directed lubrication and hydrostatic jacking features. The operating conditions explored during the test campaign characterize the static and dynamic behaviour of the bearing over a range of shaft surface speeds between 40 m/s and 95 m/s and maximum specific load of 4.75 MPa. Similar test conditions were previously investigated on the same bearing with whitemetal lined pads, allowing for a direct comparison. A thermo-elasto-hydrodynamic (TEHD) model for TPJBs with polymer-lined pads is introduced in this paper and validated against experimental test data. Experimental data along with numerical results reveal and confirm the superior performance that can be attained using TPJBs with polymer lined pads at high specific loads.

Observation of Tribological Wear on PEEK Shaft with Artificial Defect under Radial Rolling Sliding Point Contact

This paper’s aim is to develop the tribological repair method in PEEK (Poly-ether-ether-ketone) polymer mechanical parts with surface damage. The radial rolling sliding contact tests were carried out by using a machined PEEK shaft with an artificial defect as surface damage. An alumina ball and a PTFE composite pin contacted a PEEK shaft specimen under cyclic compressive stress with friction. The particle as solid lubricant from a PTFE composite pin filled up the crevice of the artificial defect. After that, the artificial defect was covered with the deformed microgrooves on the PEEK shaft surface. Due to adhesion by compressive stress and friction, the crevice of the artificial defect was closed. In a running-in process, the artificial defect could be reduced by the adhesion repair.

Research on Mechanical Properties of 210Cr12 Shaft Surface Processed with Rolling

The rolling process is one of the most effective ways for strengthening a part’s surface. As the press force exerted on specimen in rolling process, material in the surface layer will deform plastically if the press force is sufficient. That might result in grain refinement, dislocation configuration change, or phase change in specimen surface layer material. Consequently, the surface material mechanical properties can be changed. The effects of rolling parameters on surface residual stress, micro-hardness, and surface roughness for a 210Cr12 shaft have been investigated. After the rolling process, the surface residual stress of the specimen changes from tensile stress to compressive stress, and a stable residual compressive stress layer is formed. The maximum absolute value of compressive stress can be up to 216MPa. With the increase of the value of contact stress exerted on shaft surface and the number of rolling cycles, the absolute value of residual compressive stress increases firstly and then becomes stable. With the increase of depth from shaft surface to interior, the absolute value of residual compressive stress increases initially, then decreases and disappears finally. The maximum absolute value of residual compressive stress exists at the position beneath specimen surface about 0.025mm. The depth of residual stress layer is about 0.2 mm. Research results indicate that shaft surface microhardness can be improved within small range, surface roughness can be reduced up to 67%.

Study on Sealing Performance of Oil Seal with Micro-pores Textured in Rotary Shaft Surface

In order to improve the reliability and the long life cycle of the lip seals, comprehensive consideration of the liquid film cavitation and JFO mass conservation boundary conditions, the geometry model of the oil seal with micro-diamonds textured on the shaft surface is given, and its mathematical model is built, the relevant numerical calculation method is used, eventually that the film pressure distribution and the micro diamond pores structure parameters effect on the seal performance are obtained under the different operating conditions. The results showed that the dynamic pressure effect caused by the diamond pores can make the oil film pressure field between the axial surface and the lip produced regular axial and radial wave change. At the same time, the change of working conditions strengthen or weaken the change law of the oil film pressure field, so which make the reliability of the liquid pressure, lubricating property and pump suction effect also change accordingly. The size, shape and pores direction of the micro-diamonds texture have great influence on the oil seal performance and lubrication characteristics, which can help to reduce the leakage rate, control the pump suction direction, stable the liquid pressure and reduce the friction. In order to improve the stability of the liquid film and pump suction effect, reduce the leakage rate, friction and wear, the axial surface micro-diamond pores texture of which the cone width ratio is 0.4-0.6, the pores depth is 1.5-4.5μm and the tilt angle is 40°-50° shall be selected for the oil seals.

Study of the character and causes of destruction of the cardan shaft of the propeller engine

The results of studying operational destruction of a high-loaded cardan shaft of the propeller engine made of steel 38KhN3MFA are presented to elucidate the cause of damage and develop a set of recommendations and measures aimed at elimination of adverse factors. Methods of scanning electron and optical microscopy, as well as X-ray spectral microanalysis are used to determine the mechanical properties, chemical composition, microstructure, and fracture pattern of cardan shaft fragments. It is shown that the mechanical properties and chemical composition of the material correspond to the requirements of the regulatory documentation, defects of metallurgical origin both in the shaft metal and in the fractures are absent. The microstructure of the studied shaft fragments is tempered martensite. Fractographic analysis revealed that the destruction of cardan shaft occurred by a static mechanism. The fracture surface is coated with corrosion products. The revealed cracks developed by the mechanism of corrosion cracking due to violation of the protective coating on the shaft. The results of the study showed that the destruction of the cardan shaft of a propeller engine made of steel 38Kh3MFA occurred due to formation and development of spiral cracks by the mechanism of stress corrosion cracking under loads below the yield point of steel. The reason for «neck» formation upon destruction of the shaft fragment is attributed to the yield point of steel attained during operation. Regular preventive inspections are recommended to assess the safety of the protective coating on the shaft surface to exclude formation and development of corrosion cracks.

Object Detection and Classification of Metal Polishing Shaft Surface Defects Based on Convolutional Neural Network Deep Learning

Defective shafts need to be classified because some defective shafts can be reworked to avoid replacement costs. Therefore, the detection and classification of shaft surface defects has important engineering application value. However, in the factory, shaft surface defect inspection and classification are done manually, with low efficiency and reliability. In this paper, a deep learning method based on convolutional neural network feature extraction is used to realize the object detection and classification of metal shaft surface defects. Through image segmentation, the system methods setting of a Fast-R-CNN object detection framework and parameter optimization settings are implemented to realize the classification of 16,384 × 4096 large image little objects. The experiment proves that the method can be applied in practical production and can also be extended to other fields of large image micro-fine defects with a high light surface. In addition, this paper proposes a method to increase the proportion of positive samples by multiple settings of IOU values and discusses the limitations of the system for defect detection.

Simulations of the Influence of the Heat Flux at the Shaft Surface of the Conical Slide Bearing on Its Hydrodynamic Lubrication and Operating Parameters

The aim of this work is to investigate, how in the adopted model of hydrodynamic lubrication of a conical slide bearing, the change of the heat flux value at the bearing shaft, affects bearing operating parameters. In this research, the authors use, the known from the literature, Reynolds type equation, describing the stationary hydrodynamic lubrication process of a conical slide bearing. The analytical, solutions, that determine the components of the lubricating oil velocity vector and the equation (analytical solution of energy equation) determining the three-dimensional temperature distribution in the lubrication gap, was also adopted from previous works. In order to obtain numerical solutions, the Newton’s method was used, and the derivatives in the Reynolds type equation were approximated by the finite differences. An application of the method of subsequent approximations allowed considering the influence of temperature, pressure and shearing rate on the viscosity of lubricating oil. The considerations were performed by adopting the Reynolds condition of the hydrodynamic oil film. It was tested, how the assumed value of the heat flux on the bearing shaft surface affects the values of the obtained operating parameters, i.e. the transverse and longitudinal component of the load carrying capacity, friction force and coefficient of friction.