Effect of Silicon Carbide Nanoparticles on the Friction-Wear Properties of Copper-Based Friction Discs

To study the influence of nano-additives on the friction-wear characteristics of friction materials, the nano-sized silicon carbide particles which have excellent chemical and physical properties are considered to add in composite to form the modified friction material. The influence of the silicon carbide nanoparticles (SCN) on the friction-wear characteristics of copper-based friction materials (CBFM) is investigated via the SAE#2 (made in Hangzhou, China) clutch bench test with the applied pressure, rotating speed, and automatic transmission fluid (ATF) temperature taken into account. Moreover, the variations of friction torque and temperature are considered to evaluate the friction performance, and the variable coefficient is employed to describe the friction stability. The wear characteristics of friction materials are investigated by the disc changes in thickness and micro-morphology. The results show that the CBFM with SCN can provide a higher friction torque, which increased by 30% to 50% compared with CBFM. The variable coefficient of CBFM with SCN changes from 674 to 52 with the rotating speed raised from 600 rpm to 3000 rpm, which shows that the friction stability is relatively worse. Furthermore, the micromorphology shows that the CBFM with SCN has lower porosity and surface roughness, which increases the microscopic contact area and the coefficient of friction (COF). Simultaneously, the reduction in porosity also leads to a decrease in the cooling quality, bringing about a rapid temperature rise. Thus, the wear amount of CBFM with SCN increases significantly, especially for the friction disc in the axial middle position.

Modeling and simulation of marine SCR system based on Modelica

With the increasing awareness of global marine environmental protection, the emission of ship exhaust pollutants is strictly restricted. Selective catalytic reduction (SCR) technology is the mainstream technology to reduce ship NOx emission and make it meet IMO tier III regulations. A SCR reaction kinetic model based on Modelica language was established by Dymola software to predict the denitration efficiency, ammonia slip rate, and other parameters of SCR system. According to the functional structure of marine SCR system, the SCR system model is divided into urea injection module, mixer module, and SCR reactor module. The model was verified by SCR system bench test of WD10 diesel engine, which proved that the model can preferably reflect the actual situation. Using the established model, the effects of temperature, flow rate, NH3/NOx Stoichiometric Ratio (NSR), and cell density on the denitration performance of SCR system were analyzed. The results showed that the exhaust gas temperature and NSR have a great influence on the denitration efficiency. The injection amount of urea solution in marine SCR system should be based on the exhaust gas temperature and exhaust flow rate.

A GEOMETRICAL SURFACE TEXTURE STUDY OF CYCLOID DRIVE DISCS AFTER BENCH TESTS

The article presents the results of a geometrical surface texture study of cycloid drive discs after bench tests. For this purpose, the working surfaces, such as peak and valley areas of the epicycloid and the holes inner surfaces of both discs, were investigated using contact profilometry. From each surface, a transverse profiles were extracted, before and after 50 cycles of bench test. The discs and the profiles were examined for signs of wear and roughness changes. For each profile, the Ra and Rz roughness parameters were determined. On the base of the obtained profiles and the values of roughness parameters, it can be stated that the assumed test parameters provide stable working conditions, with an uninterrupted lubrication film, which results in practically negligible and unmeasurable wear. Taking into account the operating specification of a helicopter winch as an example of potential application of the presented cycloidal drive, the developed solution fulfils the requirements concerning wear resistance.

Analysis of the Influence of Transmission Housing Elasticity on the Vibration Characteristics of Gear Shafting under Coupling Effect

The influences of transmission housing elastic deformations on the vibration gear shafting characteristics are studied. The vibration model of the vehicle transmission system in consideration of the dynamics coupling of the housing and the gear shafting is constructed. Aiming at a vehicle transmission, the mathematical model of the bending and torsional gear shafting vibrations is established based on the lumped mass method. Following the elastic treatment of the box, a comprehensive stiffness model at the bearing considering the housing deformation is proposed to achieve the dynamic coupling between the box and the gear shafting system. Furthermore, the gear shafting vibration characteristics considering housing deformations are obtained by integrating multisource dynamic excitation, which is solved using an iterative method. The results are verified through a bench test. And, it shows that the elastic deformation of the housing aggravates the gear shafting vibration (bending and torsional coupled vibration). The peak frequency mostly remains the same. The maximum speed changes amplitude and associated root mean square value (calculated at the gear position) increase by 55.5% and 59.6%, respectively. Next, the maximum bearing support force and its root mean square value are increased by 63.7% and 97.6%, respectively. Finally, the largest increase in maximum vibration acceleration at the measuring point and the simulated root mean square value are 90% and 63.1%, respectively. It is concluded that the research results provide a theoretical basis for the study of transmission dynamic reliability.

Experimental Investigation and Fault Diagnosis for Buckled Wet Clutch Based on Multi-Speed Hilbert Spectrum Entropy

The multi-disc wet clutch is widely used in transmission systems as it transfers the torque and power between the gearbox and the driving engine. During service, the buckling of the friction components in the wet clutch is inevitable, which can shorten the lifetime of the wet clutch and decrease the vehicle performance. Therefore, fault diagnosis and online monitoring are required to identify the buckling state of the friction components. However, unlike in other rotating machinery, the time-domain features of the vibration signal lack efficiency in fault diagnosis for the wet clutch. This paper aims to present a new fault diagnosis method based on multi-speed Hilbert spectrum entropy to classify the buckling state of the wet clutch. Firstly, the wet clutch is classified depending on the buckling degree of the disks, and then a bench test is conducted to obtain vibration signals of each class at varying speeds. By comparing the accuracy of different classifiers with and without entropy, Hilbert spectrum entropy shows higher efficiency than time-domain features for the wet clutch diagnosis. Thus, the classification results based on multi-speed entropy achieve even better accuracy.

Study of the destruction of the chassis main cross member made of VT22 alloy

The reasons for the destruction of the chassis main cross member made of alloy VT22 are considered and analyzed in bench test conditions. The chemical composition, mechanical properties, as well as macro- and microstructure of the material were studied. The tests of the cross-arm material for crack resistance and low-cycle fatigue (LCF) with the determination of the durability were carried out. The results of analysis proved that material meets the declared performance characteristics. A fractographic study of the traverse fracture showed that the fracture occurred from several foci according to the fatigue mechanism. The length of the longest fatigue crack was 1.7 mm and the critical stress intensity factor KIc was thus attained. Proceeding from the dimensions of the part at the site of fracture, the maximum crack length and the value of the critical stress intensity factor obtained experimentally KIc = 56.5 MPa • m1/2, we have calculated the nominal tensile stress at the moment of fracture. The calculated value of the nominal stresses is 1022 MPa, which is comparable to the yield strength of the material (1100 MPa). A high level of tensile stresses in the loading cycle is considered the most probable reason for the destruction of the chassis main cross member in the conditions of bench tests.

EOR Returned Polymer Removal from Produced Water by Chemical Coagulation – A Successful Pilot Testing

Severe fouling of crude oil and produced water treatment equipment of Mangala Processing Terminal (MPT) with elastic deposits has been observed after EOR polymer breaking through to the producing wells. Fouling by polymer containing solids caused the system bottlenecking impacting on crude production rates and deterioration of water quality for injection due to increase of total solids loading. The objective of the study included developing the water treatment technology for removing the returned polymer, developing the pilot run for implementation of the technology and scaling up the process if the pilot shows success. Crude processed at MPT is produced from Mangala, Bhagyam and Aishwarya fields which are located at the north-west part of India. Full field polymer flooding has been implemented in the Mangala field from 2015. Fouling of downhole and topside equipment with elastic deposits has been reported soon after polymer breakthrough the same year. For reducing the fouling potential and solids loading, the concept of removing the returned polymer from produced water has been considered as beneficial. Removal of polymer through the chemical coagulation was considered for developing. Extensive laboratory and bench testing have been carried out. Based on the laboratory results, the pilot was developed and carried out on the flotation equipment available at MPT. In the laboratory and bench test for polymer coagulation, over 70% polymer removal was achieved with non-sticky flocks and minimal sludge. The tests also demonstrated reduced suspended solids, residual oil and filterability improvement of treated water. The pilot run confirmed effectiveness of the chemical coagulation process to remove polymer. Polymer removal > 70% was observed during the pilot. Oil removal from produced water at 60-80% was seen. Cloud point of polymer remaining in water increased from 60°C to > 110°C indicating on the significant potential reduction of remaining polymer to precipitate from treated water. The pilot results demonstrated on the applicability of the technology of chemical polymer removal at MPT and will be used for scaling up the treatment facilities.