Advances in Tribology最新文献

{"title":"Effect of Tungsten Carbides on Abrasive Wear of Hardfacing Coatings","authors":"P. Pichler, M. Leitner, F. Grün, J. Hassler","doi":"10.1155/2018/4047818","DOIUrl":"https://doi.org/10.1155/2018/4047818","url":null,"abstract":"The aim of this study is to investigate the abrasive wear loss as well as the wear mechanisms of hardfacing layers with and without tungsten carbides (WC) included in the matrix in different friction wheel test (FWT) configurations. The FWT setup is varied in regard to the materials of the rotating wheels, whereat steel and rubber materials are utilized to achieve varying wear mechanisms as representative conditions for stone milling as well as low density wood cutting processes. Coatings including fine particles of WC highlight the highest resistance against abrasive wear in rubber wheel testing condition, at which microcutting acts as the dominant effect. In comparison to the hardfacings without WC, the mean material loss majorly decreases by about 75%. On the contrary, the mean material loss of fine WC reinforced coatings increases up to 93% compared to the condition without WC if a steel wheel is utilized as rotating counterpart. Thereby, the coatings with comparably coarse WC reveal the minimum material loss with a decrease over 70% compared to the condition without WC. In conclusion, the inclusion of WC in hardfacing coatings significantly increases the wear resistance. The experimental wear test results highlight the fact that in order to achieve the optimal wear resistance the material characteristics of the hardfacings need to be properly defined considering the predominant wear mechanisms under in-service conditions.","PeriodicalId":44668,"journal":{"name":"Advances in Tribology","volume":" ","pages":""},"PeriodicalIF":2.6,"publicationDate":"2018-06-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1155/2018/4047818","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46627231","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Viscoelastic Contact Simulation under Harmonic Cyclic Load","authors":"S. Spinu","doi":"10.1155/2018/9432894","DOIUrl":"https://doi.org/10.1155/2018/9432894","url":null,"abstract":"Characterization of viscoelastic materials from a mechanical point of view is often performed via dynamic mechanical analysis (DMA), consisting in the arousal of a steady-state undulated response in a uniaxial bar specimen, allowing for the experimental measurement of the so-called complex modulus, assessing both the elastic energy storage and the internal energy dissipation in the viscoelastic material. The existing theoretical investigations of the complex modulus’ influence on the contact behavior feature severe limitations due to the employed contact solution inferring a nondecreasing contact radius during the loading program. In case of a harmonic cyclic load, this assumption is verified only if the oscillation indentation depth is negligible compared to that due to the step load. This limitation is released in the present numerical model, which is capable of contact simulation under arbitrary loading profiles, irregular contact geometry, and complicated rheological models of linear viscoelastic materials, featuring more than one relaxation time. The classical method of deriving viscoelastic solutions for the problems of stress analysis, based on the elastic-viscoelastic correspondence principle, is applied here to derive the displacement response of the viscoelastic material under an arbitrary distribution of surface tractions. The latter solution is further used to construct a sequence of contact problems with boundary conditions that match the ones of the original viscoelastic contact problem at specific time intervals, assuring accurate reproduction of the contact process history. The developed computer code is validated against classical contact solutions for universal rheological models and then employed in the simulation of a harmonic cyclic indentation of a polymethyl methacrylate half-space by a rigid sphere. The contact process stabilization after the first cycles is demonstrated and the energy loss per cycle is calculated under an extended spectrum of harmonic load frequencies, highlighting the frequency for which the internal energy dissipation reaches its maximum.","PeriodicalId":44668,"journal":{"name":"Advances in Tribology","volume":"2018 1","pages":"1-16"},"PeriodicalIF":2.6,"publicationDate":"2018-05-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1155/2018/9432894","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45661886","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Performance Evaluation of Jatropha and Pongamia Oil Based Environmentally Friendly Cutting Fluids for Turning AA 6061","authors":"T. P. Jeevan, S. R. Jayaram","doi":"10.1155/2018/2425619","DOIUrl":"https://doi.org/10.1155/2018/2425619","url":null,"abstract":"Owing to the desirable properties of vegetable oils as cutting fluids, an attempt is made to explore the potentiality of plentifully available vegetable oils as a cutting fluid for turning AA 6061. Two nonedible vegetable oils, Jatropha and Pongamia, in their chemically modified (epoxidized) versions are used as straight cutting fluids. Cutting fluids are introduced to the machining zone with the aid of Minimal Quantity Lubrication (MQL) method. Taguchi’s technique of orthogonal arrays is used to develop an effective design of experiments. The results obtained under epoxidized versions of Jatropha and Pongamia oils are compared with the results of mineral oil in terms of cutting forces and surface roughness. Experimental observations and statistical analysis show that, compared to mineral oil, the modified versions of vegetable oil-based cutting fluids are more effective in reducing the cutting forces and increasing surface finish. It is also observed that the modified Pongamia oil showed lesser flank wear compared to the other two tested oils.","PeriodicalId":44668,"journal":{"name":"Advances in Tribology","volume":"2018 1","pages":"1-9"},"PeriodicalIF":2.6,"publicationDate":"2018-05-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1155/2018/2425619","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49475119","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Microstructural Evolution in Chroming Coatings Friction Pairs under Dry Sliding Test Conditions","authors":"Xin Wang, Ru-lin Zhang, T. Zhou, Xi-cheng Wei, P. Liaw, R. Feng, Wurong Wang, Rong-bin Li","doi":"10.1155/2018/5962153","DOIUrl":"https://doi.org/10.1155/2018/5962153","url":null,"abstract":"The microstructures of subsurface layers of 20CrMnTi steel pins against chroming and nonchroming T10 under dry sliding tests were studied by means of OM (optical microscopy), XRD (X-ray diffraction), and SEM (scanning electron microscopy). Results showed that the chroming coating strengthened the disc surface and significantly affected microstructural evolution. Three layers—the matrix, deformation layer (DL), and surface layer (SL)—formed in 20CrMnTi for the chroming T10. The matrix and deformation layer (DL) formed in 20CrMnTi for the nonchroming T10. The formation of the microstructure was considered as a result of the shear deformation.","PeriodicalId":44668,"journal":{"name":"Advances in Tribology","volume":"2018 1","pages":"1-6"},"PeriodicalIF":2.6,"publicationDate":"2018-02-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1155/2018/5962153","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44325556","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Numerical Investigation of Turbulence Models for a Superlaminar Journal Bearing","authors":"A. Ding, Xiao-dong Ren, Xue-song Li, C. Gu","doi":"10.1155/2018/2841303","DOIUrl":"https://doi.org/10.1155/2018/2841303","url":null,"abstract":"With rotating machineries working at high speeds, oil flow in bearings becomes superlaminar. Under superlaminar conditions, flow exhibits between laminar and fully developed turbulence. In this study, superlaminar oil flow in an oil-lubricated tilting-pad journal bearing is analyzed through computational fluid dynamics (CFD). A three-dimensional bearing model is established. CFD results from the laminar model and 14 turbulence models are compared with experimental findings. The laminar simulation results of pad-side pressure are inconsistent with the experimental data. Thus, the turbulence effects on superlaminar flow should be considered. The simulated temperature and pressure distributions from the classical fully developed turbulence models cannot correctly fit the experimental data. As such, turbulence models should be corrected for superlaminar flow. However, several corrections, such as transition correction, are unsuitable. Among all the flow models, the SST model with low-Re correction exhibits the best pressure distribution and turbulence viscosity ratio. Velocity profile analysis confirms that a buffer layer plays an important role in the superlaminar boundary layer. Classical fully developed turbulence models cannot accurately predict the buffer layer, but this problem can be resolved by initiating an appropriate low-Re correction. Therefore, the SST model with low-Re correction yields suitable results for superlaminar flows in bearings.","PeriodicalId":44668,"journal":{"name":"Advances in Tribology","volume":"2018 1","pages":"1-14"},"PeriodicalIF":2.6,"publicationDate":"2018-01-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1155/2018/2841303","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49093939","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"FEM Design of a Cutting-Edge Support System for Micro-GT","authors":"F. Stefani, R. Francesconi, Andrea Perrone","doi":"10.1155/2018/9016906","DOIUrl":"https://doi.org/10.1155/2018/9016906","url":null,"abstract":"The design of the support system (shaft, bearings, and mechanical coupling devices) of the rotor plays a key role in the development of efficient micro-gas turbines (micro-GTs) for distributed power generation. Foil air bearings are the most widespread technical solution well suited to design a reliable support system, although they cannot withstand a large number of start-stop cycles of the units. In order to overcome such limitation, we have recently proposed an innovative support system that takes advantage of spline couplings and two bearing types (e.g., air and rolling-element bearings). The devised support system employs splines as both convenient coupling systems and actuators for the load partition between the two bearing types. In the present work, the helical spline coupling is studied by means of structural FEM analyses including contact simulation in order to design the support system. Numerical results confirm previous findings in that the load transfer through the spline coupling is mainly a function of the helix angle. In addition, friction factor and structural stiffness cannot be neglected in the accurate design of the spline coupling. Such design parameters are now included in the proposed design procedure, which formerly assumed frictionless contact and rigid bodies.","PeriodicalId":44668,"journal":{"name":"Advances in Tribology","volume":"2018 1","pages":"1-12"},"PeriodicalIF":2.6,"publicationDate":"2018-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1155/2018/9016906","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"64739025","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Expansion of the Metrological Visualization Capability by the Implementation of Acoustic Emission Analysis","authors":"P. Bergmann, F. Grün, Florian Summer, I. Gódor, Gabriel Stadler","doi":"10.1155/2017/3718924","DOIUrl":"https://doi.org/10.1155/2017/3718924","url":null,"abstract":"The acquisition and evaluation of acoustic emissions (AE) in tribology have proven to be a meaningful tool for condition monitoring and offer possibilities to deepen the understanding of tribological processes. The authors used this technology with the aim of expanding existing test methodologies towards increased visualization capability of tribological processes and investigated the correlation between tribological processes and acoustic emissions on a Ring-on-Disc and a close-to-component journal bearing test setting. The results of this study include the description of friction as well as wear processes and prove the usability of several AE evaluation parameters whereby a close correlation between AE and tribological processes can be shown. Consequently, it was possible to expand the visualization and evaluation capabilities of the test settings offering additional insights by making use of AE.","PeriodicalId":44668,"journal":{"name":"Advances in Tribology","volume":"2017 1","pages":"3718924"},"PeriodicalIF":2.6,"publicationDate":"2017-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1155/2017/3718924","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42312033","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Dynamic Characterization of Rubber O-Rings: Squeeze and Size Effects","authors":"F. Al-Bender, F. Colombo, D. Reynaerts, R. Villavicencio, T. Waumans","doi":"10.1155/2017/2509879","DOIUrl":"https://doi.org/10.1155/2017/2509879","url":null,"abstract":"This paper concerns the dynamic characterization of rubber O-rings used to introduce damping in high speed gas bearing systems. O-shaped rubber rings composed of high temperature rubber compounds are characterized in terms of stiffness and damping coefficients in the frequency range 100–800 Hz. Simple formulas with frequency independent coefficients were identified to express the viscoelastic properties of the O-rings. The formulas proposed approximate the stiffness and damping coefficients of O-rings of general size.","PeriodicalId":44668,"journal":{"name":"Advances in Tribology","volume":"2017 1","pages":"1-12"},"PeriodicalIF":2.6,"publicationDate":"2017-07-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1155/2017/2509879","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49471361","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A Novel Two-Disc Machine for High Precision Friction Assessment","authors":"Jakob Moder, F. Grün, M. Stoschka, I. Gódor","doi":"10.1155/2017/8901907","DOIUrl":"https://doi.org/10.1155/2017/8901907","url":null,"abstract":"The concept of two-disc model testing has proven to deliver valuable information for the applicability of new technologies, such as surface structuring, coatings, alternative fluids, or advanced materials, in actual machine elements. In this article an advanced two-disc machine with sophisticated control technology for dry and lubricated setup is presented. (i) All involved components are controlled via a powerful PLC unit leading to the possibility of realising extremely accurate SRRs down to . (ii) High-speed data acquisition allows local insight into tribological phenomena by providing 72 data points along one shaft rotation. (iii) Several lubrication scenarios such as fluid, mixed, and starved lubrication, as well as dry contacts, can be considered. (iv) Raw-data of all sensors, including normal force, friction force, vibration speed, stiffness (wear), infrared temperature, contact potential, and motor speed, is presented. Some example results of dry polymer-steel tribosystems and lubricated experiments are shown to elucidate the capabilities of the novel test rig.","PeriodicalId":44668,"journal":{"name":"Advances in Tribology","volume":"2017 1","pages":"1-16"},"PeriodicalIF":2.6,"publicationDate":"2017-06-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1155/2017/8901907","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48281226","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Effect of Dam Depth and Relief Track Depth on Steady-State and Dynamic Performance Parameters of 3-Lobe Pressure Dam Bearing","authors":"Ashutosh Kumar, S. Kakoty","doi":"10.1155/2017/1380367","DOIUrl":"https://doi.org/10.1155/2017/1380367","url":null,"abstract":"The present study analyzes the effect of pressure dam depth and relief track depth on the performance of three-lobe pressure dam bearing. Different values of dam depth and relief track depth are taken in nondimensional form in order to analyze their effect. Results are plotted for different parameters against eccentricity ratios and it is shown that the effect of pressure dam depth and relief track depth has great significance on stability and other performance parameters. Study of stability and performance characteristics is undertaken simultaneously.","PeriodicalId":44668,"journal":{"name":"Advances in Tribology","volume":"2017 1","pages":"1-11"},"PeriodicalIF":2.6,"publicationDate":"2017-03-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1155/2017/1380367","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48750788","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}