Browse Topic: Tribology
ABSTRACT The Department of Defense is a major consumer of petroleum products – over 700 million gallons per day. While the majority of fuel consumed is for aircraft, in terms of logistics and exposure of personnel to hazardous conditions, the amount of fuel consumed in ground vehicles is considerable, with the cost (in-theatre, delivered) ranging from $100 to $600/gallon. This paper addresses the impact that parasitic friction mechanisms (boundary lubrication and lubricant viscosity) have on engine friction and overall vehicle efficiency. A series of mechanistic models of friction losses in key engine components was applied to investigate the impact of low-friction technologies on the fuel consumption of heavy-duty, on-road vehicles. The results indicate that fuel savings in the range of 3 to 5% are feasible by reducing boundary friction and utilizing low-viscosity engine lubricants. The paper will discuss the implications of the studies (as performed for commercial heavy-duty trucks
The once rarified field of Artificial Intelligence, and its subset field of Machine Learning have very much permeated most major areas of engineering as well as everyday life. It is already likely that few if any days go by for the average person without some form of interaction with Artificial Intelligence. Inexpensive, fast computers, vast collections of data, and powerful, versatile software tools have transitioned AI and ML models from the exotic to the mainstream for solving a wide variety of engineering problems. In the field of braking, one particularly challenging problem is how to represent tribological behavior of the brake, such as friction and wear, and a closely related behavior, fluid consumption (or piston travel in the case of mechatronic brakes), in a model. This problem has been put in the forefront by the sharply crescendo-ing push for fast vehicle development times, doing high quality system integration work early on, and the starring role of analysis-based tools in
Employing the stir casting process, a unique hybrid composites were fabricated, using A356 as the matrix and reinforced with ZrSiO4 and TiB2 particulates. The produced specimens were initially in their as-cast state. Following that, the reinforcement particle concentrations were changed 2 and 4 weight percentages (wt%) of ZrSiO4 and keeping a constant 6 wt% of TiB2. Three samples were exposed to dry sliding conditions at room temperature using a tribometer. Two applied loads of magnitude 10N and 50N and a sliding velocity of 1m/s and 2m/s were selected as testing parameters. After measuring the wear rate (WR) and the coefficient of friction (COF), the worn-out pin surfaces were examined using scanning electron microscopy (SEM). The results of the study indicated that, under different sliding parametric conditions, the hybrid composite sample with a weight percentage of A356, specifically with 4% ZrSiO4 and 6% TiB2, displayed a minimal WR and a higher COF compared with the remaining
Additive manufacturing (AM) is a common way to make things faster in manufacturing era today. A mix of polypropylene (PP) and carbon fiber (CF) blended filament is strong and bonded well. Fused deposition modeling (FDM) is a common way to make things. For this research, made the test samples using a mix of PP and CF filament through FDM printer by varying infill speed of 40 meters per sec 50 meters per sec and 60 meters per sec in sequence. The tested these samples on a tribometer testing machine that slides them against a surface with different forces (from 5 to 20 N) and speeds (from 1 to 4 meters per sec). The findings of the study revealed a consistent linear increase in both wear rate and coefficient of friction across every sample analyzed. Nevertheless, noteworthy variations emerged when evaluating the samples subjected to the 40m/s infill speed test. Specifically, these particular samples exhibited notably lower wear rates and coefficients of friction compared to the remaining
In this study, we have investigated the microstructural characteristics, the mechanical properties, and the dry sliding wear behavior of a ceramic coating consisting of zirconia (ZrO2) and alumina (Al2O3) deposited by flame spraying. A series of wear tests were carried out under a variety of loads and at two different sliding speeds. The evaluation included an examination of the coating microstructure, microhardness, coefficient of friction (COF), and wear resistance of the flame-sprayed coating. The results showed that the coatings had a perfectly structured micro-architecture and were metallurgically bonded to the substrate. The Al2O3 coating exhibited a fine granular structure with pores and oxides. The microstructure of Al2O3-10 wt.% ZrO2, on the other hand, showed a blocky structure with a uniform distribution of ZrO2 inclusions in the composite coating. X-ray diffraction (XDR) results showed that the phases in both coatings were predominantly α-Al2O3 with a minor presence of γ
Micro-dimple is one of the promising surface texturing technologies to reduce friction loss due to the generation of thicker oil film caused by the cavitation occurrence around the micro-dimples. In this study, the flow behavior of oil film around micro-dimples was directly observed by laser-induced fluorescence (LIF). LIF observation for the oil flow showed that micro- dimples induced the cavitation occurrence that contributed to increase the oil film thickness. This was in good agreement with the results of the friction test, and it was thus proved that the cavitation occurrence by micro-dimples is significantly effective for the friction reduction
Digitalization offers a variety of promising tools for improving large internal combustion engine technology. This also includes the inspection of important engine components such as cylinder liners. Modern concepts for condition monitoring of the inner surfaces of cylinder liners are often based on indirect methods such as lubricating oil or vibration condition monitoring. However, a position-based inspection of roughness and lubrication properties of the liner surface is currently not possible during operation, nor is it feasible during engine standstill. For large engines in particular, the evaluation of surface properties currently requires disassembly and cutting of the inspected liner, followed by a sophisticated microscopic surface depth measurement. Although this process provides a high-resolution three-dimensional surface model, such measurement methods are destructive and costly. The goal of the research presented here is to develop a simpler and nondestructive method for
Alumina (Al2O3) thin film coatings are applied on Al alloys using Plasma Electrolytic Oxidation (PEO) method to reduce the wear and corrosion problems. Plasma Electrolytic Aluminating (PEA) is a technique which could generate Alumina coatings on cast iron, mild steel and copper alloys. In this study, the aim is to explore the anti-wear and anti-corrosion behaviours of PEA Alumina coatings on gray cast iron. The dry sliding tribology test data was obtained from Pin-on-Disk (POD) tests against SAE 52100 steel and Tungsten Carbide (WC) counterfaces. Comparing with the PEO Alumina coatings, the PEA Alumina coating has much lower Coefficient of Friction (COF) and less wear. The microstructure, chemical composition and phase composition of this coating were investigated with Scanning Electron Microscope (SEM), Energy-Dispersive X-Ray Spectroscopy (EDX) and X-Ray Diffraction (XRD), respectively. There was FeO (or FeAl2O4) found on the PEA Alumina coating. To figure out the relationship
Thermoelastic instabilities in the contact of brake friction material cause hotbands and hotspots on the surface of brake disc. These phenomena generate thermal stresses that result in generation of cracks, which limit the lifetime of the discs. In the present work, the influence of the chemical composition of brake discs on the thermoelastic behavior of the system and on the lifetime of the discs was investigated. The experimental evaluation was carried out in an inertial dynamometer using the SAE J3080 standard procedure applied on a brake system. Two discs (namely A and B) with different chemical compositions were subjected to the tests. The brake pad composition was kept fixed. The thermoelastic effects on the inner surface of the disc were observed by contact (thermocouple) and noncontact measurement techniques (thermography), as well as through photographic images of the disc’s surfaces. Disc A showed negligible amount of Nb while disc B exhibited 0.360%. Besides, disc B
On urban and emission homologation cycles, engines operate predominantly at low speeds and part loads where engine friction losses represent around 10% of the consumed fuel energy but would account for 25% of the fuel consumption once combustion efficiency is taken into account. Under such mild conditions, engine and engine oil temperatures are also lower than ideal. The influence of oil viscosity on friction losses are significant. By reducing lubricant viscosity, engine friction, fuel consumption and emissions are reduced. Tribological and machine learning models were investigated to predict the effect of oil viscosity on fuel consumption during the FTP75 emission cycle with the use of detailed actual emission test measurements. Oil viscosity was calculated with the measured oil temperature. As the same vehicle transient is followed in the cold and hot phases, the models were evaluated by comparing their prediction of fuel consumption in the hot phase versus the measured value. The
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