Development of a mathematical tool to predict engine in-cylinder friction

A better fuel-efficient automotive engine is more sought-after to promote greener environment in the era of global warming. One of the factors to cause the increase of fuel consumption in vehicles is the frictional loss within an internal combustion engine. In this study, the focus is to determine the tribological behaviour between the piston top compression ring and the engine cylinder liner for a full engine cycle. Mathematical models are derived from a 1-D Reynolds equation, assuming Half-Sommerfeld and Reynolds boundary conditions. Greenwood and Tripp rough surface contact model is applied to predict frictional properties along the ring-liner contact, considering viscous and boundary friction. It is found that the Half-Sommerfeld boundary condition predicts minimum lubricant film thickness that correlates well with literature data. However, the friction force predicted by the Reynolds boundary condition along dead centres correlates better with literature data. With friction along the cylinder liner dead centres being very significant, it is, therefore, suggested that the Reynolds boundary condition be the better mathematical model in studying the piston ring-liner tribological conjunction

Correlation analysis of biodegradable additives, temperature and loading toward tribology behaviour of musa aluminata balbisiana (MBS) oil

Identification of the effect of the tribological characteristics in lubricant application is a critical part of the experimental process. A correlation study is used to identify the effect of temperature, load and biodegradable additive on the coefficient of friction (COF) and specific wear (Ws) from the experimental data. Pearson correlation coefficient (r) and analysis of variance (ANOVA) are the statistical analysis used to identify the relationship between the parameters and the significant difference in response variable which are COF and Ws. Based on the result, there is a positive moderate linear relationship between temperature to both COF and Ws with a score of r between 0.354 to 0.676. In contrast, there is a negative linear relationship between load towards COF and Ws with a -0.285 to -0.460 score of r. There is approximately no correlation with the percentage of biodegradable additives respecting COF and Ws. The result also shows that there is no significant difference between COF and Ws using ANOVA testing with a p-value is more than 0.05. This work may facilitate improvements for other researchers to identify the variable in the experimental design proces

Optimization and Modelling of Process Parameters Involved in Ultrasonic Machining of Glass Using Design of Experiments and Regression Approach

Abstract Glass is an ideal material for parts with micro-holes and has been widely used in automotive, aerospace and woodworking industries due to its superior wear and corrosion resistance. In this research paper, the statistical analysis of the ultrasonic machining of glass using design of experiments and regression approach has been done. The performance characteristics such as material re moval rate of machined samples using ultrasonic machining process have been presented. The experimental conditions were designed by using the design of experiments approach. The analysis of results has been done using the MINITAB 14.0 software and results obtained are v alidated by conducting the confirmation experiments. The F-test and P-value has been applied to determine the significant parameters

Application of Surface Treatments to Improve Fuel Efficiency of Internal Combustion Engines

To improve the tribological performance of contacting surfaces, different surface modification methods can be employed. Surface texturing and surface coating are examples of viable techniques developed for this purpose. Surface texturing involves creating micropatterns on the contacting surfaces while surface coating requires depositing a thin layer of a suitable material on the surface(s) to improve the component’s friction and wear characteristics. The performance of textured surfaces is affected by the geometric characteristic of textures.When dealing with surface coating parameters, the parameters of interests are the type of coating materials and their thicknesses. The current study aims to experimentally study the friction variation as a result of surface texturing and surface coating on the piston rings by using a custom made piston cylinder machine. Of particular interest are their running-in behavior and the associated transient friction characteristics. A new type of texturing is also proposed for the application in piston oil control rings to reduce engine friction. Experimental studies are conducted to compare their performance of grooves with three structural angles (0, 30 and 60 degrees) and two different depths (5 and 10 microns). The optimum texture with grooves parallel to the sliding direction and depth of 5 microns was found to yield a 10% reduction in the friction force. Combination of the texturing and coating showed 12.5% improvement in frictional behavior when compared to cases when only one of them was applied

Study oil thermal-physical properties for nanocellulose nanoparticles for sae40 engine oil for tribological behaviour

Wear and friction are inevitable problems in engineering applications which causes reduced efficiency in mechanical systems. One solution to this problem is to use a lubricant that can reduce friction and wear to a minimum, resulting in increased efficiency. The development of efficient lubricant additives has received significant industrial and academic attention for tribological properties enhancement and increased thermal conductivity. In general, nano-sized particles dispersed in the lubricants, known as nano lubricants, are used in mechanical systems to reduce heat and friction effectively. Furthermore, new environmental regulations will encourage the usage of lubricants with greener lubrication technologies. Addressing this issue requires the use of lubricants that conforms to environmental standards while maintaining excellent lubrication performance. Therefore, as a new green additive, this study intends to investigate the dispersion of Cellulose Nanocrystals (CNCs) nanoparticles in engine oils. The purpose of this study is to investigate the effect of CNCs added SAE 10 W 40 (SAE 40) engine oil on the thermal-physical properties and tribological behaviour. The optimum design was analysed to indicate which parameters are statistically significant for obtaining a low coefficient of friction (COF) and low wear with CNCs added on SAE 40 engine oil. CNCs nanoparticles were dispersed in the baseline engine oil using the two-step method preparation. The two-step method preparation with a low volume concentration in the range of 0.1 % to 0.9 %., was used in the preparation of CNC’s based engine oil. Thermal-physical properties such as thermal conductivity, kinematic viscosity, viscosity index (VI), density, and specific heat were measured for all volume concentrations. Meanwhile, tribological properties of CNCs added on SAE 40 engine oil were evaluated for different sliding speeds, applied load, and temperatures. The friction-wear test involves making linear reciprocating movements like a cylinder-piston ring pair operating under actual conditions. To optimize the tribology performance parameters, the Response Surface Methodology (RSM) based on the Box-Behnken design was adopted. Stability evaluation showed CNCs added SAE 40 engine oil was stable throughout the study, and after 60 days, very little sedimentation was observed. Thermal conductivity and specific heats of CNCs added SAE 40 engine oil had increased with the volume concentration. The tribology properties observation with optimal conditions of coefficient of friction (COF) and wear rates were found at 0.1% volume concentration, effective in improving the anti-wear and scuffing resistance via the formation of self-laminating protective films. The surface morphology of the specimens revealed that the CNCs added SAE 40 engine oil produced a smoother surface. The optimization results yielded an optimum COF and surface wear rate from 500 rpm, 78.71 N, and 0.1 % volume concentrations with the highest desirability of 75.4 %. The presence of CNCs nanoparticles as an additive in SAE 40 engine oils samples ultimately improved the tribological performances. Base oil containing 0.1% CNC has excellent tribological properties, including the lowest COF and the highest wear resistance under all lubrication conditions. Based on the findings of this study, it can be concluded that cellulose nanocrystal is a promising lubricant additive, especially for green application

Thermophysical properties and tribological behavior of hybrid cellulose nanocrystal copper (ii) oxide (cnc-cuo) as lubricant additives

Enhancement in the tribological behaviour of piston ring-cylinder liner contact is necessary to reduce the fuel consumption and elongate the engine time deterioration. A novel approach for improving the tribological system and thermophysical properties are dispersing nanoparticles in SAE 40 engine oil. The organic-inorganic nanolubricants is expected to improve the properties of single component nanolubricants in achieving enhancement in thermal properties, rheological properties, stability, thermophysical properties and friction and wear behaviour. The present study aims to evaluate the thermophysical properties of CNC-CuO nanolubricants, investigate the tribological behaviour of CNC-CuO nanolubricant and investigate the optimum condition of the thermophysical properties, friction and wear performance. The nanolubricants was prepared up to 0.9% volume concentration. Thermophysical properties of CNC-CuO nanolubricants were measured at the temperature of 30°C to 90 °C. Meanwhile, tribological properties of the nanolubricants were evaluated for different loads, speeds, temperature and volume concentration. The curve fitting method and Response Surface Methodology (RSM) were used to predict the thermophysical and tribological properties. Response Surface Methodology (RSM) methods were also selected to optimize the thermophysical and tribological friction behaviour. Stability evaluation showed CNC-CuO nanolubricants having an excellent stability condition with no sedimentation observed within a month. It was proven by measuring the zeta potential up to 61.1 mV and maintaining the UV-Vis spectrophotometer's concentration ratio for more than 90%. The viscosity index result shows that the higher the concentration, the VI is improved. VI enhancement is 44.3%-47.12%. Dynamic viscosity, thermal conductivity and specific heat capacity of CNC-CuO nanolubricants increased with volume concentration and decreased with temperature. Maximum enhancement in the dynamic viscosity was 74.81%, respectively, which occurred at the temperature of 90°C at 0.5% concentration. The maximum increase of thermal conductivity was 1.80566 for a volume concentration of 0.1% at 90℃. For specific heat capacity,0.5% is the optimum concentration compared with the base fluid. The proposed correlation of the thermophysical and tribological was considered to predict the properties as the margin of deviation is closer to the points located on the bisector. The results showed that the CNC-CuO nanolubricants reduced the friction coefficient by 48-50%, 33-44%, and 9–13% under boundary, mixed, and hydrodynamic lubrication. It is observed that some severe scuffing and exfoliations phenomenon occurred in SAE 40 sample while light scuffing was found on the CNC-CuO nanolubricant. The extensive scratches happened due to micro-abrasive wear. As an overall conclusion, the addition of CNC-CuO nanoparticles into the engine oil enhances thermophysical properties and tribological behaviour with the optimum concentration at 0.5%

Multifunctional optimized group method data handling for software effort estimation

Nowadays, the trend of significant effort estimations is in demand. Due to its popularity, the stakeholder needs effective and efficient software development processes with the best estimation and accuracy to suit all data types. Nevertheless, finding the best effort estimation model with good accuracy is hard to serve this purpose. Group Method of Data Handling (GMDH) algorithms have been widely used for modelling and identifying complex systems and potentially applied in software effort estimation. However, there is limited study to determine the best architecture and optimal weight coefficients of the transfer function for the GMDH model. This study aimed to propose a hybrid multifunctional GMDH with Artificial Bee Colony (GMDH-ABC) based on a combination of four individual GMDH models, namely, GMDH-Polynomial, GMDH-Sigmoid, GMDH-Radial Basis Function, and GMDH-Tangent. The best GMDH architecture is determined based on L9 Taguchi orthogonal array. Five datasets (i.e., Cocomo, Dershanais, Albrecht, Kemerer and ISBSG) were used to validate the proposed models. The missing values in the dataset are imputed by the developed MissForest Multiple imputation method (MFMI). The Mean Absolute Percentage Error (MAPE) was used as performance measurement. The result showed that the GMDH-ABC model outperformed the individual GMDH by more than 50% improvement compared to standard conventional GMDH models and the benchmark ANN model in all datasets. The Cocomo dataset improved by 49% compared to the conventional GMDH-LSM. Improvements of 71%, 63%, 67%, and 82% in accuracy were obtained for the Dershanis dataset, Albrecht dataset, Kemerer dataset, and ISBSG dataset, respectively, as compared with the conventional GMDH-LSM. The results indicated that the proposed GMDH-ABC model has the ability to achieve higher accuracy in software effort estimation

Contribution to the Assessment of the Potential of Low Viscosity Engine Oils to Reduce ICE Fuel Consumption and CO2 Emissions

[EN] The automotive industry is currently experiencing one of its most rapidly changing periods in recent decades, driven by a growing interest in reducing the negative environmental impacts caused by fossil fuels consumption and the resulting carbon dioxide (CO2) emissions generated during the operation of the internal combustion engine (ICE) which have proven to contribute significantly to Global Warming. Given the fact that a total replacement of the current fleet, dependent of fossil fuels, is unlikely to happen in the immediate future and the urgency to reducing CO2 emissions from transportation in order to tackle Global Warming, it is possible to say that optimizing current ICE technologies and conventional vehicles and engines is a first order priority. Among the technical solutions developed to improve the efficiency of ICE, low viscosity engine oils (LVEO) have emerged as an effective and low-cost method that provides reductions in fuel consumption between 0.5% and 5%. During the development of this thesis, a test plan focused on determining fuel consumption reduction when low viscosity oils are used in light duty vehicles (LDV) and heavy duty vehicles (HDV) were carried out. The test plan has been divided in three parts; the first part was focused on the study of light-duty vehicles (LDV) using one diesel engine representative of the European market. During this part three testing modes were used: comparative motored, fired stationary points and transient homologation cycle tests. All test were performed in the engine test bed. The second part of the study consisted of another comparative test, this time using a different engine oils in a HDV fleet. The study was conducted using the urban buses fleet of the city of Valencia, including 3 buses models , with 2 different powertrain technologies. The third part of the study was focused on the friction coefficient behavior within the engine tribological pairs making comparative tests in two specialized tribometers; one of reciprocating action to simulate the lubrication conditions in the piston ring-cylinder liner contact and a "ball-on-disk" tribometer to simulate the lubrication in the distribution system. The various comparative studies have served to analyze how the friction and fuel consumption responded when LVEO were used both in the ICE and the complete vehicle contexts. The fuel consumption benefit found during the test was used to calculate the carbon footprint reduction when LVEO were used.[ES] Actualmente la industria de la automoción vive uno de los periodos de cambio más vertiginosos de las últimas décadas, marcado por un creciente interés en reducir los impactos medioambientales negativos generados por el consumo de combustibles fósiles y sus consecuentes emisiones nocivas de dioxido de carbono (CO2) generados durante el funcionamiento del motor de combustión interna alternativo (MCIA). Teniendo en cuenta que el proceso de sustitución de la flota actual por una totalmente independiente de los combustibles fósiles puede tomar varias décadas, y ante la urgencia inmediata de reducir las emisiones de CO2, se puede decir que actualmente es más urgente hacer una optimización de los vehículos con motorizaciones convencionales. Entre las soluciones técnicas que se han desarrollado para mejorar la eficiencia del MCIA destaca la utilización de aceites de baja viscosidad como un método efectivo y de bajo coste de implementación que brinda reducciones del consumo entre el 0.5% y el 5%. Durante el desarrollo de esta tesis se ha llevado a cabo un plan de ensayos enfocado en determinar valores concretos de ahorro de combustible esperados cuando se utilizan aceites de baja viscosidad en vehículos de trabajo ligero y pesado. El plan de estudios se dividió en tres partes; la primera se centró en el estudio de MCIA de vehículos de trabajo ligero, utilizando un motor Diesel representativo del mercado Europeo y llevando a cabo pruebas comparativas en arrastre, puntos de funcionamiento estacionarios y ciclos transitorios de homologación. La segunda parte del estudio consta de otro ensayo comparativo, esta vez utilizando una flota de vehículos de trabajo pesado. El estudio se realizó con la flota de autobuses urbanos de la ciudad de Valencia, incluyéndose 3 modelos de autobuses, con 2 tipos de motorización diferente. La tercera parte del estudio se centró en el comportamiento del coeficiente de friction en los pares tribológicos del motor haciendo ensayos comparativos con tribómetros especializados; uno de movimiento alternativo para simular las condiciones de la interfaz piston-camisa y un "bola y disco" para simular la lubricación en el sistema de distribución, específicamente en la interfaz leva-taqué. Los diversos estudios comparativos han servido para analizar como es la respuesta general de la fricción y el consumo de combustible cuando se usan aceites de baja viscosidad, tanto a nivel de motor como para la totalidad del vehículo, encontrando diferencias de par en los ensayos de arrastre, de consumo específico de combustible en los ensayos de motor en estado estacionario y diferencias totales de consumo de combustible en los ensayos en régimen transitorio y en flota, que a su vez han permitido estimar la reducción esperada en la huella de carbono.[CA] Actualment la indústria de l'automoció viu un dels períodes de canvi més vertiginoses de les últimes dècades, marcat per un creixent interès en reduir els impactes mediambientals negatius generats pel consum de combustibles fòssils i els seus conseqüents emissions nocives de diòxid de carboni (CO2) generats durant el funcionament del motor de combustió interna alternatiu (MCIA). Tenint en compte que el procés de substitució de la flota actual per una totalment independent dels combustibles fòssils pot prendre diverses dècades, i davant la urgència immediata de reduir les emissions de CO2, es pot dir que actualment és més urgent fer una optimització dels vehicles amb motoritzacions convencionals. Entre les solucions tècniques que s'han desenvolupat per millorar l'eficiència del MCIA destaca la utilització d'olis de baixa viscositat com un mètode efectiu i de baix cost d'implementació que brinda reduccions del consum entre el 0.5% i el 5%. Durant el desenvolupament d'aquesta tesi s'ha dut a terme un pla d'assajos enfocat a determinar valors concrets d'estalvi de combustible esperats quan s'utilitzen olis de baixa viscositat en vehicles de treball lleuger i pesat. El pla d'estudis es va dividir en tres parts; la primera es va centrar en l'estudi de MCIA de vehicles de treball lleuger, utilitzant un motor dièsel representatiu del mercat Europeu i portant a terme proves comparatives en arrossegament, punts de funcionament estacionaris i cicles transitoris d'homologació. la segona part de l'estudi consta d'un altre assaig comparatiu, aquest cop utilitzant una flota de vehicles de treball pesat. L'estudi es va realitzar amb la flota d'autobusos urbans de la ciutat de València, incloent-se 3 models d'autobusos, amb 2 tipus de motorització diferent. La tercera part de l'estudi es va centrar en el comportament del coeficient de friction en els parells tribològics del motor fent assajos comparatius amb tribómetros especialitzats; Un acció reciprocante per simular les condicions del piston camisa i un bola i disc per simular la lubricació en el sistema de distribució. Els diversos estudis comparatius han servit per analitzar com és la resposta general de la fricció i el consum de combustible quan es fan servir olis de baixa viscositat, tant a nivell de motor com la totalitat del vehicle, trobant diferències de bat a els assajos d'arrossegament, de consum específic de combustible en els assajos de motor en estat estacionari i diferències totals de consum de combustible en els assajos en règim transitori i en flota, que al seu torn han permès calcular la reducció en la petjada de carbono.Ramírez Roa, LA. (2016). Contribution to the Assessment of the Potential of Low Viscosity Engine Oils to Reduce ICE Fuel Consumption and CO2 Emissions [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/73068TESI

Predicción del desgaste de moldes de inyección de plástico y aluminio

219 p.En esta tesis doctoral se han abordado los principales mecanismos de desgaste que aparecen en los moldes de inyección de plástico y aluminio. Ambos consisten en inyectar a alta temperatura, presión y velocidad un fluido (plástico y aluminio respectivamente), en un molde cuya cavidad da forma a la pieza final tras el proceso de solidificación. Este molde tiene que aguantar cientos de miles de ciclos en este entorno agresivo, lo cual lleva a limitar la vida del molde debido al desgaste que sufren estos, requiriendo reparaciones y paradas de producción inesperadas. La formación del desgaste de los moldes se genera debido a distintos mecanismos de desgaste. Algunos de estos mecanismos son comunes para ambos casos de procesos de producción estudiados, como la erosión y la corrosión. Mientras, otros son específicos, como la abrasión en la inyección de plástico y la adhesión del aluminio (die soldering) y la fatiga térmica en la inyección de aluminio. A lo largo de esta Tesis doctoral se describe la metodología seguida para generar unos modelos de predicción de desgaste de estos mecanismos de desgaste de moldes a partir de la experimentación de laboratorio realizada

Predicción del desgaste de moldes de inyección de plástico y aluminio

219 p.En esta tesis doctoral se han abordado los principales mecanismos de desgaste que aparecen en los moldes de inyección de plástico y aluminio. Ambos consisten en inyectar a alta temperatura, presión y velocidad un fluido (plástico y aluminio respectivamente), en un molde cuya cavidad da forma a la pieza final tras el proceso de solidificación. Este molde tiene que aguantar cientos de miles de ciclos en este entorno agresivo, lo cual lleva a limitar la vida del molde debido al desgaste que sufren estos, requiriendo reparaciones y paradas de producción inesperadas. La formación del desgaste de los moldes se genera debido a distintos mecanismos de desgaste. Algunos de estos mecanismos son comunes para ambos casos de procesos de producción estudiados, como la erosión y la corrosión. Mientras, otros son específicos, como la abrasión en la inyección de plástico y la adhesión del aluminio (die soldering) y la fatiga térmica en la inyección de aluminio. A lo largo de esta Tesis doctoral se describe la metodología seguida para generar unos modelos de predicción de desgaste de estos mecanismos de desgaste de moldes a partir de la experimentación de laboratorio realizada