Various welding processes for joining aluminium alloy with steel: Effect of process parameters and observations–a review

The versatile aluminium alloys and steel are being used in automotive engines (exhaust systems), pressure vessels (flanges), turbine rotors, boilers (bonnet) and in many applications. The collective effect of these two metals created a revolution and are being utilized in most of the sectors wherein joining of these two dissimilar materials are always a major challenge faced by the manufacturers. Initially, the rivets were widely used for joining dissimilar materials owing to easy installation and flexibility, but the joint interlock fails and sudden ruptures occurred when exposed to higher load. Hence, numerous welding processes like metal inert gas welding, friction stir welding, friction stir spot welding, advanced laser welding, advanced cold metal transfer welding and hybrid welding techniques have been introduced in order to conquer the above problem because of residual stresses, cracks, distortion, and undercuts. Moreover, an appropriate standardization with controlled process inputs is still an uncertainty in joining the dissimilar materials. Hence, a detailed review on joining the dissimilar metals based on aluminium alloy and steel by various welding processes and influence of their parameters on the properties have been summarized in detail which would be a reference for manufacturing industries in the coming decades.

Experimental analysis and 1D simulation of an advanced hybrid boosting system for automotive applications in transient operation

Due to the increasingly restrictive limits of pollutant emissions, electrification of automotive engines is now mandatory. For this reason, adopting hybrid boosting systems to improve brake specific fuel consumption and time-to-boost is becoming common practice. In this paper an advanced turbocharging system is analyzed, consisting in an electrically assisted radial compressor and a traditional turbocharger. As a first step, the steady-state performance of each component was measured at the University of Genoa test rig. Subsequently another experimental campaign was carried out to evaluate the transient response of the entire turbocharging system. Two different layouts were compared: upstream and downstream. In the upstream configuration the electrically assisted compressor was placed in front of the traditional turbocharger, in the downstream configuration the e-compressor was positioned after the traditional turbocharger. The two different coupling configurations, upstream and downstream, were then modeled in 1-D simulation software following the dimensions and characteristics of the experimental line from which the exploited data originates. The models were first validated by emulating the steady-state condition and subsequently the transient response was simulated and analyzed. Secondly, the transient response of the two layouts was compared, removing the constraints imposed by the experimental activity. The practical significance of the results is outlined, with reference to the transient response of the turbocharger. The adoption of the boosting system presented here allows a fast and stable transient response. Moreover, a reduction in the engine back pressure could be achieved through an optimization of the boosting system-engine matching calculation.

Tribological evaluation of piston ring/cylinder liner assembly in automotive engines using GNP as a lubricant additive

Friction and wear are the main causes of energy dissipation in automotive engines. To minimize the frictional power losses, it is extremely important to improve the tribological characteristics of ring/liner assembly which accounts for almost 40–50% frictional power losses. The present study attempts to mitigate friction and wear of the ring/liner tribo-pair using GNP/SAE 15W40 nano-lubricant. To simulate the ring/liner interface, the tribological performance of nano-lubricants was assessed using a tribometer based on ASTMG181 standard under various operating conditions. The coefficient of friction (COF) and wear rate lowered using graphene nano-lubricants (GNL). The tribological results showed that friction coefficient, wear rate, and surface roughness of piston ring improved in the range 17.71%–42.33%, 25%–40.62%, and 61%, respectively, under GNL lubricating conditions during the boundary lubrication. Further, the characterization of wear tracks of piston ring and cylinder liner confirmed tribo-film formation on worn surfaces resulting in decreased COF and wear rate.

Substantiation of the algorithm of information technology for energy monitoring of tractor engines

It is shown that it is necessary to control the energy indicators of automotive engines to ensure the operational efficiency of agricultural machinery in operational conditions. An algorithm for monitoring the energy indicators of the machine and tractor fleet of an agricultural enterprise is proposed, reflecting the main stages of obtaining, processing, storing and applying diagnostic information. Due to the timely assessment of the state of the equipment and the performance of the necessary maintenance, the efficiency of its work is increased.

Evaluating the Mechanical and Tribological Properties of DLC Nanocoated Aluminium 5051 Using RF Sputtering

The diamond-like carbon- (DLC-) coating technique is used in the sliding parts of automotive engines, among other applications, to reduce friction and wear. In this work, DLC has been coated on the Aluminium 5051 sample to assess the mechanical and tribological properties. A sputtering deposition mechanism is used, and the DLC is coated using a graphite target. The developed DLC coatings are tested for adhesion strength, hardness, chemical composition using XRD, and wear behaviour. The developed DLC thin films have considerably increased the wear behaviour of the Aluminium 5051 sample and have fulfilled the objective of this study. The XRD data indicated the presence of amorphous carbon in the coating with a threefold increase to the hardness of the naked aluminium. This study provides insight into improving the aluminium wear resistance by developing a considerably hard coating.

Excellent Seizure and Friction Properties Achieved with a Combination of an a-C:H:Si DLC-Coated Journal and an Aluminum Alloy Plain Bearing

Friction occurring between the crank journal and main bearings accounts for a large share of the mechanical losses of automotive engines. The effects of higher in-cylinder pressures and narrower bearings have raised the specific load applied to bearings, making it essential to secure sufficient seizure resistance as well. For the purpose of meeting both requirements, we have endeavored to reduce friction and improve seizure resistance by applying a diamond-like carbon (DLC) coating to the crank journal. In the present study, a bearing tester was used that has received international standard certification from the International Organization for Standardization for reproducing the sliding behavior occurring between the crank journal and main bearings in actual engines. Test results indicated that a silicon-containing hydrogenated amorphous carbon (a-C:H:Si) DLC-coated journal showed a definite friction reduction and a marked improvement in seizure resistance. An acoustic emission (AE) analysis revealed that an adhesion-induced AE peak observed for a steel journal was not seen for the DLC-coated journal. Additionally, tin and aluminum elements in the bearing material that were transferred to and observed on the sliding surface of the steel journal were not seen on the DLC-coated journal. Accordingly, the low affinity of the DLC coating with these metal elements presumably led to the clear friction reduction and superior seizure resistance displayed by the DLC coating.

Research on the Parameters of Gasoline Engine Injectors

Automotive engines are getting more and more advanced. This causes the change in the development of injectors. The nozzle spray fuel quality has to meet certain requirements, such as sprayed droplet size, flare length, and sprayed fuel. Using the method of analysis and synthesis of scientific literature sources, the main parameters of gasoline injectors were calculated in this work. The results of the research have been compared with calculated parameters obtained from the injectors test stand.The paper has been prepared on the basis of G. Brunius’ Master Thesis.

A review of physical vapor deposition coatings for rolling bearings

Rolling bearings are critical in automotive engines, wind turbine drive trains, and numerous other mechanical systems. Rolling bearings can suffer from early failures, which result in high operation and maintenance costs. Surface engineering techniques, such as the application of coatings and additives for lubricants have been developed to improve the tribological performance of rolling bearings. In this article, the performance of physical vapor deposition coatings on components working under rolling/sliding contacts and rolling bearings is reviewed. The applications of physical vapor deposition coatings in the rolling bearing industry are summarized. The effects of coating thickness, coating mechanical properties, test conditions, coating bonding layer, and coating architecture on coating performance are discussed. At the end of the article, possible approaches to further improve the performance of physical vapor deposition coatings on rolling bearings are proposed.

Improving the cooling systems of automotive engines and methods for monitoring their condition

It has been established that the cooling system of modern tractors and trucks can include 5 to 7 independent cooling circuits. A structural diagram of a modular cooling system for automotive engines and a mathematical model of thermal processes in a heat exchanger of the modular cooling system during machine operation are proposed. It is shown that the development of an algorithm for predicting and monitoring the state of the modular cooling system is possible based on a quantitative relationship between the rate of decrease in heat dissipation capacity and the duration of machine operation.

Variable Speed DC Generator Voltage Control using a Multistage Comparator

DC generator with variable rotation will produce uncontrolled voltage, causing problems in its utilization. In this study, it is proposed to develop a voltage control on the generator, in order to produce a fairly controllable and reliable voltage, with an analog circuit using a multistage comparator. Control of the generator output voltage is carried out by adjusting the field current from a separate voltage source which is forwarded to the resistance which is regulated based on the generator output voltage level with a multilevel comparison system. The results obtained are the output voltage ranges from 26 to 30 Volts and the output current ranges from 3 to 20 Amperes. This provides operational safety for the generator and battery. This technology can be used in dc generator systems in automotive engines, windmills, and other power plants.