Applied Mechanics and Materials Vols. 799-800

Abstract: A new fatigue life simulation analysis method for spot weld joints is proposed which considers the fatigue crack propagation from the point of fracture mechanics. The traditional fatigue simulation analysis methods for spot weld joints are mainly LBF method based on force and LMS method based on stress, while there exist some issues such as the prediction accuracy is not high, modeling and computational efficiency is low. A modular spot weld model is adopted in this paper, the node forces and moments around the spot weld are extracted through the finite element analysis, then a average stress intensity factor through the crack propagation path is calculated as the evaluation parameter of fatigue life. Shear fatigue test is designed for spot weld joints with two high strength steel materials (HSLA340GI and DP600GI) and four different thicknesses, then double logarithmic regression analysis is implemented between the average stress intensity factor and the fatigue life data of spot weld joints, then a matching curve is obtained as the fatigue life prediction curve for spot welds. Comparative analysis of prediction accuracy is implemented for these three methods, the results show that the prediction accuracy of fatigue simulation method for spot weld joints in this paper is higher than traditional LBF and LMS methods.

Abstract: Atomization of liquid fuels is very important topic for combustion studies since it enhances air/ fuel mixing process and therefore ensures perfect combustion. With today’s common diesel injectors, fuel is directly injected into the combustion chamber with extremely high pressures which exceed 1300 bar in order to obtain perfect atomization. However, these high injection pressures unfortunately create some problems in the injection system such as cavitation erosion which may lead to mechanical failure. Introducing of air into the injector prior to combustion will increase fuel atomization, provide more complete combustion, enhance fuel economy and results in lower engine emissions. The aim of this study is to investigate atomization behaviour of a newly introduced diesel engine which mixes air and fuel prior to combustion chamber.

Abstract: The collaborative design of the automotive powertrain system is a complex activity, which is involved with multiple disciplines and personnel for completion. Besides, characteristic of multiple goals and no specific operator, design process is inclined to collision, thus collision detection has become critical in collaborative design on the system. In the study, collision factors in the process of collaborative design on the system are analyzed and modeled and a section-based collision detection algorithm is proposed which is competent in detecting collisions in the process of clutch case design.

Abstract: Paper considers problem of increase in key indicators of the internal combustion engines which are used as a part of a wide range of mobile objects, including motor transport surface, underwater and aircrafts. Approach to the solution of a problem of development of the optimum form of an intake system of the engine providing increase in filling of cylinders with fuel and air mix and uniform distribution of air on cylinders is offered. Besides, the requirement of symmetry in time that means a need of air intake from a throttle to the inlet valve of each cylinder for identical amount of time is put. The results of computing tests of the developed form of an intake collector confirming compliance to the developed model to the given requirements are presented. Model sample intended for installation on small-capacity atmospheric 4-cylinder IC engine is made on the base of 3d-model. Need of modification of the software of a control system of the engine for achievement of the maximum return at tests of a model sample is proved. Corresponding changes are described, comparison charts of adjusting parameters are given. Experimental stand for carrying out natural tests was assembled and used to get the external high-speed characteristic of the engine when using a regular intake collector and intake collector of the developed form. The results of tests that clearly demonstrate increase in power and a torque of the engine are given.

Abstract: In this article I focus on a mathematical description of a turbocharged engine. After expressing the mathematical description I transferred it to the computer environment of a mathematical program. I further elaborated the results and compared them with the results of a simulation model of a turbocharged engine, which is also mentioned in the second part of the article.

Abstract: Spark plug with integrated chamber increases the quality of ignition of homogenous mixture in the engine cylinder. Very small amount of burning mixture bursts (outflows) from chamber (so-called flame jet ignition) which heads into faster initial phase of burning. From view of cycle to cycle variations the procedure of consequent burning is more stable. Spark plug’s case with integrated chamber is exposed by higher thermal stress than classis spark plug. This fact has to be respected during design of spark plug with integrated chamber. This article shows the how configuration of the lower part of spark plug with integrated chamber can change the type of spark and how flame-jet ignition will affect parameters of burning mixture during operating cycle.

Abstract: This article is focused on the problematics of high-pressure fuel injectors of Common Rail system which are inside of high pressure environment. Those injectors are able to measure cycle's amount of fuels and visualization of fuel ray disintegration during outflow into high pressure environment. Article is primarily focused into a construction of pressure testing chamber which will be functional extension for high pressure systems testing device. Monitoring of measured parameters will have positive influence during designing of constructing changes on the injection unit.

Abstract: Transport is crucial for economic and social development of a society as it serves a key role for transportation of goods and people. But it is not free of negative externalities. Operation of transport vehicles require energy use and this energy is mostly generated with fossil fuel combustion. Unfortunately, the fossil fuel combustion comes with both global emissions (CO₂, N₂O, CH₄), which cause climate change, and local emissions (PM, NO_x, HC, CO, O₃), which cause adverse health effects and damage natural environment. In this paper the level of NOx emission by adding fuel additive metal oxide based nanoparticles in heavy duty engines were investigated. Three different nanoparticle additives namely Titanium Oxide (TiO₂), Silicon Oxide (SiO₂) and Zinc Oxide (ZnO), were added to diesel fuel at the dosages of 15, 20 and 25 ppm. Eventually, the most proper additive and addition dosages were indicated.

Abstract: Charging system is used to increase the charge density. Supercharging system suffers from fuel consumption penalty because of compressor powered by engine output. Turbocharging system uses wasted exhaust energy that means compressor powered by exhaust turbine but has a turbo lag problem. The electrically assisted turbocharger which can eliminate turbo lag problem and fuel consumption penalty is the topic of this paper. The purpose of this paper is to analyze the effect of electrically assisted turbocharger on diesel engine performance parameters. The AVL Boost software program was used to simulate the electrically assisted turbocharged diesel engine. Simulations results showed that electrically assisted turbocharger increases low end torque and improves fuel economy.

Abstract: In this work results of numerical modeling of the gasdynamic processes and processes of deformation proceeding in the compressor of the model test bench of the gas-distributing unit are provided. Fields of pressure and temperatures, and also component of the stress-strain state structure taking into account the imported gasdynamic and heat loads are received. A good agreement with data of physical experiments is received.