Search Results

Within the evolution of components in the automotive industry, several tools for development and optimization are being applied increasingly. Costs and performance parameters are then improved in such high rate that often the process limits are exceeded. In several designs these improvements are achieved through nominal/deterministic values for product properties and usage in its lifecycle, neglecting the fact that there is an inherent uncertainty. Several optimum solutions are not assured once a variation in input parameters for objective function is considered. Probabilistic tools may be applied in order to establish the link among such parameters and their expected variation, enabling alternative approaches for product development in an integrated way. Different solutions can be found once the uncertainty of process or usage is considered.

The study about the dynamic characteristics of a great number of mechanical parts has been promoted by the necessity of decreasing the vibrational effects in mechanical systems, as the reduction of superficial fatigue. In this way, the research around, even, a simple part like a hydrodynamic bearing is very important, especially in the automotive industry. In this case, the lubricant acts like a flexible liking element between the journal-bearing surfaces. The lubrication is essential for the engine, because it reduces the wear between the internal parts and prevents the metal contact. Due to the shear stresses present in the lubricant, the temperature rises and, consequently, it changes the lubricant properties. The viscosity is strongly dependent on the temperature and it is the parameter that characterizes the fluid flow and its dynamic behavior. Any temperature change induces a consequent modification in the lubricant behavior.

Due to the huge demand for more efficient engines, as consequence of reduced pollutant emission, not only has the automotive industry been trying to achieve deeper understanding of the physical mechanisms present in the engines, but also to improve its mathematical modeling. Concerning the journal bearings, this task has extreme relevance, when either downsizing or repowering approaches are aimed to be performed. Regarding the mathematical models, identification of a model which is able to guarantee both reliable results and non-prohibitive computational costs should be achieved. This work aims to present the comparison between hydrodynamic and elastohydrodynamic simulation, showing the particularities of each approach and its advantages and disadvantages.

In order to achieve new emission regulations and customer requirements, the peak cylinder pressure (PCP) is steadily being increased and as a consequence, the loads applied on the cranktrain have increased significantly over the last decade. The higher loads have forced a complete revision of the cranktrain design affecting the design of pistons, connecting rods, and crankshafts. Consequently, the concept and performance of the related bearings have to be improved, since they are the key elements that link the cranktrain components. The purpose of this work is to evaluate the lubrication parameters of a non-straight bearing, so called U-Shape bearing. This development presents two main challenges: one is the simulation of the lubrication parameters and the other is the achievement of an ensemble of bearing dimensions that makes the prototypes construction feasible. Due to this particular bearing design, the commercial simulation tools do not apply.