The authors have developed a coupled simulation methodology to target strong interactions between component dynamics, lubricated contacts and connecting oil supply lines in internal combustion engines. The dynamics of engine components, called bodies, is represented by a flexible multi-body approach. The mixed lubricated contacts between the component surfaces are represented by an averaged Reynolds equation considering an asperity contact model according to Greenwood and Tripp. The connections between oil bores are modelled by an oil supply line network. Within the network straight cylindrical lines are considered. The oil is assumed to be incompressible with isothermal viscosity. The flow in each line is described by a steady-state one-dimensional Euler equation, i.e. Bernoulli equation. Fictitious force effects, which result from the motion of the enclosing component, and cavitation effects are considered. The article discusses in particular the theory and the implementation of the oil supply line network as well as its coupling to the multi-body system and the hydrodynamic equations. Furthermore, the validation of the oil line model is presented. This is done via comparison with an equivalent three-dimensional computational fluid dynamics simulation. Finally, an application is shown for a single-cylinder internal combustion engine. All bodies of the model are represented to be flexible. Oil supply lines connect the big end bearing with one main bearing and with the small end bearing.

With the increasing stringent emissions legislation on ICEs, alongside requirements for enhanced fuel efficiency as key driving factors for many OEMs, there are many research activities supported by the automotive industry that focus on the development of hybrid and pure EVs. This change in direction from engine downsizing to the use of electric motors presents many new challenges concerning NVH performance, durability and component life. This paper presents the development of experimental methodology into the measurement of NVH characteristics in these new powertrains, thus characterizing the structure borne noise transmissibility through the shaft and the bearing to the housing. A feasibility study and design of a new system level test rig have been conducted to allow for sinusoidal radial loading of the shaft, which is synchronized with the shaft's rotary frequency under high-speed transient conditions in order to evaluate the phenomena in the system. The present work introduces a new component level test rig that can predict the response of new EV and hybrid systems using different types of rolling element bearings such as deep groove ball bearings, angular contact roller bearings, tapered roller bearings and the cylindrical roller bearings. Moreover, it is possible to investigate the influence of factors such as bearing clearance and the amount of axial bearing preload which will be used to further explore the capability of bearing CAE tools. The test rig has multiple novel elements compared to those previously developed. In particular, the rotational speed of the shaft, which significantly exceeds that of previously reported rigs, and the excitation frequency ramp up at the same rate as the frequency of the shaft enabling the phenomena found in Hybrid and EVs. The sinusoidal radial load is supplied using a loading device featuring a single load point to minimize undesired excitation effects. With respect to structure borne noise the system response is captured through the vibrational displacement of the shaft and bearing housing.

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Practical mechanical systems often operate with some degree of uncertainty. The uncertainties can result from poorly known or variable parameters, from uncertain inputs or from rapidly changing forcing that can be best described in a stochastic framework. In automotive applications, cylinder pressure variability is one of the uncertain parameters that engineers have to deal with when designing and analyzing internal combustion engines. Multi-body dynamics is a powerful numerical tool largely implemented during the design of new engines. In this paper the influence of cylinder pressure cyclic variability on the results obtained from the multi-body simulation of engine dynamics is investigated. Particular attention is paid to the influence of these uncertainties on the analysis and the assessment of the different engine vibration sources. A numerical transfer path analysis, based on system dynamic sub structuring is used to derive and assess the internal engine vibration sources. In order to investigate the cyclic variability of cylinder pressure, a Monte Carlo approach is adopted. Starting from measured cylinder pressure that exhibits cyclic variability, random Gaussian distribution of the equivalent force applied on the piston is generated. The aim of this paper is to outline a methodology which can be used to derive correlations between cyclic variability and statistical distribution of results. The statistical information derived can be used to advance the knowledge of the multi-body analysis and the assessment of system sources when uncertain inputs are considered.