Ondřej Maršálek

Improvements in Computational Modelling of Slide Bearings

Shrnutí Zaměrem tohoto članku je představit inovace v oblasti vypočtoveho modelovani kluznych ložisek pohonnych jednotek. Tyto inovace spočivaji, mimo jine, v rozšiřeni modelu o podminky smišeneho mazani. Vstupni data pro detailni vypočty jednotlivych kluznych ložisek jsou poskytovana vypočtovym modelem pohonne jednotky vyšši urovně, tzv. virtualnim motorem. Vysledky těchto vypočtů slouži jako teměř nezbytne informace pro spravny navrh parametrů různych typů kluznych ložisek. Prezentovane metody jsou založeny na novych programovych nastrojich, vyvinutych autory během vyzkumu, a take na komerčně dostupnych aplikacich typu ANSYS nebo ADAMS. Vypočtove modely pohonnych jednotek vyšši urovně zahrnuji pružna tělesa na zakladě redukovanych MKP modelů. Nově vyvinute vysoce specializovane programove nastroje jsou sestaveny v programovacich jazycich Fortran a Matlab. Abstract The intent of this paper is to present new improvements in the modelling of a powertrain slide bearing incorporating mixed lubrication conditions. The Virtual Engine as a model of the powertrain provides input data for detailed calculations of individual slide bearings. The results of these calculations serve as essential information for the correct parameter design of various types of slide bearings. The presented methods are based on new software tools developed by the authors during the research and also on commercial tools such as ANSYS or ADAMS. The computational models of the target powertrains incorporate flexible bodies (based on conversed FE models). The newly developed and highly specialized software tools are written in Fortran and Matlab.

Validation of Analytical Calculation of Contact Pressure

This paper discusses the selection of the most appropriate analytical approach for computational modelling of contact pressure using commercial software tool ANSYS. All the analytical relations, characterizing each computational model useful for detailed determination of the contact pressure between two rough surfaces, are presented here. Furthermore, the process of creation of the FEM model of rough surface along with the description and analysis of all the challenges associated with it are described in this paper. In the conclusion are listed results of simulations together with identification of the chosen analytical approach for fast and also accurate calculations.

Contact Area Evaluation Experiment Verified by Computational Model in MBS

This article focuses on the experimental contact area evaluation. Test rig is designed in order to investigate the piston/cylinder liner contact. The conducted experiment is based on the principle of electrical contact resistivity between two tested machinery parts. The measured results are compared with different contact model theories. The computational simulation uses precomputed database of contact pressure and contact area depending on separation distance of surfaces. This simulation is solved by Multibody System (MBS) enhanced by the user-written FORTRAN subroutine. The results of experiment and simulations are discussed.

Numerical Solution of Micro-Lubrication in Internal Combustion Engine Journal Bearing

This article describes a complex and generally applicable computational model for solving the frictional losses of directionally oriented and non-oriented sliding surfaces working under mixed lubrication regime. In the primary phase of this paper are described ways to get characteristics data describing rough surfaces together with the formula for determination of surface pattern directional dependence. Furthermore, formulae describing used contact model are listed and also the structure of the whole powertrain dynamics solution is briefly explained. In the closing section of this paper are shown and discussed results of several types of slide bearing analysis.

Multibody Based Tool for Simulation of the Turbocharger Rotor Dynamics

The turbocharger is a unique example of the rotating machinery. Not only for its very high speed, but also because of its compact design and difficult operating conditions (i.e. high temperature, harsh vibrations, etc.). Moreover, measuring of most parameters characterizing the rotor dynamics is a very difficult task. Thus, it is advantageous to replace the real turbocharger by computational model and determine the turbocharger rotor dynamics using simulation tool. The development of such tool will be presented in this paper.

The Influence of Rotor Unbalance on Turbocharger Rotor Dynamics

Shrnutí Članek analyzuje vliv nevyvahy na dynamiku rotoru turbodmychadla. Je zde prezentovan 3D vypočtovy model rotoru turbodmychadla a hydrodynamicky model kluzne ložiska. Sestaveni vysledneho vypočtoveho modelu na urovni virtualniho prototypu je provedeno v prostředi software pro řešeni dynamiky těles. Članek prezentuje vybrane vysledky, na kterych je podrobně rozebran vliv velikosti nevyvahy na dynamiku rotoru turbodmychadla. Abstract This paper describes the influence of an unbalance on turbocharger rotor dynamics. The structural model of the turbocharger rotor and the hydrodynamic model of the journal floating ring bearing are described and assembled in multibody dynamics software. Moreover, the paper presents various results describing rotor dynamics where the influence of an unbalance is discussed.

Selection Of Analytical Computational Model Of Contact Pressure

Abstract This paper presents a comparison of two contact pressure calculation methods between two real rough surfaces: a calculation based on FEM (Finite Element Method) using commercial software tool ANSYS and a calculation based on FDM (Finite Difference Method) using analytical functions implemented in programing tool MATLAB. This comparison, lately, leads to the selection of the most appropriate analytical contact model useful for time-effective and precise contact pressure determination. Surface data for numerical simulations are obtained by optical profilometry. For the case of the modelling process of 3D FEM models of rough surfaces the description of their building is included in this article. Furthermore, this paper discusses all challenges connected with the convergence of such simulations and essential post-processing of FEM simulation results, together with their comparison, along the results obtained by user-written MATLAB functions.

Multi Body Analysis Of A Turbocharger Supported By A Fully Floating Ring Bearing

Abstract This paper describes an advanced tool for turbocharger rotor dynamics analysis and its development. The hydrodynamic model of the journal bearing based on Reynolds equation is presented. The paper also describes assembly of the turbocharger rotor model. At the end the basic results are presented and analyzed.

Role Of Computational Simulations In The Design Of Piston Rings

Abstract The paper presents computational approaches using modern strategies for a dynamic piston ring solution as a fluid structural problem. Computational model outputs can be used to understand design parameter influences on defined results of a primarily integral character. Piston ring dynamics incorporates mixed lubrication conditions, the influence of surface roughness on oil film lubrication, the influence of ring movement on gas dynamics, oil film formulation on a cylinder liner and other significant influences. The solution results are presented for several parameters of SI engine piston rings.

Overview of Computational Models Used for Mixed Lubrication

The ability to describe a mixed lubrication regime correctly has higher and higher importance along with the continued downsizing trend. Therefore, this paper deals with the application of different methods for determining the contact pressure in slide bearings, as well as the description of several strategies of 3D rough surfaces computer modelling. Furthermore, in this paper are shown result example of surface roughness generation and analysis results of slide bearing operated under different lubrication regimes.