Comparison of analytical and multibody dynamic approaches in the study of a V6 engine piston

Abstract

Two methods for the modelling and analysis of the piston/cylinder interaction are compared in this paper with reference to a V6 turbocharged gasoline engine piston. The first method is a traditional analytical method based on the equation of motion derived for the axial movement of the piston, written according to the kinematics of the crank mechanism. The second method is based on a multibody analysis, performed with the software AVL Excite™ Power Unit after a modal reduction of the system. The lateral force between the piston and the cylinder calculated using the analytical method is compared to the one calculated with a simplified multibody model. The results are well correlated, but in order to identify the piston secondary motion, an advanced multibody model is necessary since the consideration of the hydrodynamic effects, the flexibility of the bodies and the real profiles of the contacting surfaces is crucial. With regard to the latter aspect, a finite element model of the system under thermal boundary conditions has been implemented to evaluate the radial deformation and proper constraints have been considered to take into account the engine block stiffness. The obtained results are important because they have an impact on the radial clearance between the piston and the liner. When the multibody model takes into account these advanced effects, the piston slap events are clearly identified after the top dead centre and corresponding secondary peaks in the lateral force acting on the thrust side are calculated. At the end, a sensitivity analysis to the change of the piston-pin offset is also performed. Apart from the expected result of a lower lateral force peak when the offset is taken towards the anti-thrust side, some interesting differences are detected about the slapping behaviour. These events are clearly recognisable only if the offset is taken towards the thrust side because of the unfavourable piston rotation just prior to their occurrences. The pronounced anti-clockwise rotation of the piston prior to the lateral force peak occurrence in case of anti-thrust side offset, on the other hand, does not allow for a proper piston slap, even if the lateral acceleration is higher due to the centre of mass position with respect to the piston pin axis.

Keywords

Multibody dynamics NVH piston lateral force piston slap tribodynamics

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References

Ungar

Ross

. Vibration and Noise due to piston slap in reciprocating machinery. J Sound Vibrat 1965; 2: 132–146.

Haddad

. Theoretical treatment of piston motion in LC piston engine for the prediction of piston slap excitation. Mech Mach Theory 1995; 30: 253–269.

Haddad

Tjan

. An analytical study of offset piston and crankshaft designs and the effect of oil film on piston slap excitation in a diesel engine. Mech Mach Theory 1995; 30: 271–284.

Boysal

Rahnejat

. Torsional vibration analysis of a multi-body single cylinder internal combustion engine model. Appl Math Model 1997; 21: 481–493.

Offner G, Herbst MH and Priebsch HH. A methodology to simulate piston secondary movement under lubricated contact conditions. SAE Paper 01P-230-291100, 2001.

Balakrishnan

Rahnejat

. Isothermal transient analysis of piston skirt-to-cylinder wall contacts under combined axial, lateral and tilting motion. J Phys D: Appl Phys 2005; 38: 787–799.

Dolatabadi

Theodossiades

Rothberg

. On the identification of piston slap events in internal combustion engines using tribodynamic analysis. Mech Syst Signal Process 2015; 58–59: 308–324.

Dolatabadi

Littlefair

De la Cruz

et al.

A transient tribodynamic approach for the calculation of internal combustion engine piston slap noise. J Sound Vibrat 2015; 352: 192–209.

Littlefair

De la Cruz

Theodossiades

et al.

Transient tribo-dynamics of thermo-elastic compliant high-performance piston skirts. Tribol Lett 2014; 53: 51–70.

10.

Cho

S-H

Ahn

S-T

Kim

Y-H

. A simple model to estimate the impact force induced by piston slap. J Sound Vibrat 2002; 255: 229–242.

11.

Geng

Chen

. Investigation into piston-slap-induced vibration for engine condition simulation and monitoring. J Sound Vibrat 2005; 282: 735–751.

12.

Chen

Randall

Peeters

. Advanced diagnostic system for piston slap faults in IC engines, based on the non-stationary characteristics of the vibration signals. Mech Syst Signal Process 2016; 75: 434–454.

13.

Koizumi T, Tsujiuchi N, Masahiro O, et al. Reduction of piston slap excitation with optimization of piston profile. In: Proceedings of FISITA World Automotive Congress, F2000H216, Seoul, China, June 2000.

14.

Koizumi T, Tsujiuchi N, Masahiro O, et al. An analytical method for piston secondary motion of small gasoline engine. In: Proceedings of the 19th international modal analysis conference, IMAC-XIX-190904.

15.

Bocchi G. Motori a quattro tempi, Hoepli, Milano, 1987, rist. 2007, pp.255-268.

16.

Mollenhauer K and Tschöke H. Handbook of diesel engines. Berlin Heidelberg: Springer-Verlag, 2010, pp.221-223.

17.

Shigley JE and Uicker JJ. Theory of machines and mechanisms. Singapore: McGraw-Hill Book Co., 1981, pp.462-464.

18.

Perera

Theodossiades

Rahnejat

. Elasto-multi-body dynamics of internal combustion engines with tribological conjunctions. Proc IMechE, Part K: J Multi-body Dynamics 2010; 224: 261–277.

19.

Funaioli E, Maggiore A and Meneghetti U. Lezioni di meccanica applicata alle macchine, vol. 2, Pàtron Editore, Bologna, 1998, pp.21–23, 33.

20.

Meng

Xie

. A new numerical analysis for piston skirt-liner system lubrication considering the effects of connecting rod inertia. Tribol Int 2012; 47: 235–243.

21.

Craig R and Bampton M. Coupling of substructures in dynamic analysis. AIAA 1968; 6: 1313–1319.

22.

Koustovasilis P and Beitelschmidt M. Model reduction comparison for the elastic crankshaft mechanism. In: Proceedings of international operational modal analysis conference (IOMAC), 2007, Copenhagen, vol. 1, pp.95–106.

23.

Cavalli M, Lavacchielli G, Riva E, et al. Virtual prototyping of a turbocharged V6 engine powertrain in AVL EXCITE Power Unit. In: Proceedings of AVL advanced simulation technologies international user conference, Graz, June 2015.

24.

Koustovasilis P and Beitelschmidt M. Model reduction of large elastic systems, a comparison study on the elastic piston rod. In: Proceedings of XII World Congress in mechanism and machine science (IFToMM), Besançon, France, June 2007.

25.

Magistrali S, Riva E and Nicoletto G. Metodi numerici per lo studio delle prestazioni NVH di una powerunit automobilistica. In: Proceedings of the AIAS Congress – 379, 2014, Rimini.

26.

AVL LIST GmbH, Excite Power Unit Rev 2014.1 Users Guide.

27.

Greenwood

Tripp

. The contact of two nominally flat rough surfaces. Proc IMechE, Part C: J Mechanical Engineering Science 1971; 185: 625–633.

28.

Rahnejat H. Tribology and dynamics of engine and powertrain. Cambridge, UK: Woodhead Publishing, 2010.

29.

Andersson P, Tamminen J and Sandström C-E. Piston ring tribology, a literature survey. VTT Research Notes 2178.

30.

Bhushan B. Introduction to tribology. 2nd ed. John Wiley & Sons, Ltd, 2013.

31.

Bocchi G. Motori a quattro tempi, Hoepli, Milano, 1987, rist. 2007, pp.113–115.

32.

Tejaskumar C and Bharatkumar S. Investigation of friction characteristics in segmented piston ring liner assembly of IC engine. In: Perspectives in Science – Recent Trends in Engineering and Material Sciences, ICEMS, vol. 8, 2016, pp.599–602.