Title: Failure probability prediction for a ceramic piston head

Authors: H. Lahtinen, S.G. Sjolind, A. Pramila

Addresses: Department of Mechanical Engineering, University of Oulu, Linnanmaa, SF-90570 Oulu, Finland. ' Department of Mechanical Engineering, University of Oulu, Linnanmaa, SF-90570 Oulu, Finland. ' Department of Mechanical Engineering, University of Oulu, Linnanmaa, SF-90570 Oulu, Finland

Abstract: The failure probability of a piston head is studied using the finite-element (FEM) and various other methods (principle of independent action of principal stresses (PIA), normal stress (NS), maximum tensile stress (MTS) and strain energy release rate (SERR)) to take into account polyaxiality of the stress field. The most severe loading condition seems to occur when the piston is at the lowest position. The loads acting on the piston head are at that moment: the fixing pressures, the temperature field and inertia forces. A comparison among the various methods developed for taking into account polyaxiality of the stress state shows that SERR gives the largest failure probabilities, the results of MTS, NS and PIA are close to each other and, moreover, the differences between the last two of these are very small. Sensitivity studies indicate that the failure probability is very sensitive to variations in the material parameters. Slight changes in the standard deviation of the breaking strengths in four-point bending tests used in the evaluation of material parameters can change the failure probability by an order of nearly two decades.

Keywords: ceramics; finite element method; FEM; piston heads; reliability; stress analysis; vehicle design; failure probability.

DOI: 10.1504/IJVD.1990.061612

International Journal of Vehicle Design, 1990 Vol.11 No.2, pp.148 - 159

Published online: 26 May 2014 *

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