A comprehensive methodology for the modeling of diesel four-stroke engine pistons for variable engine speed conditions
aDepartamento de Engenharia de Estruturas e Fundações da Escola Politécnica da Universidade de São Paulo, Av. Prof. Almeida Prado, trav.2 no. 83, Cidade Universitária, São Paulo, SP, 05508–900, Brazil bMahle Metal Leve S.A., Technical Center, Mathematical Modeling and Simulation Group, R. Brasilio Luz, 535, Santo Amaro, São Paulo, SP, 04746-901, Brazil
ABSTRACT
There are pistons that meet safety requirements according to predictions of the current finite element piston modeling methodology but fail on experimental engine tests. In this work a new methodology is proposed for modeling the behavior of diesel pistons during the thermal transient. In addition to the thermal loading, we need also to model the purely mechanical loading. However, it is not only a question of adding such mechanical loading to the analysis. Since the pressure loading is cyclic and plasticity effects are to be taken into account, how to introduce the mechanical loading together with the thermal transient is an important modeling issue. The modeling methodology proposed depends very much on this loading strategy. Selected results that show the usefulness of the methodology are reported.
Keywords:
Modeling; Diesel piston; Finite elements; Thermo-transient analysis; Variable engine speed conditions; Thermo-mechanical analysis; Thermo-elastic constitutive model; Thermo-elasto-plastic constitutive model