Material Modeling of Gray Cast Iron Based on Damage Mechanics and Its Applications to Fatigue Life Prediction

Abstract

The constitutive equation based on the concept of continuum damage mechanics is formulated for the gray cast iron as used in diesel engine parts, assuming it as an elastic damage viscoplastic solid. The microscopic stress and strain evaluation is simplified in the two-scale model for the damage evolution. Lots of material parameters in the constitutive equation are determined by using the uniaxial tensile/compressive and the fatigue test results. The local approach to fracture analysis (the uncoupled analysis) for the fatigue tests of notched circular bars is conducted by using the identified constitutive equation model and the commercial three-dimensional finite element program. The validity of the proposed model is illustrated by comparing the calculated results with the experimental results. It is expected that the developed computational modeling can be used effectively to predict the fatigue life of gray cast iron machine parts.