Establish Using FEM Method of Constitutive Model for Chip Formation in the Cutting Process of Gray Cast Iron

Abstract

The constitutive equation of mechanics, namely the stress−strain model of the material, is used to describe the mathematical expression of the mechanical properties of the material (stress−strain−intensity−time relationship). In the cutting simulation of metals, the material constitutive model needs to be established. To study the cutting mechanism of gray cast iron using the finite element method (FEM), a series of split Hopkinson press bar (SHPB) tests are carried out to achieve the stress−strain curves of gray cast iron under different strain rates and temperatures. In the cutting simulation of gray cast iron, the Johnson−Cook (JC) constitutive equation is used to reflect the mechanical behavior during the cutting process. The calculation of JC constants is analyzed deeply and obtained from the SHPB test data. One orthogonal finite element model is developed with the JC material model to reveal the cutting mechanism of gray cast iron. The chip formation, stress distribution, temperature distribution, and cutting force are investigated through the cutting simulation. At the same time, cutting experiments of gray cast iron are carried out for validating the simulation results. The results of the cutting simulation and experiments show a good agreement.

Keywords

• constitutive equation
• cast iron
• cutting
• segmented chip
• finite element simulation
• hopkinson bar
• chip formation