Abstract
In order to capture the stress-strain response of metallic materials under cyclic loading, it is necessary to consider the cyclic hardening behaviour in the constitutive model. Among different cyclic hardening approaches available in the literature, the Chaboche model proves to be very efficient and convenient to model the kinematic hardening and ratcheting behaviour of materials observed during cyclic loading. The purpose of this study is to determine the material parameters of the Chaboche kinematic hardening material model by using isotropic J2 plasticity and micromechanical crystal plasticity (CP) models as constitutive rules in finite element modelling. As model material, we chose a martensitic steel with a very fine microstructure. Thus, it is possible to compare the quality of description between the simpler J2 plasticity and more complex micromechanical material models. The quality of the results is rated based on the quantitative comparison between experimental and numerical stress-strain hysteresis curves for a rather wide range of loading amplitudes. It is seen that the ratcheting effect is captured well by both approaches. Furthermore, the results show that concerning macroscopic properties, J2 plasticity and CP are equally suited to describe cyclic plasticity. However, J2 plasticity is computationally less expensive whereas CP finite element analysis provides insight into local stresses and plastic strains on the microstructural length scale. With this study, we show that a consistent material description on the microstructural and the macroscopic scale is possible, which will enable future scale-bridging applications, by combining both constitutive rules within one single finite element model.
Highlights
Nitrogen-alloyed martensitic steels are suitable for many engineering applications due to their excellent corrosion resistance, enhanced yield strength, tensile strength and better low cycle fatigue (LCF) resistance in comparison to the typical austenitic stainless steels with a smaller amount of nitrogen [1,2,3,4]
The differences between the models and their formulation has been given and it is noted that J2 plasticity is numerically much more efficient and is typically applied in macroscopic finite element simulations on the component level, whereas crystal plasticity (CP) is applied in micromechanical models, where mechanical behaviour on the level of individual grains of a microstructure is considered
Cyclic stress-strain data from experiments at different total-strain amplitudes were used in order to identify all material parameters, including elastic constants and the parameters for isotropic and kinematic hardening
Summary
Nitrogen-alloyed martensitic steels are suitable for many engineering applications (industrial cutting knifes, roller bearings in aerospace industry) due to their excellent corrosion resistance, enhanced yield strength, tensile strength and better low cycle fatigue (LCF) resistance in comparison to the typical austenitic stainless steels with a smaller amount of nitrogen [1,2,3,4]. These beneficial effects of nitrogen make these alloys a good candidate for engineering applications that demand corrosion resistance along with high mechanical strength. A brief historical overview of different material models with their characteristic features is presented
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