Using the Nonlinear Kinematic Hardening Material Model of Chaboche for Elastic–Plastic Ratcheting Analysis

Abstract

Commonly used design codes for power plant components and pressure vessels include rules for ratcheting analysis that specify limits on accumulated strain. No guidance is provided on the use of the material model. The objective of the paper is to provide guidance that may be helpful to analysts. The Chaboche nonlinear kinematic (NLK) hardening material model is chosen as an appropriate model. Two methods are selected for its calibration that can determine the parameters for stainless steels. One is manual that requires no outside software and the other uses finite element software. Both are based on the monotonic stress–strain curve obtained from a tension specimen. The use of the Chaboche parameters for cases when ratcheting is caused by cyclic temperature fields is selected as the example of an application. The conclusion is that the number of allowable design cycles is far higher when using the parameters with temperature dependency than those at the constant maximum temperature that is being cycled.

Evaluation of Sensitivity and Calibration of the Chaboche Kinematic Hardening Model Parameters for Numerical Ratcheting Simulation

“…However, implementation of more robust complex models can be time-consuming and complicated [15,21]. Kalnins reiterated the parameter identification for the material under consideration as an essential prerequisite for using an NLK model [22]. Accordingly, the dedicated method to figure out the best set of ratcheting parameters can extremely affect the result of ratcheting prediction.…”

“…Rahman et al evaluated the use of heuristic search techniques, such as the genetic algorithm, in automating the parameter value determination of developed models, and thus overcoming the limitations involved in manual calibration [25,26]. Two approaches to determine Chaboche model parameters are used by Kalnins et al [22], namely the manual method and the numerical method, which make use of ABAQUS. They presented practicable applications of the Chaboche model in elastic-plastic ratcheting analysis.…”

“…The positive or negative segment of the last saturated cycle of hysteresis curve was adopted in calculating the ratcheting parameters. However, Kalnins et al adopted the monotonic stress-strain curve, instead of a hysteresis curve, obtained from a specimen subjected to unidirectional tension loading, to calibrate the ratcheting parameters [22]. The authors suggested that adopting the monotonic curve data for determining is predictable to present stuffy assessment of ratcheting that could be assumed suitable for design targets.…”

“…The ratcheting parameters are significantly sensitive to the elastic limit stress at which yielding instigates [22,27]. Precise application of elastic theory that causes a slight amount of nonlinear recovery was addressed [28].…”

Finite Element Implementation of a Temperature-Dependent Cyclic Plastic Model for SA508-3 Steel

“…The nonlinear kinematic hardening rule, such as the Chaboche's rule [5], is available in these commercial software tools, which can capture the cyclic plastic deformation of some metal materials. For example, a Chaboche-type material model was applied in the Low-Cycle Fatigue finite element assessment on 316L pipes for the "Wendelstein 7-X" stellarator-type nuclear fusion experiment [6], but it commonly gives a conservative prediction [7].…”