A Stabilized and Coupled Axisymmetric Non-Ordinary State Based Peridynamics Model for Ablation and Plastic Fracture in Reactor Accident
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The numerical analysis of the mechanical behaviours of axisymmetric structures plays a dominant role for their structural design, advanced manufacture and safety assessment in practical engineering applications. To analyze the ablation and fracture of the axisymmetric structures such as reactor pressure vessels (RPV) during reactor accident with extremely high temperature and pressure conditions, a stabilized and coupled axisymmetric non-ordinary state-based peridynamics (SCA-NOSB-PD) model is proposed in this work to predict the ablation, plastic damage and ductile fracture of metals. In this model, the governing equations of axisymmetric thermoplastic problems are derived based on the separation of the deformations along the in- and out-plane directions. To suppress the zero-energy modes, a stabilization method based on the linearization theory of the PD model is proposed under axisymmetric framework. Furthermore, three kinds of moving boundary models are proposed to handle the varying geometries during ablation process, including laser, contact and penetration ablation. The ablation evolution is controlled by a temperature-associated criterion. To deal with the thermoplastic coupling effects, Lemaitre’s damage model is incorporated into the SCA-NOSB-PD model to effectively describe the damage behaviours. A damage-associated criterion is then proposed to determine crack propagation. Typical numerical simulations demonstrate that the proposed model can effectively and accurately capture the thermoplastic response and predict the crack propagation. By analyzing the RPV within reactor accident, the performance illustrates the feasibility of the proposed model for ablation and plastic fracture in reactor accident involving axisymmetric features. These works were supports by the National Key Research and Development Program of China (No. 2022YFB4200039) and the National Natural Science Foundation of China (Nos. 12072061, 12072062 and 11972108).
