Interaction of Cyclic Loading (Low‐Cyclic Fatigue) with Stress Corrosion Cracking (SCC) Growth Rate

Abstract

The structural integrity analysis of nuclear power plants (NPPs) is an essential procedure since the age of NPPs is increasing constantly while the number of new NPPs is still limited. Low-cyclic fatigue (LCF) and stress corrosion cracking (SSC) are the two main causes of failure in light-water reactors (LWRs). In the last few decades, many types of research studies have been conducted on these two phenomena separately, but the joint effect of these two mechanisms on the same crack has not been discussed yet though these two loads exist simultaneously in the LWRs. SCC is mainly a combination of the loading, the corrosive medium, and the susceptibility of materials while the LCF depends upon the elements such as compression, moisture, contact, and weld. As it is an attempt to combine SCC and LCF, this research focuses on the joint effect of SCC and LCF loading on crack propagation. The simulations are carried out using extended finite element method (XFEM) separately, for the SCC and LCF, on an identical crack. In the case of SCC, da/dt(mm/sec) is converted into da/dNScc (mm/cycle), and results are combined at the end. It has been observed that the separately calculated results for SCC da/dNScc and LCF da/dNm of crack growth rate are different from those of joint/overall effect, da/dNom. By applying different SCC loads, the overall crack growth is measured as SCC load becomes the main cause of failure in LWRs in some cases particularly in the presence of residual stresses.

Prediction of the Direction of XFEM Crack Based on Von Mises Around the Crack-tip under Mode-I

“…For plastic properties, the tensile true stress-strain curve is shown in Figure 2, for which the experimental data is obtained from the "Slow Strain Rate Stress Corrosion Testing Machine" available in Fracture Mechanics Lab of Xi'an University of Science and Technology, see Figure 3. Since real structures provide results closer to the practical values [26], therefore, a simple plate of 100mm ×50mm, having an embedded extended finite element method (XFEM) crack with 15mm is used as shown in Figure 4, along with the boundary conditions and loads. All the simulations have been performed in the ABAQUS 6.14 software following the instructions provided in the manual [27].…”

Prognosis methods of stress corrosion cracking under harsh environmental conditions

“…By enriching the standard finite element mesh with additional degrees of freedom to capture crack growth, XFEM enables accurate simulations of complex crack patterns and crack interactions [ 150 ]. Rehmit [ [142] , [151] , [152] ] investigates the effect of variations in macrostructural properties of Alloy 600 on stress corrosion cracking plastic zone ahead of the crack-tip using the extended finite element method (XFEM). The results show that the plastic zone is affected by stress intensity factors, yield strength, and hardening exponent “n" of the materials.…”

Electrochemistry Numerical Study of Stress Corrosion Cracking under Near-Neutral Soil Solution

“…A simulation is conducted to analyze the stress on a pipeline domain by utilizing the small strain plasticity model. The model incorporates a user-defined isotropic hardening function, σyhard [10], which is defined as:…”