A Two-Level Non-Intrusive Coupling Method for Fatigue Analysis

Yanjie Liu,Qin Sun,K Kontis,S Pantelakis

doi:10.1051/matecconf/201823300032

Yanjie Liu, Qin Sun + Show 2 more

Open Access

https://doi.org/10.1051/matecconf/201823300032

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Abstract

concept and the continuum damage mechanics, a two-level non-intrusive coupling strategy for fatigue analysis procedure is developed to efficiently and accurately predict the fatigue damage of critical details in a large structure. Coupled multi-scale models including the global structure (coarse mesh) and local details (fine mesh) are involved to evaluate fatigue damage in local details and their effect on the global structure. In this method, the fatigue analysis in critical region is divided into two levels – the local boundary condition update and the local fatigue analysis. In the first level, the external cyclic load is transferred from global scale to the local scale. And in the second level, the local fatigue analysis driven by the local cyclic boundary is carried out. The computational procedure of this two-level analysis can be fully coupled, semi-coupled or uncoupled according to different scenarios. Furthermore, the low-cycle fatigue damage is studied and the corresponding fatigue life predictions are simulated on a plate with a central circular hole under cyclic load. The results reveal that the present method greatly improves the numerical efficiency and accords well with the traditional FE analysis with global fine mesh.

Highlights

With the rapid development of large structures applied in aerospace and civil engineering, it is significant to maintain structure integrity and safety under various loading environments during service
Many obstacles still lead to serious limitations on the practical application of fatigue life prediction of large structure
One of the most difficult problems is the compromise between accuracy and efficiency in the fatigue damage analysis of hot-spots in a large structure, especially, involving complex inelastic deformation

Summary

Introduction

With the rapid development of large structures applied in aerospace and civil engineering, it is significant to maintain structure integrity and safety under various loading environments during service. In order to overcome these barriers, the non–intrusive coupling method [9,10,11,12,13], further developed by Liu [12], provides a novel and feasible way to deal with the large structural analysis with local nonlinearities It shares the following major advantages: (1) coupled multi-scale model, i.e., it couples a global linear model (structure scale) and several local complex non-linear models where possible damage is involved (material scale) in an iterative way; (2) non-intrusiveness, i.e., it is non-intrusive with the FE solver and can be implemented into commercial code to perform large scale analysis; (3) independence of global analysis, i.e., it avoids modifying the global linear model during analysis, which means the global model will be assembled on the full structure only once and never changed, whereas the local model can be modified and performed as many times as necessary; (4) parallel computation, i.e., the local models can be individually analyzed through parallel computing for the data exchange happens between local interfaces and global interface and there is no need to exchange information between local models. In contrast with the traditional FE method with global fine mesh, the proposed two-level method puts more concentrations on local nonlinear analysis, improving the numerical efficiency

Two-level non-intrusive coupling method for fatigue analysis

Two-level fatigue life analysis procedure

Damage coupled model for low-cycle fatigue

Two–level numerical simulation of low–cycle fatigue

Conclusions