Research Article A Modified Fatigue Damage Model for High-Cycle Fatigue Life Prediction Meng Wang, 1,2 Qingguo Fei, 1,2 and Peiwei Zhang 1,2 1 Department of Engineering Mechanics, Southeast University, Nanjing 210096, China 2 Jiangsu Key Laboratory of Engineering Mechanics, Nanjing 210096, China Correspondence should be addressed to Qingguo Fei; qgfei@seu.edu.cn Received 15 November 2015; Revised 17 January 2016; Accepted 20 January 2016 Academic Editor: Konstantinos G. Anthymidis Copyright © 2016 Meng Wang et al. Tis is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Based on the assumption of quasibrittle failure under high-cycle fatigue for the metal material, the damage constitutive equation and the modifed damage evolution equation are obtained with continuum damage mechanics. Ten, fnite element method (FEM) is used to describe the failure process of metal material. Te increment of specimen’s life and damage state can be researched using damage mechanics-FEM. Finally, the lifetime of the specimen is got at the given stress level. Te damage mechanics-FEM is inserted into ABAQUS with subroutine USDFLD and the Python language is used to simulate the fatigue process of titanium alloy specimens. Te simulation results have a good agreement with the testing results under constant amplitude loading, which proves the accuracy of the method. 1. Introduction Fatigue failure, as one of the major causes of damage for the mechanical components, relates to alternative loads subjected on engineering structures, which drew increasingly researching work focusing on the fatigue life prediction. Tere are two methods to forecast the structure fatigue life: one is fatigue safe life prediction based on fatigue cumulative damage theories and the other is damage tolerance method based on fracture mechanics [1]. In general, the fatigue life of material is estimated based on the damage tolerance method. However, a high proportion of the overall lifetime for the metal high-cycle fatigue is the fatigue initiation life [2]. Damage mechanics is the theory studying the mecha- nisms and rules of solid material degradation performance by changing mechanical variables under the external loads. As an important branch of damage mechanics, the continuum damage mechanics [3–5] is a theory based on continuum mechanics and irreversible thermodynamics. Terefore, the process of fatigue crack initiation and development can be analyzed by the fatigue life prediction model based on continuum damage mechanics. And the model of fatigue damage can be classifed briefy into ductile fatigue dam- age model [6] and brittle fatigue damage model [7, 8]. Considering that the metal subjected to high-cycle fatigue could be regarded as quasibrittle material, the brittle damage mechanism is ofen employed to build a damage propagation model on the basis of irreversible thermodynamics [8], which is broadly accepted in engineering practices on account of less parameters of evolution equations. Moreover, the damage numerical analysis method is another core element of damage mechanics. Te determination of damage feld and the forecast of fatigue life have been achieved by the damage mechanics-fnite element method [9–11], which can be uti- lized to obtain the lifetime of damage initiation and damage propagation path. In this study, a brittle fatigue damage model is modifed and combined with a damage constitutive model to predict the fatigue life of the metal material in Section 2. Te method to estimate fatigue lifetime of titanium alloy components is accomplished by the commercial sofware ABAQUS which is developed by programming in Python and Fortran in Section 3. Ten, the correctness of the fatigue damage model, the fnite element model, and the simulation method is Hindawi Publishing Corporation Advances in Materials Science and Engineering Volume 2016, Article ID 2193684, 7 pages http://dx.doi.org/10.1155/2016/2193684