Papers by Keyword: Continuum Damage Mechanics

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Authors: Xian Min Chen, Qin Sun, Di Guan, Feng Ping Yang
Abstract: A damage evolution model is presented for fatigue life prediction of metallic structures. This model is formulated based on damage mechanics and the irreversible thermodynamics framework developed by LEMAITRE and CHABOCHE. Using this model, the fatigue lifetime can be predicted both in the high cycle fatigue (HCF) regime and the low cycle fatigue (LCF) regime. Based on the energy theory and material fatigue test data, the plastic strain threshold for damage initiation was modified for HCF and LCF respectively. The damage evolution parameters were determined according to the fatigue test results of standard specimens. A damage mechanics-finite element full-couple method was adopted to simulate the process of fatigue damage evolution. The numerical simulation of fatigue lives were compared with the fatigue tests of 2A12-T4 open-hole plates and good agreement was obtained.
Authors: Ivano Benedetti, R.A. Soler-Crespo, A. Pedivellano, Wei Gao, H.D. Espinosa
Abstract: A continuum model for GO membranes is developed in this study. The model is built representing the membrane as a two-dimensional, heterogeneous, two-phase continuum and the constitutive behavior of each phase (graphitic or oxidized) is built based on DFTB simulations of representative patches. A hyper-elastic continuum model is employed for the graphene areas, while a continuum damage model is more adequate for representing the behavior of oxidized regions. A finite element implementation for GO membranes subjected to degradation and failure is then implemented and, to avoid localization instabilities and spurious mesh sensitivity, a simple crack band model is adopted. The developed implementation is then used to investigate the existence of GO nano-representative volume elements.
Authors: Wen Jing Shi, Yong Bo Zhang, Wei Ping Hu
Abstract: In this paper, a fatigue life prediction method for fiber reinforced polymer composite lamina is proposed. Based on two independent introduced damage variables, the damage degree of fiber and the damage degree of matrix, the issue of lamina fatigue is transformed into the study of damage evolution for fiber and matrix. Subsequently, the damage driving force and the damage evolution equations for the fiber and the matrix are constructed, respectively. Then, a novel parameter identified method is conducted. Finally, with the failure criterion for the lamina presented, the fatigue life prediction method of the composite lamina is proposed.
Authors: Andriy Vyshnevskyy, Shehzad Khan, Joern Mosler
Abstract: One of the important considerations in the design of components is the estimation of cyclic lifetime and analysis of the critical regions of a construction. The local approach of lifetime estimation using continuum damage mechanics (CDM) has shown a great potential in predicting material failure not only for monotonic, but also for fully reversed loadings. In this paper, the CDM model of Desmorat-Lemaitre [1] was investigated regarding the prediction of cyclic lifetime. A series of experiments on tension specimens with different geometries were performed. The latter were used for the determination of model parameters as well as for the validation of the predictive capability of the model.
Authors: Michał Burak, Dariusz Skibicki, Michał Stopel
Abstract: The article presents calculations of fatigue life acc. to CDM model performed analytically and in program LS-DYNA with the model implemented there. On the basis of comparison of the obtained results with experimental fatigue lives, the possibility of estimation of fatigue life in LS-DYNA program acc. to CDM model was evaluated.
Authors: Błażej Paluszyński, Thomas Böhlke
Abstract: An overview on modeling of high-cycle fatigue is given and experimental findings of the damage accumulation are discussed. Finally we sketch an isotropic constitutive model for the description of the damage accumulation due to high-cycle fatigue.
Authors: Jin Yang Chu, Jian Xing Mao
Abstract: In this paper, the low cycle fatigue crack initiation life was regarded as a process of damage accumulation and a damage accumulation model was established based on the Continuum Damage Mechanics. By the model, we analyzed how the variable amplitude applied at the crack initiation stage influenced the low cycle fatigue life of high temperature materials. With the parameters of GQGH4169 alloy at room temperature, we determined the specific values of damage parameters by finite element method and numerical analysis method. Then, the crack initiation life predictions were carried out. The results show that using this approach can not only predict the crack initiation life of CT specimen accurately, but also reflect a definite influence of variable amplitude on the crack propagation life combining with the Paris Law, and the test costs reduced consequently.
Authors: Sanjay Kumar Sondhi, Gaurav Singh, Francesco Mastromatteo
Abstract: Safe extrapolation of short-term creep data requires development of creep models where (a) the constitutive laws are physics based, and (b) majority of model parameters are calculated rather than empirically fitted. This paper details the structure of such a physics-based creep model and its application to DS GTD-111TM superalloy. The constitutive creep law is derived from the kinetics of dislocation-particle interactions in the presence of thermal activation. This constitutive creep law is further coupled with the evolution kinetics of controlling microstructural parameters and associated damages. The model is expected to provide vital inputs for component design as well as remaining life assessment. (GTD-111TM is a trademark of the General Electric Company).
Authors: Hossein Hosseini-Toudeshky, Bijan Mohammadi
Abstract: To predict the progressive damages including the large delamination growth in composite laminates, a new interface de-cohesive constitutive law is developed which is compatible with 3D continuum damage mechanics (CDM). To avoid the difficulties of 3D mesh generation and 3D interface modeling between the layers, the interface element is implemented in the Reddy’s full layer-wise plate theory. An angle-ply laminate is analyzed to evaluate the developed CDM+Interface procedure in edge delamination initiation and evolution at final stage of CDM damage progress.
Authors: L.E. Granda Marroquín, Luis Héctor Hernández-Gómez, G. Urriolagoitia-Calderón, G. Urriolagoitia-Sosa, E.A. Merchán-Cruz
Abstract: The goal of this paper is to present the results obtained from damage evaluation in automotive axles, which are under torsion fatigue. For this purpose, a Nonlinear Damage Model is used. The mentioned shafts have to satisfy geometry requirements and their material has to be heat treated in order to improve their performance. One has to keep in mind that fatigue strength depends on material properties and geometry. In order to make a precise evaluation of the accumulated damage, the manufactured shafts were tested. In the first instance, the mechanical properties of the material were evaluated with static torsion tests. In the next step, the S-N curves were obtained with torsion fatigue tests. In all these cases, temperature was controlled. Experimental data at different load levels was gathered with strain gages in conjunction with a data acquisition system. The life cycle history of each tested shaft was stored and with this experimental evidence, damage curves were obtained and the cumulative damage of the axle was established. With these damage curves, it is possible to define the relation between damage rate and life for different stress levels.
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