Papers by Keyword: Damage Accumulation

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Authors: Bao Feng Fan, Na Yang, Qing Shan Yang, Leroy Gardner
Abstract: The mechanical behaviors of intersecting joints considering damage accumulation in steel tube structures is analyzed through the FE-program ABAQUS. The stress characteristic and failure modes of these joints are concluded. Especially, it has been analyzed influence of the change of geometric parameters to mechanical behavior of joints. Finally, the results indicate the joints have a good mechanical performance and good plastic deformation as to excessive local buckling of chord under the loads.
Authors: Andrey Benin
Abstract: Finite-element modeling of reinforced concrete structure fracture process was carried out using models of nonlinear concrete with damage accumulation. Mechanism of cracks initiation in reinforced concrete structures was ascertained and kinetics of cracks growing in concrete due to corrosion of rebars was obtained. Fracture processes of road bridge fragment and railway bridge ballastless bed under corrosion of rebars was simulated.
Authors: Wojciech Blażejewski, Pawel Gasior, Jerzy Kaleta, Radosław Rybczyński
Abstract: In this paper a study of damage accumulation evaluation of highly stressed composite layer using acoustic emission method and local strain measurements by optical fiber based sensors in form of Fiber Bragg Grating (FBG) is presented. The study was carried out using composite NOL-ring specimens. These kind of specimens can simulate behavior of the cylindrical part of the pressure vessel. Quasistatic and creep tests of CFRC made NOL specimens were performed. It has been shown that there is a correlation between changes in the strain field of composite material, detected by FBG optical sensors, and changes in acoustic emission signals. The possibility of a kind of calibration of composite material strain state monitoring system by AE measurements and at the same time evaluation of damage accumulation was confirmed.
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: V.M. Kornev
Abstract: Failure of weld joints under single and cyclic pulsating loading conditions is under consideration. A weld joint is modeled by three-layer composite. Stepwise propagation of the internal I mode crack under cyclic loading is investigated. Delamination of bimaterial composed of two structured materials is considered when a crack is located at the interface between two media. Loads under pulsating loading conditions are studied for elastic-plastic material. For analysis of this process, diagrams of quasi-brittle fracture of solids under cyclic loading conditions are proposed to be used. One of curves of the proposed diagram bears resemblance to the Kitagawa-Takahashi diagram. Estimates of average dimensionless velocity of stepwise crack propagation per loading cycle have been obtained in an explicit form for plain specimens of finite width. The relations derived for the average crack growth rate can be considered as structural expressions for plotting Paris’ curves.
Authors: Jan Willem G. van de Kuilen, Wolfgang Gard
Abstract: Service life modelling of cracked timber beams can be performed using modified damage accumulation models that describe the combined effect or long term loads (mechanical) and biological of physical wood degradation. The combined model allows for the estimation of residual service life and an analysis of crack development. The model can also be used to analyse safety factors that may need to be applied. Also, a sensitivity analysis can be performed for future risks. It is shown that the failure risk is very sensitive to the level of the applied loads, similar to time to failure analysis of non-degraded timber. Failure in timber structures occurs within a very short time frame. A practical case of cracked glulam beams is included in the paper.
Authors: Wei Huang, Jiang Qian, Bin Bin Zhuang, Qiu Shi Fu
Abstract: This paper presents the results of a numerical investigation aimed at evaluation of damage accumulation in structures under different seismic sequences. For this purpose, a multi-story RC frame model representing the typical buildings was built and subjected to four sets of different repeating seismic sequences with different magnitude. The results indicate that the aftershock sequences will increase the damage accumulation in structures, and the damage index based on the Park and Ang model can qualitatively and quantitatively ascertain the damage state of the structure instead of the single index based on the lateral drift demands. Additionally, different sequences with the identical energy input will cause the same damage state in structures.
Authors: Lei Wang, Tian Zhong Sui, Wen Qiang Lin
Abstract: The Fiber Reinforced Plastic (FRP) has been widely used in aircraft, spacecraft, watercraft and transportation because of its excellent mechanical characteristics. The fatigue characteristic of the composite laminate of FRP is important guarantee to the structure security and reliability. In this paper, according to the damage mechanical theory, a fatigue damage accumulation model based on stiffness degradation and the corresponding method of fatigue life prediction are presented. The composite material of T300/ epoxy-resin with high performance has been investigated. The tension-tension fatigue tests have been conducted on the composite laminates. The fatigue life prediction of the composite material is presented. It shows a good agreement to the experimental and theoretical results.
Authors: Peng Gang Mu, Xiao Peng Wan
Abstract: In this research, new progressive fatigue damage models are established to calculate the fatigue life and simulate damage process of composite pin joints. The proposed models based on residual strength and residual stiffness of unidirectional laminates, have three parameters to present the different damage state, which can accurately describe the growth process of fatigue damage propagation by the mathematical method. The fatigue damage models combining with stress analysis, failure analysis, and material property degradation process, can predict the fatigue life, damage state and residual material properties of composite structures under arbitrary loading conditions. Using the models, composite pin joints with different stacking sequence are analyzed, fatigue life and damage quantification are concluded simultaneously. The proposed models and the process of analysis provide a way to solve the fatigue durability of composite structures.
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