检索结果-南通市图书馆

A fatigue damage-cumulative model in peridynamics

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Aeronautics 2021年第2期34卷 329-342页

作者： Binchao LIU Rui BAO Fucheng SUI Institute of Solid Mechanics School of Aeronautic Science and EngineeingBeihang UniversityBeijing 100083China Shenyang Aircraft Design and Research Institute Shenyang 110801China

While the present structural integrity evaluation method is based on the philosophy of assumed similitude, fatigue and Damage Tolerance(F&DT) evaluations for next generation of air-vehicles require high-fidelity physical models within cyberspace. To serve the needs of F&DT evaluation in digital twin paradigm, a fatigue damage-cumulative model within peridynamic framework is proposed in this paper. Based on the concept of fatigue element block and damage accumulation law in form of Coffin-Manson relationship, the proposed model applies to both fatigue crack initiation and fatigue crack growth;fatigue crack growth rates under constant-amplitude and simple variable-amplitude block loading cases can be well predicted for three common structural materials without inputs of Paris law parameters. Additionally, the proposed model can also be easily extended to a probabilistic version;for verification, multiple-site-damage problems are simulated and the statistic nature of fatigue process in experiments can be well captured. In the end, main features of the proposed model are summarized, and distinctions from the other models are discussed. There may be a potential for the peridynamic damage-cumulative model proposed in this work to numerically predict fatigue problems in digital twin paradigm for future generations of aerospace vehicles.

关键词： fatigue crack growth rate fatigue damage fatigue element model fatigue lifetime Multiple site damage Peridynamics

Analytical Models of Concrete fatigue:A State-of-the-Art Review

在线全文

学校读者我要写书评

暂无评论

Computer Modeling in Engineering & Sciences 2023年第1期134卷 9-34页

作者： Xiaoli Wei D.A.Makhloof Xiaodan Ren College of Civil Engineering Tongji UniversityShanghai200092China Department of Civil Engineering Minia UniversityEL-Minia61111Egypt

fatigue failure phenomena of the concrete structures under long-term low amplitude loading have attractedmore *** structures,such as wind power towers,offshore platforms,and high-speed railways,may resist millions of cycles loading during their intended *** the past century,analytical methods for concrete fatigue are *** is concluded that models for the concrete fatigue calculation can fall into four categories:the empirical model relying on fatigue tests,fatigue crack growth model in fracture mechanics,fatigue damage evolution model based on damage mechanics and advanced machine learning *** this paper,a detailed review of fatigue computing methodology for concrete is presented,and the characteristics of different types of fatigue models have been stated and discussed.

关键词： Concrete fatigue lifetime fatigue crack growth fatigue damage evolution machine learning

fatigue strength evaluation of self-piercing riveted joints of AZ31 Mg alloy and cold-rolled steel sheets

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Journal of Magnesium and Alloys 2020年第1期8卷 241-251页

作者： Se-Hyung Kang Dong-Woon Han Ho-Kyung Kim Graduate School Seoul National University of Science and TechnologySeoul01811South Korea Department of Mechanical and Automotive Engineering Seoul National University of Science and TechnologySeoul01811 South Korea

The application of magnesium alloys to automobiles is increasing due to their superior specific strength and specific *** this study,an upper sheet of AZ31 magnesium alloy and a lower sheet of cold-rolled steel were joined by self-piercing riveting(SPR),a method commonly used to join automotive panels.A cross-shaped specimen was fabricated with a punching force of 35 kN,which exhibited the best joint strength for the SPR joint specimen *** and fatigue strengths were evaluated using cross-shaped specimens at loading angles of 0°,45°,and 90°.The load amplitude corresponding to the fatigue endurance limit was assumed to be at 106 cycles,and the fatigue ratios(=fatigue endurance limit/static strength)at the loading angles of 0°,45°,and 90°are 22%,13%,and 9%,*** all three loading angle specimens,fatigue cracks initiated at the triple point where the rivet shank,the upper sheet and the lower sheet are in contact with each other,with the cracks propagating through the thickness of the upper sheet and ultimately leading to *** fatigue lifetimes were evaluated through the von-Mises stress,maximum principal stress,and equivalent stress intensity *** was found that the fatigue lifetimes could be evaluated most appropriately through the maximum principal stress.

关键词： Self-piercing riveting Magnesium alloy fatigue strength Maximum principal stress fatigue lifetime

Thermal analysis and cooling structure design of the primary collimator in CSNS/RCS

在线全文

学校读者我要写书评

暂无评论

Chinese Physics C 2013年第5期37卷 76-80页

作者：邹易清王娜康玲屈化民何哲玺余洁冰 Institute of High Energy Physics Chinese Academy of Sciences Graduate University of Chinese Academy of Sciences

The rapid cycling synchrotron （RCS） of the China Spallation Neutron Source （CSNS） is a high intensity proton ring with beam power of 100 kW. In order to control the residual activation to meet the requirements of hands-on maintenance, a two-stage collimation system has been designed for the RCS. The collimation system consists of one primary collimator made of thin metal to scatter the beam and four secondary collimators as absorbers. Thermal analysis is an important aspect in evaluating the reliability of the collimation system. The calculation of the temperature distribution and thermal stress of the primary collimator with different materials is carried out by using ANSYS code. In order to control the temperature rise and thermal stress of the primary collimator to a reasonable level, an air cooling structure is intended to be used. The mechanical design of the cooling structure is presented, and the cooling efficiency with different chin numbers and wind velocity is also analyzed. Finally, the fatigue lifetime of the collimator under thermal shocks is estimated.

关键词： primary collimator cooling structure thermal analysis fatigue lifetime

A new model for life prediction of GH4133 under TMF conditions

在线全文

学校读者我要写书评

暂无评论

Journal of University of Science and Technology Beijing 2002年第4期9卷 287-291页

作者： JianguoWang HongyingWang ShipingXu LianqingWang YonglinKang StateKeyLaboratoryforAdvancedMetalsandMaterials UniversityofScienceandTeclmologvBeijing.Beijing100083China MaterialsScienceandEngineeringSchool UniversityofScienceandTechnologyBeijingBeijingBeijing100083China

Thermal mechanical cyclic strain tests were carried out under in-phase andout-of-phase conditions on a Nickel-base Superalloy GH4133 in the temperature range of 571-823 degC. Based on analyzing the present models of TMF (thermal mechanical fatigue) life prediction, a newmodel for predicting nickel-base superalloy TMF lifetime was proposed. TMF life of superalloy GH4133was calculated accurately based on the new model. Experimental TMF life has been compared with thecalculated results and all results fall in the scatter band of 1.5. The calculating results showthat the new model is not only simple, but also precise. This model will play great roles as lifeprediction of the metal materials and the engineering components subjected to non-isothermal serviceconditions.

关键词： thermal mechanical fatigue life production Nickel-base superalloy fatigue lifetime prediction model in-phase out-of-phase