通过关键词查论文: Damage Model

文章题目页数

作者: Kai Zhao, Zhi Ming Han, Xing Wang Yang
摘要: For exploring the attenuation law of limestone dynamic elastic modulus (DEM) under fatigue cyclic loading, 24 limestone specimens were used to conduct dynamic uniaxial cyclic compressive tests under different loading frequencies and stress amplitudes on MTS Test System. The tests results confirmed that the decrease of DEM goes through three different stages with the increase of cyclic numbers. And, there is no distinct correlation between three-stage evolution rule of DEM and frequencies as well as stress amplitudes. The degeneration of DEM is caused by accumulation of micro-cracks and damage increase in rock specimen. Thus, based on attenuation rule of DEM, a fatigue damage evolution model which can depict the first two stages of limestone fatigue damage development was proposed.
1281
作者: Jing Si Huo, Hui Qu
摘要: A computational model, in which the effects of high temperature on steel and concrete’s properties and the composite action and interfacial properties between steel tube and concrete core were considered, was developed using ABAQUS program. Based on a damage model of concrete at ambient condition and tested stress versus strain curves of fire-damaged concrete, a new damage model of concrete after exposure to high temperatures was developed to consider the influence of high temperatures on the damage of concrete. By introducing the damage model of fire-damaged concrete, the reasonable equivalent stress-strain relations of confined concrete and a modified steel tube-concrete interface model into the ABAQUS FE model, the mechanical behaviors of the fire-damaged CFT columns and connections were simulated precisely and verified by some relative test results.
775
作者: Sheng Ping Chen
摘要: Common concrete, lightweight aggregate concrete and self-compacting concrete with strength grade C50 were tested under freeze-thaw actions. Experimental results show that the Light weight aggregate concrete has the best freeze-thaw resistance. Furthermore, the relative dynamic elastic modulus is used to quantitatively analyze the interior damage of concrete materials subjected to freeze-thaw actions, and the freeze-thaw damage evolution equations were established by using quadratic functions, and the computational damage values agree well with the experimental results.
1776
作者: Laurent Dubar, André Dubois, Mirentxu Dubar
摘要: Since the beginning of the 90’s, research activities focused on friction and wear in metal forming have been developed at the LAMIH UMR CNRS 8201 in Valenciennes. Specific methodologies have been designed to optimize a given forming process (bulk forming process or sheet forming process). These methodologies involve prototype benches which have been built to reproduce contact conditions encountered in manufacturing plants by taking specimens and contactors from the real industrial workpieces and tools. The evaluation of the friction coefficient added to the fine analysis of the surfaces have helped us to better understand friction and wear during processes. These facilities have been settled by numerical simulation at meso and macro scales by means of finite element methods. So, this paper is the sum up of the output of these methodologies with a specific focus on wear and lubrication, at room and hot temperatures.
42
作者: Xiao Xia Sun, Wei Liu, Rui Qi Shen, Ying Hua Ye, Li Zhi Wu
摘要: The thin-walled shell axial impact deformation of one-leg electric detonator with different density charge was studied. The impact stress was analyzed, and on the basis of kinetic theory the impact deformation model was established for the thin-walled shell filled with explosive. The experiments were verified at 60 000g, 80 000g, 100 000g and 120 000g by gas gun. The results show that shell length decreases and the plastic deformation zone diameter increases after impact. Damage deformation degree decreases with increased shell strength, reduced shell and internal charging mass summation and reduced impact velocity square. The model calculated value agrees well with the test data. The deformation model can be used to predict overload damage deformation for such detonator.
279
作者: Bin Jia, Zheng Liang Li, Jun Lin Tao, Chun Tao Zhang
摘要: SPHB tests of concrete under different temperatures and various loading conditions are completed, and high-temperature dynamical behavior of concrete is obtained. Dynamical mechanical behavior of concrete with high temperature is affected by not only the strain rate effect, but also the high temperature weakening effect, and the strain rate hardening effect is coupled with high temperature weakening effect, but the latter has greater influence. Concrete failure evolution is described on basis of the damage factor, the intercoupling strain rate hardening effect and temperature weakening effect are simply set as mutually independent factors, each parameter is respectively fitted with test data, finally, concrete constitutive equation under high-temperature dynamical conditions is established, and comparative analysis with test data are conducted, indicating good coincidence with test results.
303
作者: Peng Du, Yan Yao, Ling Wang, Yin Cao
摘要: As the action mechanisms of various factors affecting concrete durability are different, it is difficult to understand the durability of concrete exposed to multiple factors using only mechanism analysis. Converting each action mechanism to an appropriate macroscopic mechanical effect can simplify complicated durability problems. Here we study concrete beams exposed to common environmental factors: cyclic freezing and thawing, bending stress and chloride attack. By converting each mechanism into a mechanical process and analyzing its effect on concrete, a damage model based on strain was established. Freezing-induced tensile stress is essentially a low-cycle fatigue tensile stress, as represented by a saw-tooth model. The maximum strains when the maximum freezing-induced tensile stress coupled with the four-point bending stress in every freeze-thaw cycle were measured, and found to increase with freeze-thaw cycling. Our damage model provides a new approach to predict the service life of concrete, and guidance for durability design of concrete.
1342
作者: Hui Ding, Li Song
摘要: Based on the static elastic-plastic analysis program REPFPA, the impact of concrete material elastic-brittle-plastic damage model and its numerical test methods was studied. This paper has introduced the visualization technology, preparation of pre-processing related modules and graphical visualization display and many other functions into the nonlinear dynamic program, which is convenient for users to operate and view the results. And the numerical experiments of dynamic response of cantilever beam problems and spherical shell under step load elastic-plastic problems was produced. Compared with the results of other scholars and literature, we’ll verify the validity of the research in this paper.
848
作者: Gui Lin Li, Li Wang, Yuan Chun Mao
摘要: This paper aims at progressive failure within surrounding rock under continuous excavation, such as mining, underground powerhouse building, etc. A meso-damage model is proposed, which include the damage law under complex stress state for brittle materials, and the damage evolution based on stiffness degradation. The damage model is embedded into the FEM program. To test and very the damage model, a example of continuous excavation of underground mining is simulated. The result shows that the crack field growth is in accordance with that the similar material experiment.
1473
作者: Hong Yan Liu, Ming Wang
摘要: On basis of the existed TCK model, the establishment process of a new rock blasting damage model is discussed by considering the relationship of crack density Cd, which indicates the shock damage extent of rock, and sound wave attenuation coefficient ap. Then, this model is inserted into the user-defined material model library of ANSYS/LS-DYNA3D software to construct the new damage model. Numerical simulation of damage to retained rock mass of dam foundation caused by rock blasting excavation in dam region with this model. Calculation results show that: as far as the blasting parameters and geological conditions in this paper, the damage to retained rock mass below caused by rock blasting excavation above is basically limited to the scope of 1.5m below the bottom of blasthole, and damage degree gradually reduces from the bottom of blasthole to faraway. Meanwhile, blasting will not cause rock mass to open along soft layer inside, whose maximum calculation displacement is only 3mm. The calculation result can be referred by the practical engineering.
4256
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