scholarly journals An investigation of the nonlinear creep damage accumulation of different materials: Application of a novel damage model

2021 ◽  
Author(s):  
Xu Zhao ◽  
Xuming Niu ◽  
Yingdong Song ◽  
Zhigang Sun
Keyword(s):  
Damage Accumulation ◽  
Damage Model ◽  
Creep Damage ◽  
Nonlinear Creep

scholarly journals An investigation of the nonlinear creep damage accumulation of different materials: Application of a novel damage model

2021 ◽  
Author(s):  
Xu Zhao ◽  
Xuming Niu ◽  
Yingdong Song ◽  
Zhigang Sun
Keyword(s):  
Damage Accumulation ◽  
Failure Modes ◽  
Damage Model ◽  
Evolutionary Process ◽  
Creep Damage ◽  
Experimental Result ◽  
Nonlinear Creep ◽  
The Novel ◽  
Proposed Model ◽  
Damage Accumulation Model

Variable creep load is one of the most important failure modes for hot-component of aero-engine. To accurately predict creep damage and remaining life, a novel nonlinear creep damage accumulation model is proposed based on the Wilshire function and isodamage line, which takes the influence of load history into account and uses ultimate tension strength to compensate the temperature effect. Experimental result of tests on four kinds of material were utilized to verify the accuracy of the proposed model and to compare it with existing models. It was determined that the novel model was better at predicting damage accumulation than all others model. Furthermore, the proposed model elucidates the evolutionary process of creep damage, and four cases of damage evolution process are discussed.

An improved nonlinear damage model of rocks considering initial damage and damage evolution

2020 ◽  
Vol 29 (7) ◽  
pp. 1117-1137 ◽  
Author(s):  
Wenlin Feng ◽  
Chunsheng Qiao ◽  
Shuangjian Niu ◽  
Zhao Yang ◽  
Tan Wang
Keyword(s):  
Damage Evolution ◽  
Least Squares Method ◽  
Damage Model ◽  
Creep Damage ◽  
Secondary Creep ◽  
Nonlinear Creep ◽  
Creep Failure ◽  
Initial Damage ◽  
Nonlinear Damage Model ◽  
Creep Damage Model

The experimental results show that the creep properties of the rocks are affected by the initial damage, and the damage evolution also has a significant impact on the time-dependent properties of the rocks during the creep. However, the effects of the initial damage and the damage evolution are seldom considered in the current study of the rocks' creep models. In this paper, a new nonlinear creep damage model is proposed based on the multistage creep test results of the sandstones with different damage degrees. The new nonlinear creep damage model is improved based on the Nishihara model. The influences of the initial damage and the damage evolution on the components in the Nishihara model are considered. The creep damage model can not only describe the changes in three creep stages, namely, the primary creep, the secondary creep, and the tertiary creep, but also reflect the influence of the initial damage and the damage evolution on creep failure. The nonlinear least squares method is used to determine the parameters in the nonlinear creep damage model. The consistency between the experimental data and the predicted results indicates the applicability of the nonlinear damage model to accurately predict the creep deformation of the rocks with initial damage.

A nonlinear creep damage model for salt rock

2018 ◽  
Vol 28 (5) ◽  
pp. 758-771 ◽  
Author(s):  
Fei Wu ◽  
Jie Chen ◽  
Quanle Zou
Keyword(s):  
Test Data ◽  
Damage Model ◽  
Creep Damage ◽  
Nonlinear Creep ◽  
Salt Rock ◽  
Creep Tests ◽  
Nonlinear Constitutive Equation ◽  
Damage Constitutive Model ◽  
Creep Damage Model ◽  
Actual Stress

In the creep tests, stress is no longer a constant and increases gradually under the influence of damage occurring during accelerating creep, which is a slow-loading process rather than a conventional creep. With the accumulation of the damage over time, the actual stress increases greatly. The increased actual stress not only generates loading strain but also causes the steady creep rate to rise. This coupling possibly explains why salt rock presents nonlinear accelerating characteristics at the accelerating creep stage. In this work, the constraint of the present creep concept was overcome by assuming that the acceleration creep phase is a coupling process of loading and creeping. Furthermore, we demonstrate that the total strain in this phase is equal to the sum of loading strain and creeping strain. A new nonlinear constitutive equation for creep was then derived, and the mechanisms underlying the nonlinear accelerating characteristics emerging at the stage of accelerating creep are further explained. A step-loading experiment on salt rock was performed for a period of six months. The characteristics of accelerating creep appeared in the last step of loading. This new nonlinear creep damage constitutive model was used to fit and analyze the test data. Obtained results show that this model fits well to these test data and also favorably represents the nonlinear characteristics of accelerating creep, thus supporting the model’s validity.

Nonlinear Creep Damage Model for Concrete under Uniaxial Compression

2003 ◽  
Vol 129 (9) ◽  
pp. 1065-1075 ◽  
Author(s):  
Claudio Mazzotti ◽  
Marco Savoia
Keyword(s):  
Uniaxial Compression ◽  
Damage Model ◽  
Creep Damage ◽  
Nonlinear Creep ◽  
Creep Damage Model

scholarly journals A Nonlinear Creep Damage Model of Layered Rock under Unloading Condition

2018 ◽  
Vol 2018 ◽  
pp. 1-8 ◽  
Author(s):  
Ruihong Wang ◽  
Yuzhou Jiang ◽  
Chao Yang ◽  
Fei Huang ◽  
Yuxuan Wang
Keyword(s):  
Rock Specimen ◽  
Damage Model ◽  
Creep Damage ◽  
Nonlinear Creep ◽  
Term Strength ◽  
Layered Rock ◽  
Rock Creep ◽  
Creep Time ◽  
Creep Damage Model

Triaxial unloading creep tests of layered rock specimen of Jinping II hydropower station were carried out using the rock creep testing machine; thus the creep deformation curves under different confining pressures were acquired. The test results showed that, in addition to the obvious unloading creep characteristics of rock specimen, the nonlinear accelerating creep deformation emerged under the last stage confining stress condition, and the whole creep curves presented the typical rock creep three stages. On the other hand, the Burgers creep model constitutive equations under the three-dimensional stress state were also deduced. Based on the creep test data, through identifying the creep parameters using the optimized algorithm, the corresponding parameters of triaxial creep constitutive model were obtained. By comparative analysis of creep parameters, it can be concluded that creep parameters nonlinearly degraded with the decrease of confining pressure gradually. Moreover, when the load is below the long-term strength of rock, the creep parameters are only related to the unloading ratio, while in the case that the load is larger than the long-term strength of rock, the unloading creep parameters are related to both unloading ratio and creep time. According to the creep parameters under the first-stage stress level, and through introducing unloading ratio damage factor to describe the degrading rule of creep parameters on other stress levels, the method of uniformity determining the creep parameters was proposed. It was assumed that the damage degree in rock interior was relative to both unloading ratio and creep time; a nonlinear creep damage model of rock under unloading was proposed, which could better reflect the nonlinear characteristics of rock creep. The results showed that rock nonlinear creep damage model achieved perfectly consistent results with the creep test.

scholarly journals Nonlinear creep damage model considering effect of pore pressure and analysis of long-term stability of rock structure

2019 ◽  
Vol 29 (1) ◽  
pp. 144-165 ◽  
Author(s):  
Yaoru Liu ◽  
Weiqiang Wang ◽  
Zhu He ◽  
Shuai Lyv ◽  
Qiang Yang
Keyword(s):  
Pore Pressure ◽  
Damage Model ◽  
Viscoelastic Model ◽  
Creep Damage ◽  
Arch Dam ◽  
Nonlinear Creep ◽  
High Arch Dam ◽  
Reservoir Impounding ◽  
Rock Structure ◽  
Creep Damage Model

Water changes natural seepage in the surrounding geological environment and weaken rock mass of valley during reservoir impounding, which result in large time-dependent deformation of foundation of dam. A nonlinear creep damage model considering water effect is proposed by taking into account the influence of pore pressure on the spherical stress tensor and yield surface. The elastic-viscoelastic model is consisted of a spring and several cascaded Kelvin models. The model is implemented in the ABAQUS user material subroutine. The accuracy of the model is verified by the triaxial creep test of saturated sandstone and dry sandstone. Then it is applied in the valley contraction analysis during impounding of Xiluodu high arch dam.

A nonlinear creep damage model for brittle rocks based on time-dependent damage

2013 ◽  
Vol 17 (sup1) ◽  
pp. s111-s125 ◽  
Author(s):  
R.B. Wang ◽  
W.Y. Xu ◽  
W. Wang ◽  
J.C. Zhang
Keyword(s):  
Damage Model ◽  
Creep Damage ◽  
Time Dependent ◽  
Nonlinear Creep ◽  
Brittle Rocks ◽  
Creep Damage Model

scholarly journals A nonlinear creep damage model for gelled waxy crude

2021 ◽  
Author(s):  
Hong-Ying Li ◽  
Qing-Bo Xie ◽  
Hao Sun ◽  
Wei Guo ◽  
Feng Yan ◽  
...  
Keyword(s):  
Damage Model ◽  
Creep Damage ◽  
Nonlinear Creep ◽  
Waxy Crude ◽  
Creep Damage Model

Non-linear creep damage model of sandstone under freeze-thaw cycle

2021 ◽  
Vol 28 (3) ◽  
pp. 954-967
Author(s):  
Jie-lin Li ◽  
Long-yin Zhu ◽  
Ke-ping Zhou ◽  
Hui Chen ◽  
Le Gao ◽  
...  
Keyword(s):  
Damage Model ◽  
Creep Damage ◽  
Freeze Thaw ◽  
Thaw Cycle ◽  
Linear Creep ◽  
Non Linear ◽  
Freeze Thaw Cycle ◽  
Creep Damage Model

Creep damage index as a sensitive indicator of damage accumulation in thermoplastic laminates

2017 ◽  
Vol 37 (3) ◽  
pp. 147-154
Author(s):  
Jiří Minster ◽  
Martin Šperl ◽  
Josef Šepitka
Keyword(s):  
Damage Accumulation ◽  
Damage Index ◽  
Creep Damage ◽  
Sensitive Indicator
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