Damage Analysis of Thermal-Mechanical Coupling on Concrete Member under High Temperature

2013 ◽  
Vol 639-640 ◽  
pp. 1187-1192
Author(s):  
Shui Ping Yin ◽  
Song Hua Tang ◽  
Yong Hong Li ◽  
Chao Chen ◽  
Fang Tian ◽  
...  
Keyword(s):  
High Temperature ◽  
Structural Damage ◽  
Damage Mechanics ◽  
Thermal Damage ◽  
Damage Model ◽  
Damage Analysis ◽  
Concrete Member ◽  
Cumulative Impact ◽  
Mechanical Coupling ◽  
Structural Resistance

The fire has brought great harm to human, so it is of vital significance to establish a scientific method of structural fire resistance design to avoid personnel casualties and economic loss in the destroy or collapse of the structure in fire. The mechanical properties of materials deteriorate at the high temperature of the fire, and the structure can be damaged easily, so the damage cumulative impact must be considered in the structural resistance capability to fire. Damage mechanics is a powerful tool in the study of structural damage and destroy. In the paper, the damage mechanics is introduced into the calculation of resistance capability to fire of concrete structure, and the thermal-damage analysis of concrete member is achieved through the second development on ANSYS platform by using the residual strength thermal-damage model at high temperature.

Damage Model and Damage Mechanical Characteristics of Loaded Rock under Freeze-Thaw Conditions

2010 ◽  
Vol 168-170 ◽  
pp. 658-662 ◽  
Author(s):  
Hui Mei Zhang ◽  
Geng She Yang
Keyword(s):  
Mechanical Properties ◽  
Structural Damage ◽  
Damage Mechanics ◽  
Coupling Effect ◽  
Damage Model ◽  
Engineering Structures ◽  
Freeze Thaw ◽  
Thaw Cycle ◽  
Loaded Rock ◽  
Total Damage

Considering the heterogeneous characteristics of rock at mesoscopic level, the damage propagation constitutive relation and evolution equation of freeze-thaw and loaded rock were established by using the theory of macro phenomenological damage mechanics and the generalized theory of strain equality. The evolutionary mechanisms of micro-structural damage and materials mechanical properties for the loaded rock were discussed under freeze-thaw condition, verified by experimental results of the freeze-thaw cycle and compression test of rock. It is shown that the freeze-thaw and loaded damage model can represent the complicated relations among the freeze-thaw, load and the damage inside the rock, reveal the coupling failure mechanism of macroscopic rock under the freeze-thaw and load from the micro-damage evolution. The combined effect of freeze-thaw and load exacerbates the total damage of rock with obvious nonlinear properties, but the coupling effect weakens the total damage. The lithology and initial damage state of the freeze-thaw and loaded rock in engineering structures in cold regions determine the weights of influence factors to mechanical properties, including environmental factor, loading factor and the coupling effects, so the rock performances different damage mechanical characteristic.

scholarly journals Study on the Damage Evolution Process and Fractal of Quartz-Filled Shale under Thermal-Mechanical Coupling

Geofluids ◽  
2021 ◽  
Vol 2021 ◽  
pp. 1-14
Author(s):  
Zhonghu Wu ◽  
Huailei Song ◽  
Liping Li ◽  
Zongqing Zhou ◽  
Yujun Zuo ◽  
...  
Keyword(s):  
Fractal Dimension ◽  
Critical Temperature ◽  
Failure Mode ◽  
Damage Evolution ◽  
Damage Mechanics ◽  
Thermal Damage ◽  
Failure Modes ◽  
Factors Affecting ◽  
Mechanical Coupling ◽  
Theory Of Damage

Filling of brittle minerals such as quartz is one of the main factors affecting the initiation and propagation of reservoir fractures in shale fracturing, in order to explore the failure mode and thermal damage characteristics of quartz-filled shale under thermal-mechanical coupling. Combining the theory of damage mechanics and thermoelasticity, RFPA2D-Thermal is used to establish a numerical model that can reflect the damage evolution of shale under thermal-solid coupling, and the compression test under thermal-mechanical coupling is performed. The test results show that during the temperature loading process, there is a temperature critical value between 60°C and 75°C. When the temperature is less than the critical temperature, the test piece unit does not appear obvious damage. When the temperature is greater than the critical temperature, the specimen unit will experience obvious thermal damage, and the higher the temperature, the more serious the cracking. Under the thermal-mechanical coupling of shale, the tensile strength and elastic modulus of shale show a decreasing trend with the increase of temperature. The failure modes of shale under thermal-solid coupling can be roughly divided into three categories: “V”-shaped failure (30°C, 45°C, and 75°C), “M”-shaped failure (60°C), and inverted “λ”-shaped failure (90°C). The larger the fractal dimension, the more complex the failure mode of the specimen. The maximum fractal dimension is 1.262 when the temperature is 60°C, and the corresponding failure mode is the most complex “M” shape. The fractal dimension is between 1.071 and 1.189, and the corresponding failure mode is “V” shape. The fractal dimension is 1.231, and the corresponding failure mode is inverted “λ” shape.

Calculation and Analysis on the Thermal Damage at High Temperature

2007 ◽  
Vol 353-358 ◽  
pp. 1191-1194
Author(s):  
Song Hua Tang ◽  
Ying She Luo ◽  
Ming Zhe Ning ◽  
Zhi Chao Wang
Keyword(s):  
High Temperature ◽  
Damage Mechanics ◽  
Thermal Damage ◽  
Thermal Stresses ◽  
Equilibrium Equations ◽  
Damage And Failure ◽  
Main Factors ◽  
New Research ◽  
In Fire ◽  
Integrated Structures

In fire resistant design traditional method based on experiment is being replaced by method based on calculation.in this paper Damage mechanics is applied to calculate and analyze the process of damage and failure of structures at high temperature through solving jointly the closed equations composed of the thermal damage evolving equation based on the residual strength, heat conduction equations, equilibrium equations, geometry equations and physics equations. An example of a truss is given to illustrate the calculation of thermal damages and stresses at high temperature. The results suggest, the bearing capacity at high temperature is influenced by these three main factors: thermal damage resulted from the elevated temperature, the thermal stresses and the original load. This provides a new research method for the modern fire-resistant design based on calculation and can be developed and applied in the numerical simulation of the process of damage and failure of the integrated structures.

Research on the Fatigue Damage of the Asphalt Pavement

2012 ◽  
Vol 256-259 ◽  
pp. 1776-1779
Author(s):  
Zhe Fu Yu
Keyword(s):  
Fatigue Crack ◽  
Fatigue Damage ◽  
Structural Damage ◽  
Damage Mechanics ◽  
Poisson Ratio ◽  
Fatigue Behavior ◽  
Damage Model ◽  
Fatigue Crack Initiation ◽  
Fatigue Cracking ◽  
Future Research

Abstract: Fatigue cracking is a main form of structural damage of asphalt pavements. In general, there are four approaches to characterize the fatigue behavior of asphalt concrete. The methods including Phenomenological Approach, damage–energy fatigue approach, fatigue fracture mechanics and fatigue damage mechanics. Based on continuum damage mechanics, fatigue cycles of structural members in test can be greatly reduced and a unified approach of predicting fatigue crack initiation and fatigue crack propagation can be constructed. Generally, one damage variable is defined to account for the relative decrease of Young’s modulus with loading and, therefore, the change of Poisson ratio can not be considered. To accurately describe the coupling relationship between damage and stress fields, a bi-variable damage model to describe the variations of shear modulus and bulk modulus is the direction of future research.

scholarly journals Numerical Study on Thermal Damage Behavior and Heat Insulation Protection in a High-Temperature Tunnel

2021 ◽  
Vol 11 (15) ◽  
pp. 7010
Author(s):  
Fangchao Kang ◽  
Yingchun Li ◽  
Chun’an Tang ◽  
Tianjiao Li ◽  
Kaikai Wang
Keyword(s):  
High Temperature ◽  
Thermal Insulation ◽  
Thermal Damage ◽  
Cold Shock ◽  
Numerical Study ◽  
Coupling Model ◽  
Tunnel Support ◽  
Mechanical Coupling ◽  
Thermal Cracks ◽  
Rock Temperature

Deepening our understanding of temperature and stress evolution in high-temperature tunnels is indispensable for tunnel support and associated disaster prevention as the rock temperature is remarkably high in hot dry rock (HDR) utilization and similar tunnel engineering. In this paper, we established a two-dimensional thermal–mechanical coupling model through RFPA2D-thermal, by which the temperature and stress field of the surrounding rock in a high-temperature tunnel with and without thermal insulation layer (TIL) were studied, followed by the evolution of thermal cracks. The associated sensitivity analysis of the TIL and airflow factors were then carried out. We found that (1) the tunnel rock is unevenly cooled down by the cold airflow, which induces thermal stress and damages the rock element when it exceeds the tensile strength of the rock mass. Those damaged rock elements accumulate and coalesce into visible cracks in the tunnel rock as the ventilation time goes, reducing the tunnel stability. (2) TIL effectively reduces the heat exchange between the airflow and tunnel rock and weakens the cold shock by the airflow, delaying the crack initiation which provides efficient time to adopt engineering measures for tunnel supporting. (3) TIL parameters are of pivotal importance to the long-term cold shock by the airflow. Increasing the TIL thickness and reducing the TIL thermal conductivity both significantly enhance the thermal insulation effect. The results cover the gap in the study of cold shock in high-temperature tunnels, which is helpful in designs to prevent thermal damage in high-temperature tunnels.

Multi-Scale Damage Analysis on Fatigue-Creep Process in Industrial Steel Structures

2019 ◽  
Author(s):  
Huajing Guo ◽  
Zhaoxia Li
Keyword(s):  
High Temperature ◽  
Fatigue Damage ◽  
Structural Damage ◽  
Early Stage ◽  
Creep Damage ◽  
Steel Structures ◽  
Degradation Process ◽  
Creep Process ◽  
Damage Analysis ◽  
Multi Scale

Abstract Fatigue-creep damage has been recognized as the elemental cause of failure of industrial steel structures exposed to high temperature. In order to better understand the degradation process, a previously developed multi-scale fatigue-creep damage is applied to evaluate the structural damage due to fatigue and creep process. In the model, the relationship between collective behavior of micro-cracks and fatigue damage variable was established and the nonlinear coupling of fatigue damage and creep damage was taken into consideration. Fatigue-creep damage analysis on a series of existing key connection shafts in industrial steel structures at high temperature are performed under different working condition and their lifetime are predicted based on the numerical calculation on the accumulated fatigue-creep damage up to structural failure. The numerical results indicate that the early stage of degeneration process is dominated by creep damage and the fatigue damage rate increases quickly at the later stage. The fatigue-creep lifetime of industrial steel structures varies significantly with different applied stress level and working temperature.

scholarly journals Numerical Study on Damage Zones Induced by Excavation and Ventilation in a High-Temperature Tunnel at Depth

Energies ◽  
2021 ◽  
Vol 14 (16) ◽  
pp. 4773
Author(s):  
Jianyu Li ◽  
Hong Li ◽  
Zheming Zhu ◽  
Ye Tao ◽  
Chun’an Tang
Keyword(s):  
High Temperature ◽  
Lateral Pressure ◽  
Numerical Study ◽  
Pressure Coefficient ◽  
Fracture Morphology ◽  
In Situ Stress ◽  
Surrounding Rock ◽  
Geothermal System ◽  
Mechanical Coupling ◽  
Lateral Pressure Coefficient

Geothermal power is being regarded as depending on techniques derived from hydrocarbon production in worldwide current strategy. However, it has artificially been developed far less than its natural potentials due to technical restrictions. This paper introduces the Enhanced Geothermal System based on Excavation (EGS-E), which is an innovative scheme of geothermal energy extraction. Then, based on cohesion-weakening-friction-strengthening model (CWFS) and literature investigation of granite test at high temperature, the initiation, propagation of excavation damaged zones (EDZs) under unloading and the EDZs scale in EGS-E closed to hydrostatic pressure state is studied. Finally, we have a discussion about the further evolution of surrounding rock stress and EDZs during ventilation is studied by thermal-mechanical coupling. The results show that the influence of high temperature damage on the mechanical parameters of granite should be considered; Lateral pressure coefficient affects the fracture morphology and scale of tunnel surrounding rock, and EDZs area is larger when the lateral pressure coefficient is 1.0 or 1.2; Ventilation of high temperature and high in-situ stress tunnel have a significant effect on the EDZs scale; Additional tensile stress is generated in the shallow of tunnel surrounding rock, and the compressive stress concentration transfers to the deep. EDZs experiences three expansion stages of slow, rapid and deceleration with cooling time, and the thermal insulation layer prolongs the slow growth stage.

Analysis of thermo-mechanical coupling damage behavior in long-term performance of microelectromechanical systems actuators

2021 ◽  
pp. 105678952110339
Author(s):  
Jiaxing Cheng ◽  
Zhaoxia Li
Keyword(s):  
Damage Mechanics ◽  
Microelectromechanical Systems ◽  
Mechanical Performance ◽  
Damage Model ◽  
Irreversible Damage ◽  
Damage Behavior ◽  
Thermal Actuators ◽  
Long Term Performance ◽  
Term Performance

Effective numerical analysis is significant for the optimal design and reliability evaluation of MEMS, but the complexity of multi-physical field couplings and irreversible damage accumulation in long-term performance make the analysis difficult. In the present paper, the continuum damage mechanics method is used to develop a creep damage model and conduct long-term performance analysis for MEMS thermal actuators with coupled thermo-mechanical damage behavior. The developed damage model can make a connection between the material deterioration due to microstructure changes and the macroscopic responses (the change of thermo-mechanical performance or structure failure). The numerical simulations of coupled thermo-mechanical behavior in long-term performance are implemented using the finite element method, which is validated through comparison with previous literature. The numerical results demonstrate that the proposed damage model and numerical method can provide effective assessment in the long-term performance of MEMS thermal actuators.

Cross-Ply Laminates under Static Three-Point Bending: A Numerical Development Model

2012 ◽  
Vol 498 ◽  
pp. 42-54 ◽  
Author(s):  
S. Benbelaid ◽  
B. Bezzazi ◽  
A. Bezazi
Keyword(s):  
Numerical Model ◽  
Damage Mechanics ◽  
Progressive Failure ◽  
Damage Model ◽  
Continuum Damage Mechanics ◽  
Failure Criteria ◽  
Continuum Damage ◽  
Damage Development ◽  
Element Analysis ◽  
Progressive Failure Analysis

This paper considers damage development mechanisms in cross-ply laminates using an accurate numerical model. Under static three points bending, two modes of damage progression in cross-ply laminates are predominated: transverse cracking and delamination. However, this second mode of damage is not accounted in our numerical model. After a general review of experimental approaches of observed behavior of laminates, the focus is laid on predicting laminate behavior based on continuum damage mechanics. In this study, a continuum damage model based on ply failure criteria is presented, which is initially proposed by Ladevèze. To reveal the effect of different stacking sequence of the laminate; such as thickness and the interior or exterior disposition of the 0° and 90° oriented layers in the laminate, an equivalent damage accumulation which cover all ply failure mechanisms has been predicted. However, the solution algorithm using finite element analysis which implements progressive failure analysis is summarized. The results of the numerical computation have been justified by the previous published experimental observations of the authors.

Accounting for frictional contact in an anisotropic damage model based on compliance tensorial variables, illustration on ceramic matrix composites

2018 ◽  
Vol 28 (8) ◽  
pp. 1150-1169 ◽  
Author(s):  
Emmanuel Baranger
Keyword(s):  
Damage Mechanics ◽  
A Priori ◽  
Damage Model ◽  
Ceramic Matrix Composites ◽  
Inelastic Strain ◽  
Ceramic Matrix ◽  
Thermomechanical Properties ◽  
Matrix Composites ◽  
Crack Network ◽  
Evolution Laws

Ceramic matrix composites have good thermomechanical properties at high or very high temperatures. The modeling of the crack networks associated to the degradation of such composites using damage mechanics is not straightforward. The main reason is the presence of a crack network mainly oriented by the loading direction, which is a priori unknown. To model this, compliance tensorial damage variables are used in a thermodynamic potential able to account for crack closure effects (unilateral contact). The damage kinematic is initially completely free and imposed by the evolution laws. The key point of the present paper is to account for friction in such cracks that can result in an apparent activation/deactivation of the shear damage. The initial model is enriched with an inelastic strain and a friction law. The plasticity criterion is expressed only using tensorial variables. The model is identified and illustrated on multiaxial data obtained at ONERA on tubes loaded in tension and torsion.

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