Modelling of Thermal Cracking Behaviours of Fiber-Reinforced Composites

2007 ◽  
Vol 334-335 ◽  
pp. 237-240
Author(s):  
Tao Xu ◽  
Shan Yong Wang ◽  
Chun An Tang ◽  
Li Song ◽  
Shi Bin Tang
Keyword(s):  
Process Analysis ◽  
Failure Process ◽  
Damage Model ◽  
Mechanical Damage ◽  
Thermal Cracking ◽  
Model Material ◽  
Thermal Mismatch ◽  
Failure Patterns ◽  
Damage And Fracture ◽  
The Matrix

In this paper, a coupled thermal-mechanical-damage model, Material Failure Process Analysis for Thermo code (abbreviated as MFPA-thermo), was applied to investigate the formation, extension and coalescence of cracks in FRCs, caused by the thermal mismatch of the matrix and the particles under uniform temperature variations. The effects of the thermal mismatch between the matrix and fibers on the stress distribution and crack development were also numerically studied. The influences of the material heterogeneity, the failure patterns of FRCs at varied temperatures are simulated and compared with the experimental results in the present paper. The results show that the mechanisms of thermal damage and fracture of the composite remarkedably depend on the difference between the coefficients of thermal expansion of the fibers and the matrix on a meso-scale. Meanwhile, the simulations indicate that the thermal cracking of the FRCs at uniform varied temperatures is an evolution process from diffused damage, nucleation, and finally linkage of cracks.

Fatigue-Cumulative Damage Model of RC Crane Girders Strengthened with FRP Strips

2008 ◽  
Vol 385-387 ◽  
pp. 165-168
Author(s):  
Shan Suo Zheng ◽  
Bin Wang ◽  
Lei Li ◽  
Liang Zhang ◽  
Pi Ji Hou
Keyword(s):  
Damage Mechanics ◽  
Flexural Rigidity ◽  
Failure Process ◽  
Damage Model ◽  
Cumulative Damage ◽  
Good Time ◽  
Failure Patterns ◽  
Damage And Fracture ◽  
Cumulative Damage Model ◽  
Frp Strips

The cumulative damage of the reinforced concrete (RC) crane girders occurred by overload, fatigue and other reasons in service may deteriorate the safety of RC crane girders seriously, so it is necessary to analyze the damage mechanism and rationally reinforce them in good time. In this paper, RC crane girder strengthened with CFRP strips is taken as a target, and the mechanical performance degradation under fatigue load is studied. According to the basic theory of continuum damage mechanics, a damage variable is defined by flexural rigidity, and fatigue- cumulative damage model, which describes the process of damage and fracture, is established. The variation law of cumulative damage of RC crane girders strengthened with FRP strips under crane load is discussed, and the failure patterns such as concrete cracking, debonding between CFRP strips and concrete, yield of steel bars etc., are studied. The criterion which can be used to estimate the cumulative damage degree of strengthened RC crane girders is proposed. Finally, the evolution of the fatigue damage in the RC crane girders strengthened with CFRP strips is numerically simulated, and the results show that the proposed model can correctly describe the damage and failure process of strengthened RC crane girders. The research will provide a reference for the damage analysis and reinforcement of RC crane girders strengthened with CFRP strips.

scholarly journals Numerical tests on thermal cracking characteristics of rocks with different scales

2018 ◽  
Vol 10 (8) ◽  
pp. 168781401879214 ◽  
Author(s):  
Yang Xiao ◽  
Rui Zhao ◽  
Qing-Xiang Huang ◽  
Jun Deng ◽  
Jun-Hui Lu
Keyword(s):  
Acoustic Emission ◽  
Thermal Destruction ◽  
Thermal Damage ◽  
Process Analysis ◽  
Failure Process ◽  
Acoustic Emissions ◽  
Thermal Cracking ◽  
Tensile Failure ◽  
Failure Patterns ◽  
Different Diameters

Realistic failure process analysis, a thermal software simulation, was used to explore the scale effect of thermal cracking of rock under the thermal–mechanical coupling loading. The patterns and characteristics of thermal destruction were analyzed by simulating the thermal cracking of rocks with the same diameter different lengths, the same length but different diameters, and the same size ratio but different sizes (same length/diameter ratio but with different diameters). The acoustic emission and energy changes were also studied during thermal destruction. The results represented that the main forms of thermal cracking are tensile failure and shear failure. The smaller the scale is (length, diameter, and size), the more complex the pattern of thermal damage exhibited as failure patterns of inverted “S” or “V.” With the increasing scale, thermal damage models were simpler. The elastic modulus was determined by the diameter of specimens, and the peak stress was determined by the length of specimens. Overall, as the scale increased, the stress intensity decreased, but the number of acoustic emissions and acoustic emission energy and the corresponding accumulation increased.

Study on the Thermal Cracking Processes of Composite Subjected to Thermal Loading

2012 ◽  
Vol 256-259 ◽  
pp. 2867-2870
Author(s):  
Shi Bin Tang ◽  
Zheng Zhao Liang ◽  
Ya Fang Zhang
Keyword(s):  
Thermal Expansion ◽  
Thermal Loading ◽  
Coefficient Of Thermal Expansion ◽  
Process Analysis ◽  
Failure Process ◽  
Thermal Cracking ◽  
The Matrix ◽  
Rock Failure Process ◽  
High Or Low Temperature ◽  
Radial Cracks

A numerical method RFPA-T (Thermal Induced Rock Failure Process Analysis) code is used to study the thermal cracking processes of quasi-brittle materials subjected to high or low temperature. The numerical results indicate that thermal stress concentrating along the interface between the matrix and the embedded grains due to their different coefficient of thermal expansion (CTE). The modeling results indicate that θ-crack is generated during temperature increment as the CTE of the embedded grain is smaller than that of the matrix. However, radial-cracks emerged when the temperature decrease. The results obtained from RFPA-T code show a good agreement with experimental evidence of crack patterns caused by thermal expansion mismatch.

Numerical Simulation on Failure Patterns of Rock Discs and Rings Subject to Diametral Line Loads

2004 ◽  
Vol 261-263 ◽  
pp. 1517-1522 ◽  
Author(s):  
Wan Cheng Zhu ◽  
K.T. Chau ◽  
Chun An Tang
Keyword(s):  
Tensile Strength ◽  
Standardized Test ◽  
Process Analysis ◽  
Failure Process ◽  
Brazilian Test ◽  
Rock Failure ◽  
Numerical Code ◽  
Failure Patterns ◽  
Rock Failure Process ◽  
Indirect Tensile

Brazilian test is a standardized test for measuring indirect tensile strength of rock and concrete disc (or cylinder). Similar test called indirect tensile test has also been used for other geomaterials. Although splitting of the disc into two halves is the expected failure mode, other rupture modes had also been observed. More importantly, the splitting tensile strength of rock can vary significantly with the specimen geometry and loading condition. In this study, a numerical code called RFPA2D (abbreviated from Rock Failure Process Analysis) is used to simulate the failure process of disc and ring specimens subject to Brazilian test. The failure patterns and splitting tensile strengths of specimens with different size and loading-strip-width are simulated and compared with existing experimental results. In addition, two distinct failure patterns observed in ring tests have been simulated using RFPA2D and thus this verifies the applicability of RFPA2D in simulating rock failure process under static loads.

Study of the Effect of Joint Trace Lengths on Failure Strength of Rock

2014 ◽  
Vol 501-504 ◽  
pp. 603-606
Author(s):  
Yun Jie Zhang ◽  
Tao Xu
Keyword(s):  
Compressive Strength ◽  
Process Analysis ◽  
Failure Process ◽  
Strain Curve ◽  
Peak Stress ◽  
Experimental Results ◽  
Peak Strain ◽  
Joint Orientation ◽  
Trace Length ◽  
Failure Patterns

Numerical simulations the different rock sample in the uniaxial compression have been conducted using Rock Failure Process Analysis program (RFPA2D) to evaluate the effects of joint trace lengths on the overall mechanical behaviour of jointed rock masses in this paper. Numerically simulated stress-strain curve, peak stress, peak strain and failure patterns were compared with the corresponding experimental results. We found that for a series of partially-spanning joint geometries with the same joint orientation, the projected area will be proportional to the square of the trace length. Thus, the relationship between compressive strength and partially-spanning joint geometry for the tests carried out to explore the influence of joint trace length may be expressed as a linear correlation between compressive strength and projected area.Numerical simulations agree well with experimental results.

Numerical Study of Effect of Joint Tip Distance from Sample End on Rock Failure

2014 ◽  
Vol 501-504 ◽  
pp. 244-247
Author(s):  
Yun Jie Zhang ◽  
Cheng Fan
Keyword(s):  
Uniaxial Compression ◽  
Numerical Study ◽  
Process Analysis ◽  
Rock Fracture ◽  
Failure Process ◽  
Strain Curve ◽  
Peak Stress ◽  
Rock Failure ◽  
Peak Strain ◽  
Failure Patterns

In this paper,the mechanical properties of rock experiencing the variation of joint tip distance from sample end under uniaxial compression condition were simulated.Numerical simulation for the different rock sample in the uniaxial compression have been conducted to evaluate the effects of joint tip distance from sample end on the overall mechanical behaviour of jointed rock masses. It was done using the Rock Failure Process Analysis program RFPA2D. Numerically simulated stress-strain curve, peak stress, peak strain and failure patterns were compared with the corresponding physical tests. We found that specimen joint tip distance from sample end corresponding value (distance from the crack tip to the compression surface) linear relationship with the compressive strength values .Numerical simulations agree well with physical results, it is shown that RFPA2D is suitable for the analysis of joint tip distance from sample end effect on rock fracture.

scholarly journals A Modified SPH Method for Dynamic Failure Simulation of Heterogeneous Material

2014 ◽  
Vol 2014 ◽  
pp. 1-14 ◽  
Author(s):  
G. W. Ma ◽  
Q. S. Wang ◽  
X. W. Yi ◽  
X. J. Wang
Keyword(s):  
Failure Process ◽  
Damage Model ◽  
Heterogeneous Materials ◽  
Dynamic Strength ◽  
Heterogeneous Material ◽  
Uniaxial Compression Test ◽  
Sph Method ◽  
Failure Patterns ◽  
Splitting Test ◽  
Particle Hydrodynamics

A modified smoothed particle hydrodynamics (SPH) method is applied to simulate the failure process of heterogeneous materials. An elastoplastic damage model based on an extension form of the unified twin shear strength (UTSS) criterion is adopted. Polycrystalline modeling is introduced to generate the artificial microstructure of specimen for the dynamic simulation of Brazilian splitting test and uniaxial compression test. The strain rate effect on the predicted dynamic tensile and compressive strength is discussed. The final failure patterns and the dynamic strength increments demonstrate good agreements with experimental results. It is illustrated that the polycrystalline modeling approach combined with the SPH method is promising to simulate more complex failure process of heterogeneous materials.

Numerical Simulation of the Effect of Joint Orientation on the Failure Strength of Rock

2013 ◽  
Vol 477-478 ◽  
pp. 577-581
Author(s):  
Yue Long Yan ◽  
Tao Xu ◽  
Yun Jie Zhang ◽  
P.L.P. Wasantha
Keyword(s):  
Numerical Simulations ◽  
Uniaxial Compression ◽  
Process Analysis ◽  
Rock Fracture ◽  
Failure Process ◽  
Strain Curve ◽  
Peak Stress ◽  
Peak Strain ◽  
Joint Orientation ◽  
Failure Patterns

The mechanical properties of rock experiencing the variation of joint orientation under uniaxial compression condition were simulated in this paper. Numerical simulations on rock sample in uniaxial compression have been conducted to evaluate the effects of joint orientation on the overall mechanical behaviour of jointed rock masses. It was done using the Rock Failure Process Analysis program RFPA2D. Numerically simulated stress-strain curve, peak stress, peak strain and failure patterns were compared with the corresponding physical tests. Numerical simulations agree well with physical results, it is shown that RFPA2D is suitable for the analysis of joint orientation effect on rock fracture.

scholarly journals The Influence of an Interlayer on Dual Hydraulic Fractures Propagation

Energies ◽  
2020 ◽  
Vol 13 (3) ◽  
pp. 555
Author(s):  
Li ◽  
Tang ◽  
Rutqvist ◽  
Hu ◽  
Li ◽  
...  
Keyword(s):  
Hydraulic Fracture ◽  
Process Analysis ◽  
Failure Process ◽  
Mechanical Damage ◽  
Fracture Propagation ◽  
Vertical Direction ◽  
Laboratory Scale ◽  
Hydraulic Fractures ◽  
Hydraulic Fracture Propagation ◽  
The Difference

Multi-cluster hydraulic fracturing of long-range horizontal wells is an approach for enhancing the productivity of low-permeability shale reservoirs. In this study, RFPA-Petrol (rock failure process analysis on petroleum problems) is applied for modeling hydraulic fracture propagation in multilayered formations. RFPA-Petrol based on coupled hydraulic-mechanical-damage (HMD) modeling was first tested by modeling a laboratory scale experiment on a physical (cement) model with a single completion. The modeling demonstrated the capability of RFPA-Petrol for simulating hydraulic fracture propagation. Then, we used RFPA-Petrol to investigate how the difference in material properties between oil-bearing layers and interlayers and the fracturing fluid properties influence the propagation of dual fractures in multilayered laboratory-scale models. In this case, the models with geological discontinuities in the vertical direction are strongly heterogeneous and RFPA-Petrol simulations successfully modeled the fracture configurations.

Numerical Study on Shear Strength and Failure Pattern of Jointed Rock under Shear Testing

2005 ◽  
Vol 297-300 ◽  
pp. 2617-2622
Author(s):  
Hou Quan Zhang ◽  
Li Song ◽  
Junjie Liu ◽  
Tao Xu ◽  
Xiong Chen ◽  
...  
Keyword(s):  
Shear Strength ◽  
Shear Failure ◽  
Numerical Study ◽  
Process Analysis ◽  
Failure Process ◽  
Failure Surface ◽  
Shear Loading ◽  
Failure Pattern ◽  
Failure Patterns ◽  
Joint Separation

The purpose of this paper is to investigate shear strength and failure pattern of rock containing two parallel open joints with different horizontal separations using RFPA2D (rock failure process analysis) code. Specimens are placed in a direct shear box. The upper is invariably loaded with normal stress 0.15MPa, the left is controlled by a constant increasing horizontal displacement 0.002mm/step. The whole shear failure process is visually represented and the failure pattern in reasonable accordance with previous experimental results is obtained. In general, only mixed mode (tensile and shear) is observed for the failure pattern in the numerical tests. Tensile cracks initiate from the tips of pre-existing joints respectively with an initiation angle of about 45°, then propagate towards another joint in a single stria; Shear cracks occur in the further process and the main direction of shear failure surface is roughly parallel to shear loading. The failure pattern of bridged rock is mainly controlled by the joint separation and the roughness of wavy shear failure surface is different, which is mostly influenced by the joint separation in the same way. The peak shear load, related to the failure patterns, decreases with the increase of joint separation, but the shear strength of intact rock is invariable.

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