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混凝土 4

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Investigation of crack segmentation and fast evaluation of crack propagation, based on deep learning

《结构与土木工程前沿（英文）》 2024年 第18卷 第4期   页码 516-535 doi: 10.1007/s11709-024-1040-z

摘要： Identifying crack and predicting crack propagation are critical processes for the risk assessment of engineering structures. Most traditional approaches to crack modeling are faced with issues of high computational costs and excessive computing time. To address this issue, we explore the potential of deep learning (DL) to increase the efficiency of crack detection and forecasting crack growth. However, there is no single algorithm that can fit all data sets well or can apply in all cases since specific tasks vary. In the paper, we present DL models for identifying cracks, especially on concrete surface images, and for predicting crack propagation. Firstly, SegNet and U-Net networks are used to identify concrete cracks. Stochastic gradient descent (SGD) and adaptive moment estimation (Adam) algorithms are applied to minimize loss function during iterations. Secondly, time series algorithms including gated recurrent unit (GRU) and long short-term memory (LSTM) are used to predict crack propagation. The experimental findings indicate that the U-Net is more robust and efficient than the SegNet for identifying crack segmentation and achieves the most outstanding results. For evaluation of crack propagation, GRU and LSTM are used as DL models and results show good agreement with the experimental data.

关键词： deep learning     crack segmentation     crack propagation     encoder−decoder     recurrent neural network    

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Dynamic crack propagation in plates weakened by inclined cracks: an investigation based on peridynamics

A. SHAFIEI

《结构与土木工程前沿（英文）》 2018年 第12卷 第4期   页码 527-535 doi: 10.1007/s11709-018-0450-1

摘要： Peridynamics is a theory in solid mechanics that uses integral equations instead of partial differential equations as governing equations. It can be applied to fracture problems in contrast to the approach of fracture mechanics. In this paper by using peridynamics, the crack path for inclined crack under dynamic loading were investigated. The peridynamics solution for this problem represents the main features of dynamic crack propagation such as crack bifurcation. The problem is solved for various angles and different stress values. In addition, the influence of geometry on inclined crack growth is studied. The results are compared with molecular dynamic solutions that seem to show reasonable agreement in branching position and time.

关键词： peridynamics     inclined crack     dynamic fracture     crack branching    

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Peridynamics versus XFEM: a comparative study for quasi-static crack problems

Jinhai ZHAO, Hesheng TANG, Songtao XUE

《结构与土木工程前沿（英文）》 2018年 第12卷 第4期   页码 548-557 doi: 10.1007/s11709-017-0434-6

摘要： Peridynamics (PD) is a nonlocal continuum theory based on integro-differential equations without spatial derivatives. The fracture criterion is implicitly incorporated in the PD theory and fracture is a natural outcome of the simulation. However, capturing of complex mixed-mode crack patterns has been proven to be difficult with PD. On the other hand, the extended finite element method (XFEM) is one of the most popular methods for fracture which allows crack propagation with minimal remeshing. It requires a fracture criterion which is independent of the underlying discretization though a certain refinement is needed in order to obtain suitable results. This article presents a comparative study between XFEM and PD. Therefore, two examples are studied. The first example is crack propagation in a double notched specimen under uniaxial tension with different crack spacings in loading direction. The second example is the specimens with two center cracks. The results show that PD as well as XFEM are well suited to capture this type of behaviour.

关键词： XFEM     peridynamic     bilateral crack     parallel double cracks     nonlocal theory    

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Correlation between tension softening relation and crack extension resistance in concrete

Xiufang ZHANG , Shilang XU ,

《结构与土木工程前沿（英文）》 2009年 第3卷 第3期   页码 323-329 doi: 10.1007/s11709-009-0041-2

摘要： Changes of the material fracture energy consumption with crack propagation can be described by a crack extension resistance curve, one of the fundamental fracture criteria in crack mechanics. Recently, experimental observation of the fracture behavior in concrete was used to develop a new fracture criterion, the crack extension resistance curve, to analyze crack propagation during the entire concrete fracture process. The variation of the crack extension resistance is mainly associated with the energy consumption in the fracture process zone ahead of the stress-free crack tip. The crack extension resistance is then a function of the softening curve, which is a basic mechanical property in the fracture process zone. The relationship between the softening curve and the crack extension resistance curve is then analyzed based on results of three-point bending beams tests. The results indicate that the characteristic points of the crack extension resistance curve is closely related to the characteristic point on used tension softening curve.

关键词： concrete     fracture process zone     crack extension GR resistance     tension softening curve    

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Fracture resistance on aggregate bridging crack in concrete

ZHANG Xiufang, XU Shilang

《结构与土木工程前沿（英文）》 2007年 第1卷 第1期   页码 63-70 doi: 10.1007/s11709-007-0006-2

摘要： Fracture toughening exhibited in quasi-brittle materials such as concrete is often mainly related to the action of aggregate bridging, which leads to the presence of a fracture process zone ahead of stress-free cracks in such materials. In this investigation, the fracture resistance induced by aggregate bridging, denoted by GI-bridging, is the primary focus. In order to quantitatively determine it, a general analytical formula is firstly developed, based on the definition of fracture energy by Hillerborg. After this, we further present the calculated procedures of determining this fracture resistance from the recorded load vs. crack opening displacement curve. Then, both numerical simulations and fracture experiments are performed on concrete three-point bending beams. Utilizing the obtained load against crack opening displacement curve, the value of G at any crack extension as well as the change of G with the crack extension is examined. It is found that G will firstly increase with the development of crack and then stay constant once the initial crack tip opening displacement reaches the characteristic crack opening displacement w0. The effects of material strength and specimen depth on this fracture resistance are also investigated. The results reveal that the values of G of different specimens at any crack propagation are strongly associated with the values of fracture energy of specimens. If the values of fracture energy between different specimens are comparable, the differences between G are ignored. Instead, if values of fracture energy are different, the G will be different. This shows that for specimens with different strengths, G will change greatly whereas for specimens that are different in depth, whether GI-bridging exhibits size effect depends on whether the fracture energy of specimens considered in the calculation of G is assumed to be a size-dependent material parameter.
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Study on the cohesion and adhesion of hot-poured crack sealants

Meng GUO, Yiqiu TAN, Xuesong DU, Zhaofeng LV

《结构与土木工程前沿（英文）》 2017年 第11卷 第3期   页码 353-359 doi: 10.1007/s11709-017-0400-3

摘要： Filling crack sealant is a main method to repair cracking of pavement. The cohesion and adhesion of crack sealant directly determine its service performance and durability. However, the competitive mechanism of cohesion and adhesion failure modes is not clear currently. This research proposed two methods to evaluate cohesion and adhesion of crack sealant, and analyzed the influence of temperature on cohesion and adhesion. The effect of moisture on low-temperature performance of crack sealant was also be evaluated by conducting a soaking test. Results show that with the decrease of temperature, the cohesion force of crack sealant increases significantly, while the adhesion force changes little. There is a critical temperature at which the cohesion force equals the adhesion force. When the temperature is higher, the adhesion force will be greater than cohesion force, and the cohesion failure will happen more easily. In contrast, the adhesion failure will happen more easily when the temperature is lower than the critical value. Soaking in 25 °C water for 24–48 hours will slightly improve the low-temperature tension performance of crack sealant. However, soaking in 60 °C water for 24 hours will decrease the failure energy of low-temperature tension and damage the durability of crack sealant.

关键词： crack sealant     concrete pavement     cohesion     adhesion     moisture damage    

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Feasibility of crack free reinforced concrete bridge deck from materials composition perspective: a state

Mahdi AREZOUMANDI

《结构与土木工程前沿（英文）》 2015年 第9卷 第1期   页码 91-103 doi: 10.1007/s11709-015-0274-1

摘要： Early age cracking on bridge deck has been the subject of many studies for years. Cracking is a major concern because it leads to premature deterioration of structures. Millions of dollars spent to repair the cracked bridge decks each year. To design an appropriate mixture for crack free bridge deck, it is important to study previous researches. This paper presents a comprehensive literature review of the performance of different materials compositions as well as methods have been used to reduce and control bridge deck cracks. Different material compositions and methods are discussed in terms of their performances as well as advantages and disadvantages.

关键词： bridge deck     crack     fiber     shrinkage     shrinkage reducing admixture    

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Stability and dynamics of rotor system with 45° slant crack on shaft

Yanli LIN, Xiaohui SI, Fulei CHU

《机械工程前沿（英文）》 2011年 第6卷 第2期   页码 203-213 doi: 10.1007/s11465-011-0131-4

摘要：

Crack on a shaft is one of the common damages in a rotor system. In this paper, transverse vibrations are calculated to compare the influences of transverse crack and slant crack on the rotor system. Results show that the vibration amplitude of the rotor system with a 45° slant crack on the shaft is larger than that with a transverse crack when the two types of crack have the same depth and the rotor system runs in the same condition. Stability and dynamic characteristics of the rotor system with a 45° slant crack on the shaft under torsional excitation are analyzed by considering opening and closing of the crack. It is shown that the instability of the transverse vibration of the rotor system increases with increasing difference between the bending stiffness in two main directions, and the vibration is stable when the two bending stiffness are identical. The spectrum analysis of the steady-state response reveals that the gravity and the eccentricity produce different frequency components, and when the two bending stiffness are identical, the multiple frequency components of the torsional excitation disappear. Further investigation shows that the vibration amplitudes in combined frequencies increase rapidly in transversal, torsional, and axial vibration with increasing slant crack depth. The results are helpful for the understanding the dynamic behavior of a rotor system with a slant crack on a shaft and can be used for the detection of the slant crack on a shaft.

关键词： rotor dynamics     slant crack     stability     torsional excitation     open and close    

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Concurrent fatigue crack growth simulation using extended finite element method

Zizi LU, Yongming LIU,

《结构与土木工程前沿（英文）》 2010年 第4卷 第3期   页码 339-347 doi: 10.1007/s11709-010-0078-2

摘要： In this paper, a concurrent simulation framework for fatigue crack growth analysis is proposed using a novel small time scale model for fatigue mechanism analysis and the extended finite element method (X-FEM) for fatigue crack growth simulation. The proposed small time scale fatigue model does not require the cycle counting as those using the classical fatigue analysis methods and can be performed concurrently with structural/mechanical analysis. The X-FEM greatly facilitates crack growth simulation without remeshing requirements ahead of the crack tip as in the classical finite element method. The basic concept and theory of X-FEM was briefly introduced and numerical predictions of stress intensity factors are verified with reference solutions under both uniaxial and multiaxial loadings. The small time scale fatigue model is integrated into the numerical simulation algorithm for concurrent fatigue crack growth analysis. Model predictions are compared with available experimental observations for model validation.

关键词： small time scale model     extended finite element method (X-FEM)     crack growth     multiaxial    

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Stress field near circular-arc interface crack tip based on electric saturation concept

Longchao DAI, Xinwei WANG

《机械工程前沿（英文）》 2009年 第4卷 第3期   页码 320-325 doi: 10.1007/s11465-009-0042-9

摘要： Within the framework of nonlinear electroelasticity, the anti-plane problem of a circular-arc interfacial crack between a circular piezoelectric inhomogeneity and an infinite piezoelectric matrix subjected to a far-field uniform loading is investigated by an electrical strip saturation model, the complex variable method, and the method of analytical continuation. Explicit closed form expressions for the complex potentials in both the matrix and the inclusion, and the stress intensity factor at the crack tip are presented. Comparison with some related solutions based on the linear electroelastic theory shows the validity of the present solutions

关键词： piezoelectric material     arc crack     strip saturation     stress intensity factor    

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Automatic detection and assessment of crack development in ultra-high performance concrete in the spatial

《结构与土木工程前沿（英文）》 2024年 第18卷 第3期   页码 350-364 doi: 10.1007/s11709-024-1042-x

摘要： Automatic detection and assessment of surface cracks are beneficial for understanding the mechanical performance of ultra-high performance concrete (UHPC). This study detects crack evolution using a novel dynamic mode decomposition (DMD) method. In this method, the sparse matrix ‘determined’ from images is used to reconstruct the foreground that contains cracks, and the global threshold method is adopted to extract the crack patterns. The application of the DMD method to the three-point bending test demonstrates the efficiency in inspecting cracks with high accuracy. Accordingly, the geometric features, including the area and its projection in two major directions, are evaluated over time. The relationship between the geometric properties of cracks and load-displacement curves of UHPC is discussed. Due to the irregular shape of cracks in the spatial domain, the cracks are then transformed into the Fourier domain to assess their development. Results indicate that crack patterns in the Fourier domain exhibit a distinct concentration around a central position. Moreover, the power spectral density of cracks exhibits an increasing trend over time. The investigation into crack evolution in both the spatial and Fourier domains contributes significantly to elucidating the mechanical behavior of UHPC.

关键词： dynamic mode decomposition     ultra-high performance concrete     crack detection     geometric features     Fourier domain    

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Some remarks on the engineering application of the fatigue crack growth approach under nonzero mean loads

Jorge Alberto Rodriguez DURAN,Ronney Mancebo BOLOY,Rafael Raider LEONI

《机械工程前沿（英文）》 2015年 第10卷 第3期   页码 255-262 doi: 10.1007/s11465-015-0342-1

摘要：

The well-known fatigue crack growth (FCG) curves are two-parameter dependents. The range of the stress intensity factor ?K and the load ratio R are the parameters normally used for describing these curves. For engineering purposes, the mathematical representation of these curves should be integrated between the initial and final crack sizes in order to obtain the safety factors for stresses and life. First of all, it is necessary to reduce the dependence of the FCG curves to only one parameter. ?K is almost always selected and, in these conditions, considered as the crack driving force. Using experimental data from literature, the present paper shows how to perform multiple regression analyses using the traditional Walker approach and the more recent unified approach. The correlations so obtained are graphically analyzed in three dimensions. Numerical examples of crack growth analysis for cracks growing under nominal stresses of constant amplitude in smooth and notched geometries are performed, assuming an identical material component as that of the available experimental data. The resulting curves of crack size versus number of cycles (a vs. N) are then compared. The two models give approximately the same (a vs. N) curves in both geometries. Differences between the behaviors of the (avs. N) curves in smooth and notched geometries are highlighted, and the reasons for these particular behaviors are discussed.

关键词： fatigue crack propagation modeling     life prediction     mean stress effects    

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Crack propagation with different radius local random damage based on peridynamic theory

《结构与土木工程前沿（英文）》 2021年 第15卷 第5期   页码 1238-1248 doi: 10.1007/s11709-021-0695-y

摘要： Drawing from the advantages of Classical Mechanics, the peridynamic theory can clarify the crack propagation mechanism by an integral solution without initially setting the factitious crack and crack path. This study implements the peridynamic theory by subjecting bilateral notch cracked specimens to the conditions of no local damage, small radius local damage, and large radius local damage. Moreover, to study the effects of local stochastic damage with different radii on the crack propagation path and Y-direction displacement, a comparison and contact methodology was adopted, in which the crack propagation paths under uniaxial tension and displacement in the Y-direction were compared and analyzed. This method can be applied to steel structures under similar local random damage conditions.

关键词： peridynamics     stochastic damage     bilateral notch crack    

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Frost heave and freezing processes of saturated rock with an open crack under different freezing conditions

Zhitao LV, Caichu XIA, Yuesong WANG, Ziliang LIN

《结构与土木工程前沿（英文）》 2020年 第14卷 第4期   页码 947-960 doi: 10.1007/s11709-020-0638-z

摘要： Frost heave experiments on saturated sandstone and tuff with an open crack are conducted under uniform and unidirectional freezing conditions. Frost heave of crack in sandstone with high permeability is more significant under uniform freezing condition than that under unidirectional freezing condition. However, frost heave of crack in tuff with low permeability is more significant under unidirectional freezing condition. To illustrate the reasons for this phenomenon, a numerical model on the freezing processes of saturated rock with an open crack considering the latent heat of pore water and water in crack is proposed and confirmed to be reliable. Numerical results show that a frozen shell that blocks the migration of water in crack to rock develops first in the outer part of the rock before the freezing of water in crack under uniform freezing condition. However, the migration path of water in crack to the unfrozen rock under freezing front exists under unidirectional freezing condition. The freezing process and permeability of rock together determine the migration of water in crack and lead to the different frost heave modes of crack for various permeable rocks under different freezing conditions. The frost heave modes of crack in rock with low or high permeability are similar under uniform freezing condition because water migration is blocked by a frozen shell and is irrelevant to rock permeability. For high permeability rock, the frost heave of crack will be weakened due to water migration under unidirectional freezing condition; however, the frost heave of crack would be more significant for low permeability rock because water migration is blocked under unidirectional freezing condition. Therefore, the freezing condition and rock permeability determine the frost heave of rock with crack together, and this should be concerned in cold regions engineering applications.

关键词： frost heave     rock with crack     freezing process     freezing condition     frost heave mode    

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混凝土裂缝端部粘聚力的计算

徐世烺,王利民

《中国工程科学》 2002年 第4卷 第5期   页码 53-58

摘要：

混凝土裂缝端部断裂过程区的粘聚力分布是导致混凝土断裂呈现非线性特性的重要原因。基于混凝土的断裂特性和虚拟裂缝端部存在粘聚力的分析模型，并通过分布函数的特性分析，提出了粘聚力分布函数的两种简化表达式：一为单参数待定式，另一为双参数待定式。由变形体叠加原理，推导出计算单参数待定函数公式和计算双参数待定函数代数方程组。进而通过裂缝张开位移实测数据即可求得粘聚力分布，并且给出了适当的算例分析和讨论。

关键词： 混凝土     裂缝张开位移     虚拟裂缝粘聚力     代数方程    

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标题 作者 时间 类型 操作

Investigation of crack segmentation and fast evaluation of crack propagation, based on deep learning

期刊论文

Dynamic crack propagation in plates weakened by inclined cracks: an investigation based on peridynamics

A. SHAFIEI

期刊论文

Peridynamics versus XFEM: a comparative study for quasi-static crack problems

Jinhai ZHAO, Hesheng TANG, Songtao XUE

期刊论文

Correlation between tension softening relation and crack extension resistance in concrete

Xiufang ZHANG , Shilang XU ,

期刊论文

Fracture resistance on aggregate bridging crack in concrete

ZHANG Xiufang, XU Shilang

期刊论文

Study on the cohesion and adhesion of hot-poured crack sealants

Meng GUO, Yiqiu TAN, Xuesong DU, Zhaofeng LV

期刊论文

Feasibility of crack free reinforced concrete bridge deck from materials composition perspective: a state

Mahdi AREZOUMANDI

期刊论文

Stability and dynamics of rotor system with 45° slant crack on shaft

Yanli LIN, Xiaohui SI, Fulei CHU

期刊论文

Concurrent fatigue crack growth simulation using extended finite element method

Zizi LU, Yongming LIU,

期刊论文

Stress field near circular-arc interface crack tip based on electric saturation concept

Longchao DAI, Xinwei WANG

期刊论文

Automatic detection and assessment of crack development in ultra-high performance concrete in the spatial

期刊论文

Some remarks on the engineering application of the fatigue crack growth approach under nonzero mean loads

Jorge Alberto Rodriguez DURAN,Ronney Mancebo BOLOY,Rafael Raider LEONI

期刊论文

Crack propagation with different radius local random damage based on peridynamic theory

期刊论文

Frost heave and freezing processes of saturated rock with an open crack under different freezing conditions

Zhitao LV, Caichu XIA, Yuesong WANG, Ziliang LIN

期刊论文

混凝土裂缝端部粘聚力的计算

徐世烺,王利民

期刊论文