Pub Date : 2023-11-25DOI: 10.1177/10567895231216008
Chunlin Wu, Huiming Yin
The inclusion-based boundary element method (iBEM) is developed to calculate the elastic fields of a bi-layered composite with inhomogeneities in one layer. The bi-material Green’s function has been applied to obtain the elastic field caused by the domain integral of the source fields on inclusions and the boundary integral of the applied loads on the surface. Using Eshelby’s equivalent inclusion method (EIM), the material mismatch between the particle and matrix phases is simulated with a continuously distributed source field, namely eigenstrain, on inhomogeneities so that the iBEM can calculate the local field. The stress singularity along the interface leads to the delamination of the bimaterials under a certain load. The crack’s energy release rate ( J) is obtained through the J-integral, which predicts the stability of the delamination. When the stiffness of one layer increases, the J-integral increases with a higher gradient, leading to lower stability. Particularly, the effect of the boundary and inhomogeneity on the J-integral is illustrated by changing the crack length and inhomogeneity configuration, which shows the crack is stable at the beginning stage and becomes unstable when the crack tip approaches the boundary; a stiffer inhomogeneity in the neighborhood of a crack tip decreases J and improves the fracture resistance. For the stable cracking phase, the J-integral increases with the volume fraction of inhomogeneity are evaluated. The model is applied to a dual-glass solar module with air bubbles in the encapsulant layer. The stress distribution is evaluated with the iBEM, and the J-integral is evaluated to predict the delamination process with the energy release rate, which shows that the bubbles significantly increase the J-integral. The effect of the bubble size, location, and number on the J-integral is also investigated. The present method provides a powerful tool for the design and analysis of layered materials and structures.
{"title":"The effects of boundary and inhomogeneities on the delamination of a bi-layered material system","authors":"Chunlin Wu, Huiming Yin","doi":"10.1177/10567895231216008","DOIUrl":"https://doi.org/10.1177/10567895231216008","url":null,"abstract":"The inclusion-based boundary element method (iBEM) is developed to calculate the elastic fields of a bi-layered composite with inhomogeneities in one layer. The bi-material Green’s function has been applied to obtain the elastic field caused by the domain integral of the source fields on inclusions and the boundary integral of the applied loads on the surface. Using Eshelby’s equivalent inclusion method (EIM), the material mismatch between the particle and matrix phases is simulated with a continuously distributed source field, namely eigenstrain, on inhomogeneities so that the iBEM can calculate the local field. The stress singularity along the interface leads to the delamination of the bimaterials under a certain load. The crack’s energy release rate ( J) is obtained through the J-integral, which predicts the stability of the delamination. When the stiffness of one layer increases, the J-integral increases with a higher gradient, leading to lower stability. Particularly, the effect of the boundary and inhomogeneity on the J-integral is illustrated by changing the crack length and inhomogeneity configuration, which shows the crack is stable at the beginning stage and becomes unstable when the crack tip approaches the boundary; a stiffer inhomogeneity in the neighborhood of a crack tip decreases J and improves the fracture resistance. For the stable cracking phase, the J-integral increases with the volume fraction of inhomogeneity are evaluated. The model is applied to a dual-glass solar module with air bubbles in the encapsulant layer. The stress distribution is evaluated with the iBEM, and the J-integral is evaluated to predict the delamination process with the energy release rate, which shows that the bubbles significantly increase the J-integral. The effect of the bubble size, location, and number on the J-integral is also investigated. The present method provides a powerful tool for the design and analysis of layered materials and structures.","PeriodicalId":13837,"journal":{"name":"International Journal of Damage Mechanics","volume":"34 37","pages":""},"PeriodicalIF":4.2,"publicationDate":"2023-11-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139237121","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-11-22DOI: 10.1177/10567895231215554
Bin Sun, Tong Guo
A multi-scale model is established to describe the relationship between the macroscopic damage evolution and microscopic cracks behaviors of concrete at elevated temperatures. The evolution equation of the ideal microscopic crack system of concrete at elevated temperatures is deduced for construct the model, which can predict the microscopic crack density and macroscopic damage of concrete at elevated temperatures. The multi-scale model fuses some advantages of the traditional microscopic and macroscopic damage models. Finally, multi-scale damage of a concrete block under high temperature is predicted and compared with the corresponding experimental results, which is utilized to support the ability of the developed model. The results show that the developed multi-scale model can be used to evaluate fire damage of concrete structures in macro-scale as well as explain its physical mechanisms in micro-scale.
{"title":"A multi-scale model from microscopic cracks to macroscopic damage of concrete at elevated temperatures","authors":"Bin Sun, Tong Guo","doi":"10.1177/10567895231215554","DOIUrl":"https://doi.org/10.1177/10567895231215554","url":null,"abstract":"A multi-scale model is established to describe the relationship between the macroscopic damage evolution and microscopic cracks behaviors of concrete at elevated temperatures. The evolution equation of the ideal microscopic crack system of concrete at elevated temperatures is deduced for construct the model, which can predict the microscopic crack density and macroscopic damage of concrete at elevated temperatures. The multi-scale model fuses some advantages of the traditional microscopic and macroscopic damage models. Finally, multi-scale damage of a concrete block under high temperature is predicted and compared with the corresponding experimental results, which is utilized to support the ability of the developed model. The results show that the developed multi-scale model can be used to evaluate fire damage of concrete structures in macro-scale as well as explain its physical mechanisms in micro-scale.","PeriodicalId":13837,"journal":{"name":"International Journal of Damage Mechanics","volume":"65 ","pages":""},"PeriodicalIF":4.2,"publicationDate":"2023-11-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139249917","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-11-07DOI: 10.1177/10567895231204951
Mateusz Kopec, Xiaochuan Liu, Dominik Kukla, Ryszard Sitek, Zbigniew L Kowalewski
In this paper, three different directions of 0°, 45° and 90° were used to manufacture the Haynes 282 alloy bars by using the Direct Metal Laser Sintering (DMLS) method. The additively manufactured specimens as well as these of the wrought Haynes 282 were subsequently subjected to comparative fatigue tests in the range of stress amplitude from ±400 MPa to ±800 MPa. The AM process enhanced the fatigue response of the nickel-based alloy in question by 200 MPa. Furthermore, it was found, that the printing direction does not affect the fatigue response of additively manufactured specimens significantly as minor differences in service life were observed for the entire stress amplitude range adopted. Finally, fatigue damage measure φ and fatigue damage parameter D approaches were used to reveal the dynamics of damage development and to monitor damage development due to fatigue.
{"title":"Effect of printing direction on fatigue response and damage development in additive manufactured Haynes 282 nickel superalloy","authors":"Mateusz Kopec, Xiaochuan Liu, Dominik Kukla, Ryszard Sitek, Zbigniew L Kowalewski","doi":"10.1177/10567895231204951","DOIUrl":"https://doi.org/10.1177/10567895231204951","url":null,"abstract":"In this paper, three different directions of 0°, 45° and 90° were used to manufacture the Haynes 282 alloy bars by using the Direct Metal Laser Sintering (DMLS) method. The additively manufactured specimens as well as these of the wrought Haynes 282 were subsequently subjected to comparative fatigue tests in the range of stress amplitude from ±400 MPa to ±800 MPa. The AM process enhanced the fatigue response of the nickel-based alloy in question by 200 MPa. Furthermore, it was found, that the printing direction does not affect the fatigue response of additively manufactured specimens significantly as minor differences in service life were observed for the entire stress amplitude range adopted. Finally, fatigue damage measure φ and fatigue damage parameter D approaches were used to reveal the dynamics of damage development and to monitor damage development due to fatigue.","PeriodicalId":13837,"journal":{"name":"International Journal of Damage Mechanics","volume":"140 3","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-11-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135475835","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Understanding the damage evolution and time-dependent property of rock creep is of great significance for predicting geohazards and evaluating the long-term stability of geotechnical structures. In this study, a three-dimensional digital image correlation system was adopted to investigate the creep behavior of sandstone under the coupling action of stress and pore water pressure. The apparent strain fields, deformation characteristics of the localization zone, and micromorphology of the fracture surface were analyzed. The results demonstrated that when the applied deviatoric stress level was above σ ci (crack initial stress) or σ cd (crack damage stress), the increase in pore water pressure promoted creep deformation evidently, improved the creep rate significantly and shortened the time-to-failure of the rock obviously. In the radial strain field, the localized development of substantial microcracks on the rock surface was concentrated in the steady-state creep, while the microcracks interconnected to form macroscopic shear cracks that dominated the accelerating creep, and this damage evolution characteristic can be used as a precursor and early warning of rock creep failure. Besides, increasing the pore water pressure also would cause the divergence point of strain curves inside and outside the localization zone to appear earlier at the secondary creep, and produce a wider localization zone at the tertiary creep. The creep fracture surface of the rock was dominated by intergranular microcracks. Increasing the pore water pressure would result in the deterioration of the cemented structure and breakage of the cemented matrix more seriously, thus stimulating the generation of more microcracks.
{"title":"Creep behavior of sandstone under the coupling action of stress and pore water pressure using three-dimensional digital image correlation","authors":"Cancan Chen, Heping Xie, Jiang Xu, Shoujian Peng, Cunbao Li, Minghui Li","doi":"10.1177/10567895231209838","DOIUrl":"https://doi.org/10.1177/10567895231209838","url":null,"abstract":"Understanding the damage evolution and time-dependent property of rock creep is of great significance for predicting geohazards and evaluating the long-term stability of geotechnical structures. In this study, a three-dimensional digital image correlation system was adopted to investigate the creep behavior of sandstone under the coupling action of stress and pore water pressure. The apparent strain fields, deformation characteristics of the localization zone, and micromorphology of the fracture surface were analyzed. The results demonstrated that when the applied deviatoric stress level was above σ ci (crack initial stress) or σ cd (crack damage stress), the increase in pore water pressure promoted creep deformation evidently, improved the creep rate significantly and shortened the time-to-failure of the rock obviously. In the radial strain field, the localized development of substantial microcracks on the rock surface was concentrated in the steady-state creep, while the microcracks interconnected to form macroscopic shear cracks that dominated the accelerating creep, and this damage evolution characteristic can be used as a precursor and early warning of rock creep failure. Besides, increasing the pore water pressure also would cause the divergence point of strain curves inside and outside the localization zone to appear earlier at the secondary creep, and produce a wider localization zone at the tertiary creep. The creep fracture surface of the rock was dominated by intergranular microcracks. Increasing the pore water pressure would result in the deterioration of the cemented structure and breakage of the cemented matrix more seriously, thus stimulating the generation of more microcracks.","PeriodicalId":13837,"journal":{"name":"International Journal of Damage Mechanics","volume":"48 24","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-11-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135819298","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-10-26DOI: 10.1177/10567895231204640
Bilal Ahmed, Taehyo Park, Jong-Su Jeon
Concrete structures are essential for shelters, storage, transportation, and defense systems. However, they are vulnerable to terrorist attacks and explosions. The most exposed component of these structures is the reinforced concrete slab, which is also the primary force-transferring member. Therefore, the present study utilizes machine learning techniques to predict the maximum vertical displacement of reinforced concrete slabs subjected to air-blast loading. This can be achieved using 11 input parameters of the slab and TNT blast to predict the maximum displacement. The dataset comprises 146 samples from various experimental and numerical blast studies on reinforced concrete slabs in the open literature. Rather than presenting the data in a tabular format, each individual data sample is transformed into an image using distinct techniques: one uses a self-similarity matrix, and the other utilizes an image generator for the tabular data. Image generation transforms tabular data into images by assigning features to pixel positions. This results in spatial dependency of the input features. Using these images, various convolutional neural networks were adopted (ResNet-18, ResNet-50, ResNet-101, EfficentNet-b0, ShuffleNet, Xception, DarkNet-53, and DenseNet-20) and trained to predict the slab maximum displacement. Most models demonstrated promising results. The performance of the models was predicted based on the root mean squared error, mean absolute error, and coefficient of determination, and the impact of input features on the maximum displacement was examined. Along with this, the initial study of the blast damage assessment on reinforced concrete slabs is explained for future work to be performed based on the proposed method.
{"title":"Blast response and damage assessment of reinforced concrete slabs using convolutional neural networks","authors":"Bilal Ahmed, Taehyo Park, Jong-Su Jeon","doi":"10.1177/10567895231204640","DOIUrl":"https://doi.org/10.1177/10567895231204640","url":null,"abstract":"Concrete structures are essential for shelters, storage, transportation, and defense systems. However, they are vulnerable to terrorist attacks and explosions. The most exposed component of these structures is the reinforced concrete slab, which is also the primary force-transferring member. Therefore, the present study utilizes machine learning techniques to predict the maximum vertical displacement of reinforced concrete slabs subjected to air-blast loading. This can be achieved using 11 input parameters of the slab and TNT blast to predict the maximum displacement. The dataset comprises 146 samples from various experimental and numerical blast studies on reinforced concrete slabs in the open literature. Rather than presenting the data in a tabular format, each individual data sample is transformed into an image using distinct techniques: one uses a self-similarity matrix, and the other utilizes an image generator for the tabular data. Image generation transforms tabular data into images by assigning features to pixel positions. This results in spatial dependency of the input features. Using these images, various convolutional neural networks were adopted (ResNet-18, ResNet-50, ResNet-101, EfficentNet-b0, ShuffleNet, Xception, DarkNet-53, and DenseNet-20) and trained to predict the slab maximum displacement. Most models demonstrated promising results. The performance of the models was predicted based on the root mean squared error, mean absolute error, and coefficient of determination, and the impact of input features on the maximum displacement was examined. Along with this, the initial study of the blast damage assessment on reinforced concrete slabs is explained for future work to be performed based on the proposed method.","PeriodicalId":13837,"journal":{"name":"International Journal of Damage Mechanics","volume":"5 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134908175","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Deep underground engineering is in a true three-dimensional stress state, and the adjustment of the three-dimensional stress state caused by engineering excavation will induce the fracture or even instability of the surrounding rock. However, three-dimensional mechanical model research suitable for the stability analysis of deep surrounding rock is very scarce. Therefore, a series of tests under different true triaxial stresses on two rocks (rhyodacite and marble) were conducted, and the characteristic strength (crack stable propagation initiation stress, crack unstable propagation initiation stress and peak strength) and deformation characteristics were further analyzed. After that, using the Lemaitre strain equivalence hypothesis and rock statistical damage theory, a new statistical damage constitutive model at true triaxial stress states was proposed, which introduced the three-dimensional strength criterion Modified Wiebols Cook to characterize the three-dimensional strength of the rock microelement. Therefore, the intermediate principal stress can be reasonably considered. The damage threshold, initial compaction effect and residual strength of the rock microelement at different true triaxial stress conditions were also considered. Then the relationships between the proposed model parameters and σ 2 and σ 3 were analyzed. Furthermore, sensitivity analysis of the influence of parameters m and F 0 in proposed model on the shape of rock stress–strain curve and peak strength was also investigated. The comparison between the results predicted by proposed model and the experimental data shows that the new model established in this study can well simulate the prepeak and postpeak deformation characteristics of rock and the intermediate principal stress effect under true triaxial stress conditions.
{"title":"A novel meso-damage constitutive model of rock under true triaxial stress with three-dimensional cracking strength, threshold and closure effect","authors":"Zhi Zheng, Jiaju Zhou, Junhong Li, Honghui Tao, Xiaofeng Han, Hongyu Xu, Qiang Zhang","doi":"10.1177/10567895231204631","DOIUrl":"https://doi.org/10.1177/10567895231204631","url":null,"abstract":"Deep underground engineering is in a true three-dimensional stress state, and the adjustment of the three-dimensional stress state caused by engineering excavation will induce the fracture or even instability of the surrounding rock. However, three-dimensional mechanical model research suitable for the stability analysis of deep surrounding rock is very scarce. Therefore, a series of tests under different true triaxial stresses on two rocks (rhyodacite and marble) were conducted, and the characteristic strength (crack stable propagation initiation stress, crack unstable propagation initiation stress and peak strength) and deformation characteristics were further analyzed. After that, using the Lemaitre strain equivalence hypothesis and rock statistical damage theory, a new statistical damage constitutive model at true triaxial stress states was proposed, which introduced the three-dimensional strength criterion Modified Wiebols Cook to characterize the three-dimensional strength of the rock microelement. Therefore, the intermediate principal stress can be reasonably considered. The damage threshold, initial compaction effect and residual strength of the rock microelement at different true triaxial stress conditions were also considered. Then the relationships between the proposed model parameters and σ 2 and σ 3 were analyzed. Furthermore, sensitivity analysis of the influence of parameters m and F 0 in proposed model on the shape of rock stress–strain curve and peak strength was also investigated. The comparison between the results predicted by proposed model and the experimental data shows that the new model established in this study can well simulate the prepeak and postpeak deformation characteristics of rock and the intermediate principal stress effect under true triaxial stress conditions.","PeriodicalId":13837,"journal":{"name":"International Journal of Damage Mechanics","volume":"72 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135993563","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-09-15DOI: 10.1177/10567895231199482
Yu Pan, Deze Yang, Wenzhong Qu, Xihua Chu
The debonding of solid filler powder and binder matrix is the main form of damage for composite solid propellant. This study proposes a coda wave interference (CWI) analysis method to quantitatively characterize and evaluate the internal powder debonding damage of composite solid propellant by experiment and discrete element simulation. In order to verify the validity of numerical simulation, the discrete element method (DEM) samples to simulate the powder debonding damage of solid propellant are established, and the DEM simulation and micro-CT scanning experiment are carried out. The micro-experimental and DEM results prove the efficiency and accuracy of DEM samples in modeling the damage behaviors of solid propellant specimens. Furthermore, in order to quantitatively characterize and evaluate powder debonding damage of solid propellant, using CWI method to analyze the damage states of solid propellants in the experiment and DEM simulation of tension. Two coda evaluation parameters based on different damage states are proposed, and the relationship curves of coda evaluation parameters and tensile strain are obtained. Though the analysis of the curve results of experiment and DEM simulation, the validity of CWI is demonstrated. The coda evaluation parameters can quantitatively identify and judge the accumulation process of initial damage, the appearance of micro holes and the failure point of propellant.
{"title":"A coda wave interferometry to characterize and evaluate the powder debonding damage of solid propellant: Experimental investigation and discrete element simulation","authors":"Yu Pan, Deze Yang, Wenzhong Qu, Xihua Chu","doi":"10.1177/10567895231199482","DOIUrl":"https://doi.org/10.1177/10567895231199482","url":null,"abstract":"The debonding of solid filler powder and binder matrix is the main form of damage for composite solid propellant. This study proposes a coda wave interference (CWI) analysis method to quantitatively characterize and evaluate the internal powder debonding damage of composite solid propellant by experiment and discrete element simulation. In order to verify the validity of numerical simulation, the discrete element method (DEM) samples to simulate the powder debonding damage of solid propellant are established, and the DEM simulation and micro-CT scanning experiment are carried out. The micro-experimental and DEM results prove the efficiency and accuracy of DEM samples in modeling the damage behaviors of solid propellant specimens. Furthermore, in order to quantitatively characterize and evaluate powder debonding damage of solid propellant, using CWI method to analyze the damage states of solid propellants in the experiment and DEM simulation of tension. Two coda evaluation parameters based on different damage states are proposed, and the relationship curves of coda evaluation parameters and tensile strain are obtained. Though the analysis of the curve results of experiment and DEM simulation, the validity of CWI is demonstrated. The coda evaluation parameters can quantitatively identify and judge the accumulation process of initial damage, the appearance of micro holes and the failure point of propellant.","PeriodicalId":13837,"journal":{"name":"International Journal of Damage Mechanics","volume":"48 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-09-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135396857","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-09-12DOI: 10.1177/10567895231196263
Ziyuan Zhao, Jianzuo Ma, Shifeng Zheng, Haibo Kou, Jun Qiu, Weiguo Li, Fangjie Zheng, Siyuan Lang
Accurately and conveniently acquiring the tensile fracture strength of rocks at different temperatures is vital no matter for the security or economical design of deep underground engineering projects. Extensive testing in the laboratory, assisted with fitting approaches, is the main method to obtain the high-temperature tensile fracture strength in the available literature. However, the high-temperature destruction test is difficult to conduct and requires numerous time and resources. In this work, considering the main physical mechanisms such as phase transition and thermal damage that affect the tensile fracture strength of rocks at high temperatures, theoretical models for predicting their temperature-dependent tensile fracture strength (TDTFS) are established based on the Force-Heat Equivalence Energy Density Principle. The presented models achieve great prediction on the different variation trends of tensile strength below and above the phase transition temperature, as well as the corresponding sudden change of strength. For rocks without phase transition, the presented model only needs some physical parameters tested at room temperature can get a good prediction capacity on the TDTFS. Moreover, a new theoretical characterization model of the equivalent thermal damage parameter was presented and take a comparison with the previous model. Finally, the potential applications and limitations of the TDTFS model are further discussed. The application threshold of the presented TDTFS models is relatively low, and they may therefore be suitable as a method for providing a rapid and preliminary evaluation of strength at a large temperature range for rock engineering.
{"title":"Modeling temperature dependence of tensile fracture strength for rocks considering phase transition and the direct effect of thermal damage","authors":"Ziyuan Zhao, Jianzuo Ma, Shifeng Zheng, Haibo Kou, Jun Qiu, Weiguo Li, Fangjie Zheng, Siyuan Lang","doi":"10.1177/10567895231196263","DOIUrl":"https://doi.org/10.1177/10567895231196263","url":null,"abstract":"Accurately and conveniently acquiring the tensile fracture strength of rocks at different temperatures is vital no matter for the security or economical design of deep underground engineering projects. Extensive testing in the laboratory, assisted with fitting approaches, is the main method to obtain the high-temperature tensile fracture strength in the available literature. However, the high-temperature destruction test is difficult to conduct and requires numerous time and resources. In this work, considering the main physical mechanisms such as phase transition and thermal damage that affect the tensile fracture strength of rocks at high temperatures, theoretical models for predicting their temperature-dependent tensile fracture strength (TDTFS) are established based on the Force-Heat Equivalence Energy Density Principle. The presented models achieve great prediction on the different variation trends of tensile strength below and above the phase transition temperature, as well as the corresponding sudden change of strength. For rocks without phase transition, the presented model only needs some physical parameters tested at room temperature can get a good prediction capacity on the TDTFS. Moreover, a new theoretical characterization model of the equivalent thermal damage parameter was presented and take a comparison with the previous model. Finally, the potential applications and limitations of the TDTFS model are further discussed. The application threshold of the presented TDTFS models is relatively low, and they may therefore be suitable as a method for providing a rapid and preliminary evaluation of strength at a large temperature range for rock engineering.","PeriodicalId":13837,"journal":{"name":"International Journal of Damage Mechanics","volume":"24 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-09-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135826435","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
In this paper, a resilience assessment framework for microencapsulated self-healing cementitious composites is proposed based on a micromechanical damage-healing model. A 3D micromechanical analytical model is constructed to analyze the performance evolution during the damage-healing process of self-healing concrete. The resilience assessment of microencapsulated self-healing concrete is defined by virtue of the residual stiffness, self-healing effect on stiffness and damage cumulative on stiffness, which corresponds to three main features of resilience; namely, the robustness, recoverability and adaptability. The assessment results indicate that the release of healing agents within microcapsules and healing process of extended microcracks allows the microencapsulated self-healing concrete to have higher resilience than conventional concrete. Moreover, a parameter sensitivity analysis is conducted to investigate the influence of the healing efficiency, the applied initial damage and the fracture toughness of the repaired microcrack on resilience of microencapsulated self-healing concrete. The results indicate that higher healing efficiency and applied initial damage leads to high resilience, and fracture toughness of the repaired microcrack makes less difference to the results. The findings of this paper lay a theoretical foundation for the resilience design of self-healing material layer of underground structures.
{"title":"A resilience assessment framework for microencapsulated self-healing cementitious composites based on a micromechanical damage-healing model","authors":"Kaihang Han, Jiann-Wen Woody Ju, Chengping Zhang, Dong Su, Hongzhi Cui, Xing-Tao Lin, Xiangsheng Chen","doi":"10.1177/10567895231197237","DOIUrl":"https://doi.org/10.1177/10567895231197237","url":null,"abstract":"In this paper, a resilience assessment framework for microencapsulated self-healing cementitious composites is proposed based on a micromechanical damage-healing model. A 3D micromechanical analytical model is constructed to analyze the performance evolution during the damage-healing process of self-healing concrete. The resilience assessment of microencapsulated self-healing concrete is defined by virtue of the residual stiffness, self-healing effect on stiffness and damage cumulative on stiffness, which corresponds to three main features of resilience; namely, the robustness, recoverability and adaptability. The assessment results indicate that the release of healing agents within microcapsules and healing process of extended microcracks allows the microencapsulated self-healing concrete to have higher resilience than conventional concrete. Moreover, a parameter sensitivity analysis is conducted to investigate the influence of the healing efficiency, the applied initial damage and the fracture toughness of the repaired microcrack on resilience of microencapsulated self-healing concrete. The results indicate that higher healing efficiency and applied initial damage leads to high resilience, and fracture toughness of the repaired microcrack makes less difference to the results. The findings of this paper lay a theoretical foundation for the resilience design of self-healing material layer of underground structures.","PeriodicalId":13837,"journal":{"name":"International Journal of Damage Mechanics","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-09-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135980618","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
In the excavation of water-related underground projects such as hydropower and energy reserves, the surrounding rock surfers complex stress path and stress state redistribution, resulting in damage and failure under the hydro-mechanical coupling condition. However, the rock hydro-mechanical coupling characteristics under complex stress paths are unclear and corresponding theoretical models are scarce. In this study, a series of tests such as triaxial compression, unloading confining pressure and cyclic loading and unloading were carried out to study the effects of different stress paths, stress levels and seepage pressure on rock deformation, strength, failure and permeability. Based on test results, the damage evolutions under three different testing paths were analyzed, a new seepage-stress coupling statistical damage model which can better simulate the compaction stage is proposed. The prediction results of the proposed model under different stress paths are in good agreement with the experimental results. Under different stress paths, the fitting relationship between parameters R0 and n and σeff is similar and has good correlation.
{"title":"Seepage-stress combined experiment and damage model of rock in different loading and unloading paths","authors":"Zhi Zheng, Hongyu Xu, Wei Wang, Qiang Zhang, Yujie Wang, Qiancheng Sun, Honghui Tao, Xiaofeng Han","doi":"10.1177/10567895231193056","DOIUrl":"https://doi.org/10.1177/10567895231193056","url":null,"abstract":"In the excavation of water-related underground projects such as hydropower and energy reserves, the surrounding rock surfers complex stress path and stress state redistribution, resulting in damage and failure under the hydro-mechanical coupling condition. However, the rock hydro-mechanical coupling characteristics under complex stress paths are unclear and corresponding theoretical models are scarce. In this study, a series of tests such as triaxial compression, unloading confining pressure and cyclic loading and unloading were carried out to study the effects of different stress paths, stress levels and seepage pressure on rock deformation, strength, failure and permeability. Based on test results, the damage evolutions under three different testing paths were analyzed, a new seepage-stress coupling statistical damage model which can better simulate the compaction stage is proposed. The prediction results of the proposed model under different stress paths are in good agreement with the experimental results. Under different stress paths, the fitting relationship between parameters R0 and n and σeff is similar and has good correlation.","PeriodicalId":13837,"journal":{"name":"International Journal of Damage Mechanics","volume":" ","pages":""},"PeriodicalIF":4.2,"publicationDate":"2023-09-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44620287","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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