Pub Date : 2023-12-16DOI: 10.1177/10567895231215557
Jiahui Shen, Mário Rui Tiago Arruda, Alfonso Pagani
Higher-order theories have a broad range of successful applications but also suffer from localization instability and mesh-size dependency when modeling quasi-brittle materials such as concrete with strain-softening behavior. To overcome the above difficulties, this paper proposes a fracture energy regularization method with a unified, consistent crack bandwidth specifically tailored for higher-order beam theories. The Carrera unified formulation (CUF) is applied to develop scalable structural theories and related finite elements. To evaluate the accuracy of the new crack bandwidth, three typical experimental quasi-static benchmarks of pure concrete structures are utilized. A modified Mazars damage model with tensile and compressive softening laws is implemented in these benchmarks. The comparison between numerical and experimental results demonstrates that the proposed method can accurately determine the correct crack bandwidth and preserve the dissipated energy per unit area of a fracture surface. Moreover, this robust estimation of crack bandwidth reduces the mesh dependency in general, ensuring the high efficiency of the CUF model.
{"title":"A consistent crack bandwidth for higher-order beam theories: Application to concrete","authors":"Jiahui Shen, Mário Rui Tiago Arruda, Alfonso Pagani","doi":"10.1177/10567895231215557","DOIUrl":"https://doi.org/10.1177/10567895231215557","url":null,"abstract":"Higher-order theories have a broad range of successful applications but also suffer from localization instability and mesh-size dependency when modeling quasi-brittle materials such as concrete with strain-softening behavior. To overcome the above difficulties, this paper proposes a fracture energy regularization method with a unified, consistent crack bandwidth specifically tailored for higher-order beam theories. The Carrera unified formulation (CUF) is applied to develop scalable structural theories and related finite elements. To evaluate the accuracy of the new crack bandwidth, three typical experimental quasi-static benchmarks of pure concrete structures are utilized. A modified Mazars damage model with tensile and compressive softening laws is implemented in these benchmarks. The comparison between numerical and experimental results demonstrates that the proposed method can accurately determine the correct crack bandwidth and preserve the dissipated energy per unit area of a fracture surface. Moreover, this robust estimation of crack bandwidth reduces the mesh dependency in general, ensuring the high efficiency of the CUF model.","PeriodicalId":13837,"journal":{"name":"International Journal of Damage Mechanics","volume":"9 4p2","pages":""},"PeriodicalIF":4.2,"publicationDate":"2023-12-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138968010","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 : 2023-12-11DOI: 10.1177/10567895231217036
Suvadeep Sen, Badri Prasad Patel
Conscious efforts on reduction of greenhouse gas emissions have led to an energy transition to renewable energy, however uncertainties of renewable energy production have resulted in higher thermal cycling demands from conventional power plants. Thermal load cycling at high temperature regions of steam turbine components leads to enhanced creep-fatigue damage accumulation. It is well established that such damage mechanism is numerically best predicted by unified constitutive modeling including damage as a variable as per the formalism of continuum damage mechanics at an expense of considerable computational efforts using finite element analysis. In this paper, the non-iterative Asymptotic Numerical Method (ANM), currently limited to partial cycle analysis with linear hardening plasticity model, is proposed for the first time to address cyclic viscoplasticity problems including damage capable of handling multiple cycles and most generalized loading conditions. Regularization techniques additionally necessary to implement loading-unloading-reloading criteria and advanced constitutive models etc. are presented. The constitutive model chosen for the formulation includes the non-linear multiple back stress variable modified Chaboche model to include damage combined with modified Chaboche-Rousselier isotropic hardening model to include damage, power law for viscoplasticity, Lemaitre’s damage potential and Kachanov-Rabotnov’s creep damage law. The method is verified with defined error measures and then applied to two high pressure steam turbine rotors, one with and another without thermal stress relief groove (TSRG) at the inlet under service type loading conditions to study the beneficial effect of the TSRG on creep-fatigue damage evolution. The accumulated errors of the proposed ANM and computational time are compared to a conventional Newton-Raphson solution.
{"title":"Continuum damage mechanics of cyclic viscoplasticity using asymptotic numerical method","authors":"Suvadeep Sen, Badri Prasad Patel","doi":"10.1177/10567895231217036","DOIUrl":"https://doi.org/10.1177/10567895231217036","url":null,"abstract":"Conscious efforts on reduction of greenhouse gas emissions have led to an energy transition to renewable energy, however uncertainties of renewable energy production have resulted in higher thermal cycling demands from conventional power plants. Thermal load cycling at high temperature regions of steam turbine components leads to enhanced creep-fatigue damage accumulation. It is well established that such damage mechanism is numerically best predicted by unified constitutive modeling including damage as a variable as per the formalism of continuum damage mechanics at an expense of considerable computational efforts using finite element analysis. In this paper, the non-iterative Asymptotic Numerical Method (ANM), currently limited to partial cycle analysis with linear hardening plasticity model, is proposed for the first time to address cyclic viscoplasticity problems including damage capable of handling multiple cycles and most generalized loading conditions. Regularization techniques additionally necessary to implement loading-unloading-reloading criteria and advanced constitutive models etc. are presented. The constitutive model chosen for the formulation includes the non-linear multiple back stress variable modified Chaboche model to include damage combined with modified Chaboche-Rousselier isotropic hardening model to include damage, power law for viscoplasticity, Lemaitre’s damage potential and Kachanov-Rabotnov’s creep damage law. The method is verified with defined error measures and then applied to two high pressure steam turbine rotors, one with and another without thermal stress relief groove (TSRG) at the inlet under service type loading conditions to study the beneficial effect of the TSRG on creep-fatigue damage evolution. The accumulated errors of the proposed ANM and computational time are compared to a conventional Newton-Raphson solution.","PeriodicalId":13837,"journal":{"name":"International Journal of Damage Mechanics","volume":"10 11","pages":""},"PeriodicalIF":4.2,"publicationDate":"2023-12-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138980366","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 : 2023-12-11DOI: 10.1177/10567895231215553
Grzegorz Szczęsny, M. Kopeć, Adrian Łukaszewicz, Zbigniew L. Kowalewski
Implant breaking destabilizing the fracture may be caused by its structural defect, inappropriate use, or massive overloads. We present the patient, who broke the plate stabilizing comminuted clavicular fracture at the sixth postoperative week due to the, primarily reported, simple loading of the limb that should not exceeded admissible limits. Macroscopic examination excluded its manufacturing defect of an explant, but revealed areas of fatigue fractures, as well as anterior and inferior bending of its edges. Mechanical analysis proved sufficient material durability. Those findings clearly showed that the plate broke in consequence of repetitive overloads exceeding its durability. Patient, when acquitted with those results, confessed that the plate broke, while fishing. Moreover, he reported an episode of alcohol overuse that could contribute to implant failure bringing the risk of additional injury. Biomechanical analysis confirmed that mechanical loads throwing the spinner exceed values adequate for plate breaking. Thus, the real circumstances of the complication seem to be unveiled pointing out to facts that some patients disobey postoperative recommendations to avoid overloading of stabilized extremity, thus participating actively in this type of complications, that they dissemble the real circumstances of the complications, and that they may exhibit risky and irrational behavior. Basing on the presented case we concluded that in some cases plaster cast immobilization supporting stabilized fracture may be beneficial precluding banned activities and preventing from secondary injuries reducing the risk of postoperative complications.
{"title":"Identification of the damage mechanism in orthopaedic implant. Case study including the biomechanical analysis","authors":"Grzegorz Szczęsny, M. Kopeć, Adrian Łukaszewicz, Zbigniew L. Kowalewski","doi":"10.1177/10567895231215553","DOIUrl":"https://doi.org/10.1177/10567895231215553","url":null,"abstract":"Implant breaking destabilizing the fracture may be caused by its structural defect, inappropriate use, or massive overloads. We present the patient, who broke the plate stabilizing comminuted clavicular fracture at the sixth postoperative week due to the, primarily reported, simple loading of the limb that should not exceeded admissible limits. Macroscopic examination excluded its manufacturing defect of an explant, but revealed areas of fatigue fractures, as well as anterior and inferior bending of its edges. Mechanical analysis proved sufficient material durability. Those findings clearly showed that the plate broke in consequence of repetitive overloads exceeding its durability. Patient, when acquitted with those results, confessed that the plate broke, while fishing. Moreover, he reported an episode of alcohol overuse that could contribute to implant failure bringing the risk of additional injury. Biomechanical analysis confirmed that mechanical loads throwing the spinner exceed values adequate for plate breaking. Thus, the real circumstances of the complication seem to be unveiled pointing out to facts that some patients disobey postoperative recommendations to avoid overloading of stabilized extremity, thus participating actively in this type of complications, that they dissemble the real circumstances of the complications, and that they may exhibit risky and irrational behavior. Basing on the presented case we concluded that in some cases plaster cast immobilization supporting stabilized fracture may be beneficial precluding banned activities and preventing from secondary injuries reducing the risk of postoperative complications.","PeriodicalId":13837,"journal":{"name":"International Journal of Damage Mechanics","volume":"38 8","pages":""},"PeriodicalIF":4.2,"publicationDate":"2023-12-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138981036","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 : 2023-12-06DOI: 10.1177/10567895231215558
H. Darban, Raimondo Luciano, Michał Basista
The buckling instability of micro- and nanopillars can be an issue when designing intelligent miniaturized devices and characterizing composite materials reinforced with small-scale beam-like particles. Analytical modeling of the buckling of miniaturized pillars is especially important due to the difficulties in conducting experiments. Here, a well-posed stress-driven nonlocal model is developed, which allows the calculation of the critical loads and buckling configurations of the miniaturized pillars on an elastic foundation and with arbitrary numbers of edge cracks. The discontinuities in bending slopes and deflection at the damaged cross-sections due to the edge cracks are captured through the incorporation of both rotational and translational springs. A comprehensive analysis is conducted to investigate the instability of pillars containing a range of one to four cracks. This analysis reveals interesting effects regarding the influence of crack location, nonlocality, and elastic foundation on the initial and subsequent critical loads and associated buckling configurations. The main findings are: (i) the shielding and amplification effects related to a system of cracks become more significant as the dimensions of pillars reduce, (ii) the influence of the shear force at the damaged cross-section related to the translational spring must not be neglected when dealing with higher modes of buckling and long cracks, (iii) an elastic foundation decreases the effects of the cracks and size dependency on the buckling loads, and (iv) the effects of the edge cracks on the critical loads and buckling configurations of the miniaturized pillars are highly dependent on the boundary conditions.
{"title":"Effects of multiple edge cracks, shear force, elastic foundation, and boundary conditions on bucking of small-scale pillars","authors":"H. Darban, Raimondo Luciano, Michał Basista","doi":"10.1177/10567895231215558","DOIUrl":"https://doi.org/10.1177/10567895231215558","url":null,"abstract":"The buckling instability of micro- and nanopillars can be an issue when designing intelligent miniaturized devices and characterizing composite materials reinforced with small-scale beam-like particles. Analytical modeling of the buckling of miniaturized pillars is especially important due to the difficulties in conducting experiments. Here, a well-posed stress-driven nonlocal model is developed, which allows the calculation of the critical loads and buckling configurations of the miniaturized pillars on an elastic foundation and with arbitrary numbers of edge cracks. The discontinuities in bending slopes and deflection at the damaged cross-sections due to the edge cracks are captured through the incorporation of both rotational and translational springs. A comprehensive analysis is conducted to investigate the instability of pillars containing a range of one to four cracks. This analysis reveals interesting effects regarding the influence of crack location, nonlocality, and elastic foundation on the initial and subsequent critical loads and associated buckling configurations. The main findings are: (i) the shielding and amplification effects related to a system of cracks become more significant as the dimensions of pillars reduce, (ii) the influence of the shear force at the damaged cross-section related to the translational spring must not be neglected when dealing with higher modes of buckling and long cracks, (iii) an elastic foundation decreases the effects of the cracks and size dependency on the buckling loads, and (iv) the effects of the edge cracks on the critical loads and buckling configurations of the miniaturized pillars are highly dependent on the boundary conditions.","PeriodicalId":13837,"journal":{"name":"International Journal of Damage Mechanics","volume":"28 12","pages":""},"PeriodicalIF":4.2,"publicationDate":"2023-12-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138598129","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 : 2023-12-02DOI: 10.1177/10567895231215474
Ali Mahmoudi, Arash P. Jirandehi, Mohammad Ali Amooie, M. Khonsari
A reliable approach based on an entropy-damage model for assessing remaining useful fatigue life is presented. Two damage models are presented and evaluated to assess their effectiveness in predicting remaining useful life. The first model focuses on reduced toughness caused by fatigue degradation, while the second is based on accumulating entropy during fatigue loading. The entropy-based approach employs infrared thermography to anticipate entropy accumulation and damage status. Outcomes reveal that the entropy-driven technique offers enhanced precision. Moreover, its damage growth rate remains consistent, regardless of the number of cycles leading to failure, ensuring a more stable tracking of damage evolution. It successfully predicts the remaining useful life and can treat variable load sequencing without knowing the loading history. An extensive set of experimental results with carbon steel 1018 are presented to illustrate the utility of the approach.
{"title":"Entropy-based damage model for assessing the remaining useful fatigue life","authors":"Ali Mahmoudi, Arash P. Jirandehi, Mohammad Ali Amooie, M. Khonsari","doi":"10.1177/10567895231215474","DOIUrl":"https://doi.org/10.1177/10567895231215474","url":null,"abstract":"A reliable approach based on an entropy-damage model for assessing remaining useful fatigue life is presented. Two damage models are presented and evaluated to assess their effectiveness in predicting remaining useful life. The first model focuses on reduced toughness caused by fatigue degradation, while the second is based on accumulating entropy during fatigue loading. The entropy-based approach employs infrared thermography to anticipate entropy accumulation and damage status. Outcomes reveal that the entropy-driven technique offers enhanced precision. Moreover, its damage growth rate remains consistent, regardless of the number of cycles leading to failure, ensuring a more stable tracking of damage evolution. It successfully predicts the remaining useful life and can treat variable load sequencing without knowing the loading history. An extensive set of experimental results with carbon steel 1018 are presented to illustrate the utility of the approach.","PeriodicalId":13837,"journal":{"name":"International Journal of Damage Mechanics","volume":"116 13","pages":""},"PeriodicalIF":4.2,"publicationDate":"2023-12-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138607470","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 : 2023-11-28DOI: 10.1177/10567895231215555
Xin Xiong, K. Zhou, Feng Gao, Chun Xu, Jie-lin Li
The study of the constitutive model under stress loading for rock after undergoing freeze-thaw weathering cycles (FTWCs) treatment has important theoretical significance for the site operation and numerical calculation of rock mass engineering in cold regions. In this work, a series of FTWCs treatment tests of sandstone were carried out, and the evolution characteristics of the T2 spectrum distribution curve for sandstone before and after FTWCs treatment were analyzed utilizing nuclear magnetic resonance (NMR) technology. The schematic diagram of freeze-thaw damage evolution for sandstone was drawn, and the damage evolution mechanism was analyzed. Evolution laws of the stress-strain curves, peak and residual strength, peak and residual strain, and Young's modulus of sandstone under different FTWCs and confining pressures were analyzed by conventional triaxial compression tests. A piecewise constitutive model under triaxial stress loading for sandstone after undergoing FTWCs treatment was established, and the model considered the significant influence of FTWCs on the nonlinear deformation in the compaction stage and residual strength. By introducing error analysis indexes, the proposed model and published models were compared with the experimental data, it was found that the proposed model's performance is better than the published models, which indicated that the proposed model has good performance and strong universality.
{"title":"A new damage constitutive model for frozen-thawed sandstone under triaxial conditions: Considering the characteristics of pre-peak compaction and post-peak residual strength","authors":"Xin Xiong, K. Zhou, Feng Gao, Chun Xu, Jie-lin Li","doi":"10.1177/10567895231215555","DOIUrl":"https://doi.org/10.1177/10567895231215555","url":null,"abstract":"The study of the constitutive model under stress loading for rock after undergoing freeze-thaw weathering cycles (FTWCs) treatment has important theoretical significance for the site operation and numerical calculation of rock mass engineering in cold regions. In this work, a series of FTWCs treatment tests of sandstone were carried out, and the evolution characteristics of the T2 spectrum distribution curve for sandstone before and after FTWCs treatment were analyzed utilizing nuclear magnetic resonance (NMR) technology. The schematic diagram of freeze-thaw damage evolution for sandstone was drawn, and the damage evolution mechanism was analyzed. Evolution laws of the stress-strain curves, peak and residual strength, peak and residual strain, and Young's modulus of sandstone under different FTWCs and confining pressures were analyzed by conventional triaxial compression tests. A piecewise constitutive model under triaxial stress loading for sandstone after undergoing FTWCs treatment was established, and the model considered the significant influence of FTWCs on the nonlinear deformation in the compaction stage and residual strength. By introducing error analysis indexes, the proposed model and published models were compared with the experimental data, it was found that the proposed model's performance is better than the published models, which indicated that the proposed model has good performance and strong universality.","PeriodicalId":13837,"journal":{"name":"International Journal of Damage Mechanics","volume":"94 1","pages":""},"PeriodicalIF":4.2,"publicationDate":"2023-11-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139222445","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 : 2023-11-28DOI: 10.1177/10567895231212329
Adrian Łukaszewicz, M. Kopeć, Grzegorz Szczęsny, Zbigniew L. Kowalewski
Implant fractures complicate orthopaedic procedures requiring secondary surgeries. However, it is not exactly known when the damage initiation starts and which factors predispose them to the highest degree. Thus, the aim of the study was to characterize changes observed in orthopaedic implants after their removal from the bone. Particular efforts were made to determine, which of them occur during the process of its production, installation, usage and removal. Such identification enabled to specify the role of lesions emerging during each period and their role in the implant’s deformation or fracture. The paper was focused on implants dedicated to the stabilization of the femur fractures since the bone transfers the highest loads. External surface and geometric features of eight representative implants were observed under standard and stereoscopic cameras, as well as under light and scanning electron microscopes. Macroscopic analysis of the investigated implants exhibited a number of defects in the form of scratches, abrasions, deformations and chipping. The wear degree of each implant was different and strictly depended on how it was implanted in the patient's body, as well as on how the patient exploited it through his mobility. Four different sources of implant integrity changes were identified: manufacturing-related changes, implant application-related changes, daily life-related changes and implant removal-related changes.
{"title":"Characteristics of orthopaedic implants damage and mechanisms of its initiation","authors":"Adrian Łukaszewicz, M. Kopeć, Grzegorz Szczęsny, Zbigniew L. Kowalewski","doi":"10.1177/10567895231212329","DOIUrl":"https://doi.org/10.1177/10567895231212329","url":null,"abstract":"Implant fractures complicate orthopaedic procedures requiring secondary surgeries. However, it is not exactly known when the damage initiation starts and which factors predispose them to the highest degree. Thus, the aim of the study was to characterize changes observed in orthopaedic implants after their removal from the bone. Particular efforts were made to determine, which of them occur during the process of its production, installation, usage and removal. Such identification enabled to specify the role of lesions emerging during each period and their role in the implant’s deformation or fracture. The paper was focused on implants dedicated to the stabilization of the femur fractures since the bone transfers the highest loads. External surface and geometric features of eight representative implants were observed under standard and stereoscopic cameras, as well as under light and scanning electron microscopes. Macroscopic analysis of the investigated implants exhibited a number of defects in the form of scratches, abrasions, deformations and chipping. The wear degree of each implant was different and strictly depended on how it was implanted in the patient's body, as well as on how the patient exploited it through his mobility. Four different sources of implant integrity changes were identified: manufacturing-related changes, implant application-related changes, daily life-related changes and implant removal-related changes.","PeriodicalId":13837,"journal":{"name":"International Journal of Damage Mechanics","volume":"464 1","pages":""},"PeriodicalIF":4.2,"publicationDate":"2023-11-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139222608","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 : 2023-11-25DOI: 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.
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