Pub Date : 2021-12-28DOI: 10.1142/s1756973721440029
F. Parrinello, I. Benedetti
The present contribution proposes a formulation based on the use of hybrid equilibrium elements (HEEs), for the analysis of inter-element delamination and fracture propagation problems. HEEs are defined in terms of quadratic stress fields, which strongly verify both the homogeneous and inter-element equilibrium equations and they are employed with interfaces, initially exhibiting rigid behavior, embedded at the elements’ sides. The interface model is formulated in terms of the same degrees of freedom of the HEE, without any additional burden. The cohesive zone model (CZM) of the extrinsic interface is rigorously developed in the damage mechanics framework, with perfect adhesion at the pre-failure condition and with linear softening at the post-failure regime. After a brief review, the formulation is computationally tested by simulating the behavior of a double-cantilever-beam with diagonal loads; the obtained numerical results confirm the accuracy and potential of the method.
{"title":"Inter-Element Crack Propagation with High-Order Stress Equilibrium Element","authors":"F. Parrinello, I. Benedetti","doi":"10.1142/s1756973721440029","DOIUrl":"https://doi.org/10.1142/s1756973721440029","url":null,"abstract":"The present contribution proposes a formulation based on the use of hybrid equilibrium elements (HEEs), for the analysis of inter-element delamination and fracture propagation problems. HEEs are defined in terms of quadratic stress fields, which strongly verify both the homogeneous and inter-element equilibrium equations and they are employed with interfaces, initially exhibiting rigid behavior, embedded at the elements’ sides. The interface model is formulated in terms of the same degrees of freedom of the HEE, without any additional burden. The cohesive zone model (CZM) of the extrinsic interface is rigorously developed in the damage mechanics framework, with perfect adhesion at the pre-failure condition and with linear softening at the post-failure regime. After a brief review, the formulation is computationally tested by simulating the behavior of a double-cantilever-beam with diagonal loads; the obtained numerical results confirm the accuracy and potential of the method.","PeriodicalId":43242,"journal":{"name":"Journal of Multiscale Modelling","volume":null,"pages":null},"PeriodicalIF":1.5,"publicationDate":"2021-12-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49482971","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-12-20DOI: 10.1142/s1756973721440030
A. Materna, H. Lauschmann, J. Ondracek
{"title":"Residual Stress Around the Fatigue Crack front in a Rectangular Sample cut from CT Specimen","authors":"A. Materna, H. Lauschmann, J. Ondracek","doi":"10.1142/s1756973721440030","DOIUrl":"https://doi.org/10.1142/s1756973721440030","url":null,"abstract":"","PeriodicalId":43242,"journal":{"name":"Journal of Multiscale Modelling","volume":null,"pages":null},"PeriodicalIF":1.5,"publicationDate":"2021-12-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49035536","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-12-14DOI: 10.1142/s1756973721440017
M. Lo Cascio, I. Benedetti
Numerical tools which are able to predict and explain the initiation and propagation of damage at the microscopic level in heterogeneous materials are of high interest for the analysis and design of modern materials. In this contribution, we report the application of a recently developed numerical scheme based on the coupling between the Virtual Element Method (VEM) and the Boundary Element Method (BEM) within the framework of continuum damage mechanics (CDM) to analyze the progressive loss of material integrity in heterogeneous materials with complex microstructures. VEM is a novel numerical technique that, allowing the use of general polygonal mesh elements, assures conspicuous simplification in the data preparation stage of the analysis, notably for computational micro-mechanics problems, whose analysis domain often features elaborate geometries. BEM is a widely adopted and efficient numerical technique that, due to its underlying formulation, allows reducing the problem dimensionality, resulting in substantial simplification of the pre-processing stage and in the decrease of the computational effort without affecting the solution accuracy. The implemented technique has been applied to an artificial microstructure, consisting of the transverse section of a circular shaped stiff inclusion embedded in a softer matrix. BEM is used to model the inclusion that is supposed to behave within the linear elastic range, while VEM is used to model the surrounding matrix material, developing more complex nonlinear behaviors. Numerical results are reported and discussed to validate the proposed method.
{"title":"Coupling BEM and VEM for the Analysis of Composite Materials with Damage","authors":"M. Lo Cascio, I. Benedetti","doi":"10.1142/s1756973721440017","DOIUrl":"https://doi.org/10.1142/s1756973721440017","url":null,"abstract":"Numerical tools which are able to predict and explain the initiation and propagation of damage at the microscopic level in heterogeneous materials are of high interest for the analysis and design of modern materials. In this contribution, we report the application of a recently developed numerical scheme based on the coupling between the Virtual Element Method (VEM) and the Boundary Element Method (BEM) within the framework of continuum damage mechanics (CDM) to analyze the progressive loss of material integrity in heterogeneous materials with complex microstructures. VEM is a novel numerical technique that, allowing the use of general polygonal mesh elements, assures conspicuous simplification in the data preparation stage of the analysis, notably for computational micro-mechanics problems, whose analysis domain often features elaborate geometries. BEM is a widely adopted and efficient numerical technique that, due to its underlying formulation, allows reducing the problem dimensionality, resulting in substantial simplification of the pre-processing stage and in the decrease of the computational effort without affecting the solution accuracy. The implemented technique has been applied to an artificial microstructure, consisting of the transverse section of a circular shaped stiff inclusion embedded in a softer matrix. BEM is used to model the inclusion that is supposed to behave within the linear elastic range, while VEM is used to model the surrounding matrix material, developing more complex nonlinear behaviors. Numerical results are reported and discussed to validate the proposed method.","PeriodicalId":43242,"journal":{"name":"Journal of Multiscale Modelling","volume":null,"pages":null},"PeriodicalIF":1.5,"publicationDate":"2021-12-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45785861","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-12-13DOI: 10.1142/s1756973721440054
E. V. Arcieri, S. Baragetti
{"title":"Cyclic Loading on Damaged AA7075-T6 Specimens: Numerical Modelling and Experimental Testing","authors":"E. V. Arcieri, S. Baragetti","doi":"10.1142/s1756973721440054","DOIUrl":"https://doi.org/10.1142/s1756973721440054","url":null,"abstract":"","PeriodicalId":43242,"journal":{"name":"Journal of Multiscale Modelling","volume":null,"pages":null},"PeriodicalIF":1.5,"publicationDate":"2021-12-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49115422","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-12-13DOI: 10.1142/s1756973721440042
L. Malíková, H. Šimonová, B. Kucharczyková
{"title":"Crack Deflection Under Mixed-Mode Loading Conditions in Fine-Grained Composites Based on Water Glass-Activated Slag","authors":"L. Malíková, H. Šimonová, B. Kucharczyková","doi":"10.1142/s1756973721440042","DOIUrl":"https://doi.org/10.1142/s1756973721440042","url":null,"abstract":"","PeriodicalId":43242,"journal":{"name":"Journal of Multiscale Modelling","volume":null,"pages":null},"PeriodicalIF":1.5,"publicationDate":"2021-12-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48078481","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-10-29DOI: 10.1142/s1756973721430010
M. Rouhi, V. Tan, T. Tay
Structural performance of unidirectional composites (UD) is directly dependent on its ingredient’s properties, ply configurations and the manufacturing effects. Prediction of mechanical properties using multiscale manufacturing simulation and micromechanical models is the focus of this study. Particular problem of coupled dual-scale deformation-flow process such as the one arising in RTM, Vacuum-Assisted Resin Infusion (VARI) and Vacuum Bag Only (VBO) prepregs is considered. A finite element formulation of porous media theory framework is employed to predict the element-wise local volume fractions and the deformation of a preform in a press forming process. This formulation considers coupling effects between macro-scale preform processes and mesoscale ply processes as well as coupling effects between the solid and fluid phases. A number of different micromechanical models are assessed and the most suitable one is used to calculate mechanical properties from volume fractions. Structural performance of the “deformed” geometry is then evaluated in mechanical analysis. An integrated platform is designed to cover the whole chain of analysis and perform the properties’ calculation and transfer them between the modules in a smooth mapping procedure. The paper is concluded with a numerical example, where a compression-relaxation test of a planar fluid filled prepreg at globally un-drained condition is considered followed by a mechanical loading analysis. The development is user friendly and interactive and is established to enable design and optimization of composites.
{"title":"An Integrated Multiscale Simulation Routine to Predict Mechanical Performance from Manufacturing Effects","authors":"M. Rouhi, V. Tan, T. Tay","doi":"10.1142/s1756973721430010","DOIUrl":"https://doi.org/10.1142/s1756973721430010","url":null,"abstract":"Structural performance of unidirectional composites (UD) is directly dependent on its ingredient’s properties, ply configurations and the manufacturing effects. Prediction of mechanical properties using multiscale manufacturing simulation and micromechanical models is the focus of this study. Particular problem of coupled dual-scale deformation-flow process such as the one arising in RTM, Vacuum-Assisted Resin Infusion (VARI) and Vacuum Bag Only (VBO) prepregs is considered. A finite element formulation of porous media theory framework is employed to predict the element-wise local volume fractions and the deformation of a preform in a press forming process. This formulation considers coupling effects between macro-scale preform processes and mesoscale ply processes as well as coupling effects between the solid and fluid phases. A number of different micromechanical models are assessed and the most suitable one is used to calculate mechanical properties from volume fractions. Structural performance of the “deformed” geometry is then evaluated in mechanical analysis. An integrated platform is designed to cover the whole chain of analysis and perform the properties’ calculation and transfer them between the modules in a smooth mapping procedure. The paper is concluded with a numerical example, where a compression-relaxation test of a planar fluid filled prepreg at globally un-drained condition is considered followed by a mechanical loading analysis. The development is user friendly and interactive and is established to enable design and optimization of composites.","PeriodicalId":43242,"journal":{"name":"Journal of Multiscale Modelling","volume":null,"pages":null},"PeriodicalIF":1.5,"publicationDate":"2021-10-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43692166","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-10-29DOI: 10.1142/s1756973721420026
Chenkai Yang, Jiuhao Ge, Baowang Hu
To reduce the time of simulation for rotating Eddy current testing (RECT) technique, a simplified model without modeling probe was proposed previously. However, the applicability of the simplified simulation model was unknown. In this paper, the applicability of the simplified model for the RECT technique was investigated. The application condition of the simplified model was provided by comparing it with the results of the traditional simulation model. The simplified model was suitable for the study of cracks shorter than 70% size of the uniform Eddy current induced by the probe in a traditional model or experiment. The experiment was conducted to validate the simplified model. Moreover, using the simplified model, the effects of crack depth, orientation, and exciting frequency were studied. The deeper the crack depth was, the greater peak value of [Formula: see text] signal was. The crack angle was linear with the phase of signal. The exciting frequency affected the amplitude and phase of the signal at the same time.
{"title":"Investigation of Rotating Eddy Current Testing Simulation Using Simplified Model","authors":"Chenkai Yang, Jiuhao Ge, Baowang Hu","doi":"10.1142/s1756973721420026","DOIUrl":"https://doi.org/10.1142/s1756973721420026","url":null,"abstract":"To reduce the time of simulation for rotating Eddy current testing (RECT) technique, a simplified model without modeling probe was proposed previously. However, the applicability of the simplified simulation model was unknown. In this paper, the applicability of the simplified model for the RECT technique was investigated. The application condition of the simplified model was provided by comparing it with the results of the traditional simulation model. The simplified model was suitable for the study of cracks shorter than 70% size of the uniform Eddy current induced by the probe in a traditional model or experiment. The experiment was conducted to validate the simplified model. Moreover, using the simplified model, the effects of crack depth, orientation, and exciting frequency were studied. The deeper the crack depth was, the greater peak value of [Formula: see text] signal was. The crack angle was linear with the phase of signal. The exciting frequency affected the amplitude and phase of the signal at the same time.","PeriodicalId":43242,"journal":{"name":"Journal of Multiscale Modelling","volume":null,"pages":null},"PeriodicalIF":1.5,"publicationDate":"2021-10-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48434974","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-10-25DOI: 10.1142/s1756973721430022
Zhoucheng Su, Dan Wang, T. Guo, N. Sridhar
In this paper, we present a computational micromechanical analysis of unidirectional (UD) carbon fiber-reinforced plastics (CFRPs) using representative volume elements (RVEs). The RVEs consist of randomly distributed fibers, matrix, and interfaces between the fibers and matrix. Periodic boundary conditions (PBCs) and proportional stressing are implemented to facilitate micromechanical analysis of the composites under controlled stress states. In particular, the failure mechanisms of the RVEs under combined transverse and in-plane shear stressing are investigated. The ratio of in-plane shear stress over transverse stress is kept constant during each simulation. By varying this ratio, the mechanical responses of composites under different stress states are systematically studied and the failure envelopes for different fiber volume fractions are extracted. We find the failure envelope converges as the fiber volume fraction increases. The framework developed in this study can be extended to different stress states allowing us to conveniently examine the failure criteria for UD CFRP composites comprehensively.
{"title":"Micromechanical Modeling of Unidirectional CFRP Composites with Proportional Stressing","authors":"Zhoucheng Su, Dan Wang, T. Guo, N. Sridhar","doi":"10.1142/s1756973721430022","DOIUrl":"https://doi.org/10.1142/s1756973721430022","url":null,"abstract":"In this paper, we present a computational micromechanical analysis of unidirectional (UD) carbon fiber-reinforced plastics (CFRPs) using representative volume elements (RVEs). The RVEs consist of randomly distributed fibers, matrix, and interfaces between the fibers and matrix. Periodic boundary conditions (PBCs) and proportional stressing are implemented to facilitate micromechanical analysis of the composites under controlled stress states. In particular, the failure mechanisms of the RVEs under combined transverse and in-plane shear stressing are investigated. The ratio of in-plane shear stress over transverse stress is kept constant during each simulation. By varying this ratio, the mechanical responses of composites under different stress states are systematically studied and the failure envelopes for different fiber volume fractions are extracted. We find the failure envelope converges as the fiber volume fraction increases. The framework developed in this study can be extended to different stress states allowing us to conveniently examine the failure criteria for UD CFRP composites comprehensively.","PeriodicalId":43242,"journal":{"name":"Journal of Multiscale Modelling","volume":null,"pages":null},"PeriodicalIF":1.5,"publicationDate":"2021-10-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43007424","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-10-25DOI: 10.1142/s1756973721430034
Maruri Takamura, Kotaro Uehara, J. Koyanagi, Shinichi Takeda
Ultrasonic welding is an energy-efficient technology that enables quick bonding of thermoplastic composite materials under normal temperature and pressure conditions. Here, numerical multi-timescale simulation is proposed to understand the welding principle, using numerical simulations of ultrasonic welding. The simulation results are validated by comparing with temperature measurements in welding tests. In the multi-timescale simulations, microsecond-scale simulations are performed first. The ultrasonic wave is modeled as a vibration load, and the energy dissipation per vibration at 25, 75, 125, 175, 225, and 275∘C is analyzed. Then, the time derivative of the temperature rise is obtained. In the normal scale simulations, the ultrasonic wave and holding pressure are replaced by a constant load, and the entire process of ultrasonic welding is simulated. The slope of the temperature rise is fitted to the time derivative of the temperature rise obtained from the microsecond-scale simulations, using the material constant as a parameter. Explicit multi-timescale simulations were performed to investigate the relationship between stress concentration and temperature rise due to ED geometry. The result reveals similar temperature behavior to the experimental one, indicating the validity of the multi-timescale method. It suggests that viscoelastic energy dissipation and stress concentration are responsible for the temperature spike.
{"title":"Multi-Timescale Simulations of Temperature Elevation for Ultrasonic Welding of CFRP with Energy Director","authors":"Maruri Takamura, Kotaro Uehara, J. Koyanagi, Shinichi Takeda","doi":"10.1142/s1756973721430034","DOIUrl":"https://doi.org/10.1142/s1756973721430034","url":null,"abstract":"Ultrasonic welding is an energy-efficient technology that enables quick bonding of thermoplastic composite materials under normal temperature and pressure conditions. Here, numerical multi-timescale simulation is proposed to understand the welding principle, using numerical simulations of ultrasonic welding. The simulation results are validated by comparing with temperature measurements in welding tests. In the multi-timescale simulations, microsecond-scale simulations are performed first. The ultrasonic wave is modeled as a vibration load, and the energy dissipation per vibration at 25, 75, 125, 175, 225, and 275∘C is analyzed. Then, the time derivative of the temperature rise is obtained. In the normal scale simulations, the ultrasonic wave and holding pressure are replaced by a constant load, and the entire process of ultrasonic welding is simulated. The slope of the temperature rise is fitted to the time derivative of the temperature rise obtained from the microsecond-scale simulations, using the material constant as a parameter. Explicit multi-timescale simulations were performed to investigate the relationship between stress concentration and temperature rise due to ED geometry. The result reveals similar temperature behavior to the experimental one, indicating the validity of the multi-timescale method. It suggests that viscoelastic energy dissipation and stress concentration are responsible for the temperature spike.","PeriodicalId":43242,"journal":{"name":"Journal of Multiscale Modelling","volume":null,"pages":null},"PeriodicalIF":1.5,"publicationDate":"2021-10-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46043481","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-10-09DOI: 10.1142/s1756973721500098
A. Dubey, J. Kumar, S. Kesarwani, R. Verma
This paper highlights the reinforcement of two different fibers in the manufacturing of hybrid laminate composites. The feasibility of glass and carbon fiber-based hybrid composites is proposed for various high performances due to their versatile mechanical properties. However, anisotropic and non-homogeneity nature creates several machining challenges for manufacturers. It can be regulated through the selection of proper cutting conditions during the machining test. The effect of process constraints like spindle speed (rpm), feed rate (mm/min), and stacking sequences ([Formula: see text] was evaluated for the optimum value of thrust force and Torque during the drilling test. The cost-effective method of hand layup has been used to fabricate the composites. Four different hybrid composites were developed using different layers of carbon fiber and glass fiber layers. The outcomes of variables on machining performances were analyzed by variation of feed rate and speed to acquire the precise holes in the different configurations. The application potential of the proposed composites is evaluated through the machining (drilling) efficiency. The optimal condition for the drilling procedure was investigated using the multiobjective optimization-Grey relation analysis (MOO-GRA) approach. The findings of the confirmatory test show the feasibility of the MOO-GRA module in a machining environment for online and offline quality control.
{"title":"Investigation on Thrust and Torque Generation During Drilling of Hybrid Laminates Composite with Different Stacking Sequences Using Multiobjective Optimization Module","authors":"A. Dubey, J. Kumar, S. Kesarwani, R. Verma","doi":"10.1142/s1756973721500098","DOIUrl":"https://doi.org/10.1142/s1756973721500098","url":null,"abstract":"This paper highlights the reinforcement of two different fibers in the manufacturing of hybrid laminate composites. The feasibility of glass and carbon fiber-based hybrid composites is proposed for various high performances due to their versatile mechanical properties. However, anisotropic and non-homogeneity nature creates several machining challenges for manufacturers. It can be regulated through the selection of proper cutting conditions during the machining test. The effect of process constraints like spindle speed (rpm), feed rate (mm/min), and stacking sequences ([Formula: see text] was evaluated for the optimum value of thrust force and Torque during the drilling test. The cost-effective method of hand layup has been used to fabricate the composites. Four different hybrid composites were developed using different layers of carbon fiber and glass fiber layers. The outcomes of variables on machining performances were analyzed by variation of feed rate and speed to acquire the precise holes in the different configurations. The application potential of the proposed composites is evaluated through the machining (drilling) efficiency. The optimal condition for the drilling procedure was investigated using the multiobjective optimization-Grey relation analysis (MOO-GRA) approach. The findings of the confirmatory test show the feasibility of the MOO-GRA module in a machining environment for online and offline quality control.","PeriodicalId":43242,"journal":{"name":"Journal of Multiscale Modelling","volume":null,"pages":null},"PeriodicalIF":1.5,"publicationDate":"2021-10-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48728030","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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