Pub Date : 2023-10-12DOI: 10.14311/app.2023.42.0022
Jonathan Glinz, Julia Maurer, Martin Holzleitner, Francesco Pace, Antonios Stamopoulos, Michal Vopálenský, Ivana Kumpová, Michael Eckl, Johann Kastner, Sascha Senck
The reinforcement of fused filament fabricated (FFF) components with continuous fibers allows for high versatility in the design of mechanical properties for a specific applications needs. However, the bonding quality between continuous fibers and the FFF matrix material has high impact on the overall performance of the composite. To investigate the bonding quality within additively manufactured (AM) continuous fiber reinforced specimens, tensile tests have been performed which revealed a sudden reduction in tensile stress, that most likely was not related to actual rupture of continuous fibers. Consequently, within this work we will expand upon these findings and present results of fast on-the-fly in-situ investigations performed on continuous carbon fiber reinforced specimens of the same AM build. During these investigations, specimens are loaded under the same conditions while fast XCT scans, with a total scan time of 12 seconds each, were performed consecutively. The resulting three-dimensional image data reveals internal meso- and macro-structural changes over time/strain to find the cause of the aforementioned reduction in tensile stress.
{"title":"Fast continuous in-situ XCT of additively manufactured carbon fiber reinforced tensile test specimens","authors":"Jonathan Glinz, Julia Maurer, Martin Holzleitner, Francesco Pace, Antonios Stamopoulos, Michal Vopálenský, Ivana Kumpová, Michael Eckl, Johann Kastner, Sascha Senck","doi":"10.14311/app.2023.42.0022","DOIUrl":"https://doi.org/10.14311/app.2023.42.0022","url":null,"abstract":"The reinforcement of fused filament fabricated (FFF) components with continuous fibers allows for high versatility in the design of mechanical properties for a specific applications needs. However, the bonding quality between continuous fibers and the FFF matrix material has high impact on the overall performance of the composite. To investigate the bonding quality within additively manufactured (AM) continuous fiber reinforced specimens, tensile tests have been performed which revealed a sudden reduction in tensile stress, that most likely was not related to actual rupture of continuous fibers. Consequently, within this work we will expand upon these findings and present results of fast on-the-fly in-situ investigations performed on continuous carbon fiber reinforced specimens of the same AM build. During these investigations, specimens are loaded under the same conditions while fast XCT scans, with a total scan time of 12 seconds each, were performed consecutively. The resulting three-dimensional image data reveals internal meso- and macro-structural changes over time/strain to find the cause of the aforementioned reduction in tensile stress.","PeriodicalId":7150,"journal":{"name":"Acta Polytechnica CTU Proceedings","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-10-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"136058354","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 : 2023-10-12DOI: 10.14311/app.2023.42.0083
Pavel Vrtal, Tomáš Kohout, Luboš Nouzovský, Zdeněk Svatý
The purpose of this paper is to present a series of dynamic tests for testing the protective and security barrier of the PROBAR system, developed by STRIX Chomutov, a.s., according to the PAS 68:2013 standard. The goal of the tests was to assess how the obstacle resist impacts and whether it can absorb the energy exerted on it. Verification of the mechanical properties of the device was performed in two types of impact configurations. Emphasis was placed on the behaviour of both the obstacle and the vehicle during the impact and in the short time interval after the collision. In terms of criteria for evaluating the impact tests, it can be stated that Test 2 exceeded the Theoretical Head Impact Velocity (THIV) criterion by 20 km h−1, while Test 1 did not exceed the limit value. However, all values for other criteria (ASI, PHD, HIC, 3ms) were within the specified limits, and the safety barrier met the required criteria which allows to be certificated.
本文的目的是介绍一系列动态测试，用于测试PROBAR系统的防护和安全屏障，该系统由STRIX Chomutov公司根据PAS 68:2013标准开发。测试的目的是评估障碍物如何抵抗冲击，以及它是否能吸收施加在它身上的能量。在两种类型的冲击配置下，对该装置的机械性能进行了验证。重点放在障碍物和车辆在碰撞期间以及碰撞后短时间间隔内的行为上。在评估冲击试验的标准方面，可以说试验2超出了理论头部撞击速度(THIV)标准20 km h - 1，而试验1没有超过极限值。然而，其他标准(ASI, PHD, HIC, 3ms)的所有值都在规定的范围内，并且安全屏障符合允许认证的要求标准。
{"title":"Dynamic tests of the protective and security barrier system probar","authors":"Pavel Vrtal, Tomáš Kohout, Luboš Nouzovský, Zdeněk Svatý","doi":"10.14311/app.2023.42.0083","DOIUrl":"https://doi.org/10.14311/app.2023.42.0083","url":null,"abstract":"The purpose of this paper is to present a series of dynamic tests for testing the protective and security barrier of the PROBAR system, developed by STRIX Chomutov, a.s., according to the PAS 68:2013 standard. The goal of the tests was to assess how the obstacle resist impacts and whether it can absorb the energy exerted on it. Verification of the mechanical properties of the device was performed in two types of impact configurations. Emphasis was placed on the behaviour of both the obstacle and the vehicle during the impact and in the short time interval after the collision. In terms of criteria for evaluating the impact tests, it can be stated that Test 2 exceeded the Theoretical Head Impact Velocity (THIV) criterion by 20 km h−1, while Test 1 did not exceed the limit value. However, all values for other criteria (ASI, PHD, HIC, 3ms) were within the specified limits, and the safety barrier met the required criteria which allows to be certificated.","PeriodicalId":7150,"journal":{"name":"Acta Polytechnica CTU Proceedings","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-10-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"136058537","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 : 2023-10-12DOI: 10.14311/app.2023.42.0017
Jan Falta, Nela Krčmářová, Tomáš Fíla, Martin Vavro, Leona Vavro
This article focuses on the mechanical properties of basalt in compressive loading at different strain-rates. The study employs advanced instrumentation for the evaluation of the results in dynamic conditions, while standard uni-axial loading device is used for evaluation in quasi-static conditions. Basalt specimens were subjected to four different loading-rates from 200–600 s−1 on which the stress-strain dependence was evaluated together with DIC analysis of crack initiation and disintegration process. Understanding the mechanical properties of basalt can provide insights for engineers and designers in creating structures that are durable and able to withstand different loading conditions. The findings of this study can have implications for a wide range of industries, including aerospace, automotive, and construction, among others.
{"title":"Mechanical properties of basalt: a study on compressive loading at different strain rates using SHPB","authors":"Jan Falta, Nela Krčmářová, Tomáš Fíla, Martin Vavro, Leona Vavro","doi":"10.14311/app.2023.42.0017","DOIUrl":"https://doi.org/10.14311/app.2023.42.0017","url":null,"abstract":"This article focuses on the mechanical properties of basalt in compressive loading at different strain-rates. The study employs advanced instrumentation for the evaluation of the results in dynamic conditions, while standard uni-axial loading device is used for evaluation in quasi-static conditions. Basalt specimens were subjected to four different loading-rates from 200–600 s−1 on which the stress-strain dependence was evaluated together with DIC analysis of crack initiation and disintegration process. Understanding the mechanical properties of basalt can provide insights for engineers and designers in creating structures that are durable and able to withstand different loading conditions. The findings of this study can have implications for a wide range of industries, including aerospace, automotive, and construction, among others.","PeriodicalId":7150,"journal":{"name":"Acta Polytechnica CTU Proceedings","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-10-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"136058544","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 : 2023-10-12DOI: 10.14311/app.2023.42.0012
Alexander Engel, Anne Jung
Auxetic structures, which is a term used to describe materials with a negative Poisson’s ratio, show beneficial properties like a low density, a high energy absorption capacity and an increased indentation resistance. This enables applications in many fields, such as aerospace and sports industries. Given their potential, many studies have already been conducted. Previously, the geometry of a selected auxetic re-entrant structure was optimized to maximize its mass-specific energy absorption capacity for ideal usage in lightweight applications. Moreover, a homogeneous material was used, whereas the combination of multiple materials could drastically increase the performance of such structures. Hence, in this study the use of two different materials combined into a modified re-entrant structure is investigated via Finite Element simulation. The Poisson’s ratio could thus be improved, which leads toa more pronounced and longer lasting auxetic effect.
{"title":"Simulation of a multimaterial model for modified auxetic structures","authors":"Alexander Engel, Anne Jung","doi":"10.14311/app.2023.42.0012","DOIUrl":"https://doi.org/10.14311/app.2023.42.0012","url":null,"abstract":"Auxetic structures, which is a term used to describe materials with a negative Poisson’s ratio, show beneficial properties like a low density, a high energy absorption capacity and an increased indentation resistance. This enables applications in many fields, such as aerospace and sports industries. Given their potential, many studies have already been conducted. Previously, the geometry of a selected auxetic re-entrant structure was optimized to maximize its mass-specific energy absorption capacity for ideal usage in lightweight applications. Moreover, a homogeneous material was used, whereas the combination of multiple materials could drastically increase the performance of such structures. Hence, in this study the use of two different materials combined into a modified re-entrant structure is investigated via Finite Element simulation. The Poisson’s ratio could thus be improved, which leads toa more pronounced and longer lasting auxetic effect.","PeriodicalId":7150,"journal":{"name":"Acta Polytechnica CTU Proceedings","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-10-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"136058352","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 : 2023-10-12DOI: 10.14311/app.2023.42.0051
Nela Krčmářová, Jan Falta, Tomáš Fíla, David Čítek
Ultra high performance concrete is a modern cementitious material which exhibits excellent mechanical properties such as damage tolerance, fracture toughness and durability. These features make this materials suitable for wide range of applications where is the material subjected to different modes of loading and different loading rates.This paper deals with measurement of the Ultra high performance concrete reinforced with steel fibres in quasi-static compression mode of deformation and two elevated strain rates using split Hopkinson pressure bar. The results of the measurement show high increase of the mechanical properties with elevated strain rate.
{"title":"Response of the ultra high performance concrete under dynamic compressive loading","authors":"Nela Krčmářová, Jan Falta, Tomáš Fíla, David Čítek","doi":"10.14311/app.2023.42.0051","DOIUrl":"https://doi.org/10.14311/app.2023.42.0051","url":null,"abstract":"Ultra high performance concrete is a modern cementitious material which exhibits excellent mechanical properties such as damage tolerance, fracture toughness and durability. These features make this materials suitable for wide range of applications where is the material subjected to different modes of loading and different loading rates.This paper deals with measurement of the Ultra high performance concrete reinforced with steel fibres in quasi-static compression mode of deformation and two elevated strain rates using split Hopkinson pressure bar. The results of the measurement show high increase of the mechanical properties with elevated strain rate.","PeriodicalId":7150,"journal":{"name":"Acta Polytechnica CTU Proceedings","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-10-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"136058545","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}
Adhesive bonding presents many advantages, such as efficient manufacturing and improved structural performance [1]. However, in structures subjected to fatigue, cracks might initiate and propagate in joints, leading to in-service failure [2]. Most adhesively bonded joints are subjected to combination of peel and shear loads, so mixed I+II mode loading conditions are present [3]. In this work, Cracked Lap Shear specimens, which feature mixed I+II mode loading conditions, were tested under fatigue loading. During tests, crack growth was monitored using Visual Testing and Digital Image Correlation. With Digital Image Correlation, opening and sliding displacements in the bondline were extracted from the substrates’ displacement fields and compared against a Finite Element Model, revealing a highly strained process zone ahead of the crack tip. Results highlight the usefulness of DIC in capturing the deformation behaviour of adhesive joints under mixed mode loading conditions.
{"title":"Analysis of peel and shear strains in cracked lap shear specimens subjected to fatigue loading using digital image correlation","authors":"Alessandra Panerai, Gianmarco Piccoli, Luca Michele Martulli, Andrea Bernasconi, Michele Carboni","doi":"10.14311/app.2023.42.0067","DOIUrl":"https://doi.org/10.14311/app.2023.42.0067","url":null,"abstract":"Adhesive bonding presents many advantages, such as efficient manufacturing and improved structural performance [1]. However, in structures subjected to fatigue, cracks might initiate and propagate in joints, leading to in-service failure [2]. Most adhesively bonded joints are subjected to combination of peel and shear loads, so mixed I+II mode loading conditions are present [3]. In this work, Cracked Lap Shear specimens, which feature mixed I+II mode loading conditions, were tested under fatigue loading. During tests, crack growth was monitored using Visual Testing and Digital Image Correlation. With Digital Image Correlation, opening and sliding displacements in the bondline were extracted from the substrates’ displacement fields and compared against a Finite Element Model, revealing a highly strained process zone ahead of the crack tip. Results highlight the usefulness of DIC in capturing the deformation behaviour of adhesive joints under mixed mode loading conditions.","PeriodicalId":7150,"journal":{"name":"Acta Polytechnica CTU Proceedings","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-10-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"136058355","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 : 2023-10-12DOI: 10.14311/app.2023.42.0037
Tomáš Kohout, Pavel Vrtal, Adam Hoffmann, Tomáš Blodek
The aim of the paper is to verify the applicability of the T2GO skiddometer for measuring the coefficient of friction for forensic practice in accordance with the legislative framework of the Czech Republic. In the introduction, the article discusses the problem of friction coefficient measurement. The results of the comparison with dynamic measuring devices used in the Czech Republic and the determination of the mutual compliance rate with these devices, based on data obtained within the National Comparative Measurement Action, are presented. The article concludes with an interpretation and discussion of the results. In cases where no sufficient mutual compliance was found, an analysis and reasoning of these results is provided. Last but not least, based on the results, a procedure is proposed for future use of the T2GO skiddometer in practice within the legislative conditions of the Czech Republic.
{"title":"The possibilities of utilising the skiddometer T2GO for forensic engineering","authors":"Tomáš Kohout, Pavel Vrtal, Adam Hoffmann, Tomáš Blodek","doi":"10.14311/app.2023.42.0037","DOIUrl":"https://doi.org/10.14311/app.2023.42.0037","url":null,"abstract":"The aim of the paper is to verify the applicability of the T2GO skiddometer for measuring the coefficient of friction for forensic practice in accordance with the legislative framework of the Czech Republic. In the introduction, the article discusses the problem of friction coefficient measurement. The results of the comparison with dynamic measuring devices used in the Czech Republic and the determination of the mutual compliance rate with these devices, based on data obtained within the National Comparative Measurement Action, are presented. The article concludes with an interpretation and discussion of the results. In cases where no sufficient mutual compliance was found, an analysis and reasoning of these results is provided. Last but not least, based on the results, a procedure is proposed for future use of the T2GO skiddometer in practice within the legislative conditions of the Czech Republic.","PeriodicalId":7150,"journal":{"name":"Acta Polytechnica CTU Proceedings","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-10-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"136058528","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 : 2023-10-12DOI: 10.14311/app.2023.42.0046
Barbora Kotlánová, Soňa Rusnáková, Raphael Olabanji Ogunleye, Jakub Javořík
The presented research aims at measuring the volume changes of elastomers using digital image correlation (DIC) in the 3D configuration (stereo DIC). The deformation measurement method in stereo configuration was applied during the mechanical testing of two types of test specimens (dumbbells, cylinders) in uniaxial tension. In this configuration, two cameras were used. The test specimens were measured up to a specified strain value, and the measured data were used to obtain the strain dependence of Poisson’s ratio and the bulk modulus, which are crucial for hyperelastic models. The measurement results reveal that the stereo DIC method provides relatively less scattered data in the low-strain regions for dumbbell-shaped test specimens and is suitable for measuring various test specimen shapes.
{"title":"Volume changes measurement of elastomers using 3D DIC","authors":"Barbora Kotlánová, Soňa Rusnáková, Raphael Olabanji Ogunleye, Jakub Javořík","doi":"10.14311/app.2023.42.0046","DOIUrl":"https://doi.org/10.14311/app.2023.42.0046","url":null,"abstract":"The presented research aims at measuring the volume changes of elastomers using digital image correlation (DIC) in the 3D configuration (stereo DIC). The deformation measurement method in stereo configuration was applied during the mechanical testing of two types of test specimens (dumbbells, cylinders) in uniaxial tension. In this configuration, two cameras were used. The test specimens were measured up to a specified strain value, and the measured data were used to obtain the strain dependence of Poisson’s ratio and the bulk modulus, which are crucial for hyperelastic models. The measurement results reveal that the stereo DIC method provides relatively less scattered data in the low-strain regions for dumbbell-shaped test specimens and is suitable for measuring various test specimen shapes.","PeriodicalId":7150,"journal":{"name":"Acta Polytechnica CTU Proceedings","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-10-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"136058531","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 : 2023-09-27DOI: 10.14311/app.2023.41.0015
Jan Kruntorád, Lukáš Týfa
The railway is perceived as a modern, safe and environmentally sustainable way of transporting people and goods. In the past, appropriate innovations in the field of infrastructure and vehicles, combined with an attractive operational concept, have gradually become the backbone of public transport in the country. Even in this system, similar to other transport systems, there are accidents (events of emergency) or potentially risky situations. The paper places the issue of railway safety in the legislative context and uncovers the points of view from which the safety of railway traffic can be viewed.
{"title":"Vision Zero application on Czech railways","authors":"Jan Kruntorád, Lukáš Týfa","doi":"10.14311/app.2023.41.0015","DOIUrl":"https://doi.org/10.14311/app.2023.41.0015","url":null,"abstract":"The railway is perceived as a modern, safe and environmentally sustainable way of transporting people and goods. In the past, appropriate innovations in the field of infrastructure and vehicles, combined with an attractive operational concept, have gradually become the backbone of public transport in the country. Even in this system, similar to other transport systems, there are accidents (events of emergency) or potentially risky situations. The paper places the issue of railway safety in the legislative context and uncovers the points of view from which the safety of railway traffic can be viewed.","PeriodicalId":7150,"journal":{"name":"Acta Polytechnica CTU Proceedings","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-09-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135587300","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}
Smart transport planning based on the use of available data while supporting sustainable transport modes is an integral part of the Smart city concept. This article presents a critical analysis of the Level of Service of Public Transport Operation Assessment Method, which is based on two indicators - the reliability index and the travel speed index. The method is applied to a larger sample of data from several different cities, it makes it possible to evaluate the possible shortcomings of the method, since the method has not yet been applied to such a large number of case studies.
{"title":"Level of service of public transport operation - pilot study","authors":"Markéta Jirmanová, Vojtěch Novotný, Nikol Dousková","doi":"10.14311/app.2023.41.0008","DOIUrl":"https://doi.org/10.14311/app.2023.41.0008","url":null,"abstract":"Smart transport planning based on the use of available data while supporting sustainable transport modes is an integral part of the Smart city concept. This article presents a critical analysis of the Level of Service of Public Transport Operation Assessment Method, which is based on two indicators - the reliability index and the travel speed index. The method is applied to a larger sample of data from several different cities, it makes it possible to evaluate the possible shortcomings of the method, since the method has not yet been applied to such a large number of case studies.","PeriodicalId":7150,"journal":{"name":"Acta Polytechnica CTU Proceedings","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-09-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135587299","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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