Engineering Fracture Mechanics最新文献

{"title":"Methodology for compiling torque load spectra of tractor power take-off shafts based on nonlinear damage accumulation","authors":"Xianghai Yan ,&nbsp;Jinhai Zhang ,&nbsp;Jingyun Zhang ,&nbsp;Yiwei Wu ,&nbsp;Junjiang Zhang ,&nbsp;Liyou Xu","doi":"10.1016/j.engfracmech.2024.110685","DOIUrl":"10.1016/j.engfracmech.2024.110685","url":null,"abstract":"<div><div>To obtain the load spectrum of the Power Take-Off (PTO) shaft during field operations under the rotary tillage condition of tractors, and in light of the limitations of traditional fatigue damage models for load spectra, a nonlinear damage model based on the Lemaitre model is proposed. This paper first establishes a dynamic torque stress testing system to acquire the PTO shaft torque loads at an engine speed of 2000 rpm, which are then preprocessed. Subsequently, the four-point rainflow counting method is employed to statistically count the mean and range values of the load signals, and a Q-Q plot is used for distribution testing. Following this, the time-domain method is utilized for frequency extrapolation to establish an 8x8 two-dimensional load spectrum, which is then converted into a one-dimensional load spectrum using the mean value method. Finally, damage assessment and life prediction of the load spectrum are conducted based on the Miner theory, the Corten-Dolan theory, and the nonlinear damage model based on the Lemaitre model. The results indicate that the mean values of the load signals follow a normal distribution, while the range values follow a Weibull distribution, and that the mean and range values are mutually independent. The peak threshold obtained through time-domain extrapolation is 380 N.m, and the trough threshold is 120 N.m, with the statistical characteristics of the extrapolated signal remaining largely consistent with those of the original signal. The fatigue life predicted by the nonlinear damage model based on the Lemaitre model is 1.76E8, which is the closest to the actual life compared to the other two models, with a calculation accuracy 724 times that of the Miner theory and 239 times that of the Corten-Dolan theory. This verifies the effectiveness and accuracy of the proposed method, providing a reference for future load spectrum life prediction and fatigue bench tests of tractors.</div></div>","PeriodicalId":11576,"journal":{"name":"Engineering Fracture Mechanics","volume":"314 ","pages":"Article 110685"},"PeriodicalIF":4.7,"publicationDate":"2025-02-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143165314","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}

{"title":"Dynamic behavior of a running crack crossing mortar-granite interface with different interface inclinations","authors":"Jie Liu ,&nbsp;Xiaohui Zeng ,&nbsp;Weiquan Zheng ,&nbsp;Haopeng Lai ,&nbsp;Yulin Wang ,&nbsp;Fei Wang ,&nbsp;Hao Qiu","doi":"10.1016/j.engfracmech.2024.110705","DOIUrl":"10.1016/j.engfracmech.2024.110705","url":null,"abstract":"<div><div>High-strength mortar is widely applied in fractured rock reinforcement due to its strong bonding strength, where crack propagation crossing the interface is commonly seen. To investigate the dynamic crack propagation behavior across the interface, A side material cleavage triangle (SMCT) sample was adopted in this study with different interface inclinations and mortar strength considered. Impact testing of a split Hopkinson pressure bar (SHPB) system was conducted and cohesive models were established to explore the penetration process of the extending crack. With the numerical result and the measurement of the crack propagation gauges (CPGs), the dynamic stress intensity factor (DSIF) was determined using an experiment-based numerical method. The investigation results show that the excited crack always propagates across the mortar-granite interface regardless of the stiffness difference, and this phenomenon remains unchanged with increasing interface inclination. For SMCT specimens, as the strength grade of mortar increases, the time taken for cracks to propagate through the interface increases. As the interfacial inclination increases, the time taken during crack penetration through the interface is longer. Using Python coding, cohesive elements can be embedded in batches in the numerical model to simulate crack propagation behavior at the interface. As the interface inclination increases, the DSIF in both the mortar and granite regions exhibits an upward trend.</div></div>","PeriodicalId":11576,"journal":{"name":"Engineering Fracture Mechanics","volume":"314 ","pages":"Article 110705"},"PeriodicalIF":4.7,"publicationDate":"2025-02-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143165853","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}

{"title":"Effect of fibre content on low-temperature failure strength and toughness of different sized BFRC under static and dynamic loadings: An experimental study","authors":"Liu Jin ,&nbsp;Meiyu Fan ,&nbsp;Wenxuan Yu ,&nbsp;Chenxi Xie ,&nbsp;Xiuli Du","doi":"10.1016/j.engfracmech.2024.110737","DOIUrl":"10.1016/j.engfracmech.2024.110737","url":null,"abstract":"<div><div>Basalt fibres (BF) have been increasingly wide-used in many concrete structures, which also have a good application prospect in low-temperature environment. The comprehensive investigations on static/dynamic mechanical properties of Basalt Fibre-Reinforced Concrete (i.e., BFRC) have become a key scientific issue to be solved urgently. This paper aims to conduct comprehensive tests on uniaxial compressive and splitting-tensile failures of various sized BFRC (side lengths of 70 ∼ 200 mm) with various volume contents (0 ∼ 0.5 %) under static/dynamic loadings at different temperatures (20 ∼ -90 °C), with a special focus of the fibre reinforcement effect and cryogenic enhancement effect on toughness and nominal strengths as well as the corresponding size effect. Test results indicate that static/dynamic nominal strengths increase linearly with the decrease of temperature, exhibiting a significant cryogenic enhancement effect. This cryogenic effect can be enhanced by the incorporation of BF, wherein the fibre pull-out (Model-1) replaces fibre rupture (Model-2) as the dominate failure mode at low temperatures. Static/dynamic compressive toughness of BFRC is significantly improved with the adding fibre content <span><math><msub><mi>V</mi><mi>f</mi></msub></math></span> (the incorporation of 0.5 %<span><math><msub><mi>V</mi><mi>f</mi></msub></math></span> BF can bring a maximum increase of nearly 1.5 times), showing a fibre reinforcement effect, especially at ambient temperature. Nominal strengths decrease with the adding specimen sizes, performing a significant size effect, which is gradually strengthened with the decrease of temperature. However, both the incorporation of BF and the increasing loading strain-rate could weaken the size effect. Finally, according to test results, empirical formulas for the effective predication of nominal strengths of BFRC considering the quantitative coupling effects of fibre volume contents and temperatures have been proposed. The present research aims to provide effective references for safety design and large-scale applications of BFRC engineering structures under extreme cryogenic environments.</div></div>","PeriodicalId":11576,"journal":{"name":"Engineering Fracture Mechanics","volume":"314 ","pages":"Article 110737"},"PeriodicalIF":4.7,"publicationDate":"2025-02-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143166101","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}

{"title":"An evaluation method for the hygrothermal effect on fatigue crack propagation in CFRP–strengthened RC beam","authors":"Dongyang Li ,&nbsp;Guang Qin ,&nbsp;Jiaying Su ,&nbsp;Minglang Xue ,&nbsp;Zhanbiao Chen ,&nbsp;Wen Li ,&nbsp;Jiaxiang Lin ,&nbsp;Peiyan Huang","doi":"10.1016/j.engfracmech.2024.110760","DOIUrl":"10.1016/j.engfracmech.2024.110760","url":null,"abstract":"<div><div>Hygrothermal effects on the fatigue crack propagation behavior of Carbon fiber reinforced polymer (CFRP)–strengthened reinforced concrete (RC) beam was studied based on experimental and numerical methods. Quasi-static tests and hygrothermal fatigue tests of RC beams were conducted to investigate the coupling effect of the hygrothermal environment and fatigue load on the crack propagation behavior. Digital image correlation (DIC) method was applied to track the whole process of fatigue main crack initiation and propagation in real time, in order to obtain the fatigue crack length and crack propagation rate. Stress intensity factor (SIF) of main crack was calculated through finite element method considering material nonlinearity and hygrothermal influence. Results showed that SIF considering hygrothermal influence slightly increased compared to that at indoor atmospheric environment, and the influence of temperature on SIF was greater than that of relative humidity. The fatigue crack propagation curves showed a segmented phenomenon and different fitting function were adopted. It was found that the fatigue crack propagation rate increased with the increase of temperature at the same maximum stress intensity factor <em>K_max</em>. However, the increase of relative humidity had a limited effect on the fatigue crack propagation curves, showing less influence on the fatigue crack propagation behavior compared with that of temperature. Finally, environmental equations based on Paris Law were proposed to quantify the effect of temperature and humidity on fatigue crack propagation in RC beams strengthened with CFRP.</div></div>","PeriodicalId":11576,"journal":{"name":"Engineering Fracture Mechanics","volume":"314 ","pages":"Article 110760"},"PeriodicalIF":4.7,"publicationDate":"2025-02-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143164581","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}

{"title":"Closed-form solution to the debonding of embedded Through-Section FRP bar-to-concrete joints with interfacial defects","authors":"Kaiming Pan ,&nbsp;Yanjie Wang ,&nbsp;Hongbo Liu ,&nbsp;Zhimin Wu ,&nbsp;Mengdi Jia ,&nbsp;Yifeng Chen","doi":"10.1016/j.engfracmech.2024.110708","DOIUrl":"10.1016/j.engfracmech.2024.110708","url":null,"abstract":"<div><div>The Embedded Through-Section (ETS) technique has recently received significant attention in strengthening existing reinforced concrete (RC) structures through the use of fibre-reinforced polymer (FRP) bars inserted into predrilled holes in concrete using adhesive. Interfacial bond defects are easily observed in practical applications of ETS FRP bar-to-concrete joints due to poor construction or environmental deterioration, resulting in degradations in both local bond behavior and global performance of ETS-strengthened concrete systems. This paper presents a closed-form analytical solution to evaluate the effect of interfacial defects on the debonding response of ETS- FRP bar-to-concrete joints and examine the interfacial defect criticality from size and location aspects. A set of closed-form solutions for the load-slip curve, debonding load, interfacial bond stress, tensile stress as well as effective bond length are derived throughout the debonding process. After validating the analytical solutions with self-conducted test results and existing experimental and numerical data, a parametric analysis is performed to quantify the influence of interfacial defects on the load responses. The results show that the analytical predictions can accurately describe the debonding behavior of ETS FRP bar-to-concrete joints with different defect lengths and locations. It is revealed that bond defects adversely affect both the debonding load and maximum load; however, enhancing the bond strength and embedded length can alleviate such a detrimental impact. Furthermore, defects near the loading point in short joints or close to the embedded end in long joints can maximize the load-bearing capacity. These findings emphasize the critical role of interfacial defects in the debonding analysis and practical design of RC beams strengthened with FRP bars using the ETS technique.</div></div>","PeriodicalId":11576,"journal":{"name":"Engineering Fracture Mechanics","volume":"314 ","pages":"Article 110708"},"PeriodicalIF":4.7,"publicationDate":"2025-02-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143164587","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}

{"title":"Creep-fatigue crack growth behavior under mean stress effect in polymer electrolyte membrane: Experimental analysis and numerical crack growth modeling","authors":"Liang Cai ,&nbsp;Wei Li ,&nbsp;Pilin Song ,&nbsp;Ibrahim Elbugdady ,&nbsp;Gang Liu ,&nbsp;Zhenduo Sun","doi":"10.1016/j.engfracmech.2024.110789","DOIUrl":"10.1016/j.engfracmech.2024.110789","url":null,"abstract":"<div><div>The creep-fatigue crack growth behavior of polymer electrolyte membrane under cyclic loading with distinct mean stress is investigated. The crack under cyclic loading with higher mean stress displays enhanced propagation rate. Identical cyclic plastic zone size is found under different stress ratios, implying that the fatigue damage primarily depends on stress amplitude. The creep damage leads to the occurrence of crack-front micropores, thereby accelerating crack growth. The enlargement of hydrophobic domain is detected at high stress ratio, which reveals the creep effect on failure process from phase morphology aspect. A damage-based numerical model is established to predict creep-fatigue crack growth.</div></div>","PeriodicalId":11576,"journal":{"name":"Engineering Fracture Mechanics","volume":"314 ","pages":"Article 110789"},"PeriodicalIF":4.7,"publicationDate":"2025-02-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143164610","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}

{"title":"A physics-enhanced deep learning approach for prediction of stress intensity factors in bimaterial interface cracks","authors":"Luyang Zhao ,&nbsp;Qian Shao","doi":"10.1016/j.engfracmech.2024.110720","DOIUrl":"10.1016/j.engfracmech.2024.110720","url":null,"abstract":"<div><div>Stress intensity factors (SIFs) are pivotal in understanding cracking behaviors and predicting crack propagation in layered materials. This study introduces a physics-enhanced deep learning approach for the efficient prediction of SIFs in bimaterial interface fracture problems. Guided by linear elastic fracture mechanics theory, three sets of features are designed and extracted to comprehensively represent the influential factors determining SIFs, including loads, boundary conditions, crack patterns, and material properties. Specifically, loads and boundary conditions are represented by stress fields on the crack-free configuration obtained from coarse finite element simulations, while crack characterization is achieved through level set functions. The inherent heterogeneity of multi-layered structures is addressed by spatially distributing material properties, such as Young’s modulus and Poisson’s ratio, throughout the domain. Subsequently, a compact convolutional neural network is trained on labeled data to map these features to SIFs of bimaterial interface cracks. The predictive performance and generalization capability of the proposed model are demonstrated across diverse problem settings, encompassing various interfaces, loads, boundary conditions, and crack patterns. Effective knowledge extraction and transfer are showcased between problems with distinct loading modes, highlighting the good explainability of the proposed model. Moreover, the model demonstrates efficacy in scenarios with large or irregular geometries by focusing on a localized region surrounding the crack. This strategy not only enhances the adaptability of the proposed model to diverse geometries but also reduces the data collection and model training costs.</div></div>","PeriodicalId":11576,"journal":{"name":"Engineering Fracture Mechanics","volume":"314 ","pages":"Article 110720"},"PeriodicalIF":4.7,"publicationDate":"2025-02-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143164996","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}

{"title":"Very-high-cycle-fatigue behaviour of ultrasonic-assisted TIG welded TC4 joints: Microcrack initiation and life prediction influenced by dislocations and oxides under shear stress","authors":"Hailong Deng ,&nbsp;Yufan Sun ,&nbsp;Mingkai Li ,&nbsp;Yupeng Guo ,&nbsp;Jie Liu ,&nbsp;Jianhang Kong ,&nbsp;Xiangxin He ,&nbsp;Yu Huan","doi":"10.1016/j.engfracmech.2024.110746","DOIUrl":"10.1016/j.engfracmech.2024.110746","url":null,"abstract":"<div><div>Titanium alloy welded structures are commonly applied in aircraft industry manufacturing. Therefore, the behaviour of Ti-6Al-4 V (TC4) welded joints was investigated at very-high-cycle-fatigue (VHCF) conditions using ultrasonic-assisted tungsten inert gas (TIG) welding, aims to reveal the mechanism of crack initiation and fine granular area (FGA) formation, as well as to develop a model for predicting fatigue life. In particular, the data suggest that <em>S-N</em> curves are single-linear at both stress ratios, while three failure modes and three defect types were found. Transmission electron microscopy (TEM) analysis combined with image processing method revealed the presence of dislocation structures in FGA, indicating that stress concentration effect led to the generation of high-density dislocations, the produces lattice distortion and crystal slip at maximum ά martensitic Schmidt factor plane, concludes that the dislocation piles up together with oxides produced by oxygen aggregation promotes the microcrack initiation. Meanwhile, the cracks near fatal defect were driven by tensile and shear stresses with the propagation mode of Mode I + Mode II, and the region was observed to consist of discontinuous nano fine grain layers and broken martensitic laths. Additionally, the <em>S-N</em> curves with higher point-to-line convergence are reconstructed based on the defect size and defect depth. Finally, based on failure mechanism and linear elastic deformation theory, a VHCF life prediction model is developed by considering the modified maximum shear stress, mean stress and stress intensity factors (SIF) value with the effect of Schmidt factor mean value and defect features, which can improve the safety of structures.</div></div>","PeriodicalId":11576,"journal":{"name":"Engineering Fracture Mechanics","volume":"314 ","pages":"Article 110746"},"PeriodicalIF":4.7,"publicationDate":"2025-02-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143164998","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}

{"title":"The electrical discharge characteristics and ignition mechanism of coal mine roof fracture under stress","authors":"Chenguang Wang ,&nbsp;Deming Wang ,&nbsp;Haihui Xin ,&nbsp;Wei Zhang ,&nbsp;Tengfei Chen ,&nbsp;Kang Zhang","doi":"10.1016/j.engfracmech.2024.110744","DOIUrl":"10.1016/j.engfracmech.2024.110744","url":null,"abstract":"<div><div>Underground goaf is a high-risk area of thermodynamic disaster accidents in coal mines, and the thermodynamic disaster accidents occurring in goaf may be inextricably linked with the activities of the roof. This paper conducts in-depth research on the instantaneous electrical discharge characteristics and ignition mechanism induced in the process of rock damage by building a force-electric ignition experimental system. The results showed that the electric discharge generated by rocks during the fracture process could penetrate air and produce the photoelectric effect. The instantaneous electric discharge capacity and luminous intensity generated during rock fracturing were mainly affected by the quartz content and compressive strength of the rock, and the experiment confirmed that the electrical discharge of rocks during the fracture process can ignite methane-air. The piezoelectric effect during the loading process of rocks can significantly enhance their electric discharge capacity. In this paper, the viewpoint that the electric discharge of coal seam roof in the process of fracturing ignites the methane in goaf and causes disasters was proposed. The research results explored the synergistic discharge mechanism during rock fracture process, and elucidated the enhancing effect of piezoelectric effect in rock fracture discharge process. The research can provide a theoretical basis for the disaster-causing mechanism in the process of roof fracturing caused by mine pressure in goaf.</div></div>","PeriodicalId":11576,"journal":{"name":"Engineering Fracture Mechanics","volume":"314 ","pages":"Article 110744"},"PeriodicalIF":4.7,"publicationDate":"2025-02-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143165000","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}

{"title":"Effect of temperature and geometry on the brittle failure of an 18MND5 steel in the lower part of the ductile to brittle transition","authors":"Emmanuelle Catel ,&nbsp;Aboubakr Amzil ,&nbsp;Eric Lorentz ,&nbsp;Anna Dahl ,&nbsp;Jacques Besson","doi":"10.1016/j.engfracmech.2024.110745","DOIUrl":"10.1016/j.engfracmech.2024.110745","url":null,"abstract":"<div><div>Tests on cracked CT and SENT specimens (152 tests) extracted from a nuclear pressure vessel steel (18MND5) were conducted between <span><math><mrow><mo>−</mo><mn>150</mn></mrow></math></span> <span><math><msup><mrow></mrow><mrow><mo>∘</mo></mrow></msup></math></span>C and <span><math><mrow><mo>−</mo><mn>50</mn></mrow></math></span> <span><math><msup><mrow></mrow><mrow><mo>∘</mo></mrow></msup></math></span>C together with tests on smooth and notched bars. Tests on tensile bars were used to calibrate a temperature-dependent hardening law. Tests on cracked specimens that exhibited brittle failure only were analyzed using the Beremin model. Special care was taken to evaluate local stresses using enhanced mixed finite elements. The Beremin model was able to represent the entire database provided the reference failure stress <span><math><msub><mrow><mi>σ</mi></mrow><mrow><mi>u</mi></mrow></msub></math></span> increases with temperature. Finally, the results were also interpreted using the Master Curve approach, which was adapted to account for different stress states using the <span><math><mi>Q</mi></math></span>-parameter.</div></div>","PeriodicalId":11576,"journal":{"name":"Engineering Fracture Mechanics","volume":"314 ","pages":"Article 110745"},"PeriodicalIF":4.7,"publicationDate":"2025-02-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143165259","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}