International Journal of Fatigue最新文献

{"title":"Fatigue-induced fracture failure of acrylic-polycarbonate laminated aircraft canopy","authors":"Ik-Sik Kim,&nbsp;Kyung-Suk Sohn,&nbsp;Naghyon Kim,&nbsp;Namtae Kim,&nbsp;Hongchul Lee","doi":"10.1016/j.ijfatigue.2024.108680","DOIUrl":"10.1016/j.ijfatigue.2024.108680","url":null,"abstract":"<div><div>The fatigue-induced fracture failure of the aircraft canopy occurred in the poly(methyl methacrylate) (PMMA) layer laminated on polycarbonate (PC) during flight. For more than 24 years, the aircraft had been operated at high altitudes and supersonic flight. To identify the root cause and the mechanism for the formation of the fracture, the fracture surfaces were investigated. The fracture morphologies were characterized using optical microscope (OM) and scanning electron microscope (SEM).</div><div>In macroscopic observations, the main crack showed a total length of approximately 1.6 m from the front to the right of the crack stop groove when viewed from the front of the canopy. The main crack ran about 0.9 m including partly curved line from the front part to the upper middle one and then reached about 0.7 m in a straight line perpendicular to the right of the crack stop groove. There were two crack ends in the main crack: one was at the lower part of the front, the other was at the right end of the crack stop groove. Numerous macro-cracks visible to the naked eye were distributed only on the front surface of the canopy.</div><div>In microscopic examination, the voids on the front surface of the outer PMMA layer were formed by the friction heat with air during the supersonic flight. The voids served as the origins, the actual starting point of the crack. The voids slowly grew to macro-cracks vertically or horizontally by the thermal stress during flying at high altitudes. Cracks proceeded in the direction of 90 degrees while being bisected in V-shapes downward from the surface of the PMMA layer with the action of thermal tension. The crack growth represents the typical characteristics of the fatigue crack: multi-origins, ratchet marks, and beach marks. The main crack grew further, forming a slight curved line by connecting adjacent macro-cracks arranged in an almost vertical direction. When crack growth reached a critical point, the catastrophic fracture progressed rapidly from the primary origin of the fatigue crack to both ends due to the action of lateral force. Fast crack zones on both sides showed the same dimple and river patterns.</div><div>This study explains that the combined and synergistic interaction of the fatigue crack and environmental stresses iteratively occurred on the front surface in the outer PMMA layer of the aircraft canopy due to the continual exposure to high altitudes and supersonic flights, consequently resulting in the fatigue-induced fracture failure.</div></div>","PeriodicalId":14112,"journal":{"name":"International Journal of Fatigue","volume":"191 ","pages":"Article 108680"},"PeriodicalIF":5.7,"publicationDate":"2024-11-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142663095","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The hysteresis loop on the near-threshold fatigue crack growth curves generated by stepped load reduction and constant-amplitude loading methods in a Ni-based superalloy","authors":"Jiafen Cao,&nbsp;Wanlin Guo","doi":"10.1016/j.ijfatigue.2024.108698","DOIUrl":"10.1016/j.ijfatigue.2024.108698","url":null,"abstract":"<div><div>Fatigue crack growth (FCG) tests were conducted on compact tension specimens made of a Ni-based superalloy to investigate the near-threshold FCG behaviors using both the stepped load reduction method (LRM) and the constant-amplitude loading method (CALM) at three stress ratios (<em>R</em> = 0.05, 0.5 and 0.7) under ambient condition. It is found that after the FCG threshold being approached by the LRM, a remarkable hysteresis plateau occurs on the subsequent FCG curve generated by the CALM for <em>R</em> ≤ 0.5, resulting a hysteresis loop on the near-threshold region, but the situation becomes complicated at <em>R</em> = 0.7. In the appearance of hysteresis plateau, the FCG life to fracture can be over 10⁷ cycles longer than that without hysteresis plateau. For FCG rate faster than 10⁻⁸ m/cycle, the fractography is dominated by transgranular feature which is insensitive to the microstructure of the alloy. In the hysteresis plateau region where FCG rate is lower than 10⁻⁹ m/cycle, fractography shows a wide optical dark zone where microstructure-sensitive crystallographic facet feature dominates, while when no hysteresis at <em>R</em> = 0.7, the optical dark zone is too narrow for the fracture feature transition so that crystallographic facet, transgranular as well as mosaic features can be observed simultaneously. As FCG in the hysteresis plateau under the CALM can be significantly slower than that under the stepped LRM, it is recommend that the stepped LRM should be used to generate the material basic FCG curves for fatigue life prediction of high durability structures.</div></div>","PeriodicalId":14112,"journal":{"name":"International Journal of Fatigue","volume":"191 ","pages":"Article 108698"},"PeriodicalIF":5.7,"publicationDate":"2024-11-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142663214","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Mode I fatigue delamination growth behavior and model for multidirectional laminates with the same overall stiffness","authors":"Luohuan Zou ,&nbsp;Yu Gong ,&nbsp;Dingli Tian ,&nbsp;Sizhuo Hao ,&nbsp;Jianyu Zhang ,&nbsp;Libin Zhao ,&nbsp;Ning Hu","doi":"10.1016/j.ijfatigue.2024.108697","DOIUrl":"10.1016/j.ijfatigue.2024.108697","url":null,"abstract":"<div><div>In order to isolate the influence of ply orientation on the mode I fatigue delamination propagation behavior of carbon fiber reinforced composite laminates, multidirectional laminates with the same overall stiffness are designed while three different interfaces (0//0, 45//45, and 90//90), which can avoid the coupling effect of remote plies. Test results show that the fatigue delamination behavior is obviously affected by the interface angle. In addition, a novel and simple method for determining the fatigue delamination resistance is proposed. The measured fatigue delamination resistance is lower than the quasi-static one for all interfaces. The specimen with 45//45 interface exhibits more significant delamination resistance, whereas the delamination resistances of specimens with 0/0 and 90//90 interfaces are similar, which is consistent with the phenomenon of more bridging fibers accompanying in the delamination process of 45//45 interface. In order to consider the effect of fiber bridging and reduce the dispersion of the data, experimental data are further processed using a normalized model considering the effect of fiber bridging. The normalized results can be characterized by a single curve, suggesting that the normalized model is effective in describing the fatigue delamination behavior in the presence of fiber bridging.</div></div>","PeriodicalId":14112,"journal":{"name":"International Journal of Fatigue","volume":"191 ","pages":"Article 108697"},"PeriodicalIF":5.7,"publicationDate":"2024-11-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142663211","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Assessment of dwell-fatigue properties of nickel-based superalloy coated with a multi-layered thermal and environmental barrier coating","authors":"Ivo Šulák,&nbsp;Karel Obrtlík","doi":"10.1016/j.ijfatigue.2024.108693","DOIUrl":"10.1016/j.ijfatigue.2024.108693","url":null,"abstract":"<div><div>A three-layered experimental thermal and environmental barrier coating (TEBC) was deposited using air plasma spraying technology on cylindrical specimens of nickel-based superalloy MAR-M247. TEBC consists of mullite (Al₆Si₂O₁₃) and hexacelsian (BaAl₂Si₂O₈) upper layer, Y₂O₃ stabilised ZrO₂ interlayer and CoNiCrAlY bond coat deposited on the grit-blasted surface of MAR-M247. The cyclic plastic response and damage mechanisms in uncoated and TEBC-coated MAR-M247 have been studied in isothermal dwell-fatigue tests conducted under strain control with constant strain amplitude at 900 °C. In each cycle, 5-minute dwells were introduced in both tensile and compression peaks of the hysteresis loop. Fatigue hardening/softening curves, stress relaxation curves, cyclic stress–strain curves and fatigue life curves are reported. Ceaseless mild softening has been found in both uncoated and TEBC-coated MAR-M247. TEBC-coated MAR-M247 showed an improved lifetime in the whole range of tested strain amplitudes. Data obtained from stress relaxation curves were used to assess the fraction of creep damage. The generalised damage accumulation rule was used to evaluate damage due to fatigue-creep-environment interaction. A study of the surface relief and internal microstructure using SEM and TEM helped to interpret the specifics of fatigue behaviour of uncoated and TEBC-coated material. The effectiveness of this newly developed TEBC, together with the dwell sensitivity of MAR-M247, were discussed from the perspective relevant to dwell-fatigue cyclic straining.</div></div>","PeriodicalId":14112,"journal":{"name":"International Journal of Fatigue","volume":"191 ","pages":"Article 108693"},"PeriodicalIF":5.7,"publicationDate":"2024-11-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142663210","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Sub-modelling based fatigue evaluation of welded details in composite trapezoidal corrugated web girders under coupled thermal-structural loading","authors":"Zhi-Yu Wang ,&nbsp;Lin-Hai Shi ,&nbsp;Yong-Bo Shao ,&nbsp;Qi-Fei Wang","doi":"10.1016/j.ijfatigue.2024.108685","DOIUrl":"10.1016/j.ijfatigue.2024.108685","url":null,"abstract":"<div><div>Exploring the long-term performance of welded details in composite trapezoidal corrugated web (TCW) girders is a significant focus for the service life of these structures exposed to atmospheric environment and traffic flow. The majority of the present studies have been conducted without accounting for thermal stresses induced by temperature differences and accurately reflecting internal force transfers for the composite girders in flexural bending. The fatigue behaviour of the welded details in these girders under coupled thermal-structural loading is investigated herein through experimental and numerical methods. The results indicated three stages for the structural degradation from the test performance and justified a proper allowance of the cross-sectional stress in coordination with the flexural curvature in the derivation of <em>S</em>-<em>N</em> relations comparable to similar details in related design codes. A sub-modelling procedure is implemented to capture the thermal gradient, the local stress concentration, and the crack distribution in global modelling while replicate the semi-elliptical surface crack at the external side of the fillet weld toe in local modelling. The fatigue lives predicted from the proposed analytical model match reasonably well with experimental and numerical results, indicating its good applicability incorporating characteristic geometric correction factors into classical theoretical calculation for fatigue evaluation.</div></div>","PeriodicalId":14112,"journal":{"name":"International Journal of Fatigue","volume":"191 ","pages":"Article 108685"},"PeriodicalIF":5.7,"publicationDate":"2024-11-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142663220","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Anisotropy cyclic plasticity constitutive modelling for Ni-based single-crystal superalloys based on Kelvin decomposition","authors":"Yuheng Yun ,&nbsp;Yongsheng Fan ,&nbsp;Duoqi Shi ,&nbsp;Tianxiao Sui ,&nbsp;Xiaoguang Yang","doi":"10.1016/j.ijfatigue.2024.108679","DOIUrl":"10.1016/j.ijfatigue.2024.108679","url":null,"abstract":"<div><div>Nickel-based single-crystal (SC) superalloys exhibited excellent exceptional mechanical properties at high temperatures due to the elimination of internal grain boundaries, contributed a strong orientation-dependent material response. The anisotropy of SC superalloys was modeled viscoplastically from a macroscopic viewpoint based on the Kelvin decomposition theory [1] which was a decomposition of the stress space according to the elastic matrix eigen-directions to control the viscoplastic flow by Kelvin stress decoupled from each other. Compared to the classical phenomenological macro model, the proposed model effectively captures the slip deformation mechanism of SC superalloys with the inherent ability to simulate anisotropic because of the two criterions framework controlled by Kelvin stress. Compared with others, the proposed model was able to simulate time-dependent inelastic deformation and cyclic deformation behavior under complex loading. The kinematic hardening and isotropic hardening models incorporated microscopic quantities, such as dislocation density and channel phase width, connecting the macroscopic mechanical response with the microscopic state to achieve multiscale constitutive modelling. The parameter identification and finite element implementation were conducted on a SC superalloy [2]. Simulation results demonstrated the accuracy of the proposed model in predicting deformation behavior under various orientations, rate-dependent effects, isothermal and non-isothermal cyclic deformation. Comparison with the classical anisotropic matrix macroscopic phenomenological approaches highlights the superior capability of the proposed model to simulate the orientation-dependent mechanical properties of single-crystal alloys.</div></div>","PeriodicalId":14112,"journal":{"name":"International Journal of Fatigue","volume":"191 ","pages":"Article 108679"},"PeriodicalIF":5.7,"publicationDate":"2024-11-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142663209","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Cyclic functional degradation of NiTi shape memory alloy wires in wide ranges of strain rate and ambient temperature","authors":"Di Song ,&nbsp;Shan Gong ,&nbsp;Bo Xu ,&nbsp;Chao Yu","doi":"10.1016/j.ijfatigue.2024.108683","DOIUrl":"10.1016/j.ijfatigue.2024.108683","url":null,"abstract":"<div><div>Shape memory alloy (SMA) dampers frequently experience cyclic loading over a broad spectrum of strain rates and ambient temperatures, resulting in a significant thermo-mechanical coupling effect during cyclic deformation. Nevertheless, the impact of this coupling effect on the functional degradation of SMAs has not been thoroughly examined, particularly in scenarios involving severe deformation. In this study, a series of strain-controlled cyclic loading–unloading tests were conducted on NiTi SMA wires utilizing various combinations of strain rates ranging from 5 × 10⁻⁴ to 6 × 10⁻²/s and different ambient temperatures (313–393 K). The functional degradation was exacerbated by increasing ambient temperature and loading rate due to the complex interactions among the inelastic deformation mechanisms and thermo-mechanical coupling effects. Furthermore, although the cyclic deformation behavior of NiTi SMA wires varied with the loading rate, this rate dependence diminished with increasing ambient temperature. The synergistic effect of elevated strain rates and high temperatures markedly accelerated the fatigue failure of NiTi SMA wires and substantially altered the underlying microstructural morphology. These findings can provide valuable support for evaluating the service performance of NiTi SMA dampers under various engineering conditions and contribute to developing a cyclic constitutive model for NiTi SMAs.</div></div>","PeriodicalId":14112,"journal":{"name":"International Journal of Fatigue","volume":"191 ","pages":"Article 108683"},"PeriodicalIF":5.7,"publicationDate":"2024-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142663213","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Quantitative assessment of compression fatigue history effect on the subsequent tension fatigue limit of strain localized material","authors":"Bowen Chen ,&nbsp;Shigeru Hamada ,&nbsp;Takanori Kato ,&nbsp;Taizo Makino ,&nbsp;Hiroshi Noguchi","doi":"10.1016/j.ijfatigue.2024.108682","DOIUrl":"10.1016/j.ijfatigue.2024.108682","url":null,"abstract":"<div><div>This study conducts compressive fatigue tests with an extended notch on a strain-localized material for quantitative evaluation of damage during compression fatigue and the corresponding effect of loading history on subsequent tensile fatigue limits. Hence, fatigue crack “growth” and “propagation” of two types are found in damage accumulation (DA) mode. The former features several simultaneous multi-crack initiations and independent extensions. Contrarily, the latter features coalescence between the main and secondary cracks. Moreover, the near-crack-tip mechanics causing crack extension and non-propagation in the respective fatigue crack extension types are discussed. Furthermore, a method for subsequent tensile fatigue limit prediction considering the compression fatigue effect is proposed by studying the non-propagating crack length, Vickers hardness, and residual stress in the DA mode during compression fatigue, corresponding to Murakami–Endo’s equation parameters for a mechanically small crack. Thus, this study is anticipated to hold great significance for understanding fatigue damage caused by different load blocks and improving Miner’s rule.</div></div>","PeriodicalId":14112,"journal":{"name":"International Journal of Fatigue","volume":"191 ","pages":"Article 108682"},"PeriodicalIF":5.7,"publicationDate":"2024-10-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142592804","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Ratcheting-fatigue behavior and fracture mechanism of 316H ASS under cyclic random loading block","authors":"Wei-Tong Zhou ,&nbsp;Guo-Yan Zhou ,&nbsp;Jun Si ,&nbsp;Xue-Yao Xiong ,&nbsp;Shan-Tung Tu","doi":"10.1016/j.ijfatigue.2024.108681","DOIUrl":"10.1016/j.ijfatigue.2024.108681","url":null,"abstract":"<div><div>In this study, a set of programmed random factors with non-zero mean were designed. Then various stress levels (15, 18 and 22 <em>KN</em>) were multiple superimposed to factors to form one random loading block (RLB), the blocks were repeated to failure to investigate the synergistic damage of 316H ASS under low-cycle fatigue (LCF), high-cycle fatigue (HCF) and ratcheting effect. The lifetime of cyclic RLB tests decreased with the increase of block-mean stresses <span><math><mrow><msubsup><mi>σ</mi><mrow><mi>m</mi></mrow><mrow><mi>Block</mi></mrow></msubsup></mrow></math></span> (208、255 and 311.5 MPa). The normalized strain amplitudes indicate that when the <span><math><mrow><msubsup><mi>σ</mi><mrow><mi>m</mi></mrow><mrow><mi>Block</mi></mrow></msubsup></mrow></math></span> amplitude below the yield strength (208 and 255 MPa), a stable ratchet accumulation phase allows the specimens to exhibit cyclic hardening behavior. When <span><math><mrow><msubsup><mi>σ</mi><mrow><mi>m</mi></mrow><mrow><mi>Block</mi></mrow></msubsup></mrow></math></span> (311.5 MPa) exceeds the yield strength, the ratcheting strain increases significantly and the specimens exhibit cyclic softening behavior. Especially, the transgranular cleavage fracture, quasi-cleavage fracture and intergranular secondary cracks were identified when the failure of cyclic RLB tests were induced by LCF, HCF and ratcheting. With the increase of <span><math><mrow><msubsup><mi>σ</mi><mrow><mi>m</mi></mrow><mrow><mi>Block</mi></mrow></msubsup></mrow></math></span> amplitude, the decrease of LAGB proportion and the increase of dislocation density further reduce the fatigue resistance. In addition to dislocation motion, the α’-martensite phase transformation induced by ratcheting-fatigue has been further demonstrated as a mechanism for coordinated deformation. The percentage of stresses (within one block) that exceeds the diverge critical stress (375.6 MPa) of stacking faults (SFs) determines the α’-martensite nucleation mechanism.</div></div>","PeriodicalId":14112,"journal":{"name":"International Journal of Fatigue","volume":"191 ","pages":"Article 108681"},"PeriodicalIF":5.7,"publicationDate":"2024-10-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142663217","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A physics-informed neural network method for identifying parameters and predicting remaining life of fatigue crack growth","authors":"Wangwang Liao,&nbsp;Xiangyun Long,&nbsp;Chao Jiang","doi":"10.1016/j.ijfatigue.2024.108678","DOIUrl":"10.1016/j.ijfatigue.2024.108678","url":null,"abstract":"<div><div>Predicting the remaining life of fatigue cracks is crucial for planning maintenance and repair strategies to prevent untoward incidents. This paper proposes a novel physics-informed neural network (PINN) method for identifying parameters and predicting remaining fatigue crack growth life (FCGL). Initially, the relationship between crack length and fatigue cycles is established through a neural network, and the gradient of fatigue cycles with respect to crack length is obtained by automatic differentiation. Subsequently, a composite loss function is designed to incorporate this gradient within the confines of physical knowledge, ensuring that the established relationship not only aligns with observed data but also adheres to physical knowledge. Furthermore, during the network training, the parameters in physical models are simultaneously updated to better conform to the individuality of the monitored subject. All predicted remaining FCGLs fall within the 1.5 times error band. Compared to purely data-driven or physics-based methods, the proposed method offers more robust and accurate predictions of remaining FCGLs.</div></div>","PeriodicalId":14112,"journal":{"name":"International Journal of Fatigue","volume":"191 ","pages":"Article 108678"},"PeriodicalIF":5.7,"publicationDate":"2024-10-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142586603","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}