Thin-Walled Structures最新文献_第7页

A novel machine learning framework for impact force prediction of foam-filled multi-layer lattice composite structures 用于泡沫填充多层晶格复合结构冲击力预测的新型机器学习框架

IF 5.7 1区工程技术

Thin-Walled Structures Pub Date : 2024-10-21 DOI: 10.1016/j.tws.2024.112607

Jiye Chen , Yufeng Zhao , Hai Fang , Zhixiong Zhang , Zheheng Chen , Wangwang He

{"title":"A novel machine learning framework for impact force prediction of foam-filled multi-layer lattice composite structures","authors":"Jiye Chen , Yufeng Zhao , Hai Fang , Zhixiong Zhang , Zheheng Chen , Wangwang He","doi":"10.1016/j.tws.2024.112607","DOIUrl":"10.1016/j.tws.2024.112607","url":null,"abstract":"<div><div>Numerical simulations can provide valuable insights for the optimization of design and operational management; however, they are often impractical and computationally intensive. Machine learning methods are appealing to these problems due to their sufficient efficiency and accuracy. In this study, a novel framework for predicting the impact responses of foam-filled multi-layer lattice composite structures (FMLCSs) was proposed by combining the accurate finite element (FE) analyses, surrogate models, fast Fourier transform (FFT) method, and inverse FFT (IFFT) method. Firstly, reliable FM models were established to simulate the crashworthiness of the five FMLCSs under impact loading, including an analysis of energy transformation. Subsequently, surrogate models, namely radial basis function (RBF), polynomial response surface (PRS), Kriging (KRG), and back propagation neural network (BPNN), combined with methods of FFT and IFFT, were employed to predict the impact force-time series of the FMLCSs. More than 1000 frequency points were employed for each type of FMLCS, and all the R-square (<em>R</em><sup>2</sup>) values of the established surrogate models exceeded 0.95, indicating that the proposed framework accurately predicted the impact duration and impact responses in the frequency domain. In addition, parameter sensitivity analysis revealed that a high peak impact force was accompanied by a short impact duration. Moreover, increasing the lattice-web height resulted in a significant increase in the impact duration.</div></div>","PeriodicalId":49435,"journal":{"name":"Thin-Walled Structures","volume":"205 ","pages":"Article 112607"},"PeriodicalIF":5.7,"publicationDate":"2024-10-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142539527","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

High-strength cold-formed steel stiffened channel section: Axial compressive strength and initial geometric imperfections 高强度冷弯加劲槽钢截面：轴向抗压强度和初始几何缺陷

IF 5.7 1区工程技术

Thin-Walled Structures Pub Date : 2024-10-21 DOI: 10.1016/j.tws.2024.112604

Damir Akchurin , Shahabeddin Torabian , Benjamin W. Schafer

引用次数: 0

Peridynamics model of torsion-warping: Application to lattice beam structures 扭转变形的周动力学模型：晶格梁结构的应用

IF 5.7 1区工程技术

Thin-Walled Structures Pub Date : 2024-10-21 DOI: 10.1016/j.tws.2024.112603

Sajal, Pranesh Roy

{"title":"Peridynamics model of torsion-warping: Application to lattice beam structures","authors":"Sajal, Pranesh Roy","doi":"10.1016/j.tws.2024.112603","DOIUrl":"10.1016/j.tws.2024.112603","url":null,"abstract":"<div><div>This paper presents a finite deformation beam model based on Simo-Reissner theory in peridynamics (PD) framework to deal with torsion induced warping deformation. Seven degrees of freedom, viz. three translational, three rotational, and one warping amplitude are considered at each material point. The governing equations of the beam are obtained by employing global balance of linear and angular momenta in conjunction with Simo's assumption on the deformation field. The relation between PD resultant force, moment, bi-moment, and bi-shear states with their classical counterparts is established using the constitutive correspondence method. Numerical implementation strategy is furnished for both quasi-static and dynamic cases. The solution for quasi-static load is obtained through the Newton-Raphson method. The proposed model is validated against finite element solutions considering cantilever beam and lattice structures. Quasi-static deformation responses of 3 <span><math><mo>×</mo></math></span> 3 <span><math><mo>×</mo></math></span> 3 octet and single unit compression-torsion lattice structures are presented further to demonstrate the effectiveness of proposed beam model. A new bond breaking criterion is proposed based on critical stretch, critical relative rotation, and critical relative warping amplitude and failure of the compression-torsion lattice structures under compressive load is simulated. The Newmark-beta method is utilized to solve the governing equations for dynamic loading. Numerical simulations include dynamic analysis of octet and compression-torsion lattice structures.</div></div>","PeriodicalId":49435,"journal":{"name":"Thin-Walled Structures","volume":"206 ","pages":"Article 112603"},"PeriodicalIF":5.7,"publicationDate":"2024-10-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142663991","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

4D printed bio-inspired polygonal metamaterials with tunable mechanical properties 具有可调机械特性的 4D 印刷生物启发多边形超材料

IF 5.7 1区工程技术

Thin-Walled Structures Pub Date : 2024-10-21 DOI: 10.1016/j.tws.2024.112609

Xueli Zhou , Hongpei Liu , Jifeng Zhang , Lei Ren , Lu Zhang , Qingping Liu , Bingqian Li , Chao Xu , Luquan Ren

{"title":"4D printed bio-inspired polygonal metamaterials with tunable mechanical properties","authors":"Xueli Zhou , Hongpei Liu , Jifeng Zhang , Lei Ren , Lu Zhang , Qingping Liu , Bingqian Li , Chao Xu , Luquan Ren","doi":"10.1016/j.tws.2024.112609","DOIUrl":"10.1016/j.tws.2024.112609","url":null,"abstract":"<div><div>Conventional vibration isolators are designed and assembled so that their structure and vibration isolation performance cannot be adjusted and have a single function when facing complex working conditions. Inspired by a cat's adaptive adjustment of its limb structure to land safely when leaping from a height, we designed a bio-inspired polygonal metamaterial and 3D-molded it based on 4D printing of shape memory polymers (SMP). Based on the shape memory effect of the SMP, the BPM can obtain arbitrary temporary shapes under the combined effect of temperature and force. According to the analysis of the energy absorption test, by change the compressive strain of the BPM temporary shape, it is possible to adjust the shape of the single-cell structure while decreasing its specific energy absorption by up to 80 %. The locally controllable compressive deformation and programmable mechanical properties of the BPM structure are achieved through rational structural parameter design. In addition, thermally tunable vibration-absorbing behavior is achieved by combining the tunable stiffness properties of the printed material. This study provides new possibilities for intelligent tuning of cushion vibration isolators under complex and variable operating conditions.</div></div>","PeriodicalId":49435,"journal":{"name":"Thin-Walled Structures","volume":"205 ","pages":"Article 112609"},"PeriodicalIF":5.7,"publicationDate":"2024-10-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142539526","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

A novel concurrent multiscale method based on the coupling of Direct FE2 and CPFEM 基于直接 FE2 和 CPFEM 耦合的新型并行多尺度方法

IF 5.7 1区工程技术

Thin-Walled Structures Pub Date : 2024-10-21 DOI: 10.1016/j.tws.2024.112610

Yehui Cui , Zhilang Zhang

{"title":"A novel concurrent multiscale method based on the coupling of Direct FE2 and CPFEM","authors":"Yehui Cui , Zhilang Zhang","doi":"10.1016/j.tws.2024.112610","DOIUrl":"10.1016/j.tws.2024.112610","url":null,"abstract":"<div><div>Performing concurrent simulations of macroscopic behaviors and microscopic structures using the crystal plasticity finite element method (CPFEM) presents a substantial difficulty with existing numerical techniques. To address this issue, a novel multi-scale method is proposed that couples CPFEM with a multiscale FEM, specifically Direct FE<sup>2</sup>. This facilitates the implementation of Direct CP-FE<sup>2</sup> in this work. The micro representative volume elements (RVEs) equipped with a crystal plasticity constitutive model and the macro mesh are integrated into a monolithic solution scheme within the Direct FE<sup>2</sup> framework. The proposed method integrates the multiscale simulation capability of Direct FE<sup>2</sup> with the crystal plasticity model of CPFEM. Alpha titanium (α-Ti), which exhibits two distinct plastic mechanisms of slip and twinning, is chosen as the subject of investigation for conducting numerical experiments. The accuracy and efficiency of the Direct CP-FE<sup>2</sup> model are evaluated through multiple plate tension and beam bending tests. The effective validation against the FEM model demonstrated the capability of Direct CP-FE<sup>2</sup> to forecast macroscopic deformation behaviors. Meanwhile, the Direct CP-FE<sup>2</sup> model can reveal the activation of slip/twinning systems and the evolution of crystal texture at a microscopic level. The influence of the grain orientation-dependent effect can be well considered into the macroscopic analysis with the help of Direct CP-FE<sup>2</sup>. Based on the testing examples, we demonstrate that the yield state of the macrostructure is enhanced when the crystal orientation is closer to the (0001) direction. Consequently, there exist very little crystal rotation behavior, hindering the evolution of the crystal texture.</div></div>","PeriodicalId":49435,"journal":{"name":"Thin-Walled Structures","volume":"206 ","pages":"Article 112610"},"PeriodicalIF":5.7,"publicationDate":"2024-10-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142554943","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Residual behaviour and damage assessment of UHPC-filled double-skin steel tubular columns after lateral impact UHPC 填充双层钢管柱在受到横向冲击后的残余行为和损伤评估

IF 5.7 1区工程技术

Thin-Walled Structures Pub Date : 2024-10-19 DOI: 10.1016/j.tws.2024.112602

Weiqiang Wang , Zhilong Xiong , Yang Yu , Da Chen , Chengqing Wu

{"title":"Residual behaviour and damage assessment of UHPC-filled double-skin steel tubular columns after lateral impact","authors":"Weiqiang Wang , Zhilong Xiong , Yang Yu , Da Chen , Chengqing Wu","doi":"10.1016/j.tws.2024.112602","DOIUrl":"10.1016/j.tws.2024.112602","url":null,"abstract":"<div><div>Ultra-high performance concrete (UHPC)-filled double-skin steel tubular (DST) column has great potential to be used in the protective structures. Although its lateral impact behaviour has been well understood, the residual behaviour after lateral impact remains unexplored. As a result, this study extensively investigated the residual behaviour and damage assessment of UHPC-filled DST columns after lateral impact. Firstly, a set of six DST columns were designed and tested under lateral impact, followed by static axial compression. In addition, two intact columns were subjected to static axial compression for comparative analysis. Secondly, the refined finite element models were developed and validated using the current test data, and the impact resistant mechanism of UHPC-filled DST columns with different impact locations was analysed. Thirdly, the suitability of different damage indexes for the damage assessment of impacted UHPC-filled DST columns was evaluated. Two damage indexes, the ratio of mid-height deflection to column height (<span><math><msub><mi>R</mi><mn>1</mn></msub></math></span>), and the ratio of local deflection to the column diameter (<span><math><msub><mi>R</mi><mn>2</mn></msub></math></span>), were proposed for the DST columns. Finally, two types of machine learning-based models were developed to predict the impact damage of UHPC-filled DST columns. The prediction models were interpreted locally and globally using the additive feature attribution method Shapley Additive Explanation (SHAP). The machine learning-based prediction models can rapidly evaluate the damage extent of impacted UHPC-filled DST column, which hold great significance for the selection of strengthening and retrofitting schemes.</div></div>","PeriodicalId":49435,"journal":{"name":"Thin-Walled Structures","volume":"205 ","pages":"Article 112602"},"PeriodicalIF":5.7,"publicationDate":"2024-10-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142539523","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

A novel joining technology for hybrid busbars in electric vehicle batteries 电动汽车电池中混合动力母线的新型连接技术

IF 5.7 1区工程技术

Thin-Walled Structures Pub Date : 2024-10-19 DOI: 10.1016/j.tws.2024.112590

D.P.M. da Costa , M.M. Kasaei , R.J.C. Carbas , E.A.S. Marques , L.F.M. da Silva

{"title":"A novel joining technology for hybrid busbars in electric vehicle batteries","authors":"D.P.M. da Costa , M.M. Kasaei , R.J.C. Carbas , E.A.S. Marques , L.F.M. da Silva","doi":"10.1016/j.tws.2024.112590","DOIUrl":"10.1016/j.tws.2024.112590","url":null,"abstract":"<div><div>In this paper, a joining by forming technique is suggested to join aluminium and copper sheets, aimed at potential hybrid busbar manufacturing. The technique, called hole hemming, is performed through the deformation of the aluminium sheet to create a mechanical interlock with the copper sheet, requiring neither heat, welding, nor additional elements/materials. Initially, the feasibility of this joining process is assessed using an analytical model to determine the parameters required for achieving a mechanical interlock while avoiding fractures. The accuracy of the process windows developed by this model is validated through comparisons with experimental results and numerical simulations. In these simulations, the Modified Mohr-Coulomb criterion is employed to predict ductile damage. Furthermore, a new design incorporating branches in the aluminium sheet holes is introduced. This innovation allows for fracture-free joint manufacturing beyond the safe limits predicted by the analytical model, thereby expanding the range of feasible process parameters. Subsequently, the mechanical performance of joints with and without branches is evaluated through destructive shear and cross-tension tests at both room temperature and an elevated temperature of 120 °C, simulating the maximum service conditions for busbars. The results demonstrate that hole hemming effectively joins AA6082-T4 and Cu-ETP R240 sheets, validating the proposed designs. Specifically, the hybrid aluminium and copper joints exhibit a maximum shear strength of 4.35 kN and a displacement of 12.11 mm at room temperature. In cross-tension tests, the joints achieve a maximum strength of 1.73 kN and a displacement of 9.86 mm. Although performance slightly diminishes at elevated temperatures, it remains excellent for both destructive test configurations.</div></div>","PeriodicalId":49435,"journal":{"name":"Thin-Walled Structures","volume":"205 ","pages":"Article 112590"},"PeriodicalIF":5.7,"publicationDate":"2024-10-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142539473","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Nonlinear vibration analysis of sandwich plates with inverse-designed 3D auxetic core by deep generative model 利用深度生成模型对带有逆设计三维辅助核心的夹层板进行非线性振动分析

IF 5.7 1区工程技术

Thin-Walled Structures Pub Date : 2024-10-19 DOI: 10.1016/j.tws.2024.112599

Xi Fang, Hui-Shen Shen, Hai Wang

{"title":"Nonlinear vibration analysis of sandwich plates with inverse-designed 3D auxetic core by deep generative model","authors":"Xi Fang, Hui-Shen Shen, Hai Wang","doi":"10.1016/j.tws.2024.112599","DOIUrl":"10.1016/j.tws.2024.112599","url":null,"abstract":"<div><div>Building on a deep generative model (DGM), this paper introduces an innovative sandwich plate structure featuring an inverse-designed auxetic 3D lattice core and conducts a detailed investigation of its nonlinear vibration characteristics and effective Poisson's ratios under various parameter settings. By incorporating a conditional estimator and quality loss evaluation functions, the enhanced conditional generative adversarial networks are capable of designing 3D truss auxetic topologies that achieve customized negative Poisson's ratios without reliance on subjective experience. Additionally, lattice specimens are created using 3D metal printing, and the mechanical properties of these DGM-based 3D auxetic structures are validated through vibration experiments and finite element models. These structures exhibit significantly superior natural frequencies compared to those obtained through conventional topology optimization methods reported in existing literature. The study also explores the impact of different functionally graded configurations, temperature variations, boundary conditions, and dimensional parameters on the natural frequency, nonlinear vibration response, and effective Poisson's ratio of the inverse designed auxetic sandwich plates.</div></div>","PeriodicalId":49435,"journal":{"name":"Thin-Walled Structures","volume":"206 ","pages":"Article 112599"},"PeriodicalIF":5.7,"publicationDate":"2024-10-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142572867","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Uniaxial compression performance of anti-tetrachiral structures considering the effects of cell size and boundary conditions 考虑单元尺寸和边界条件影响的反四手性结构的单轴压缩性能

IF 5.7 1区工程技术

Thin-Walled Structures Pub Date : 2024-10-18 DOI: 10.1016/j.tws.2024.112580

Jinwen Xia , Youjiang Cui , Baolin Wang , Kaifa Wang

{"title":"Uniaxial compression performance of anti-tetrachiral structures considering the effects of cell size and boundary conditions","authors":"Jinwen Xia , Youjiang Cui , Baolin Wang , Kaifa Wang","doi":"10.1016/j.tws.2024.112580","DOIUrl":"10.1016/j.tws.2024.112580","url":null,"abstract":"<div><div>Anti-tetrachiral structures (AS) are typical metamaterials known for their negative Poisson's ratio, and have great potential application in reducting the damage of the ship caused by collisions. The existing analysis of the mechanical properties of AS is conducted by applying the energy method to a unit cell with periodic boundary conditions (PBC). In available works, the shear force at the structure's boundaries is neglected. But is it permissible to disregard the impact of shear forces at the boundaries on the structure's equivalent mechanical properties? By examining the deformation relationship between the ribs and the nodal rings, we developed a uniaxial compression model for AS under both free and constrained boundary conditions, which accurately predicts the mechanical properties of the AS structure. This model was validated through numerical simulations and experiments. The findings reveal that the equivalent mechanical properties of AS exhibit a size dependence related to the cell size. For example, for AS with equivalent density and identical overall dimensions, the equivalent Young's modulus of an AS with 2×2 cells will be twice that of an AS with 4×4 cells. Furthermore, the size effect of the structure can be neglected when the number of cells larger than 8×8. Moreover, it is found that the present model considering boundary conditions exhibits an equivalent Young's modulus 25 % higher than the model neglecting boundary conditions. The study's findings indicate that the presence of boundary conditions can disrupt PBC, leading to significant discrepancies between theoretical derivations and practical applications.</div></div>","PeriodicalId":49435,"journal":{"name":"Thin-Walled Structures","volume":"205 ","pages":"Article 112580"},"PeriodicalIF":5.7,"publicationDate":"2024-10-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142539524","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Explainable machine learning models for predicting the ultimate bending capacity of slotted perforated cold-formed steel beams under distortional buckling 用于预测开槽穿孔冷弯型钢在扭曲屈曲下的极限弯曲承载力的可解释机器学习模型

IF 5.7 1区工程技术

Thin-Walled Structures Pub Date : 2024-10-18 DOI: 10.1016/j.tws.2024.112587

L. Simwanda , P. Gatheeshgar , F.M. Ilunga , B.D. Ikotun , S.M. Mojtabaei , E.K. Onyari

{"title":"Explainable machine learning models for predicting the ultimate bending capacity of slotted perforated cold-formed steel beams under distortional buckling","authors":"L. Simwanda , P. Gatheeshgar , F.M. Ilunga , B.D. Ikotun , S.M. Mojtabaei , E.K. Onyari","doi":"10.1016/j.tws.2024.112587","DOIUrl":"10.1016/j.tws.2024.112587","url":null,"abstract":"<div><div>This study develops explainable machine learning (ML) models to predict the ultimate bending capacity of cold-formed steel (CFS) beams with staggered slotted perforations, focusing on distortional buckling behavior. Utilizing a dataset from 432 non-linear finite element analysis simulations of CFS Lipped channels, ten ML algorithms, including four basic and six ensemble models, were evaluated. Ensemble models, specifically CatBoost and XGBoost, demonstrated superior accuracy, with test-set performances reaching a coefficient of determination (<span><math><msup><mrow><mi>R</mi></mrow><mrow><mn>2</mn></mrow></msup></math></span>) of 99.9%, outperforming traditional analytical methods such as the Direct Strength Method (DSM). SHapley Additive Explanations (SHAP) were applied to highlight how features like plate thickness and root radius critically influence predictions. The findings underscore the enhanced predictive capabilities of ML models for structural performance, suggesting a significant potential to refine traditional design methodologies and optimize CFS beam designs.</div></div>","PeriodicalId":49435,"journal":{"name":"Thin-Walled Structures","volume":"205 ","pages":"Article 112587"},"PeriodicalIF":5.7,"publicationDate":"2024-10-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142539525","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0