International Journal of Solids and Structures最新文献_第2页

Influence of block arrangement on mechanical performance in topological interlocking assemblies: A study of the versatile block 块体排列对拓扑互锁组件机械性能的影响：对多功能块的研究

IF 3.4 3区工程技术

International Journal of Solids and Structures Pub Date : 2024-10-20 DOI: 10.1016/j.ijsolstr.2024.113102

{"title":"Influence of block arrangement on mechanical performance in topological interlocking assemblies: A study of the versatile block","authors":"","doi":"10.1016/j.ijsolstr.2024.113102","DOIUrl":"10.1016/j.ijsolstr.2024.113102","url":null,"abstract":"<div><div>Topological interlocking assemblies (TIA) are arrangements of blocks kinematically constrained by a fixed frame, such that all rigid body motions of each block are prevented by the neighbouring blocks and the frame. In the literature, several blocks are introduced that can be arranged into interlocking assemblies, however only few of them can be arranged in non-unique ways. This study investigates a particularly versatile interlocking block called the Versatile Block: this block can be arranged in three different doubly periodic ways given by wallpaper symmetries. We investigate the hypothesis that the arrangement of copies of the same block influences the mechanical response of a TIA. We examine the interlocking mechanism and the correlation between arrangement and overall structural performance in planar TIA consisting of the Versatile Block. Furthermore, we analyse load transfer mechanisms within the assemblies and from the assemblies onto the frame. For fast apriori evaluation of the load transfer onto the frame we introduce a combinatorial model called Interlocking Flows. To investigate our assemblies from a mechanical point of view we conduct several finite element studies. These reveal a strong influence of arrangement on the structural behaviour, for instance, an impact on both the point and amount of maximum deflection under a given load, thereby confirming our hypothesis. We also evaluate the accuracy of the proposed Interlocking Flow model by a comparison with the finite element simulations.</div></div>","PeriodicalId":14311,"journal":{"name":"International Journal of Solids and Structures","volume":null,"pages":null},"PeriodicalIF":3.4,"publicationDate":"2024-10-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142554886","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"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 multi-scale constitutive model for AlSi10Mg alloy fabricated via laser powder bed fusion 通过激光粉末床熔融技术制造的 AlSi10Mg 合金的多尺度构成模型

IF 3.4 3区工程技术

International Journal of Solids and Structures Pub Date : 2024-10-19 DOI: 10.1016/j.ijsolstr.2024.113111

{"title":"A multi-scale constitutive model for AlSi10Mg alloy fabricated via laser powder bed fusion","authors":"","doi":"10.1016/j.ijsolstr.2024.113111","DOIUrl":"10.1016/j.ijsolstr.2024.113111","url":null,"abstract":"<div><div>Additively Manufactured (AM) aluminum alloys find extensive applications in various fields due to their favorable properties. Numerical simulations play a crucial role in reducing experimental costs and enhancing reliability. Developing a reliable constitutive numerical model requires careful consideration of the hierarchical microstructure inherent in AM aluminum alloys. In response, a multiscale constitutive model has been formulated for the AlSi10Mg alloy, fabricated through laser powder bed fusion. This model incorporates crystal plasticity theory and micromechanics-based homogenization methods to establish representative volume elements at different length scales. These scales include the grain scale, polycrystalline scale, and macro scale, thus facilitating a seamless transition between them. The model is calibrated using macroscopic and average phase stress–strain relationships, demonstrating its capability to predict lattice strain in each phase. Additionally, this model incorporates a quantitative analysis of the effects of two-phase structure, melt pool structure, and porosity by adjusting microstructure parameters. The developed model is embedded into a user-defined material subroutine, providing an efficient approach to investigate microstructure-property relationships in AM alloys.</div></div>","PeriodicalId":14311,"journal":{"name":"International Journal of Solids and Structures","volume":null,"pages":null},"PeriodicalIF":3.4,"publicationDate":"2024-10-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142532451","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"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

Three-dimensional buckling analysis of stiffened plates with complex geometries using energy element method 利用能量元素法对具有复杂几何形状的加劲板进行三维屈曲分析

IF 3.4 3区工程技术

International Journal of Solids and Structures Pub Date : 2024-10-18 DOI: 10.1016/j.ijsolstr.2024.113105

{"title":"Three-dimensional buckling analysis of stiffened plates with complex geometries using energy element method","authors":"","doi":"10.1016/j.ijsolstr.2024.113105","DOIUrl":"10.1016/j.ijsolstr.2024.113105","url":null,"abstract":"<div><div>A novel numerical method, energy element method (EEM), is proposed for the three-dimensional (3D) buckling analysis of stiffened plates with complex geometries. The problem is formulated in a cuboidal domain, and any complex geometric stiffened plate is modeled by assigning cutouts within the cuboidal domain. The stiffened plate is considered as an energy body and is discretized using Gauss points with variable stiffness properties to simulate its energy distribution. Incorporating the extended interval integration, Gauss quadrature, variable stiffness properties, and Chebyshev polynomials, the strain energy of stiffened plates with complex geometries can be numerically simulated by putting the stiffness and thickness of Gauss points in the cutouts to zero in the cuboidal domain. Using the principle of minimum potential energy and Ritz solution procedure, the deformation and buckling behaviors of stiffened plates with complex geometries can be captured. As a result of the new formulations in EEM, new standard energy functionals and solving procedures have been developed. In addition, Gauss points are generated within the energy elements accounting for the geometric boundaries of the stiffened plate, which are characterized by level set functions. EEM is employed to investigate complex-shaped stiffened plates with straight or curvilinear stiffeners, and the results are compared to those obtained using FEM or mesh-free method. The precision, generalization, and stability of EEM are demonstrated.</div></div>","PeriodicalId":14311,"journal":{"name":"International Journal of Solids and Structures","volume":null,"pages":null},"PeriodicalIF":3.4,"publicationDate":"2024-10-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142532426","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"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

Hydro-mechanical modeling of cohesive crack propagation of concrete lining in high internal pressure tunnels 高内压隧道混凝土衬砌内聚裂缝扩展的水力机械建模

IF 3.4 3区工程技术

International Journal of Solids and Structures Pub Date : 2024-10-16 DOI: 10.1016/j.ijsolstr.2024.113108

{"title":"Hydro-mechanical modeling of cohesive crack propagation of concrete lining in high internal pressure tunnels","authors":"","doi":"10.1016/j.ijsolstr.2024.113108","DOIUrl":"10.1016/j.ijsolstr.2024.113108","url":null,"abstract":"<div><div>High pressure tunnels with concrete lining have been extensively utilized in project practice. However, due to the characteristic of concrete being susceptible to cracking under tension, the lining inevitably develops cracks under high internal water pressure, posing a serious threat to the operation of tunnels. This study aims at developing a hydro-mechanical numerical model of cohesive crack propagation of concrete lining in high internal pressure tunnels. In this regard, the determination of cohesive element parameters is elucidated, the contact simulation within the software ABAQUS is improved to accurately characterize the interface between lining and surrounding rock, and the numerical calculation process in ABAQUS is realized using indirect coupled method. The simulation results align well with the physical model test and engineering monitoring data, demonstrating that the proposed method can accurately simulate the hydraulic interactions of high pressure tunnel. Additionally, a comparison with calculation models employing tie constraints to simulate the lining-surrounding rock interface is conducted. Finally, comparison with traditional continuum method reveals that while both methods exhibit consistent overall trends. It is recommended to choose the proposed method when describing the discontinuous propagation process of cracks, which cannot be simulated by the continuum analysis method.</div></div>","PeriodicalId":14311,"journal":{"name":"International Journal of Solids and Structures","volume":null,"pages":null},"PeriodicalIF":3.4,"publicationDate":"2024-10-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142532422","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"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

An optimal penalty method for the joint stiffening in beam models of additively manufactured lattice structures 用于叠加制造晶格结构梁模型连接刚度的优化惩罚方法

IF 3.4 3区工程技术

International Journal of Solids and Structures Pub Date : 2024-10-16 DOI: 10.1016/j.ijsolstr.2024.113107

{"title":"An optimal penalty method for the joint stiffening in beam models of additively manufactured lattice structures","authors":"","doi":"10.1016/j.ijsolstr.2024.113107","DOIUrl":"10.1016/j.ijsolstr.2024.113107","url":null,"abstract":"<div><div>Additive manufacturing is revolutionizing structural design, with lattice structures becoming increasingly prominent due to their superior mechanical properties. However, simulating these structures quickly and accurately using the finite element method (FEM) remains challenging. Recent research has highlighted beam element simulation within FEM as a more efficient alternative to traditional solid FE simulations, achieving similar accuracy with reduced computational resources. However, a significant challenge is managing the lack of rigidity at nodes and the prevalence of low aspect ratio beams. While various methodologies have been proposed to address these issues, there is still a gap in the comprehensive evaluation of their limitations. An optimal node penalization methodology is required to expand the limited range of accurately represented lattice behavior. A preliminary study investigates lattice geometries through comparative analysis of solid and beam FE simulations. Built on this, we developed a methodology suitable to linear, dynamics and nonlinear beam FE simulations, contributing to enhanced computational speed and accuracy. Several lattice structures were printed using material jetting and quasi-static compressive tests were conducted to validate the methodology’s accuracy. The numerical results reveal a good accuracy between the proposed beam FE methodology and the experimental data, offering a better alternative to conventional FEM for energy absorption in terms of computing time.</div></div>","PeriodicalId":14311,"journal":{"name":"International Journal of Solids and Structures","volume":null,"pages":null},"PeriodicalIF":3.4,"publicationDate":"2024-10-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142532452","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"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

Finite element analysis of crack propagation, crack-gap-filling, and recovery behavior of mechanical properties in oxidation-induced self-healing ceramics 氧化诱导自修复陶瓷中裂纹扩展、裂隙填充和机械性能恢复行为的有限元分析

IF 3.4 3区工程技术

International Journal of Solids and Structures Pub Date : 2024-10-11 DOI: 10.1016/j.ijsolstr.2024.113104

{"title":"Finite element analysis of crack propagation, crack-gap-filling, and recovery behavior of mechanical properties in oxidation-induced self-healing ceramics","authors":"","doi":"10.1016/j.ijsolstr.2024.113104","DOIUrl":"10.1016/j.ijsolstr.2024.113104","url":null,"abstract":"<div><div>The oxidation-induced self-healing of cracks is an attractive function for the application of ceramics in high-temperature structural components requiring high reliability. To further optimize materials or components for practical applications, the development of numerical simulation techniques is of importance. In this study, we examined crack growth, crack-gap-filling by oxide, and re-cracking behaviors in chevron-notched specimens under various load and temperature conditions by adopting a finite element analysis (FEA) approach incorporating a damage-healing constitutive model based on fracture mechanics and oxidation kinetics. Furthermore, by implementing the mechanical properties and oxidation kinetic parameters of reported self-healing ceramics composites into the FEA, we examined the effects of the composition and composite structure on the cracking and healing behaviors. Crack-gap-filling simulations suggested that the damage variables gradually decreased from the crack tip, and the minimum healing time was determined by the time required for the complete filling of the element at the crack mouth with the largest crack opening width. Furthermore, the recovery of the stiffness and strength could be successfully reproduced after complete healing with a reasonable healing temperature and time. The proposed FEA approach could also contribute to estimating the minimum healing time required at various temperatures to heal a given damage for various composites.</div></div>","PeriodicalId":14311,"journal":{"name":"International Journal of Solids and Structures","volume":null,"pages":null},"PeriodicalIF":3.4,"publicationDate":"2024-10-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142440995","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"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

Three-dimensional elastic–plastic lattice-spring model based on sapphire crystal structure and its application to impact characterisation studies 基于蓝宝石晶体结构的三维弹塑性晶格弹簧模型及其在冲击特性研究中的应用

IF 3.4 3区工程技术

International Journal of Solids and Structures Pub Date : 2024-10-10 DOI: 10.1016/j.ijsolstr.2024.113097

{"title":"Three-dimensional elastic–plastic lattice-spring model based on sapphire crystal structure and its application to impact characterisation studies","authors":"","doi":"10.1016/j.ijsolstr.2024.113097","DOIUrl":"10.1016/j.ijsolstr.2024.113097","url":null,"abstract":"<div><div>A thirteen-node octahedral three-dimensional lattice-spring model based on the sapphire crystal structure is established by applying the parameter mapping theory, and the finite element stiffness matrix is mapped into the linear spring stiffness coefficients of the lattice-spring model according to the parameter mapping method, so that the selection of the spring stiffness coefficients has a strict mathematical derivation. The elastic–plastic potential function that unifies the elastic–plastic characteristics of the material and the fracture energy is established. The lattice-spring model is tested by three algorithms, including longitudinal wave velocity, three-dimensional crack extension path under dynamic indentation, and impact compression deformation and lattice size sensitivity test, and the test results show that the established three-dimensional lattice-spring model has a high computational accuracy. The correctness of the calculation of the lattice-spring model is verified by comparing the calculation of the evolution process of spherical impact damage on the edge of sapphire under different crystal directions with the experiment.</div></div>","PeriodicalId":14311,"journal":{"name":"International Journal of Solids and Structures","volume":null,"pages":null},"PeriodicalIF":3.4,"publicationDate":"2024-10-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142444611","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"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

Elastic wave propagation in periodic stress-driven nonlocal Timoshenko beams 周期应力驱动非局部季莫申科梁中的弹性波传播

IF 3.4 3区工程技术

International Journal of Solids and Structures Pub Date : 2024-10-10 DOI: 10.1016/j.ijsolstr.2024.113103

{"title":"Elastic wave propagation in periodic stress-driven nonlocal Timoshenko beams","authors":"","doi":"10.1016/j.ijsolstr.2024.113103","DOIUrl":"10.1016/j.ijsolstr.2024.113103","url":null,"abstract":"<div><div>Nonlocal theories are well established to model statics and dynamics of small-size structures. Recent studies investigated elastic wave propagation in nonlocal beams and attention focused on periodic nonlocal beams, either endowed with resonators or resting on supports, for relevant applications at small scale. In this context, this work proposes a stress-driven nonlocal Timoshenko beam formulation and develops an original and comprehensive analytical/computational framework for wave propagation analysis in bare and periodic beams.</div><div>The framework addresses infinite and finite beams. First, exact analytical expressions are derived for the dispersion curves of the bare beam, which provide full insight into the effects of nonlocality. Second, an exact Plane Wave Expansion method is devised for periodic beams, either equipped with mass-spring resonators or resting on elastic supports; both <span><math><mrow><mi>ω</mi><mrow><mo>(</mo><mi>q</mi><mo>)</mo></mrow></mrow></math></span> and <span><math><mrow><mi>q</mi><mrow><mo>(</mo><mi>ω</mi><mo>)</mo></mrow></mrow></math></span> dispersion curves are derived in this work, where <span><math><mi>ω</mi></math></span> is the frequency and <span><math><mi>q</mi></math></span> is the wave number. Third, an approximate homogenization approach is formulated to estimate opening frequencies and sizes of band gaps induced by mass-spring resonators. Finally, a two-field finite element method is proposed to calculate the transmittance of finite periodic beams.</div><div>Numerical applications investigate the dispersion diagram of bare and periodic beams for different internal lengths of the stress-driven nonlocal model. Remarkably, results for finite periodic beams validate the predictions from wave propagation analysis of corresponding infinite ones. Moreover, parametric analyses show the capability of the stress-driven nonlocal model in capturing typical small-size effects.</div></div>","PeriodicalId":14311,"journal":{"name":"International Journal of Solids and Structures","volume":null,"pages":null},"PeriodicalIF":3.4,"publicationDate":"2024-10-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142532423","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"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

Dynamic digital image correlation method for rolling convective contact 滚动对流接触的动态数字图像相关方法

IF 3.4 3区工程技术

International Journal of Solids and Structures Pub Date : 2024-10-09 DOI: 10.1016/j.ijsolstr.2024.113096

{"title":"Dynamic digital image correlation method for rolling convective contact","authors":"","doi":"10.1016/j.ijsolstr.2024.113096","DOIUrl":"10.1016/j.ijsolstr.2024.113096","url":null,"abstract":"<div><div>Digital image correlation (DIC) is an increasingly popular and effective non-contact method for measuring full-field displacements and strains of deformable bodies under load. Current DIC methods applied to bodies undergoing large displacements and rotations require a large measurement area for both the reference (i.e., undeformed) image and the deformed images. This can limit the resulting resolution of the displacement and strain fields. To address this issue, we propose a two-stage dynamic DIC method capable of measuring displacements and strains under material convection with high resolution. During the first stage, the reference image is assembled from smaller, high-resolution images of the undeformed object obtained using a spatially-fixed or moving frame. Following capture, each sub-image is rigidly translated and rotated into its appropriate place, thereby producing a full, high-resolution image of the reference body. In stage two, images of the loaded and deformed body, again obtained using a small camera frame with high resolution, are aligned with matching regions of the undeformed composite image using BRISK feature detection before performing DIC. We demonstrate the method on a contact problem whereby an elastomeric roller travels along a rigid surface. In doing so, we obtain fine-resolution measurements of the state of strain of the region of the roller sidewall in contact with the substrate, even as new material convects through the region of interest. We present these measurements as a series of images and videos capturing strain evolution as the roller transitions from static loads to a fully dynamic steady-state, documenting the effectiveness of the method.</div></div>","PeriodicalId":14311,"journal":{"name":"International Journal of Solids and Structures","volume":null,"pages":null},"PeriodicalIF":3.4,"publicationDate":"2024-10-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142440996","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"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 force-density framework for flexible multi-body dynamic analysis of clustered tensegrity structures 用于集群张弦结构柔性多体动态分析的力密度框架

IF 3.4 3区工程技术

International Journal of Solids and Structures Pub Date : 2024-10-09 DOI: 10.1016/j.ijsolstr.2024.113098

{"title":"A force-density framework for flexible multi-body dynamic analysis of clustered tensegrity structures","authors":"","doi":"10.1016/j.ijsolstr.2024.113098","DOIUrl":"10.1016/j.ijsolstr.2024.113098","url":null,"abstract":"<div><div>This paper develops a versatile and effective force-density framework for the flexible multi-body dynamic analysis of clustered tensegrity structures. In this framework, the force density is selected as the basic variable instead of force, and the clustered tensegrity structure is mathematically described in a vector and matrix form, encompassing topology, geometry, material, and force properties. A non-negative variable is defined as an indicator of the member stress state, and a complementary function is constructed to address the discontinuity issues that arise from the unidirectional axial stiffness of cables. Dynamic formulas are established within this force-density framework, with nodal coordinates selected as generalized parameters and formulations constructed in a matrix form. A complementary framework is established as an alternative for solving the dynamic equations, transforming the isolated steps of Newton’s iteration and cable state judgment (slack or tension) into a unified one, bringing more potential for improving solving efficiency. Numerical simulations are carried out to validate the approach, demonstrating that it effectively reveals the dynamic oscillation, tension changes, and cable slack behavior of clustered tensegrity structures during shape control. Comparative studies highlight the advantage of computational efficiency. The method proposed in this paper provides a robust mathematical model for studying clustered tensegrity structures, particularly regarding the shape control of deployable, active, and intelligent structures, aiding in understanding dynamic oscillation, tension changes, and cable slack behavior during their deformation. The methods can also be applied to cable net structures and other prestressed pin-jointed systems.</div></div>","PeriodicalId":14311,"journal":{"name":"International Journal of Solids and Structures","volume":null,"pages":null},"PeriodicalIF":3.4,"publicationDate":"2024-10-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142428682","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"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