发布求助
文献互助 智能选刊 最新文献

Journal of nanomechanics & micromechanics最新文献

筛选
英文 中文
Thermal Buckling Behavior of Nanobeams Using an Efficient Higher-Order Nonlocal Beam Theory 基于高效高阶非局部梁理论的纳米梁热屈曲行为
Journal of nanomechanics & micromechanics Pub Date : 2013-02-25 DOI: 10.1061/(ASCE)NM.2153-5477.0000057
A. Tounsi, A. Semmah, A. A. Bousahla
{"title":"Thermal Buckling Behavior of Nanobeams Using an Efficient Higher-Order Nonlocal Beam Theory","authors":"A. Tounsi, A. Semmah, A. A. Bousahla","doi":"10.1061/(ASCE)NM.2153-5477.0000057","DOIUrl":"https://doi.org/10.1061/(ASCE)NM.2153-5477.0000057","url":null,"abstract":"AbstractThis paper presents an efficient higher-order nonlocal beam theory for the thermal buckling of nanobeams. The displacement field is chosen based on assumptions that the in-plane and transverse displacements consist of bending and shear components, and the shear components of in-plane displacements give rise to the parabolic variation of shear strain through the thickness in such a way that shear stress vanishes on the nanobeam surfaces. Therefore, there is no need to use a shear correction factor. The present model is capable of capturing both the small-scale effect and transverse shear deformation effects of nanobeams, and it has strong similarities with the nonlocal Euler–Bernoulli beam theory in aspects such as equations of motion, boundary conditions, and stress resultant expressions. Using the nonlinear strain–displacement relations, the equilibrium and stability equations of nanobeams are derived. The theoretical development presented herein may serve as a reference for nonlocal theories as ...","PeriodicalId":90606,"journal":{"name":"Journal of nanomechanics & micromechanics","volume":"3 1","pages":"37-42"},"PeriodicalIF":0.0,"publicationDate":"2013-02-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1061/(ASCE)NM.2153-5477.0000057","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"58475717","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 101
Poromechanics Parameters of Fluid-Saturated Chemically Active Fibrous Media Derived from a Micromechanical Approach. 基于微力学方法的饱和化学活性纤维介质孔隙力学参数。
Journal of nanomechanics & micromechanics Pub Date : 2013-01-01 DOI: 10.1061/(ASCE)NM.2153-5477.0000069
Anil Misra, Ranganathan Parthasarathy, Viraj Singh, Paulette Spencer
{"title":"Poromechanics Parameters of Fluid-Saturated Chemically Active Fibrous Media Derived from a Micromechanical Approach.","authors":"Anil Misra,&nbsp;Ranganathan Parthasarathy,&nbsp;Viraj Singh,&nbsp;Paulette Spencer","doi":"10.1061/(ASCE)NM.2153-5477.0000069","DOIUrl":"https://doi.org/10.1061/(ASCE)NM.2153-5477.0000069","url":null,"abstract":"<p><p>The authors have derived macroscale poromechanics parameters for chemically active saturated fibrous media by combining microstructure-based homogenization with Hill's volume averaging. The stress-strain relationship of the dry fibrous media is first obtained by considering the fiber behavior. The constitutive relationships applicable to saturated media are then derived in the poromechanics framework using Hill's Lemmas. The advantage of this approach is that the resultant continuum model assumes a form suited to study porous materials, while retaining the effect of discrete fiber deformation. As a result, the model is able to predict the influence of microscale phenomena such as fiber buckling on the overall behavior, and in particular, on the poromechanics constants. The significance of the approach is demonstrated using the effect of drainage and fiber nonlinearity on monotonic compressive stress-strain behavior. The model predictions conform to the experimental observations for articular cartilage. The method can potentially be extended to other porous materials such as bone, clays, foams, and concrete.</p>","PeriodicalId":90606,"journal":{"name":"Journal of nanomechanics & micromechanics","volume":"3 4","pages":""},"PeriodicalIF":0.0,"publicationDate":"2013-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1061/(ASCE)NM.2153-5477.0000069","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"32833478","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 5
Correlating Micromorphology and Nanomorphology to High Strain Rate Performance of Nanoparticle Reinforced Polymeric Materials 纳米颗粒增强聚合物材料的微形貌和纳米形貌与高应变率性能的关系
Journal of nanomechanics & micromechanics Pub Date : 2012-12-01 DOI: 10.1061/(ASCE)NM.2153-5477.0000045
Mohammad R. Irshidat, A. Al-ostaz, A. Cheng
{"title":"Correlating Micromorphology and Nanomorphology to High Strain Rate Performance of Nanoparticle Reinforced Polymeric Materials","authors":"Mohammad R. Irshidat, A. Al-ostaz, A. Cheng","doi":"10.1061/(ASCE)NM.2153-5477.0000045","DOIUrl":"https://doi.org/10.1061/(ASCE)NM.2153-5477.0000045","url":null,"abstract":"AbstractThis paper focuses on correlating micromorphology and nanomorphology to the performance of nano-enhanced polymers subjected to blast loading, studying the behavior of these materials at high strain rates, and evaluating the effect of voids’ size and amount on the strain rate sensitivity of nanomaterials. Three polyurea-based elastomeric materials are investigated in this study: unreinforced polyurea, exfoliated graphene nanoparticle (xGnP)–reinforced polyurea, and polyhedral oligomeric silsesquioxane (POSS)–reinforced polyurea. Three-dimensional computed tomography scan images show large amounts of randomly distributed voids in the materials. The study found that POSS-reinforced polyurea has the largest number but the smallest void size among the three tested materials. Computational parametric evaluation is conducted to investigate the effect of such defects on the behavior of these materials. Dynamic nonlinear explicit finite-element code AUTODYN is used to perform three-dimensional analyses for...","PeriodicalId":90606,"journal":{"name":"Journal of nanomechanics & micromechanics","volume":"11 1","pages":"55-64"},"PeriodicalIF":0.0,"publicationDate":"2012-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1061/(ASCE)NM.2153-5477.0000045","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"58475475","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 1
Mechanical Energy Absorption Characteristics of Hollow and Water-Filled Carbon Nanotubes upon Low-Speed Crushing 空心充水碳纳米管低速破碎时的机械能吸收特性
Journal of nanomechanics & micromechanics Pub Date : 2012-11-15 DOI: 10.1061/(ASCE)NM.2153-5477.0000049
Jun Xu, Baoxing Xu, Yueting Sun, Yibing Li, Xi Chen
{"title":"Mechanical Energy Absorption Characteristics of Hollow and Water-Filled Carbon Nanotubes upon Low-Speed Crushing","authors":"Jun Xu, Baoxing Xu, Yueting Sun, Yibing Li, Xi Chen","doi":"10.1061/(ASCE)NM.2153-5477.0000049","DOIUrl":"https://doi.org/10.1061/(ASCE)NM.2153-5477.0000049","url":null,"abstract":"AbstractUsing molecular dynamics simulations, the prospects are explored of using bundles, forests, and single carbon nanotubes (CNTs) for absorbing mechanical energies upon crushing. In particular, the deformation and energy absorption characteristics are compared between hollow and water-filled CNTs. It is shown that the buckling properties of hollow CNTs strongly depend on their geometrical parameters, whereas the critical buckling load and postbuckling stress can be significantly elevated with a filament of water, leading to pronounced energy absorption densities. Additional enhancements result from CNT bundles and forests. The present study may provide some insight into the potential application of employing CNTs as advanced energy absorption materials.","PeriodicalId":90606,"journal":{"name":"Journal of nanomechanics & micromechanics","volume":"2 1","pages":"65-70"},"PeriodicalIF":0.0,"publicationDate":"2012-11-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1061/(ASCE)NM.2153-5477.0000049","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"58475216","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 6
Mechanics of SWCNT Aggregates Studied by Incremental Constrained Minimization 基于增量约束最小化的swcnts聚集体力学研究
Journal of nanomechanics & micromechanics Pub Date : 2012-06-01 DOI: 10.1061/(ASCE)NM.2153-5477.0000043
M. Lan, H. Waisman
{"title":"Mechanics of SWCNT Aggregates Studied by Incremental Constrained Minimization","authors":"M. Lan, H. Waisman","doi":"10.1061/(ASCE)NM.2153-5477.0000043","DOIUrl":"https://doi.org/10.1061/(ASCE)NM.2153-5477.0000043","url":null,"abstract":"AbstractThe stress-strain behavior of short single-walled carbon nanotube (SWCNT) aggregates is investigated by a novel incremental constrained minimization approach. An AIREBO potential is used to model the interactions within and between CNTs. The idea is to homogenously disperse SWCNTs in the computational cell at random positions and orientations following spherical uniform distributions, and incrementally deform the cell although restraining the movement of atoms at the ends of nanotubes. The stress-strain response of the system is obtained in each loading direction, and it is shown to converge to an isotropic behavior (a similar response in all directions) as the number of CNTs in the system increases. It is also shown that the Young’s modulus of the system increases linearly with the CNT aggregates density. Finally, the method is shown to agree well with results obtained from molecular dynamics simulations running at near zero degrees kelvin, however they are obtained at only a fraction of the CPU ...","PeriodicalId":90606,"journal":{"name":"Journal of nanomechanics & micromechanics","volume":"2 1","pages":"15-22"},"PeriodicalIF":0.0,"publicationDate":"2012-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1061/(ASCE)NM.2153-5477.0000043","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"58475438","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 6
Thermal and Mechanical Responses of BCC Metals to the Fast-Transient Process in Small Volumes BCC金属对小体积快速瞬态过程的热力学响应
Journal of nanomechanics & micromechanics Pub Date : 2012-03-19 DOI: 10.1061/(ASCE)NM.2153-5477.0000048
D. Faghihi, G. Voyiadjis
{"title":"Thermal and Mechanical Responses of BCC Metals to the Fast-Transient Process in Small Volumes","authors":"D. Faghihi, G. Voyiadjis","doi":"10.1061/(ASCE)NM.2153-5477.0000048","DOIUrl":"https://doi.org/10.1061/(ASCE)NM.2153-5477.0000048","url":null,"abstract":"AbstractPlasticity in heterogeneous metallic materials with small volumes is governed by the interactions of dislocations within the bulk. Energy (heat) transfer, on the other hand, is micromechanically related to the interaction within phonons, electrons, or photons. To address the experimentally observed characteristics of small-volume metallic components such as thin films, these microstructural interactions need to be included in modeling. This gives rise to a large variety of generalized multiscale models that are developed on the continuum level and used to bridge the gap between the micromechanical and classical continuum models by means of certain characteristic time and length scales. A higher-order strain gradient model accounting for the size effect is combined in this paper with the generalized heat equation to identify the coupling effect of thermal and mechanical behavior of body-centered cubic (BCC) materials with small volumes and in transient time. A fully thermodynamically consistent fra...","PeriodicalId":90606,"journal":{"name":"Journal of nanomechanics & micromechanics","volume":"2 1","pages":"29-41"},"PeriodicalIF":0.0,"publicationDate":"2012-03-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1061/(ASCE)NM.2153-5477.0000048","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"58475051","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 5
Role of Dislocation Density on the Sample-Size Effect in Nanoscale Plastic Yielding 位错密度对纳米塑性屈服中试样尺寸效应的影响
Journal of nanomechanics & micromechanics Pub Date : 2012-03-19 DOI: 10.1061/(ASCE)NM.2153-5477.0000047
A. Rinaldi, P. Peralta, K. Sieradzki, E. Traversa, S. Licoccia
{"title":"Role of Dislocation Density on the Sample-Size Effect in Nanoscale Plastic Yielding","authors":"A. Rinaldi, P. Peralta, K. Sieradzki, E. Traversa, S. Licoccia","doi":"10.1061/(ASCE)NM.2153-5477.0000047","DOIUrl":"https://doi.org/10.1061/(ASCE)NM.2153-5477.0000047","url":null,"abstract":"AbstractThe sample-size dependence of plastic yielding in nanoscale metal pillars is not a purely geometrical fact, explainable just in terms of shape and geometry of the pillar, but depends on the actual content of inner dislocations. The present study discusses the role of the initial density of bulk dislocations ρ on the power-law scaling that describes the strengthening effect in yield stress. This paper reports on in-situ mechanical tests on highly miniaturized focused-ion-beam (FIB)–machined Ni pillars and buttons (i.e., very short pillars) of diameters D∼200–300 nm specifically conducted to highlight the decrease in hardness and the disappearance of the power—law scaling that may accompany a controlled decrease in ρ. From an experimental standpoint, it is further demonstrated that nanoindentation tests on pillars make for a useful companion test to standard microcompression to assess actual hardness increase with reducing sample size.","PeriodicalId":90606,"journal":{"name":"Journal of nanomechanics & micromechanics","volume":"53 1","pages":"42-48"},"PeriodicalIF":0.0,"publicationDate":"2012-03-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1061/(ASCE)NM.2153-5477.0000047","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"58475520","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 14
Ab Initio Study of Coupling between Electronic and Phononic Contribution to Stress-Dependent Thermal Conductivity of Au, Si, and SiC Au, Si和SiC的应力相关热导率中电子和声子耦合的从头算研究
Journal of nanomechanics & micromechanics Pub Date : 2012-03-12 DOI: 10.1061/(ASCE)NM.2153-5477.0000046
V. Samvedi, V. Tomar
{"title":"Ab Initio Study of Coupling between Electronic and Phononic Contribution to Stress-Dependent Thermal Conductivity of Au, Si, and SiC","authors":"V. Samvedi, V. Tomar","doi":"10.1061/(ASCE)NM.2153-5477.0000046","DOIUrl":"https://doi.org/10.1061/(ASCE)NM.2153-5477.0000046","url":null,"abstract":"AbstractThis work presents an understanding of strain-thermal conductivity correlation in a metal (Au), in a semiconductor (Si), and in a ceramic (SiC) using ab initio density functional theory and utilizing a modified nonequilibrium Green’s function (NEGF) approach. Separately, electronic and phononic contributions to thermal conductivity values are calculated as a function of applied tensile strain and temperature. Analyses show that electron thermal conductivity shows a significant decrease with increase in Fermi gap (metal to semiconductor to ceramic). The electronic thermal conduction has less than 5% contribution to overall thermal conductivity in the case of Si and SiC with the value being of the same order as phononic thermal conductivity in the case of Au. Phonons are dominant carriers of heat transport in Si and SiC, with such contribution reducing with increase in temperature and increase in strain. Similar reduction is observed in the case of electronic thermal conduction in Si and SiC. In the...","PeriodicalId":90606,"journal":{"name":"Journal of nanomechanics & micromechanics","volume":"2 1","pages":"49-53"},"PeriodicalIF":0.0,"publicationDate":"2012-03-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1061/(ASCE)NM.2153-5477.0000046","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"58475493","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 6
Modeling Carbon Nanotube Reinforced Composite Materials 碳纳米管增强复合材料建模
Journal of nanomechanics & micromechanics Pub Date : 2012-03-01 DOI: 10.1061/(ASCE)NM.2153-5477.0000039
R. M. Hackett, J. G. Bennett
{"title":"Modeling Carbon Nanotube Reinforced Composite Materials","authors":"R. M. Hackett, J. G. Bennett","doi":"10.1061/(ASCE)NM.2153-5477.0000039","DOIUrl":"https://doi.org/10.1061/(ASCE)NM.2153-5477.0000039","url":null,"abstract":"Micromechanics modeling is employed to characterize the mechanical behavior of a transversely isotropic, isothermal material system of a hollow carbon nanotube embedded in a polymeric matrix. The characterization yields five independent constants of the homogenized system. In particular, the derivation of the transverse shear modulus is a focus of the work because, up to this point, it has not been satisfactorily resolved. Numerical examples of each of the independent constants, obtained from the derived expressions, are presented, and are based on appropriate values of the properties of the carbon nanotube and epoxy matrix. The numerical results are presented graphically.","PeriodicalId":90606,"journal":{"name":"Journal of nanomechanics & micromechanics","volume":"2 1","pages":"7-14"},"PeriodicalIF":0.0,"publicationDate":"2012-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1061/(ASCE)NM.2153-5477.0000039","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"58475170","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 4
Mechanical Properties of Nanocomposite Cement Incorporating Surface-Treated and Untreated Carbon Nanotubes and Carbon Nanofibers 表面处理和未处理碳纳米管和碳纳米纤维纳米复合水泥的力学性能
Journal of nanomechanics & micromechanics Pub Date : 2012-03-01 DOI: 10.1061/(ASCE)NM.2153-5477.0000041
R. Al-Rub, Bryan M. Tyson, Ardavan Yazdanbakhsh, Z. Grasley
{"title":"Mechanical Properties of Nanocomposite Cement Incorporating Surface-Treated and Untreated Carbon Nanotubes and Carbon Nanofibers","authors":"R. Al-Rub, Bryan M. Tyson, Ardavan Yazdanbakhsh, Z. Grasley","doi":"10.1061/(ASCE)NM.2153-5477.0000041","DOIUrl":"https://doi.org/10.1061/(ASCE)NM.2153-5477.0000041","url":null,"abstract":"To study the effects of functionalized carbon nanotubes (CNTs) and carbon nanofibers (CNFs) on the mechanical properties of cement composites, both untreated and treated CNFs and CNTs were added to cement paste in concentrations of 0.1% and 0.2% by weight of cement. The surface-treated nanofilaments were functionalized in a solution of sulfuric acid (H2SO4) and nitric acid (HNO3). The nano- filaments were dispersed by using an ultrasonic mixer and were then cast into molds. Each specimen was tested in a custom-made three-point flexural test fixture to record the mechanical properties (i.e., the Young's modulus, flexural strength, ductility, and modulus of toughness) at the age of 7, 14, and 28 days. The microstructure was analyzed by using a scanning electron microscope. Untreated CNTs and CNFs were found to enhance the mechanical properties of cementitious materials, whereas the acid-treated CNTs and CNFs degraded the mechanical properties. DOI: 10.1061/(ASCE)NM.2153-5477.0000041. © 2012 American Society of Civil Engineers. CE Database subject headings: Nanotechnology; Cement; Mechanical properties; Carbon. Author keywords: Carbon nanotubes; Carbon nanofibers; Cement; Surface treatment; Mechanical properties.","PeriodicalId":90606,"journal":{"name":"Journal of nanomechanics & micromechanics","volume":"2 1","pages":"1-6"},"PeriodicalIF":0.0,"publicationDate":"2012-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1061/(ASCE)NM.2153-5477.0000041","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"58475397","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 139
首页 上一页 下一页 尾页
0
×
引用
GB/T 7714-2015
复制
MLA
复制
APA
复制
导出至
BibTeX EndNote RefMan NoteFirst NoteExpress
×
提示
您的信息不完整，为了账户安全，请先补充。
现在去补充
×
提示
您因"违规操作"
具体请查看互助需知
我知道了
×
提示
现在去查看 取消
×
提示
确定
请完成安全验证×
相关产品
×
本文献相关产品
联系我们：info@booksci.cn Book学术提供免费学术资源搜索服务，方便国内外学者检索中英文文献。致力于提供最便捷和优质的服务体验。 Copyright © 2023 布克学术 All rights reserved.
京ICP备2023020795号-1
ghs 京公网安备 11010802042870号
Book学术文献互助
Book学术文献互助群
群 号：604180095
Book学术官方微信
小红书