International Journal of Machine Tools & Manufacture最新文献

{"title":"Grain refinement and columnar-to-equiaxed transition of Ti6Al4V during additive manufacturing via different laser oscillations","authors":"Guoqing Dai ,&nbsp;Zhonggang Sun ,&nbsp;Yusheng Li ,&nbsp;Jayant Jain ,&nbsp;Ayan Bhowmik ,&nbsp;Junji Shinjo ,&nbsp;Jinzhong Lu ,&nbsp;Chinnapat Panwisawas","doi":"10.1016/j.ijmachtools.2023.104031","DOIUrl":"https://doi.org/10.1016/j.ijmachtools.2023.104031","url":null,"abstract":"<div><p>Conventional additive manufacturing produces coarse columnar grains, which affect the mechanical properties of additively manufactured titanium alloys. This study developed a novel integrated additive manufacturing technology termed oscillation laser melting deposition, including linear, circular, 8-shape, and infinite, was developed to modify the microstructure and improve the mechanical properties of Ti6Al4V. The results showed that significant grain refinement and columnar-to-equiaxed transition (CET) can be induced by laser oscillation. The prior β grain size of the sample with infinite laser oscillation decreased by 54.24% in the single-track zone and by 42.55% in the overlap remelting zone. The ultimate tensile strength of the sample with infinite laser oscillation increased by 16.95% and 32.37% in the parallel and vertical directions, and the elongation also increased by 83.60% and 13.77%, respectively. The anisotropy of (10-10) and (11-22) was also significantly eliminated. The temperature variation and thermal field evolution were also investigated, and the complex oscillation changed the fluid flow velocity orientation, reduced the temperature gradient, and promoted the nucleation of equiaxed grains. In addition, the strengthening mechanisms of the different laser oscillations were revealed. Therefore, the oscillation laser melting deposition technology can become a new approach for overcoming the key bottlenecks of additive manufacturing.</p></div>","PeriodicalId":14011,"journal":{"name":"International Journal of Machine Tools & Manufacture","volume":"189 ","pages":"Article 104031"},"PeriodicalIF":14.0,"publicationDate":"2023-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49825805","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}

{"title":"Analysis of burr formation in finish machining of nickel-based superalloy with worn tools using micro-scale in-situ techniques","authors":"Hamzah Zannoun ,&nbsp;Julius Schoop","doi":"10.1016/j.ijmachtools.2023.104030","DOIUrl":"https://doi.org/10.1016/j.ijmachtools.2023.104030","url":null,"abstract":"<div><p>The formation of burrs is among the most significant factors affecting quality and productivity in machining. Burrs are a negative byproduct of machining processes that are difficult to avoid because of a limited understanding of the complex burr formation mechanisms in relation to cutting conditions, including both process parameters and tool condition. Thus, the objective of this work was to characterize burr formation under finish machining conditions via a high-speed, high-resolution in-situ experimental method. Various parameters pertaining to burr geometry such as height, thickness, and initial negative shear angle were measured both during and after cutting. Results showed that varying the conditions of uncut chip thickness, tool-wear, and cutting speed all have a significant effect on burr formation, although certain burr metrics were found to be insensitive with respect to different process conditions because the difference was statistically insignificant. This study provides new insights into the relationships between the workpiece material's microstructure, machining parameters, and tool condition on both crack formation and propagation/plasticity during burr formation. Using digital image correlation (DIC) and a physics-based process model not previously utilized for burr formation analysis, the displacement and corresponding flow stress were calculated at the exit burr root location. This novel semi-analytical approach revealed that the normalized stress at the exit burr root was approximately equal to the flow stress for a variety of different conditions, indicating the potential for model-based prediction of burr formation mechanics. Finally, this study investigates factors that influence fracture evolution during exit burr formation. It was found that negative exit burrs are a direct result of high strain rate and high uncut chip thickness, which was expected, but also a microstructural size effect and a tool-wear effect, neither of which have been previously reported. By harnessing ultra-high-speed imaging and advanced optical microscopy techniques, this manuscript deals with the fundamentals of burr formation, including new insights into material response at the grain-scale to the loads imposed with both sharp and worn tools.</p></div>","PeriodicalId":14011,"journal":{"name":"International Journal of Machine Tools & Manufacture","volume":"189 ","pages":"Article 104030"},"PeriodicalIF":14.0,"publicationDate":"2023-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49888441","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}

{"title":"Femtosecond laser printing patterned nanoparticles on flexible substrate by tuning plasmon resonances via polarization modulation","authors":"Yu Zhou ,&nbsp;Guohu Luo ,&nbsp;Yongxiang Hu ,&nbsp;Di Wu ,&nbsp;Cheng Hu ,&nbsp;Minni Qu","doi":"10.1016/j.ijmachtools.2023.104040","DOIUrl":"https://doi.org/10.1016/j.ijmachtools.2023.104040","url":null,"abstract":"<div><p>Nanoparticles patterned on stretchable films for broad applications lack efficient fabrication methods. In this study, femtosecond laser-induced transfer was employed to assemble nanoparticles into a well-defined array on a flexible substrate while mitigating the inevitable plasmon resonances. The metal islands patterned on the substrate are regularly transferred as spherical nanoparticles onto the polymer, with a small deposition deviation and large embedded depth after laser irradiation. However, inhomogeneous laser absorption in the patterned array severely amplifies the printing deviation and narrows the process window, particularly for smaller patterns and complex arrangements. Plasmon resonance excited by an incident laser causes a localized optical field distribution, which accounts for absorption enhancement or suppression. The field distribution from the numerical simulation exhibited periodicity related to the laser parameters and array geometry. A theoretical model was established to clarify the propagation of plasmon resonance waves. The field distribution was modulated by adjusting the polarization direction, guided by theoretical and simulation analyses. Finally, regular and complex nanoparticle arrays were successfully fabricated after tuning the plasmon resonances. This study provides an effective method for fabricating programmable nanoparticle arrays on flexible films.</p></div>","PeriodicalId":14011,"journal":{"name":"International Journal of Machine Tools & Manufacture","volume":"189 ","pages":"Article 104040"},"PeriodicalIF":14.0,"publicationDate":"2023-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49825806","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}

{"title":"Review on field assisted metal additive manufacturing","authors":"Chaolin Tan ,&nbsp;Runsheng Li ,&nbsp;Jinlong Su ,&nbsp;Dafan Du ,&nbsp;Yang Du ,&nbsp;Bonnie Attard ,&nbsp;Youxiang Chew ,&nbsp;Haiou Zhang ,&nbsp;Enrique J. Lavernia ,&nbsp;Yves Fautrelle ,&nbsp;Jie Teng ,&nbsp;Anping Dong","doi":"10.1016/j.ijmachtools.2023.104032","DOIUrl":"https://doi.org/10.1016/j.ijmachtools.2023.104032","url":null,"abstract":"<div><p>Additive manufacturing (AM) offers unprecedented design freedom and manufacturing flexibility for processing complex components. Despite the numerous advantages of AM over conventional manufacturing methods, there are still some issues and bottlenecks that hinder the wide-scale industrial adaptation of AM techniques. The emerging field-assisted additive manufacturing (FAAM) is a designation that combines different auxiliary energy fields (e.g., ultrasound, magnetism, etc.) to overcome limitations in AM by benefiting from the intrinsic advantages of auxiliary fields. This work provides an up-to-date and dedicated review of FAAM in metallic materials, assisted by mainstream auxiliary magnetic, acoustic, mechanical, and thermal fields, as well as some emerging fields. The work principle and interaction mechanism between the field and the deposited metallic materials are elucidated. FAAM processes simulation and modelling are also reviewed. The auxiliary fields can affect the melt pool convection and dynamics, alter the temperature profile and thermal history during material solidification and induce stress or plastic deformation to the deposited materials. Hence, the effects of the auxiliary fields on the melt pool dynamics, solidification kinetics, densification behaviour, microstructure and texture, mechanical properties and fatigue performance are reviewed and discussed in detail. The perspectives on the research gap and further development trends of FAAM are also discussed.</p></div>","PeriodicalId":14011,"journal":{"name":"International Journal of Machine Tools & Manufacture","volume":"189 ","pages":"Article 104032"},"PeriodicalIF":14.0,"publicationDate":"2023-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49864692","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}

{"title":"Gradient microstructure and prominent performance of wire-arc directed energy deposited magnesium alloy via laser shock peening","authors":"Xinzhi Li,&nbsp;Xuewei Fang,&nbsp;Mugong Zhang,&nbsp;Hongkai Zhang,&nbsp;Yusong Duan,&nbsp;Ke Huang","doi":"10.1016/j.ijmachtools.2023.104029","DOIUrl":"https://doi.org/10.1016/j.ijmachtools.2023.104029","url":null,"abstract":"<div><p>Wire-arc directed energy deposition (DED) has attracted significant interest for the fabrication of large-sized, lightweight Mg-alloy components. However, these components generally exhibit poor mechanical properties and limited corrosion resistance owing to their inherent residual stress and non-equilibrium microstructures. Herein, laser shock peening (LSP) was adopted to successfully modify the stress state and microstructure of AZ31 Mg-alloy fabricated using wire-arc DED. The influence of LSP on the residual stress, mechanical properties, electrochemical behaviour, and microstructural evolution was systematically investigated. The experimental results indicate that, compared with the as-built specimen, the performance of the LSP-treated specimen was notable, with a ≈63.8% decrease in the corrosion current density and ≈30% and ≈13% decreases in the yield strength (YS) and ultimate tensile strength, respectively. The enhanced corrosion resistance can be attributed to the LSP-induced compressive residual stress, nanograins, and nanoparticles. Nanocrystallisation, particle refinement, dense mechanical twins (MTs), and planar dislocation arrays (PDAs) jointly contributed to the enhancement of the YS. The LSP-induced nanocrystallisation was rationalized by the accumulation of PDAs, the intersection of multiple nano-MTs, and the transformation of nano-MTs blocks into sub-grains and then into nanograins owing to continuous dynamic recrystallisation. The particle refinement mechanism involved dislocation proliferation and the development of dislocation slip bands, which eventually led to fragmentation and separation. Therefore, this study introduces a LSP post-treatment technology for the residual stress regulation, microstructural modification, and performance enhancement of Mg alloys fabricated using wire-arc DED. Based on the ability of LSP to tailor the microstructure and performance of Mg alloys, a novel method of wire-arc DED with online LSP treatment is proposed. This method can achieve in-situ surface strengthening and the integrated formation of large-sized components with complex geometries.</p></div>","PeriodicalId":14011,"journal":{"name":"International Journal of Machine Tools & Manufacture","volume":"188 ","pages":"Article 104029"},"PeriodicalIF":14.0,"publicationDate":"2023-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49885801","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}

{"title":"The curved uncut chip thickness model: A general geometric model for mechanistic cutting force predictions","authors":"David Hajdu ,&nbsp;Asier Astarloa ,&nbsp;Istvan Kovacs ,&nbsp;Zoltan Dombovari","doi":"10.1016/j.ijmachtools.2023.104019","DOIUrl":"https://doi.org/10.1016/j.ijmachtools.2023.104019","url":null,"abstract":"<div><p>The curved uncut chip thickness model is introduced to predict the cutting forces for general uncut chip geometries using the mechanistic approach. Classical geometric models assume that the cutting force is distributed along straight elementary sections of the uncut chip area, which has limited physical validity, but makes mathematical treatments easier for simple cases. The new model assumes that the flow of the material on the contact area of the tool is given by a continuous vector field, according to which the curved uncut chip thickness is measured. The cutting force is distributed along these paths, which leads to a mathematically unique and consistent solution for regular and complex cutting edge geometries. These curved paths can be generated by basic mechanical models, which mimic the more realistic motion of the chip segments along the rake face, without the need of explicit time-consuming cutting simulations. The presented computational procedure generalizes cutting force prediction based on geometric parameters, orthogonal cutting data and the orthogonal to oblique transformations only. The effectiveness of the model for various cutting edge geometries (e.g., thread turning inserts) under extreme cutting conditions is presented in case studies, laboratory and industrial experiments.</p></div>","PeriodicalId":14011,"journal":{"name":"International Journal of Machine Tools & Manufacture","volume":"188 ","pages":"Article 104019"},"PeriodicalIF":14.0,"publicationDate":"2023-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49886141","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}

{"title":"Effects of laser oscillation on metal mixing, microstructure, and mechanical property of Aluminum–Copper welds","authors":"Wenkang Huang ,&nbsp;Wayne Cai ,&nbsp;Teresa J. Rinker ,&nbsp;Jennifer Bracey ,&nbsp;Wenda Tan","doi":"10.1016/j.ijmachtools.2023.104020","DOIUrl":"https://doi.org/10.1016/j.ijmachtools.2023.104020","url":null,"abstract":"<div><p>Laser welding<span><span> of dissimilar metals is important in many industrial applications. However, as dissimilar metals get mixed during the melting process, intermetallic compounds are often formed in the welds which can significantly undermine the electrical and mechanical properties of the welds. This poses a critical challenge to the widespread utilization of this welding technique. Compared with conventional line-scan laser welding, oscillating laser welding offers additional processing parameters to control the welding process. Although some work has been reported on oscillating laser welding of dissimilar metals, a mechanistic understanding of this process was still missing. The research objective of this work was to reveal the physical mechanisms and evaluate their relative significance to the fluid flow, metal mixing, and </span>microstructure evolution in the molten pool in oscillating laser welding of dissimilar metals. A combination of experiments and simulations was leveraged to achieve the objective. Four fluid flows have been found to determine the metal mixing in the molten pool, and their dependences on the laser oscillating parameters were discussed. In addition, the thermo-solutal conditions of the molten pool solidification were quantified as functions of the laser oscillating parameters, and the effects of the thermo-solutal conditions on the final weld microstructures were analyzed.</span></p></div>","PeriodicalId":14011,"journal":{"name":"International Journal of Machine Tools & Manufacture","volume":"188 ","pages":"Article 104020"},"PeriodicalIF":14.0,"publicationDate":"2023-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49886142","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}

{"title":"Nanomachining of van der Waals nanowires: Process and deformation mechanism","authors":"Zihan Li ,&nbsp;Yongda Yan ,&nbsp;Xin Hu ,&nbsp;Cheng Yan Xu ,&nbsp;Yang Li ,&nbsp;Yanquan Geng","doi":"10.1016/j.ijmachtools.2023.104018","DOIUrl":"https://doi.org/10.1016/j.ijmachtools.2023.104018","url":null,"abstract":"<div><p>The edges of van der Waals materials exhibit unique physical and chemical properties, and they are promising for applications in many fields, such as optoelectronics, energy storage, and catalysis. Van der Waals material nanostructures with a controllable high density of edges are difficult to produce by current fabrication methods. In the present study, a simple nanomachining process to fabricate van der Waals nanowires with a high density of edges is proposed. This method used a linear-edge diamond tool to cut the basal plane of van der Waals film materials into a one-dimensional nanowire at the nanoscale. Experimental tests were performed to investigate the influences of the cutting thickness, film thickness, cutting direction, and material properties on the machining outcomes. The results showed that the van der Waals materials possessed low Young's moduli ranging from 24 to 238 GPa by cutting with a cutting thickness of larger than 30 nm, and the out-of-plane cutting direction led to the best machining quality and controllable preparation of van der Waals nanowires. To support the interpretation of the process outcomes, molecular dynamics simulation and transmission electron microscopy were performed to reveal the material-removal mechanism during nanocutting of van der Waals materials. From analysis of the chip-deformation process, interlayer slipping was found to dominate the plastic processing of the van der Waals materials, accompanied by intralayer bending and intralayer fracture in the out-of-plane cutting direction. By contrast, the brittle removal state occurred when cutting in the in-plane direction. This study provides important insights into the material-removal mechanism of van der Waals materials prepared by nanoscale mechanical cutting.</p></div>","PeriodicalId":14011,"journal":{"name":"International Journal of Machine Tools & Manufacture","volume":"188 ","pages":"Article 104018"},"PeriodicalIF":14.0,"publicationDate":"2023-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49885799","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}

{"title":"A review of static and dynamic analysis of ball screw feed drives, recirculating linear guideway, and ball screw","authors":"Changyou Li ,&nbsp;Mengtao Xu ,&nbsp;Wenjun Song ,&nbsp;Hongzhuang Zhang","doi":"10.1016/j.ijmachtools.2023.104021","DOIUrl":"https://doi.org/10.1016/j.ijmachtools.2023.104021","url":null,"abstract":"<div><p>Static and dynamic analysis of key structural components of the machine tool is the crucial stage in transferring the physical to the virtual domain for digital manufacturing trends. The modeling technique of rolling kinematic joints with high nonlinearity can directly influence the accuracy and efficiency of prediction. Existing literature replicates the nonlinear static and dynamic characteristics considering the rolling element contact interface and proposes the theoretical modeling approach for the feed drives. However, there is a lack of systematic literature surveys. This paper reviews the current progress placed at the nonlinear analytical model of rolling kinematic joints, including ball screw feed drives, recirculating linear guideways, and ball screws. Advanced investigations on nonlinear dynamic stiffness and vibration response associated with ball screw feed drives are covered. Specifically, for linear guideways and ball screws, the stiffness and load distribution models can be divided into two categories: with and without consideration of the component structural deformations. Moreover, the corresponding detailed modeling process is introduced. The time-dependent modeling principle highlighting the recirculation motion of rolling elements is summarized, and friction and wear behavior is briefly discussed. The paper ends with the current research advancement and scarcity and recommends promising modeling tendencies. Particularly, the modeling tendencies require integrated model research on ball screw feed drives considering the more detailed nonlinear joint. Moreover, a fusion of multi-physics parameters is expected to achieve the high-fidelity mechanical model of key structural components for intelligent manufacturing demand.</p></div>","PeriodicalId":14011,"journal":{"name":"International Journal of Machine Tools & Manufacture","volume":"188 ","pages":"Article 104021"},"PeriodicalIF":14.0,"publicationDate":"2023-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49886143","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}

{"title":"New precision electroforming process for the simultaneous improvement of thickness uniformity and microstructure homogeneity of wafer-scale nanotwinned copper arrays","authors":"Xiaofei Zhan,&nbsp;Chunjian Shen,&nbsp;Zengwei Zhu,&nbsp;Di Zhu","doi":"10.1016/j.ijmachtools.2023.104006","DOIUrl":"https://doi.org/10.1016/j.ijmachtools.2023.104006","url":null,"abstract":"<div><p>Nanotwinned (nt) Cu has received much attention because of its superior mechanical and electrical properties, but only a few production processes can yield nt-Cu parts with uniform thickness and a homogeneous microstructure on the wafer scale. To solve this problem, a new precision electroforming process is proposed that combines auxiliary cathodes with pulse reverse current (PRC) electroforming, which provides a synergistic effect to increase the homogeneity of the thickness and a nanoscale twin structure. As a practical example of the proposed process, 4-inch nt-Cu lamina arrays were fabricated and numerically modeled to probe into the synergistic mechanisms. The intrinsic correlations among the array element spacing, current waveform, and main forms of thickness nonuniformity were determined. In addition, the effects of the processing parameters on the microstructural evolution and microhardness of the nt-Cu arrays were analyzed. The results indicated that such a significant improvement in thickness uniformity and microstructure homogeneity were due to the auxiliary-cathode/PRC combination, which enables maximization of the PRC leveling efficiency by inducing a uniform current distribution; this effectively ensures that the microstructures are uniform across all laminae on the wafer scale. Additionally, thick nt-Cu deposited on the current-crowding regions was preferentially stripped during the application of reverse current. This alleviates the adverse effects of the current redistribution resulting from the auxiliary cathode on the thickness uniformity of the laminae and offers additional possibilities for homogeneous growth of nt-Cu. The new precision electroforming process has significant potential to produce wafer-scale components with uniform thickness and specific microstructures.</p></div>","PeriodicalId":14011,"journal":{"name":"International Journal of Machine Tools & Manufacture","volume":"187 ","pages":"Article 104006"},"PeriodicalIF":14.0,"publicationDate":"2023-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49862597","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}