Additive manufacturing最新文献

{"title":"Abnormal aging behaviors induced by high-density dislocations for an ultra-high-strength titanium alloy prepared by laser-directed energy deposition","authors":"Junwei Yang ,&nbsp;Haibo Tang ,&nbsp;Yansong Zhang ,&nbsp;Yihe Zhang ,&nbsp;Yanyan Zhu ,&nbsp;Bingsen Liu ,&nbsp;Zhuodan Cui","doi":"10.1016/j.addma.2024.104559","DOIUrl":"10.1016/j.addma.2024.104559","url":null,"abstract":"<div><div>Additively manufactured high-strength titanium alloys generally possess equal strength and lower plasticity compared to wrought alloys owing to the different microstructures formed in the aging treatment. To examine the formation mechanism of these microstructures, an ultra-high-strength titanium alloy TB18(Ti-4.2Al-5V-5Cr-5Mo-1Nb) was prepared by laser direct energy deposition (LDED) and forging respectively, and the aging behaviors and microstructures were characterized and compared in depth. It is found that during aging, the precipitation of the LDEDed alloy is 1–2 h earlier than that of the wrought alloy, and precipitates primarily form at the reticular sub-grain boundaries. Fine short-rod α laths then form inside the sub-grains due to the inhibition of the reticulations. The sub-grain boundaries in LDEDed alloy are generated due to the local deformation and recovery of the inter-dendritic zone rich of Cr and O atoms and show high thermal stability in the solution treatment, which differs from that of the wrought alloys. These boundaries possess a dislocation density several times higher than that of the inner-grain zones and promote the prior precipitation of α laths with Type 2 orientations at the early stage of aging. In the tensile test of the aged alloys, the dislocations in the LDEDed alloy pile up at the α/β interface, which can cause stress concentration and damage the plasticity.</div></div>","PeriodicalId":7172,"journal":{"name":"Additive manufacturing","volume":"95 ","pages":"Article 104559"},"PeriodicalIF":10.3,"publicationDate":"2024-09-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142664055","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":"Fabrication of customized microneedle with high 3D capability and high structural precision","authors":"Zhaolun Chen ,&nbsp;Zhi Wang ,&nbsp;Lan Jiang ,&nbsp;Weina Han ,&nbsp;Zhuo Zhao ,&nbsp;Libo Ren ,&nbsp;Lingtao Zhang ,&nbsp;Jianhui Jiang ,&nbsp;Pei Zuo","doi":"10.1016/j.addma.2024.104509","DOIUrl":"10.1016/j.addma.2024.104509","url":null,"abstract":"<div><div>Advanced 3D fabrication techniques are essential for the processing of 3D devices, which mainly focusing on excellent 3D fabrication capability and high structural precision. Although 3D printing technology allows for the creation of complex 3D structures with extensive customization, it faces notable challenges in achieving precise micro/nanostructures within materials due to incomplete resin curing bonds. Here, we propose integrating projection micro-stereolithography (PμSL) with femtosecond (fs) laser Bessel beam drilling to create 3D structures with advanced customization, precise structures (including size accuracy and aspect ratio), and efficient processing. Starting with the drilling process using Bessel beams, we have achieved micro-holes with a diameter of approximately 1μm and the aspect ratio reached 1017:1 on 3D printed items by regulating the transparency and elasticity of the products. Furthermore, we have applied this technology to produce tailor-made microneedles, including slanted-tip microneedles and porous microneedles, demonstrating its ability for extensive, efficient micro-hole processing with a peak drilling speed of 200,000 holes per second. This technology offers an innovative approach to creating three-dimensional devices with intricate cavity structures, and its impressive processing capabilities suggest potential for broad industrial implementation.</div></div>","PeriodicalId":7172,"journal":{"name":"Additive manufacturing","volume":"95 ","pages":"Article 104509"},"PeriodicalIF":10.3,"publicationDate":"2024-09-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142571324","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":"Impact of melt pool geometry variability on lack-of-fusion porosity and fatigue life in powder bed fusion-laser beam Ti–6Al–4V","authors":"Justin P. Miner ,&nbsp;Austin Ngo ,&nbsp;Christian Gobert ,&nbsp;Tharun Reddy ,&nbsp;John J. Lewandowski ,&nbsp;Anthony D. Rollett ,&nbsp;Jack Beuth ,&nbsp;Sneha Prabha Narra","doi":"10.1016/j.addma.2024.104506","DOIUrl":"10.1016/j.addma.2024.104506","url":null,"abstract":"<div><div>Powder bed fusion-laser beam (PBF-LB) parts experience a significant decline in fatigue performance when process-induced defects are present. In this work, a decline in 4-point bend fatigue life was observed in PBF-LB Ti–6Al–4V coupons fabricated at constant power with increasing scanning velocity and which underwent subsequent stress relief and surface machining. Specifically, the presence of pores that resemble lack-of-fusion (LoF) and a decline in fatigue life were observed at scanning velocities lower than that expected from prior published work. It was hypothesized that this unexpected presence of LoF pores resulted from melt pool geometry variability that was not considered in prior work when the LoF criterion was implemented. Further, these pores can be small in size and infrequent in their occurrence when the melt pool geometry variability is not severe. Such sparse pores are challenging to characterize using conventional 2D characterization methods. This work leverages tall and narrow coupon geometry and high-resolution X-ray micro computed tomography (X-<span><math><mi>μ</mi></math></span>CT) to capture LoF porosity. The results show that a modified melt pool overlap-based LoF criterion considering melt pool geometry variability captures the unexpected occurrence of LoF pores observed in X-<span><math><mi>μ</mi></math></span>CT. In addition, the LoF percent metric displays a strongly negative correlation with fatigue performance. The insights from this work provide guidance on characterizing melt pool geometry variability across scan lines to systematically evaluate processing parameters that generate LoF pores, which, in turn, could lower fatigue performance.</div></div>","PeriodicalId":7172,"journal":{"name":"Additive manufacturing","volume":"95 ","pages":"Article 104506"},"PeriodicalIF":10.3,"publicationDate":"2024-09-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142592605","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}

{"title":"Structural build-up of 3D printed earth by drying","authors":"Mahan Motamedi ,&nbsp;Romain Mesnil ,&nbsp;Anh-Minh Tang ,&nbsp;Jean-Michel Pereira ,&nbsp;Olivier Baverel","doi":"10.1016/j.addma.2024.104492","DOIUrl":"10.1016/j.addma.2024.104492","url":null,"abstract":"<div><div>In recent years, the potential of earth materials in construction has emerged as a sustainable pathway, offering environmental benefits compared to traditional methods. When used in raw form, earth materials can be recycled at the end of a building life, reducing construction waste. In parallel, integrating additive manufacturing into the architecture, engineering, and construction (AEC) sector has brought about a shift in construction dynamics, combining efficiency with precision. This paper bridges the study of 3D printing with earth-based fresh mortars, emphasising the capabilities of the “Forced Layer Drying” (FLD) technique in the additive manufacturing process to increase the mechanical performance of the printing mortar.</div><div>This paper begins by defining the requisite rheological properties for successful 3D printing. A chosen material for this paper is Speswhite kaolin. An instrumental aspect of our research is exploring an established model for the drying rate of saturated porous media, such as earth and concrete, and its application to predict the evaporation rate of saturated earth-based mortar in 3D printing with forced drying conditions. The Wind Tunnel experiment was conducted to validate this model, examining the interplay of airflow speed and temperature on the evaporation rate. Further deepening this study, the soil water content and undrained shear strength are correlated, specifically based on models derived from oedometer geotechnical standard tests. This facilitated a comprehensive understanding of porous earth-based materials in various moisture scenarios. Our findings confirm that airflow, temperature, and the geometry of the printed object play instrumental roles in affecting evaporation rate, consequent mechanical performance, and structural build-up of the material. The paper wraps up by offering insights into the practical application of 3D printing using earth-based mortars, with a special focus on FLD technique.</div></div>","PeriodicalId":7172,"journal":{"name":"Additive manufacturing","volume":"95 ","pages":"Article 104492"},"PeriodicalIF":10.3,"publicationDate":"2024-09-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142593203","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 dynamic volumetric heat source model for laser additive manufacturing","authors":"John Coleman ,&nbsp;Gerald L. Knapp ,&nbsp;Benjamin Stump ,&nbsp;Matt Rolchigo ,&nbsp;Kellis Kincaid ,&nbsp;Alex Plotkowski","doi":"10.1016/j.addma.2024.104531","DOIUrl":"10.1016/j.addma.2024.104531","url":null,"abstract":"<div><div>Melt pool scale models of laser powder bed fusion (LPBF) offer insights into the process-structure-property relationships in additive manufacturing (AM). These models often neglect physical phenomena such as vapor cavity formation and fluid mechanics to reduce computational demands. Instead, volumetric heat source models are used to represent the effects that these phenomena have on the predicted melt pool dimensions. Generally, the dimensions and effective absorption of the volumetric heat source are calibrated to reproduce melt pool dimensions observed in metallographic cross sections taken from single-track experiments on bare plate. However, the transient nature of LPBF often deviates the melt pool dimensions from the assumed steady-state conditions of single-track experiments, motivating the need for a volumetric heat source model that more generally considers the dynamic relationship between melt pool shape and laser-material interactions. Here, we introduce a two-parameter volumetric heat source model that integrates several existing models into a generalized mathematical expression, providing independent control over the radial heat distribution via the parameter <span><math><mi>k</mi></math></span> and the volumetric shape of the heat source via the parameter <span><math><mi>m</mi></math></span>. This parameterization enables the calibration of melt pool shape predictions through simultaneous adjustment of these parameters, while keeping the radial heat source dimensions consistent with the experimental spot size (D4σ) and constraining the heat source depth and absorption to physically derived expressions for cavities. Consequently, the proposed volumetric heat source model adapts to changes in the local melt pool conditions due to scanning strategy and part geometry by dynamically adjusting the heat source depth and absorption. We demonstrate the capabilities of the proposed model through comparisons with a collection of experiments from the Additive Manufacturing Benchmark (AMBench).</div></div>","PeriodicalId":7172,"journal":{"name":"Additive manufacturing","volume":"95 ","pages":"Article 104531"},"PeriodicalIF":10.3,"publicationDate":"2024-09-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142663888","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":"Scalability enhancement in projection-based 3D printing through optical expansion","authors":"Minsung Kim,&nbsp;Gilseon Yoo,&nbsp;Bogeun Kim,&nbsp;Yeongjun Song,&nbsp;Brian J. Lee","doi":"10.1016/j.addma.2024.104511","DOIUrl":"10.1016/j.addma.2024.104511","url":null,"abstract":"<div><div>In the rapidly evolving field of additive manufacturing (AM), projection-based 3D printing emerges as a transformative solution to traditional manufacturing constraints. This study introduces a novel approach in projection-based 3D printing, utilizing a unique “infinity-corrected optical system” inspired by microscopy technology. The advanced optical system allows 3D printing to achieve performance comparable to multiple UV projectors while utilizing only a single UV light engine, offering a cost-efficient solution. This method enhances the print speed and expands the printable area, while maintaining the print resolution, addressing the shortcomings in existing 3D printing techniques. By employing a single UV projector along with integrated fixed optical components, this system offers a stable, reliable, and economically viable printing process. This innovation marks a pivotal advancement in mass production, mass customization, and large-area 3D printing, effectively bridging current technological gaps and paving the way for advanced manufacturing systems.</div></div>","PeriodicalId":7172,"journal":{"name":"Additive manufacturing","volume":"95 ","pages":"Article 104511"},"PeriodicalIF":10.3,"publicationDate":"2024-09-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142571325","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}

{"title":"Texture optimization based on crystal plasticity modeling to improve strength and control anisotropy in heat treated additive manufactured Al-Mn-Sc alloy","authors":"Yuan Gao,&nbsp;Xiaobin Guo","doi":"10.1016/j.addma.2024.104524","DOIUrl":"10.1016/j.addma.2024.104524","url":null,"abstract":"<div><div>Heat treatment is a common method used to control mechanical properties, but its effects on strength and anisotropy remain uncertain. Therefore, studying the microstructural evolution resulting from heat treatment and its impact on strength is essential for optimizing heat treatment processes to reduce anisotropy. While the Hall<img>Petch relation has demonstrated the influence of grain size on yield strength, the effect of grain orientation on strength is still unclear and does not adequately predict the anisotropy of strength. In this work, the relationship between grain orientation and strength anisotropy is elucidated through crystal plasticity modeling on the basis of experimental results. Two-dimensional geometry models were constructed from the electron back-scattered diffraction results of additive manufactured (AMed) and heat-treated samples. Crystal plasticity modeling was applied along various directions to assess the influence of texture on the anisotropy of strength. The modeling results indicated that the presence of grains with &lt;100&gt; and &lt;102&gt; orientations in the AMed Al-Mn-Sc alloy and of grains with &lt;112&gt; orientations in the heat-treated state are detrimental to the yield strength. To increase the yield strength and maintain the anisotropy of the yield strength within a 5 % range, the &lt;100&gt; texture was optimized to 43 % &lt;110&gt; and 57 % &lt;113&gt; textures. Consequently, the yield strength increased by 11 MPa along the building direction and 21 MPa along the transverse direction. This optimization approach effectively enhances the strength and reduces the anisotropy in AMed alloys under various conditions.</div></div>","PeriodicalId":7172,"journal":{"name":"Additive manufacturing","volume":"95 ","pages":"Article 104524"},"PeriodicalIF":10.3,"publicationDate":"2024-09-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142578997","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":"Effect of Al(OH)3 on the properties of silica-based ceramic cores prepared by laser powder bed fusion combined with vacuum infiltration","authors":"Heng Liu ,&nbsp;Ren-Zhong Zhang ,&nbsp;Jia-Min Wu ,&nbsp;Wei-Kang Li ,&nbsp;Shi-Xiang Zhou ,&nbsp;Jie Zhang ,&nbsp;Wen Zheng ,&nbsp;Chun-Ze Yan ,&nbsp;Shi-Feng Wen ,&nbsp;Chun-Sheng Ye ,&nbsp;Yu-Sheng Shi ,&nbsp;Chao-Yue Chen ,&nbsp;Zhong-Ming Ren","doi":"10.1016/j.addma.2024.104527","DOIUrl":"10.1016/j.addma.2024.104527","url":null,"abstract":"<div><div>Silica-based ceramic cores, with low coefficients of thermal expansion, low sintering temperatures, and excellent acid and alkali leaching capabilities, are essential materials for the production of hollow blades. However, their mechanical properties are suboptimal, and they present various processing challenges. In this study, silica-based ceramic cores were prepared using a combination of vacuum infiltration (VI) and laser powder bed fusion (LPBF) techniques. Al(OH)₃ was employed as a mineralizer to enhance the post-sintering mechanical properties and improve the efficiency of the vacuum infiltration process, thereby enhancing the overall performance of the silica-based ceramic cores. The VI process facilitated the penetration of nano-SiO₂ into the samples, increasing their density and promoting the formation of cristobalite during sintering at 1225°C. Additionally, the Al(OH)₃ powder, through pyrolysis into Al₂O₃ during sintering, reduced microcracks, inhibited excessive cristobalite transformation, and improved the VI process, resulting in enhanced room-temperature flexural strength. By optimizing the Al(OH)₃ content and the VI process, significant improvements in the microstructure and properties of the silica-based ceramic cores were achieved. After three rounds of vacuum infiltration and the addition of 4 wt% Al(OH)₃, the samples exhibited a high-temperature creep of 0.17 mm, with flexural strengths of 15.23 MPa at room temperature and 23.55 MPa at high temperature.</div></div>","PeriodicalId":7172,"journal":{"name":"Additive manufacturing","volume":"95 ","pages":"Article 104527"},"PeriodicalIF":10.3,"publicationDate":"2024-09-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142592603","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":"Laser assisted cold spray of aluminum alloy 6061: Experimental results","authors":"Samuel Boese ,&nbsp;Aidan Sevinsky ,&nbsp;Ahmad Nourian-Avval ,&nbsp;Ozan Özdemir ,&nbsp;Sinan Müftü","doi":"10.1016/j.addma.2024.104548","DOIUrl":"10.1016/j.addma.2024.104548","url":null,"abstract":"<div><div>Laser-assisted cold spray (LACS) is investigated for its potential to improve the mechanical properties of cold spray deposits made by using nitrogen as the gas that carries the powder. High strength cold spray deposits are typically achieved by using the more expensive and resource limited helium. In this work, a laser collocated with the spray spot was used in nitrogen CS operations and the porosity, adhesion strength, tensile strength, and fatigue performance of aluminum alloy 6061 (Al6061) were examined. Using the laser improved all the performance metrics. By increasing the spray spot temperature from 180°C to 455°C, the porosity of the deposit reduced to 0.24 % from 1.73 %. The adhesion strength was increased from 18.4 MPa to 76.6 MPa. The tensile strength was increased from 34.3 MPa to 167.6 MPa, and the elongation was increased from 0.07 % to 15.58 %. It was shown that using laser heating during deposition increases the residual stress in the deposit, but its effects can be counteracted by using a hotplate beneath the substrate. Fatigue testing showed that fatigue performance was largely driven by tensile strength. These results are discussed in the context of in-situ temperature data and metallographic analysis. Analysis indicates these improvements are due to the combined effects of material softening, improved bonding between particles, and various heat treatment modalities.</div></div>","PeriodicalId":7172,"journal":{"name":"Additive manufacturing","volume":"95 ","pages":"Article 104548"},"PeriodicalIF":10.3,"publicationDate":"2024-09-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142663895","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":"Surface roughness and pore evolutions in multi-layer laser powder bed fusion of extra-low interstitial Ti-5Al-2.5Sn powder: A numerical study","authors":"Yifu Long ,&nbsp;Xizhong An ,&nbsp;Ju Wang ,&nbsp;Meng Li ,&nbsp;Qiong Wu ,&nbsp;Chuanning Jiang ,&nbsp;Junfei Liu ,&nbsp;Dechun Ren ,&nbsp;Haibin Ji ,&nbsp;Shujun Li ,&nbsp;Xing Zhang","doi":"10.1016/j.addma.2024.104530","DOIUrl":"10.1016/j.addma.2024.104530","url":null,"abstract":"<div><div>In this paper, the three-dimensional discrete element method (DEM) and computational fluid dynamics (CFD) coupled approach was used to numerically reproduce the whole process of laser powder-bed-fusion (L-PBF) additive manufacturing (AM) of extra-low interstitial (ELI) Ti-5Al-2.5Sn powder. The effects of key parameters such as scanning strategy and hatch spacing (<em>h</em>) on the surface roughness (<em>Ra</em>) and pores during multi-layer printing are systematically investigated by characterizing the molten pool characteristics and thermal behavior upon laser motion; and the melt volume in this duration is quantified by the volume of fluid (VOF) method to demonstrate inter-layer interactions. The results show that <em>Ra</em> can be categorized according to the scanning directions. Along the scanning direction, the <em>Ra</em> is affected by the heat accumulation effect and increases as the <em>h</em> decreases. In this case, the <em>Ra</em> caused by the Marangoni effect can be reduced by increasing the melt volume at the end of the track through the layer rotation. The <em>Ra</em> perpendicular to the scanning direction is caused by the ripple-like surface formed by track overlap and decreases as the <em>h</em> decreases. For defects, the pores formed by shrinkage due to insufficient melting or by lack of fusion (LoF) due to incomplete track overlap decrease with the decrease of <em>h</em>. The LoF pores caused by weak inter-layer metallurgical bonding are affected by the surface morphology of the previous layer, which is increased as the <em>h</em> increases. The layer rotation can also reduce such LoF pores. On this basis, a quality control chart suitable for actual production is established.</div></div>","PeriodicalId":7172,"journal":{"name":"Additive manufacturing","volume":"95 ","pages":"Article 104530"},"PeriodicalIF":10.3,"publicationDate":"2024-09-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142663989","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}