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| 1 | A Multiscale Understanding of the Thermodynamic and Kinetic Mechanisms of Laser Additive Manufacturing显示文摘 | Dongdong Gu Chenglong Ma Mujian Xia Donghua Dai Qimin Shi | 2017 | Engineering2017，3，5： | 15 |
| 2 | Comprehensive eco-environmental effects of the shelter-forest ecological engineering along the Tarim Desert Highway显示文摘In this work, we report a comprehensive study about the eco-environmental effects of the shelter forest along the Tarim Desert Highway, including the effects on aeolian environment, soil, micro-climate, biodiversity, and groundwater. The results show that: (1) The movement of windblown sand near the ground surface was affected by the shelter forest. The wind speed and sediment transport rate in the shelter forest decreased by 64%―80% and 87.45%―99.02%, respectively. In addition, there were also significant changes in the sand flux structure, the sand grain size, and the deflation and deposition on the ground surface. (2) Compared to the natural mobile sand, the soil bulk density in the forest area decreased while the total salt content, the total porosity, and the water content increased. In addition, the soil fertility was significantly improved in the forest area, and showed the 'first rapid, then slow' variation pattern. (3) The shelter forest showed positive effects on the micro-climate. Within the 6 m height above the ground, the air temperature in the shelter forest at different heights was lower than that in the mobile sand, while the air humidity was higher, while, the soil temperature was also lower in the shelter forest than mobile sand. (4) The number of soil microbial species increased significantly with the improvement of habitat in the shelterbelt. However, the population of different species was not distributed evenly across the surveyed area. (5) Currently, no significant effects of groundwater-pumping and forest-irrigation water have been found on the groundwater level and its salinity. The variation amplitude of both groundwater level and salinity was at the level of centimeters and 1g/L, respectively. No obvious variation trend has been observed. | LEI JiaQiang LI ShengYu JIN ZhengZhong FAN JingLong WANG HaiFeng FAN DongDong ZHOU HongWei GU Feng QIU YongZhi XU Bo | 2008 | Chinese Science Bulletin2008，53，S2： | 14 |
| 3 | Selective laser melting 3D printing of Ni-based superalloy: understanding thermodynamic mechanisms显示文摘A mesoscopic model has been established to investigate the thermodynamic mechanisms and densification behavior of nickel-based superalloy during additive manufacturing/three-dimensional(3D) printing(AM/3DP)by numerical simulation, using a finite volume method(FVM). The influence of the applied linear energy density(LED) on dimensions of the molten pool, thermodynamic mechanisms within the pool, bubbles migration and resultant densification behavior of AM/3DP-processed superalloy has been discussed. It reveals that the center of the molten pool slightly shifts with a lagging of 4 lm towards the center of the moving laser beam. The Marangoni convection, which has various flow patterns, plays a crucial role in intensifying the convective heat and mass transfer, which is responsible for the bubbles migration and densification behavior of AM/3DP-processed parts. At an optimized LED of 221.5 J/m, the outward convection favors the numerous bubbles to escape from the molten pool easily and the resultant considerably high relative density of 98.9 % is achieved. However, as the applied LED further increases over 249.5 J/m, the convection pattern is apparently intensified with the formation of vortexes and the bubbles tend to be entrapped by the rotating flow within the molten pool, resulting in a large amount of residual porosity and a sharp reduction in densification of the superalloy. The change rules of the relative density and the corresponding distribution of porosity obtained by experiments are in accordance with the simulation results. | Mujian Xia Dongdong Gu Guanqun Yu Donghua Dai Hongyu Chen Qimin Shi | 2016 | Science Bulletin2016，61，13： | 13 |
| 4 | Classification and regionalization of the forming environment of windblown sand disasters along the Tarim Desert Highway显示文摘Through the systematic field survey and observations, the factor quantification as well as setting the criteria, the sand disaster-forming environment along the Tarim Desert Highway can be divided into four grades by the classification and regionalization based on fuzzy mathematics. The length of the regions with significant sand disaster accounted for 37.1% of the total highway length. Particularly, the area along the Tarim Desert Highway, based on the sand disaster-forming environment classification as well as the difference in the five basic landform units along the highway, combined with the difference of wind regime, can be divided into five regions, in which the length of the regions suffering severe sand damage occupied 64.3% of the total highway length. In addition, the index of disaster formation grade along the highway decreased from north to south, showing a repeated spatial pattern in small length scales. | LEI JiaQiang LI ShengYu FAN DongDong ZHOU HongWei GU Feng QIU YongZhi XU Bo LIU Shang DU WenYi YAN ZengHui WANG YongChang | 2008 | Chinese Science Bulletin2008，53，S2： | 11 |
| 5 | How does the motor relearning program improve neurological function of brain ischemia monkeys?显示文摘The motor relearning program can significantly improve various functional disturbance induced by ischemic cerebrovascular diseases. However, its mechanism of action remains poorly understood. In injured brain tissues, glial fibrillary acidic protein and neurofilament protein changes can reflect the condition of injured neurons and astrocytes, while vascular endothelial growth factor and basic fibroblast growth factor changes can indicate angiogenesis. In the present study, we induced ischemic brain injury in the rhesus macaque by electrocoagulation of the M1 segment of the right middle cerebral artery. The motor relearning program was conducted for 60 days from the third day after model establishment. Immunohistochemistry and single-photon emission CT showed that the numbers of glial fibrillary acidic protein-, neurofilament protein-, vascular endothelial growth factor- and basic fibroblast growth factor-positive cells were significantly increased in the infarcted side compared with the contralateral hemisphere following the motor relearning program. Moreover, cerebral blood flow in the infarcted side was significantly improved. The clinical rating scale for stroke was used to assess neurological function changes in the rhesus macaque following the motor relearning program. Results showed that motor function was improved, and problems with consciousness, self-care ability and balance function were significantly ameliorated. These findings indicate that the motor relearning program significantly promoted neuronal regeneration, repair and angiogenesis in the surroundings of the infarcted hemisphere, and improve neurological function in the rhesus macaque following brain ischemia. | Yong Yin Zhen Gu Lei Pan Lu Gan Dongdong Qin Bo Yang Jin Guo Xintian Hu Tinghua Wang Zhongtang Feng | 2013 | Neural Regeneration Research2013，8，16： | 9 |
| 6 | Effect of Trace Addition of Ceramic on Microstructure Development and Mechanical Properties of Selective Laser Melted AlSi10Mg Alloy显示文摘Selective laser melting(SLM)is an emerging additive manufacturing technology for fabricating aluminum alloys and aluminum matrix composites.Nevertheless,it remains unclear how to improve the properties of laser manufactured aluminum alloy by adding ceramic reinforcing particles.Here the effect of trace addition of TiB2 ceramic(1%weight fraction)on microstructural and mechanical properties of SLM-produced AlSi10Mg composite parts was investigated.The densification level increased with increasing laser power and decreasing scan speed.A near fully dense composite part(99.37%)with smooth surface morphology and elevated inter-layer bonding was successfully obtained.A decrease of lattice plane distance was identified by X-ray diffraction with the laser scan speed decreased,which implied that the crystal lattices were distorted due to the dissolution of Si and TiB2 particles.A homogeneous composite microstructure with the distribution of surface-smoothened TiB2 particles was present,and a small amount of Si particles precipitated at the interface between reinforcing particles and matrix.In contrast to the AlSi10Mg alloy,the composites showed a stabilized microhardness distribution.A higher ultimate tensile strength of 380.0 MPa,yield strength of 250.4 MPa and elongation of 3.43%were obtained even with a trace amount of ceramic addition.The improvement of tensile properties can be attributed to multiple mechanisms including solid solution strengthening,load-bearing strengthening and dispersion strengthening.This research provides a theoretical basis for ceramic reinforced aluminum matrix composites by additive manufacturing. | Yuxin Li Dongdong Gu Han Zhang Lixia Xi | 2020 | Chinese Journal of Mechanical Engineering2020，33，2： | 7 |
| 7 | Effects of laser scanning strategies on selective laser melting of pure tungsten显示文摘Three types of scanning strategies,including the chessboard scanning strategy,the zigzag scanning strategy and the remelting scanning strategy,were conducted to study the effects of scanning strategies on surface morphology,microstructure,mechanical properties and the grain orientation of selective laser melted pure tungsten.The results showed that the pores and cracks were main defects in SLM-processed tungsten parts.The pores could be eliminated using the remelting scanning strategy.However,the cracks seemed to be inevitable regardless of the applied scanning strategies.The microstructures of SLM-processed tungsten were columnar grains and showed strong epitaxial growth along the building direction.A compressive strength of 923 MPa with an elongation of 7.7%was obtained when the zigzag scanning strategy was applied,which was the highest among the three scanning strategies.By changing the scanning strategies,the texture of SLM-processed tungsten in the direction of processing could be changed. | Dongdong Gu Meng Guo Hongmei Zhang Yixuan Sun Rui Wang Lei Zhang | 2020 | International Journal of Extreme Manufacturing2020，2，2： | 6 |
| 8 | Materials creation adds new dimensions to 3D printing显示文摘Additive manufacturing(AM),interchangeably termed as3D printing(3DP),has been defined as one of the key technologies in the national development strategies of a number of countries around the world.America Makes,as the National Additive Manufacturing Innovation Institute,is the nation’s leading and collaborative partner in AM/3DP technology research,discovery,creation,and innovation,working efficiently to innovate and accelerate AM/3DP to increase America’s global manufacturing competitiveness(http://gffzzb38569dfd6524cc3s5wpn0kb0pc9o6wbx.ffgz.tsg.suse.edu.cn).German | Dongdong Gu | 2016 | Science Bulletin2016，61，22： | 6 |
| 9 | In uence of Particle Size on Laser Absorption and Scanning Track Formation Mechanisms of Pure Tungsten Powder During Selective Laser Melting显示文摘A three-dimensional laser absorption model based on ray tracing was established to describe the coupled interaction of a laser beam with particles in the powder layers of pure tungsten(W)material processed by selective laser melting(SLM).The influence of particle size on the powder-to-laser absorptivity and underlying absorption behavior was investigated.An intrinsic relationship between the absorption,distribution of absorbed irradiance within the powder layers,and surface morphology and geometric characteristics(e.g.,contact angle,width and height of tracks,and remelted depth)of the laser scanning tracks is presented here.Simulation conclusions indicate that the absorptivity of the powder layers considerably exceeds the single powder particle value or the dense solid material value.With an increase in particle size,the powder layer absorbs less laser energy.The maximum absorptivity of theWpowder layers reached 0.6030 at the particle size of 5 lm.The distribution of laser irradiance on the particle surface was sensitive to particle size,azimuthal angle,and the position of the powder particles on the substrate.The maximum irradiance in the powder layers decreased from 1.117×10^–3 to 0.85×10^–3W·μm^-2 and the contour of the irradiance distribution in the center of the irradiated area gradually contracted when the particle size increased from 5 to 45 lm.An experimental study on the surface morphologies and cross-sectional geometric characteristics of SLM-fabricated W material was performed,and the experimental results validated the mechanisms of the powder-to-laser-absorption behavior that were obtained in simulations.This work provides a scientific basis for the application of the ray-tracing model to predict the wetting and spreading ability of melted tracks during SLM additive manufacturing in order to yield a sound laser processability. | Jiayao Zhang Dongdong Gu Ying Yang Hongmei Zhang Hongyu Chen Donghuai Dai Kaijie Lin | 2019 | Engineering2019，5，4： | 6 |
| 10 | Influence of additive multilayer feature on thermodynamics, stress and microstructure development during laser 3D printing of aluminum-based material显示文摘A transient three dimensional model for describing the temperature behavior,thermo-capillary convection,microstructure evolution and the resultant mechanical properties during selective laser melting of Al N/Al Si10 Mg composite is proposed.The powder-solid transformation,temperature dependent physical properties and the preservation of the heat are taken into account.The effect of the additive manufacturing multilayer feature on the molten pool dynamics,cooling rate,crystal size,microstructure morphology,micro-hardness and types of the residual stress has been investigated.It shows that the operating temperature and the thermo-capillary convection obtained within the molten pool generally increases as the processing multilayers are successively added,while the thermal effect depth is negatively reduced.The preferential direction of the heat diffusion generally changes from a downward pattern,then to the slightly strengthened horizontal direction and finally to a typically horizontal one for various deposited layers being processed.Therefore,the microstructure of the solidified part along the building direction(Region I to Region V) undergoes an interesting transformation:directional columnar cellular microstructure,crosswise-extended cellular microstructure,refined cellular microstructure,fragmentation microstructure and the coarse cellular microstructure.The tensile stress and the compressive stress are comprehensively obtained within the finally solidified layers,significantly influencing the microhardness. | Donghua Dai Dongdong Gu Reinhart Poprawe Mujian Xia | 2017 | Science Bulletin2017，62，11： | 6 |
| 11 | Laser Cladding Fe-Al-Cr Coating with Enhanced Mechanical Properties显示文摘Dense Fe-Al-Cr coatings with approximately 50 μm in thickness are successfully prepared on the 1045 carbon steel substrates via a laser cladding process. Proper Cr content(5 at% Cr) will lead to decrease in the melting point, and improves the viscosity of the liquid and the nucleation rate of the molten pool, leading to refining grains of the solidification structure. As a result, the Fe-29 Al-5 Cr laser cladding layer exhibits the best hardness, plasticity properties, and wear resistance at 400 °C. Excessive Cr for the Fe-29 Al-7.5 Cr coating leads to the formation of Cr2 Al in the grain boundaries and thermal vacancies during the solidification process, resulting in inferior mechanical properties and poor tribological behavior. | 罗西希 姚正军 ZHANG Pingze GU Dongdong CHEN Yu | 2019 | Journal of Wuhan University of Technology(Materials Science)2019，34，5： | 4 |
| 12 | Anisotropic corrosion resistance of TiC reinforced Ni-based composites fabricated by selective laser melting显示文摘Electrochemical measurements on three planes of TiC/Inconel 718 composites fabricated by selective laser melting(SLM) were performed to study the corrosion property. The results showed that the YZplane with dense and fine columnar structures possessed high microhardness and superior corrosion resistance in 3.5 wt% NaCl solution. For the XZ-plane, a decreased anti-corrosion property was observed owing to its inhomogeneous microstructures. While the XY-plane with large irregular pores and clustered ring-like structures was more susceptible to corrosion compared with the other two planes. Comparative analysis suggested that the anisotropic corrosion behaviors were significantly dependent on the surface defects, microstructure characteristics and added reinforcements. | Hongmei Zhang Dongdong Gu Lixia Xi Han Zhang Mujian Xia Chenglong Ma | 2019 | Journal of Materials Science & Technology2019，35，6： | 4 |
| 13 | Selective Laser Melting of in--situ TiC/Ti5Si3 composites with novel reinforcement architecture and elevated performance显示文摘 | Gu Dongdong Hagedom Y Meiners W | 2011 | Surface and Coatings Technology2011，205，11： | 1 |
| 14 | Preparation of TiN-Ti5Si3 in-situ composites by Selective Laser Melting显示文摘 | Dongdong Gu Yifu Shen Zhijian Lu | 2009 | Materials Letters2009，63，： | 1 |
| 15 | Thermodynamics of Molten Pool Predicted by Computational Fluid Dynamics in Selective Laser Melting of Ti6Al4V:Surface Morphology Evolution and Densification Behavior显示文摘The three-dimensional physical model of the randomly packed powder material irradiated by the laser beam was established,taking into account the transformation of the material phase,the melt spreading and the interaction of the free surface of the molten pool and the recoiling pressure caused by the material evaporation during the selective laser melting.Influence of the processing parameters on the thermal behavior,the material evaporation,the surface morphology and the densification behavior in the connection region of the molten pool and the substrate was studied.It was shown that the powder material underwent the transformation from the partial melting state to the complete melting state and finally to the overheating state with the applied laser energy density increasing from 167 J/mm^(3) to 417 J/mm^(3).Therefore,the solidified track ranged from the discontinuous tracks with the rough surface to the continuous tracks with residual porosities,then to the continuous and dense tracks and terminally to the fluctuated tracks with the increase in the laser energy density.Meanwhile,the laser energy effect depth was maintained the positive relationship with the laser energy density.The vortex velocity obtained in the free surface of the molten pool towards to the rear region in the opposite laser scan direction promoted the melt convection to the edge region of the molten pool as the laser energy density was higher than 277 J/mm^(3),demonstrating the efficient energy dissipation from the center of the irradiation region to the whole part of the molten pool and the attendant production of the sufficient melt volume.Therefore,the efficient spreading of the molten pool and the metallurgical bonding ability of the melt with the substrate was obtained at the optimized laser energy density of 277 J/mm^(3).However,the severe material evaporation would take place as the melt was overheated,resulting in the formation of the residual pores and poor surface quality. | Donghua Dai Dongdong Gu Qing Ge Chenglong Ma Xinyu Shi Han Zhang | 2020 | Computer Modeling in Engineering & Sciences2020，，9： | 1 |
| 16 | Balling phenomena during direct laser sintering of multi-component Cu-based metal powder显示文摘 | Dongdong Gu Yifu Shen | 2006 | Journal of Alloys and Compounds2006，，1： | 1 |
| 17 | Influence of processing parameters on particulate dispersion in direct laser sintered WC-Cop/Cu MMCs显示文摘 | Gu Dongdong Shen yifu | 2008 | International Journal of Refractory Metals and Hard Materials2008，26，5： | 1 |
| 18 | Growth morphologies and mechanisms of TiC grains during Selective Laser Melting of Ti–Al–C composite powder显示文摘 | Dongdong Gu Yifu Shen Guangbin Meng | 2009 | Materials Letters2009，，29： | 1 |
| 19 | Laser Additive Manufacturing of Bio-inspired Metallic Structures显示文摘High-performance/multifunctional metallic components primarily determine the service performance of equip-ment applied in the aerospace,aviation,and automobile industries.Organisms have developed structures with specific properties over millions of years of natural evolution,thereby providing inspiration for the design of high-performance structures to satisfy the increasing demands of modern industries.From the perspective of manufacturing,the ability of conventional processing technologies is inadequate for fabricating these complex structural configurations.By contrast,laser additive manufacturing(AM)is an effective method for fabricating complex metallic bio-inspired structures owing to its layer-by-layer deposition advantage.Herein,recent devel-opments in the laser AM of bio-inspired cellular,plate,and truss structures,as well as the materials used in laser AM for bio-inspired printing are briefly reviewed.The organisms being imitated include butterfly,Norway spruce,mantis shrimp,beetle,and water spider,which expand the diversity of multifunctional structures for laser AM.The mechanical properties and functions of laser-AM-processed bio-inspired structures are discussed.Additionally,the challenges,possible outcomes,and directions of utilizing laser AM technology to fabricate high-performance/multifunctional metallic bio-inspired structures in the future are outlined. | Jiankai Yang Dongdong Gu Kaijie Lin Yicha Zhang Meng Guo Luhao Yuan Han Zhang Hongmei Zhang | 2022 | Chinese Journal of Mechanical Engineering(Additive Manufacturing Frontiers)2022，1，1： | 1 |
| 20 | Interfacial-Strain-Induced Structural and Polarization Evolutions in Epitaxial Multiferroic BiFeO_3(001) Thin Films显示文摘Varying the film thickness is a precise route to tune the interfacial strain to manipulate the properties of the multiferroic materials.Here,to explore the effects of the interfacial strain on the properties of the multiferroic BiFeO_3films,we investigated thickness-dependent structural and polarization evolutions of the BiFeO_3 films.The epitaxial growth with an atomic stacking sequence of BiO/TiO_2 at the interface was confirmed by scanning transmission electron microscopy.Combining X-ray diffraction experiments and first-principles calculations,a thickness-dependent structural evolution was observed from a fully strained tetragonality to a partially relaxed one without any structural phase transition or rotated twins.The tetragonality(c/a) of the BiFeO_3 films increases as the film thickness decreases,while the polarization is in contrast with this trend,and the size effect including the depolarization field plays a crucial role in this contradiction in thinner films.These findings offer an alternative strategy to manipulate structural and polarization properties by tuning the interfacial strain in epitaxial multiferroic thin films. | 郭海中 Ruiqiang Zhao Kui-juan Jin Lin Gu Dongdong Xiao Zhenzhong Yang Xiaolong Li Le Wang Xu He Junxing Gu Qian Wan Can Wang Huibin Lu Chen Ge Meng He Guozhen Yang | 2015 | 功能材料信息2015，12，3： | 1 |
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