Oil film vortex severely reduces the stability of hydrostatic bearings. A solid-liquid interface with drag and slip properties can weaken the oil film vortex of the bearing. Here, a combined picosecond laser ablation ...Oil film vortex severely reduces the stability of hydrostatic bearings. A solid-liquid interface with drag and slip properties can weaken the oil film vortex of the bearing. Here, a combined picosecond laser ablation and chemical modification method is proposed to prepare surfaces with microbulge array structure on 6061 aluminum alloy substrates. Because of the low surface energy of the perfluorododecyltriethoxysilane modification and the bulge geometry of the microbulge array structure, the surface shows excellent superhydrophobicity. The optimum contact angle in air for water is 164°, and that for oil is 139°. Two surfaces with “lotus-leaf effect” and “rose-petal effect” were obtained by controlling the processing parameters. The drag reduction properties of superhydrophobic surfaces were systematically investigated with slip lengths of 22.26 and 36.25 μm for deionized water and VG5 lubricant, respectively. In addition, the superhydrophobic surface exhibits excellent mechanical durability and thermal stability. The proposed method provides a new idea for vortex suppression in hydrostatic bearings and improves the stability of bearings in high-speed operation.展开更多
Weld seam detection is an important part of automated welding.At present,few studies have been conducted on annular weld seams,and a lot of defects exist in the point cloud model of the tube sheet obtained by RGB-D ca...Weld seam detection is an important part of automated welding.At present,few studies have been conducted on annular weld seams,and a lot of defects exist in the point cloud model of the tube sheet obtained by RGB-D cameras and photography methods.Aiming at the above problems,this paper proposed an annular weld seam detection network named WeldNet where a voxel feature encoding layer was adaptively improved for annular weld seams,the sparse convolutional network and region proposal network(RPN)were used to detect annular weld seam position,and an annular weld seam detection loss function was designed.Further,an annular weld seam dataset was established to train the network.Compared with the random sampling consistency(RANSAC)method,WeldNet has a higher detection accuracy,as well as a higher detection success rate which has increased by 23%.Compared with U-Net,WeldNet has been proven to achieve a better detection result,and the intersection over the union of the weld seam detection is improved by 17.8%.展开更多
Nanostructured surfaces with dimensions on a scale of a few millimeters exhibit remarkable hydrophobicity.The geometry of these nanostructures considerably affects their wettability.However,determining the optimal geo...Nanostructured surfaces with dimensions on a scale of a few millimeters exhibit remarkable hydrophobicity.The geometry of these nanostructures considerably affects their wettability.However,determining the optimal geometry is challenging due to the abundance of geometry parameters and the difficulty in numerically describing their effects on wettability at the mesoscopic scale.In addition,the fabrication of nanostructured surfaces with precise geometries is challenging.We establish a lattice Boltzmann method(LBM)model to address these challenges.We use the model to gain mesoscopic insights into the interaction between droplets and nanostructures.Our model can accurately reproduce contact angles(CAs)on various nanostructured surfaces and enables investigation of the effects of nanostructure geometry on wettability.We optimize the geometry of the nanostructures using the insights provided by the LBM model on the wettability mechanisms.Our analysis indicates that cones with dimensions of 40μm in width and 33μm in height exhibit the highest hydrophobicity.We successfully fabricate a superhydrophobic surface with the desired geometry via laser scanning,achieving a CA of 163°.We believe that this approach,which combines the LBM model and laser manufacturing,will enable a better understanding of the wettability mechanism and provide a high-performance approach for fabricating superhydrophobic surfaces.展开更多
The mechanism of ultraviolet(UV) nanosecond laser cutting of thermoplastic films and the influence of process parameters on process quality are systematically discussed.The photothermal effect plays a dominant role in...The mechanism of ultraviolet(UV) nanosecond laser cutting of thermoplastic films and the influence of process parameters on process quality are systematically discussed.The photothermal effect plays a dominant role in the interaction between the UVnanosecond laser and thermoplastic materials.In this photothermal reaction,a heat source with the focal point as the core is formed,around which a thermal carbonization layer,a thermal melting layer,and a thermal expansion layer are formed in order from the inside to the outside.Among them,the thermal carbonization layer is not prevalent,and the thermal melting layer and thermal expansion layer are prevalent.The process quality can be adjusted by adjusting the cutting speed,the laser power,and the repetition number of cuts to regulate the process of heat generation and heat dissipation.In the effective range,the faster the cutting speed and the lower the laser power,the smaller the kerf width and heat-affected zone(HAZ) width.Within a certain range,the depth of kerf can be increased by increasing the repetition number of cuts.展开更多
基金supported by the National Key R&D Program of China(Grant No. 2020YFB2007600)National Natural Science Foundation of China(Grant Nos. 51875223 and 52188102)Guangdong HUST Industrial Technology Research Institute, Guangdong Provincial Key Laboratory of Manufacturing Equipment Digization(Grant No. 2020B1212060014)。
文摘Oil film vortex severely reduces the stability of hydrostatic bearings. A solid-liquid interface with drag and slip properties can weaken the oil film vortex of the bearing. Here, a combined picosecond laser ablation and chemical modification method is proposed to prepare surfaces with microbulge array structure on 6061 aluminum alloy substrates. Because of the low surface energy of the perfluorododecyltriethoxysilane modification and the bulge geometry of the microbulge array structure, the surface shows excellent superhydrophobicity. The optimum contact angle in air for water is 164°, and that for oil is 139°. Two surfaces with “lotus-leaf effect” and “rose-petal effect” were obtained by controlling the processing parameters. The drag reduction properties of superhydrophobic surfaces were systematically investigated with slip lengths of 22.26 and 36.25 μm for deionized water and VG5 lubricant, respectively. In addition, the superhydrophobic surface exhibits excellent mechanical durability and thermal stability. The proposed method provides a new idea for vortex suppression in hydrostatic bearings and improves the stability of bearings in high-speed operation.
基金supported by the Key Research&Development Plan of China(Grant No.2022YFB3404800)the Key Research&Development Plan of Hubei Province(Grant No.2021BAA195)the National Natural Science Foundation of China(Grant No.52188102)。
文摘Weld seam detection is an important part of automated welding.At present,few studies have been conducted on annular weld seams,and a lot of defects exist in the point cloud model of the tube sheet obtained by RGB-D cameras and photography methods.Aiming at the above problems,this paper proposed an annular weld seam detection network named WeldNet where a voxel feature encoding layer was adaptively improved for annular weld seams,the sparse convolutional network and region proposal network(RPN)were used to detect annular weld seam position,and an annular weld seam detection loss function was designed.Further,an annular weld seam dataset was established to train the network.Compared with the random sampling consistency(RANSAC)method,WeldNet has a higher detection accuracy,as well as a higher detection success rate which has increased by 23%.Compared with U-Net,WeldNet has been proven to achieve a better detection result,and the intersection over the union of the weld seam detection is improved by 17.8%.
基金supported by the National Key R&D Program of China(Grant No.2020YFB2007600)the Science Challenge Project(Grant No.TZ2018006)+1 种基金the National Natural Science Foundation of China(Grant No.51875223)Guangdong Provincial Key Laboratory of Manufacturing Equipment Digitization(Grant No.2020B1212060014)。
文摘Nanostructured surfaces with dimensions on a scale of a few millimeters exhibit remarkable hydrophobicity.The geometry of these nanostructures considerably affects their wettability.However,determining the optimal geometry is challenging due to the abundance of geometry parameters and the difficulty in numerically describing their effects on wettability at the mesoscopic scale.In addition,the fabrication of nanostructured surfaces with precise geometries is challenging.We establish a lattice Boltzmann method(LBM)model to address these challenges.We use the model to gain mesoscopic insights into the interaction between droplets and nanostructures.Our model can accurately reproduce contact angles(CAs)on various nanostructured surfaces and enables investigation of the effects of nanostructure geometry on wettability.We optimize the geometry of the nanostructures using the insights provided by the LBM model on the wettability mechanisms.Our analysis indicates that cones with dimensions of 40μm in width and 33μm in height exhibit the highest hydrophobicity.We successfully fabricate a superhydrophobic surface with the desired geometry via laser scanning,achieving a CA of 163°.We believe that this approach,which combines the LBM model and laser manufacturing,will enable a better understanding of the wettability mechanism and provide a high-performance approach for fabricating superhydrophobic surfaces.
基金supported by the National Natural Science Foundation of China(Grant Nos.52005206&51905191)the China Postdoctoral Science Foundation(Grant No.2020TQ0110)+4 种基金the Ministry of Industry and Information Technology’s Special Project for High-quality Development of the Manufacturing Industry(Grant No.TC200H02H)the National Key R&D Program of China(Grant No.2020YFB2007600)the Key Research&Development Plan of Hubei Province(Grant No.2020BAB051)Guangdong HUST Industrial Technology Research Institute,Guangdong Provincial Key Laboratory of Manufacturing Equipment Digitization(Grant No.2020B1212060014)Guangdong Basic and Applied Basic Research Foundation(Grant No.2020A1515011393)。
文摘The mechanism of ultraviolet(UV) nanosecond laser cutting of thermoplastic films and the influence of process parameters on process quality are systematically discussed.The photothermal effect plays a dominant role in the interaction between the UVnanosecond laser and thermoplastic materials.In this photothermal reaction,a heat source with the focal point as the core is formed,around which a thermal carbonization layer,a thermal melting layer,and a thermal expansion layer are formed in order from the inside to the outside.Among them,the thermal carbonization layer is not prevalent,and the thermal melting layer and thermal expansion layer are prevalent.The process quality can be adjusted by adjusting the cutting speed,the laser power,and the repetition number of cuts to regulate the process of heat generation and heat dissipation.In the effective range,the faster the cutting speed and the lower the laser power,the smaller the kerf width and heat-affected zone(HAZ) width.Within a certain range,the depth of kerf can be increased by increasing the repetition number of cuts.
