bluuebunny/crossref_metadata_2025_split huggingface dataset:
Design and aerodynamic performance study of subsonic Y-shaped inlet
Authors: Yan Ziguang , Zhao Zhifang , Li Linjie , Wu Mengwei 
Published: November 2024

Abstract
A Y-shaped inlet with a quadrate import was designed by the super-ellipse method in this paper, and according to the variation pattern of the cross-section of the inlet, the variation pattern of the short and long axis of the super-ellipse was deduced. For many different flight situations, the numerical simulations of the Y-shaped inlet were made. The result shows (1) If 0.2≤Ma≤0.8, the total pressure recovery coefficient exceeds 0.96, and the total pressure distortion coefficient is close to 0.1, meeting the criterion of the design; (2) When Ma=0.8, for many different attack angle α=-4°∼22°, the total pressure recovery coefficient is close to 0.97, reaching the level of practical application, and it has little impact on total pressure recovery coefficient and the distortion coefficient. (3) These results demonstrate high total pressure recovery and low distortion coefficients across various flight conditions, indicating its potential for practical applications and future inlet designs.
Design and optimization of the exhaust system for an aviation piston engine
Authors: Chen Jinqian , Zhang Chen , Chen Wei , Zhang Zhecheng 
Published: November 2024

Abstract
To further enhance the performance of an aviation piston engine, an engine performance simulation analysis model was constructed by using GT-Power software to design improvements to its exhaust system. The impacts of different exhaust system schemes on the exhaust process, the in-cylinder combustion, and the heat release process at a cruising speed of 5500 RPM were analyzed. Based on the results, under cruising speed conditions, a new exhaust system was designed for the engine by referring to the structural form of a resonant exhaust system. The D-optimal Latin hypercube sampling method was used to obtain sample data for the experimental design of the structural parameters of the designed exhaust system. The response surface approximation models characterizing power and fuel consumption rate were established by using the least squares method. The significance of the impact of each structural parameter on engine performance was analyzed through a multifactor analysis of variance. The key structural parameters of the designed exhaust system were then subjected to multi-objective optimization. The results indicate that at 5500 RPM, the designed exhaust system can increase engine power by 2.88%; after optimization, engine power can be further increased by 3.15%, and the fuel consumption rate is reduced by 4.07%.
Effect of tempering process on the structure and properties of M51/X32 bimetal band saw blade
Authors: Zhao Gusiyang , Liu Yan , Song Zhuo , Li Guimao , Fu Bo , Xia Changsheng , Ning Qu 
Published: November 2024

Abstract
The mechanical properties of band saw have a great influence on the cutting life. In this paper, through the systematic study of M51/X32 bimetallic band saw blade with different tempering temperatures and times, the metallography of the bimetallic band saw blade under different heat treatment conditions was analyzed. The mechanical properties of the bimetallic band saw blade under different conditions were tested. The results showed that the carbide in the metallography of the tooth tip was uniform and tended to be spherical when tempering at 600°C for five times. The mechanical properties such as hardness, tensile strength, and fatigue properties are well matched, which can extend the service life of bimetallic band saw blades and ensure the cutting quality.
Reaction chamber design for an organic molecular layer deposition instrument
Authors: Zhu Shuai , Li Pengfei , Yang Dada , Hou Yang , Sheng Qiaorui 
Published: November 2024

Abstract
In the molecular layer deposition (MLD) process, the reaction chamber plays a crucial role as the deposition carrier. The geometry of the reaction chamber directly affects the deposition processes of delivery, heating of reactive gases, and purging of excessive molecules. In this study, we designed an MLD instrument for the preparation of pure organic polymer layered coatings and investigated key structural parameters of its reaction chamber. By the Computational Fluid Dynamics (CFD) method, precursor delivery, nitrogen purge, vacuuming, and oil bath heating in the deposition process were modeled. The flow field distribution under different inlet and outlet heights and the temperature field distribution under different axial heights of the chamber were analyzed, and the most suitable parameters were thus determined. The results showed that when the heights of precursor inlet, nitrogen inlet, and vacuum pumping outlet were selected as 50 mm, 45 mm, and 50 mm, respectively, the chamber could serve better deposition and purge efficiency. When the axial height of the chamber is 185 mm, both the chamber and the fluoro rubber sealing ring meet the temperature requirements.
Study on the mechanical properties and microstructures of Al-Cu-Mg alloy thick plates obtained by different hot rolling processes
Authors: Zhu Kai , Liu Qilong , Fu Jinlai , Lv Jing , Yan Lizhen , Li Yanan , Li Xiwu 
Published: November 2024

Abstract
In the research, the microstructures of large-scale 2324 aluminum alloy thick plates obtained through two different hot rolling processes are investigated by using Scanning Electron Microscopy (SEM), Energy Dispersive Spectroscopy (EDS), and Electron Backscatter Diffraction (EBSD). Additionally, the tensile properties of the plates are evaluated at room temperature. The results indicate that the thick plates produced by Process A exhibit higher tensile and yield strengths along the L (longitudinal) and LT (long transverse) directions. The higher proportion of deformed microstructures is an important factor contributing to their enhanced tensile and yield strengths. Meanwhile, the different rolling processes have minimal impact on the kind and distribution of the second phase in the hot-rolled thick plates, with the second phase primarily consisting of Al2Cu and Al2CuMg phases, which are distributed in a streamlined way along the rolling direction of the thick plates. The microstructures of the hot-rolled thick plates obtained from both hot-rolling processes are dominated by deformed structures. The thick plates produced by Process B have relatively smaller grain sizes and a higher degree of fragmentation, making their microstructure more susceptible to recrystallization transformation during subsequent solution heat treatment.
Simulation-based analysis of welding process parameters for TC4ELI titanium alloy thick-walled cylinders
Authors: Gao Guanghui , Cheng Xiaowei , Gao Yue 
Published: November 2024

Abstract
In this paper, ABAQUS is used to numerically simulate the residual stresses during welding of titanium alloy thick-walled cylinders. A detailed simulation analysis of the stress field during the welding process is performed by establishing an accurate finite element model, defining the thermal physical properties, boundary conditions, and heat source model, and using the indirect heat-force coupling method. The results of the study show that the distribution of the weld stress field has an important influence on weld quality, material properties, and structural strength. The movement of the welding heat source results in a dynamic change in the stress field, which gives rise to a significant stress concentration at and in the vicinity of the welding heat source.
Study on tensile damage evolution of Ti6Al4V alloy based on DIC technique
Authors: Mao Dexin , Li Lei , Li Xiaodong , Sun Zhankun , Zhang Li , Liu Qiao 
Published: November 2024

Abstract
Both optical microscopy (OM) and scanning electron microscopy (SEM) were used to analyze the microstructure of the Ti6Al4V alloy and evaluate its tensile damage behavior. Using Lemaitre’s definition of damage, the variation rule of damage during the reduction of elastic modulus was obtained. Combining the digital image correlation (DIC) analysis approach allowed for an experimental investigation of the alloys’ tensile mechanical characteristics. The strains at 500 independent points were extracted using VIC-2D software. The damage factor of the whole strain field was established by equations and 3D graphics, and the damage evolution process was visualized and analyzed. The results show that the Ti6Al4V alloy has good plasticity, and its fracture mode is a ductile fracture. The sample’s modulus of elasticity falls, and the extent of damage increases as the stretching continues. The sample undergoes a localized violent deformation during the tensile process, as opposed to a homogenous deformation state. The harm progressively concentrates and increases at an increased rate.
The integrated performance of adaptive temperature control and temperature measurement of PTC materials with high thermal cycle repeatability
Authors: Yang Yinfa , Hao Jianmin , Chen Hua , Cheng Wenlong 
Published: November 2024

Abstract
As the temperature increases, the resistance of the positive temperature coefficient (PTC) material becomes larger. Using this material can reduce the complexity of the temperature control system. In this paper, a new PTC material is developed by means of melt blending, which still has operable PTC characteristics after 60 high and low temperature cycles. The data points collected in multiple thermal cycles were fitted to obtain the relationship between the sample’s temperature and resistance. In addition, the integrated performance of adaptive temperature control and temperature measurement of PTC materials is proposed for the first time. Based on the prepared samples, the temperature control characteristics of PTC materials on the controlled object under different environmental conditions are studied experimentally, and the temperature value converted from the resistance value is compared with the temperature value measured by the platinum resistance. The results show that the prepared sample has good temperature control performance, and the material has an operable temperature measurement function in the PTC effect range.
Study on the influence of trace elements H on the properties of A356 aluminum alloy
Authors: Lv Jianjun , Zhang Jiang , Hong Xiaolu , Zhou Peixu , Chen Dahui , Peng Yingjiang 
Published: November 2024

Abstract
The vacuum melt purification refining technology can significantly reduce the content of hydrogen elements in alloy melts and prevent defects such as hydrogen-induced pinholes. This article investigates the effect of hydrogen content on the chemical composition, mechanical properties, and structural defects of A356 alloy melt by using vacuum melt purification refining technology to reduce the hydrogen content in A356 alloy melt. The experimental results show that: 1) there is basically no loss of chemical elements during the vacuum melting process; 2) The use of vacuum refining and purification control technology can control the hydrogen content inside the melt to be ≤ 0.10ml/100g; 3) The effect of H content on the metallographic structure of A356 alloy is not significant, but it has a certain improvement on the tensile strength at room temperature, but the increase is ≤ 5%.
Study on warm formability of 2219 aluminum alloy with pre-deformation
Authors: Gao Qi , Zhang Zhichao , Meng Jinlong , Fan Xiaobo 
Published: November 2024

Abstract
The manufacturing process of launch vehicle storage tanks requires urgent simplification, which can be improved by forming the local features after artificial aging. Therefore, a new process of warm flanging aluminum alloys with pre-deformation was proposed to meet this requirement. The mechanical properties of 2219 aluminum alloy with pre-deformation were investigated at different temperatures using thermomechanical property testing. The deformation law of warm flanging was analyzed through simulation. The flanging limit of 2219 aluminum alloy with pre-deformation was obtained through experiments. Results showed that the ductility of 2219 aluminum alloy with pre-deformation increased then decreased with the increasing temperature, a maximum strain of 0.65 was obtained at 200°C. The equivalent strain gradually rose from the corner zone to the straight wall zone during flanging. The maximum equivalent strain is located at the edge of the straight wall, which gradually decreases with the increasing flanging coefficient. A flanging coefficient of 0.60 can be obtained at 200°C without splitting or seriously thinning. These results guide the local flanging of the integral bottom of 2219 aluminum alloy.
Quality evaluation and crack cause analysis of a type B sleeve service welding
Authors: Xu Yan , Bai Qiang , Yang Fengping , Feng Zhenjun , Chang Yonggang , Li Liang 
Published: November 2024

Abstract
Type B sleeve repair technology is important in service welding repair because the quality of fillet weld directly affects the sealing and bearing capacity of Type B sleeve repair. In this paper, a cover weld crack at 0 o ‘clocks of fillet weld found by non-destructive testing is analyzed. The tensile strength of fillet weld and longitudinal weld is much higher than the technical requirements of X80 steel grade pipe, the welding material belongs to a strong matching state, and its impact toughness value is low. At the same time, the hardness test was carried out at the fillet weld, and the hardness of the tube body at the welding position of the cover was higher than that at other positions, and there was a risk of cracking. The defects were dissected as hot cracks, and the reason was related to the strong matching of the selected welding material. It is suggested that when selecting welding materials for lap fillet welding, it is possible to try to reduce the matching strength level of the weld without affecting the sealing and bearing capacity.
Large amplitude and small size ultrasonic milling for BT40 tool holders
Authors: Zhao Yu , Li Xuewei , Shu Shengrong , Wu Chenjun 
Published: November 2024

Abstract
The current ultrasonic milling tool holders are relatively long in structure, and the tool is susceptible to generating detrimental radial vibrations during high-speed rotation. To achieve high-quality milling of difficult-to-machine materials, a longitudinal-torsional ultrasonic oscillator suitable for BT40 tool holders has been proposed, which can generate a large amplitude while maintaining a compact length. A longitudinal vibration ultrasonic transducer with an exponential front cover is designed using the analytical method. Based on the principle of acoustic wave reflection, four spiral grooves are introduced on the exponential variable cross-section bar to convert the longitudinal vibration into longitudinal-torsional composite vibration. The effects of groove width, groove depth, and spiral angle on the longitudinal-torsional resonance were analyzed using the single-factor method in finite element software, and the optimal spiral groove parameter combination was determined. The longitudinal-torsional ultrasonic transducer is assembled with the BT40 tool holder to construct a longitudinal-torsional ultrasonic tool holder model, and modal analysis was performed. The resonant frequency was determined to be 22, 845 Hz. An experimental platform was established to carry out impedance analysis and amplitude testing on the longitudinal-torsional ultrasonic tool holder. The results show that its resonant frequency is 22, 152 Hz, which is slightly different from the simulation value. The tool holder’s maximum longitudinal amplitude is 11.2 μm, and the maximum torsional amplitude is 4.3 μm, with a torsional-to-longitudinal ratio of 0.38. The performance of the longitudinal-torsional ultrasonic tool holder meets the processing requirements of most ultrasonic milling applications, and the correctness of the design method is verified.
Numerical analysis of oil liquid sloshing in fuel tanks of plug-in hybrid electric vehicles under different structure baffles
Authors: Zhang Enhui , Chen Hao , Wang Lihe , Huang Jianbin , Xu Fei 
Published: November 2024

Abstract
To solve a large amount of oil liquid sloshing in the fuel tank and a series of problems caused by oil liquid sloshing in the plug-in hybrid electric vehicle (PHEV) under the condition of electric drive only, this paper analyzes the oil liquid sloshing in fuel tank under different liquid filling rates under complex situations. After determining the representative liquid filling rates, the optimal scheme is finally determined. We conduct the specific analysis of different types, structures, and installation modes of fuel tank baffles under the same working conditions and liquid filling amount. The results show that the less liquid is filled in the fuel tank, the larger the sloshing amplitude is, and the more complicated the sloshing situation is. When the oil liquid sloshes, the non-porous baffle has an obvious zoning effect on the oil liquid and suppresses the oil liquid fluctuations effect, but the oil liquid fluidity is poor. The angle between the linear baffle and the oil liquid flow direction is larger, which has a better attenuation effect on the impact force of oil liquid. In conditions of significant oil liquid sloshing, a high baffle enhances the contact area of the oil liquid, resulting in improved inhibition effects. After considering various advantages and disadvantages, the analysis of the cruciform baffle found that the cruciform baffle limited the multi-directional movement of oil liquid, caused substantial vortex inside the oil liquid, and attenuated the kinetic energy generated by oil liquid sloshing. This greatly reduced the impact of the oil liquid on the fuel tank wall and improved the effect of suppressing oil liquid fluctuations.
Initial sizing of a hybrid hydrogen fuel cell commercial aircraft with electric aft-fuselage propulsion
Authors: Fan Zhouwei , Tan Zhaoguang , Wang Haiqiang , Wang Yuhan 
Published: November 2024

Abstract
Hybrid hydrogen fuel cell (HH2FC) aircraft is one of the viable technological pathways to reduce carbon emissions in the aviation industry. For a configuration with aft-fuselage propulsion, a novel method is established for the initial sizing of the HH2FC aircraft in a situation where empirical data is lacking. The carbon emission reduction capabilities and potential for reducing fuel and carbon tax costs can be preliminarily assessed by the proposed initial sizing method. A case study on a narrow-body aircraft indicates that, at the current technological level, the carbon emissions and cost of the HH2FC aircraft will increase to achieve the same payload and range as the conventional aircraft. However, with the improvement of hydrogen technologies, such as fuel cell power density and hydrogen tank gravimetric density, HH2FC aircraft will reduce 6.6% carbon emissions compared to conventional aircraft. As a result, both economic and environmental benefits can be achieved in the future.
Failure mechanism analysis of the crack located at the neck of stainless steel flange
Authors: Yuan Meng , Yao Yuan , Zhu Wenfang , Zhang Fang , Zhong Fengping , Huang Liuyi , Peng Chao , Volodymyr Korzhyk 
Published: November 2024

Abstract
During new pipeline installation supervision inspections in a large petrochemical project, several dozen flanges, made of S30403, failed due to lateral cracks in the neck areas. A detailed analysis of the failure modes and mechanisms of the flanges was carried out. The chemical composition, hardness, metallographic, microstructure structure and EDS analysis in crack zones were tested by spark discharge optical emission spectrometer, Brinell hardness tester, metalloscope, and scanning electron microscope, respectively. It was proved that in the metallographic structures, excessive wire- and network-like ferrites and a large amount of carbides were observed. The crack originated from the outer surface of the neck of the flange and extended to the center of the flanges along the wire- and network-like ferrites. Meanwhile, a large amount of impurities were found inside the cracks as well, which were confirmed as chromium oxides. It was indicated that the flange may have cracked during the forging process, and then oxidation occurred at a high temperature. Some micro-cracks were formed at the aggregating areas of non-metallic inclusions during the forging of the flange, and masses of ferrites provided the path for rapid crack growth. Therefore, the failure of the flanges should be caused by improper heat treatment processes and excessive non-metallic inclusions in the materials.
Influence of meshing stiffness variation on the vibration characteristics of main reduction gears
Authors: Pan Yunping , Feng Zhongyin , Zhang Cheng 
Published: November 2024

Abstract
The meshing stiffness of the main and passive gears of the main reducer of the rear axle of a commercial vehicle is taken as the object of this study, aiming to optimize the influence of the meshing stiffness of the main and passive gears on the vibration and noise, enhance the meshing performance of the gear teeth, reduce the vibration and noise of the main reducer, and improve the vibration performance of the main reducer. Through UG 3D modeling software and ADAMS dynamics simulation, the dynamics characteristics of hypoid gears under different gear tooth meshing stiffness coefficients are analyzed and simulated. It is concluded that under the meshing stiffness coefficients of 0.8 to 0.9 times, the translational vibration acceleration and angular acceleration of the passive gears are smaller, the translational vibration and torsional vibration are smoother, and it can improve the performance of the meshing vibration of the gear system of the main gear reducer.
Cyclic creep behavior and life prediction of DZ125 alloy under different stress ratios
Authors: Chen Haowen , Niu Xuming , Sun Zhigang , Song Yingdong , Zhang Lu 
Published: November 2024

Abstract
In order to study the creep behavior and mechanism of DZ125 alloy under cyclic creep under different stress ratios, cyclic creep experiments are performed under a temperature of 850°C and peak stress of 500 MPa, with stress ratios of 0.1, 0.3, 0.5, 0.7, 0.9, and 1, and the mechanical behavior and microstructure of creep samples under different stress ratios are compared and analyzed. The accuracy of several life prediction models is compared. The results show that cyclic hardening or cyclic softening will occur under different stress ratios due to grain boundary slip and dislocation plugging. According to the results of fracture analysis, as the stress ratio rises, the proportion of creep damage increases, and the fracture mode shifts from transgranular fracture to intergranular fracture. Several life prediction models are selected, and the results show that the FS frequency separation model and M-G model have better life prediction accuracy.
Buckling analysis of nanoscale beams based on nonlocal Timoshenko beam theory
Authors: Li Gen 
Published: November 2024

Abstract
Eigen-buckling problems of nanoscale beams continue to be of great research interest, and the nonlocal theory is widely used. However, the existing research generally adopted some simplified assumptions of nonlocal effects. This article studies the buckling behaviors of the nonlocal Timoshenko beam, where the nonlocal effects are considered both on the governing equations and boundary conditions. The variational principle is adopted to obtain the nonlocal governing equations and boundary conditions. The buckling solutions for nanoscale beams are obtained analytically. Numerical comparisons validate the correctness of the present results. Parameter study shows that the buckling characteristic of nonlocal beams is different from that of classical beams, and the nonlocal effect is dependent on boundary conditions and geometry size of nanoscale beams.