Static Load Analysis of Twin-screw Kneaders

Jing Wei,Guang-Hui Zhang,Qi Zhang,Junseong Kim,SungKi Lyu 한국정밀공학회 2008 International Journal of Precision Engineering and Vol.9 No.3

A static load analysis of twin-screw kneaders is required not only for the dynamic analysis, but also because it is the basis of the stiffness and strength calculations that are essential for the design of bearings. In this paper, the static loads of twin-screw kneaders are analyzed, and a mathematical model of the force and torque moments is presented using a numerical integration method based on differential geometry theory. The calculations of the force and torque moments of the twin-screw kneader are given. The results show that the Mx and My components of the fluid resistance torque of the rotors change periodically in each rotation cycle, but the Mz component remains constant. The axis forces Fz in the female and male rotors are also constant. The static load calculated by the proposed method tends to be conservative compared to traditional methods. The proposed method not only meets the static load analysis requirements for twin-screw kneaders, but can also be used as a static load analysis method for screw pumps and screw compressors.

Dynamic analysis and load-sharing characteristic of multiple pinion drives in tunnel boring machine

Jing Wei,Qinchao Sun,Wei Sun,Jin Cai,Jin Zeng 대한기계학회 2013 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.27 No.5

A dynamic model of multi-gear drive in a tunnel boring machine is demonstrated in this study in which the effects of inertia on the driving mechanism and cutter head are considered. With the nonlinear coupling factors between the ring gear and multiple pinions considered,a dynamic analysis of multiple pinion drives is conducted, and their load-sharing characteristic is proposed. The load-sharing coefficients at different rotating cutter head speeds and input torques are determined and are found to reach up to 1.2-1.3. A simulated experimental platform of multiple pinion drives is performed, and subsequent torque distributions are measured under step load in the driving shaft of pinions. An imbalance in torque distribution of pinions is verified, and the load-sharing coefficients in each pinion can reach 1.262. Torque load fluctuation is regarded as system noise that can directly be coupled into the control system in the control strategy.

Effects of flank deviation on load distributions for helical gear

Jing Wei,Wei Sun,Licun Wang 대한기계학회 2011 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.25 No.7

Flank deviation is one of the important factors that greatly affect helical gear strength. A qualitative analysis is performed using finite element method (FEM) for the effects of flank deviation on load distributions for helical gear based on ANSI/AGMA ISO 1328-1 (standard for cylindrical gears - ISO System of Accuracy - Part 1: Definitions and Allowable Values of Deviations Relevant to Corresponding Flanks of Gear Teeth). To analyze the effects of flank deviation, tooth contact analysis (TCA) is developed and load distributions of helical gears with flank deviation are presented. Load distributions in contact lines are derived and compared to each other under grade 5 and 7 after taking five types of flank deviation, including single pitch deviation, profile form deviation, profile slope deviation and helix form deviation as well as helix slope deviation, into account. It is found that the effects of individual flank deviation on load distribution have the superposition property. Flank crowning and tip relief corrections must be carefully regarded in the design process because of the effects of flank deviation on load distributions.

Model-based view planning for building inspection and surveillance using voxel dilation, Medial Objects, and Random-Key Genetic Algorithm

Jing, Wei,Shimada, Kenji Society for Computational Design and Engineering 2018 Journal of computational design and engineering Vol.5 No.3

Model-based view planning is to find a near-optimal set of viewpoints that cover the surface of a target geometric model. It has been applied to many building inspection and surveillance applications with Unmanned Aerial Vehicle (UAV). Previous approaches proposed in the past few decades suffer from several limitations: many of them work exclusively for 2D problems, generate only a sub-optimal set of views for target surfaces in 3D environment, and/or generate a set of views that cover only part of the target surfaces in 3D environment. This paper presents a novel two-step computational method for finding near-optimal views to cover the surface of a target set of buildings using voxel dilation, Medial Objects (MO), and Random-Key Genetic Algorithm (RKGA). In the first step, the proposed method inflates the building surfaces by voxel dilation to define a sub-volume around the buildings. The MO of this sub-volume is then calculated, and candidate viewpoints are sampled using Gaussian sampling around the MO surface. In the second step, an optimization problem is formulated as (partial) Set Covering Problem and solved by searching through the candidate viewpoints using RKGA and greedy search. The performance of the proposed two-step computational method was measured with several computational cases, and the performance was compared with two previously proposed methods: the optimal-scan-zone method and the randomized sampling-based method. The results demonstrate that the proposed method outperforms the previous methods by finding a better solution with fewer viewpoints and higher coverage ratio compared to the previous methods.

Effects of dynamic transmission errors and vibration stability in helical gears

Jing Wei,Pan Gao,Xinglong Hu,Wei Sun,Jing Zeng 대한기계학회 2014 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.28 No.6

Transmission error is an important reason for instability in helical gears. A six-degree-of-freedom dynamic model coupled flexional,torsional and axial motion of a helical gear transmission system, which includes time varying mesh stiffness, bearing supporting stiffness,mesh damping and backlash, is developed, after taking into account the dynamic characteristics and vibration responses of helical gear inthree dimensions. Influences of involute contact ratio, bearing supporting stiffness, mesh damping and backlash on the dynamic transmissionerrors and vibration stability of the helical gear system are investigated using numerical simulation technique. The effects on dynamictransmission errors and stabilities by contact ratio, supporting stiffness and mesh damping as well as gear backlash are analyzed. The intrinsic relationship between above parameters and dynamic transmission errors and stabilities for helical gear system are presented. The stable and unstable regions under different parameters are given. The results in this paper can be helpful to the dynamic and stabledesign of a helical gear transmission system.

A Study on Rotor Profiles Design for a Novel Twinscrew Kneader

Jing Wei,Qingchao Sun,Xujian Sun,Wei Sun 한국정밀공학회 2013 International Journal of Precision Engineering and Vol. No.

The profile curve design method and the mathematical model of conjugate surfaces of twin-screw kneader used for high viscosity material mixing, transportation and malaxating are established according to the principle of gear engagement. A novel twin-screw kneader and the equations of the profile curves of the rotors as well as the rotor design are proposed. The working principles of the twin screw kneader are analyzed and numerical simulations for dynamic characteristics of the flow field are carried out Threedimensional,isothermal and steady state numerical analysis of a non-Newtonian fluid are presented, based on computational fluid dynamics (CFD) theory, and the characteristics under the conditions of different speeds and center distances are studied, such as pressure distributions, velocity fields, the maximum shear stresses and the mass flow rates. The results provide a theoretical basis for performance predictions and reasonable design for the novel twin-screw kneader.

Influence of Screw Rotors Tip Angle on Mixing Performance for One Novel Twin-screw Kneader

Jing Wei,Dabing Chen,Dongming Zhou,Aiqiang Zhang,Yuliang Yang 한국고분자학회 2015 폴리머 Vol.39 No.3

Twin-screw kneader is an efficient polymer processing equipment. In this paper, the mixing performance of one novel intermeshing counter-rotating twin-screw kneader with different tip angles of the male rotor is simulated using the mesh superimposition technique (MST). Statistical analysis is carried out for the flow field using particle tracking technique, and distributive mixing performance is evaluated using the residence time distribution and segregation scale, while the dispersive mixing performance is estimated using the parameters such as shear rate, stretching rate and mixing index. The results show that the best distributive mixing performance is achieved when the tip angle is 0˚, while the optimal dispersive mixing performance is obtained when the tip angle is 20˚. The results in this paper provide a data basis for the selection of parameters and optimization of the performance for the screw rotors.

Study of Synchronization Characteristics of a Multi- Source Driving Transmission System Under an Impact Load

Jing Wei,Ruizhi Shu,Datong Qin,Teik C. Lim,Aiqiang Zhang,Fanming Meng 한국정밀공학회 2016 International Journal of Precision Engineering and Vol.17 No.9

Multi-source driving transmission systems, in which the gear assembly is driven by multiple induction motors, are extensively used in new energy, aerospace, marine engineering, and in other fields. The multi-source driving system faces an even-load distribution problem, i.e., torque or speed synchronization issues. In this study, the synchronization characteristics of a multi-source driving transmission system under an impact load at different load change rates are studied. An accurate electromechanical coupling dynamic model of the system considering the flexible shafts, support bearing and meshing gear pair is established by applying virtual equivalent shaft elements. By considering the time-varying meshing and the coupling effects of the dynamic electric motor and the speed, torque and stator current synchronization characteristics are investigated using this model. Computational results show that the influence of the load change rate on the speed synchronization characteristics of the system is minor, but has a significant influence on the torque and stator current synchronization characteristics. The stator current root mean square value (RMS) can be chosen as a feedback signal to monitor the synchronization characteristics of the system. The proposed research provides the theoretical basis for the formulation of the synchronization control strategy for multi-source driving transmission systems.

A Study on Optimum Design Method of Gear Transmission System for Wind Turbine

Jing Wei,Cheng Lv,Wei Sun,Xiang Liu,Yang Wang 한국정밀공학회 2013 International Journal of Precision Engineering and Vol. No.

As the key components of wind turbine, the weight of gear transmission system becomes larger and larger with the increasing power of wind turbine. Lightweight and high reliability has been the developing tendency for planetary gear transmission system for working reliability and reducing costs. A coupled nonlinear dynamics modeling for planetary gear transmission system in wind turbine is established after comprehensive considering these non-linear factors associated with time-varying mesh stiffness, dynamic transmission error, gear mesh impact and input varying load. Load factors of planetary gear transmission system are induced from the coupled nonlinear dynamics modeling. Then a novel optimum design approach including lightweight and reliability as constraints is presented. The optimization results show that the reliability of original parameters is higher than that of the optimized parameters,while the volume of planetary gear transmission system can greatly be decreased with the overall system reliability requirements.

Myocardial Blood Flow Quantified by Low-Dose Dynamic CT Myocardial Perfusion Imaging Is Associated with Peak Troponin Level and Impaired Left Ventricle Function in Patients with ST-Elevated Myocardial Infarction

Jingwei Pan,Mingyuan Yuan,Mengmeng Yu,Yajie Gao,Chengxing Shen,Yining Wang,Bin Lu,Jiayin Zhang 대한영상의학회 2019 Korean Journal of Radiology Vol.20 No.5

Objective: To investigate the association of myocardial blood flow (MBF) quantified by dynamic computed tomography (CT) myocardial perfusion imaging (MPI) with troponin level and left ventricle (LV) function in patients with ST-segment elevated myocardial infarction (STEMI). Materials and Methods: Thirty-five STEMI patients who successfully had undergone reperfusion treatment within 1 week of their infarction were consecutively enrolled. All patients were referred for dynamic CT-MPI. Serial high-sensitivity troponin T (hs-TnT) levels and left ventricular ejection fraction (LVEF) measured by echocardiography were recorded. Twenty-six patients with 427 segments were included for analysis. Various quantitative parameters derived from dynamic CT-MPI were analyzed to determine if there was a correlation between hs-TnT levels and LVEF on admission and again at the 6-month mark. Results: The mean radiation dose for dynamic CT-MPI was 3.2 ± 1.1 mSv. Infarcted territories had significantly lower MBF (30.5 ± 7.4 mL/min/100 mL versus 73.4 ± 8.1 mL/min/100 mL, p < 0.001) and myocardial blood volume (MBV) (2.8 ± 0.9 mL/100 mL versus 4.2 ± 1.1 mL/100 mL, p = 0.044) compared with those of reference territories. MBF showed the best correlation with the level of peak hs-TnT (r = -0.682, p < 0.001), and MBV showed a moderate correlation with the level of peak hs-TnT (r = -0.437, p = 0.026); however, the other parameters did not show any significant correlation with hs-TnT levels. As for the association with LV function, only MBF was significantly correlated with LVEF at the time of admission (r = 0.469, p = 0.016) and at 6 months (r = 0.585, p = 0.001). Conclusion: MBF quantified by dynamic CT-MPI is significantly inversely correlated with the level of peak hs-TnT. In addition, patients with lower MBF tended to have impaired LV function at the time of their admission and at 6 months.