Comparison of the mechanical performance between two-stage and flat-face cutter head for the rock tunnel boring machine (TBM)

Geng Qi,Wei Zhengying,He Fei,Meng Hao 대한기계학회 2015 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.29 No.5

To overcome the drawbacks of the large flat-face TBM cutter head (for example, enormous rock cutting forces and eccentric forcescause excessive deformation of the cutter head and damage to the main bearing), a two-stage cutter head is introduced. The two-stagecutter head was designed using grey relational analysis method according to the flat-face cutter head applied in the West Qinling Tunnel,China. The mechanical performance analysis models of the two cutter heads in the layered-banded rock (LBR) mixed ground were builtto calculate the cutter heads’ rock cutting thrust and torque, eccentric forces and overturning moments. The two cutter heads’ deformationand stress distribution were also compared. We concluded that with the same penetration, the thrust, torque, eccentric force, overturningmoment, deformation and maximum stress of the two-stage cutter head were smaller than those of the flat-face cutter head.

Numerical and experimental method to determine the boring diameters of a two-stage TBM cutterhead to prevent rock burst

Geng Qi,Wei Zhengying,Meng Hao 대한기계학회 2014 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.28 No.11

A two-stage tunnel boring machine (TBM) cutterhead with a pilot-enlargement boring method was presented to reduce the risk of rockbursts resulting from boring with a TBM with a large flat-face cutterhead. A reduced scale similarity experiment was designed on rocktunnel boring to determine the boring diameters of the two stages, and numerical simulation models were built. A micron X-ray computerizedtomography system was adopted to examine the failure area of the excavated testing piece and validate the numerical models. Stress distribution and energy release rate (ERR) were used in the numerical simulations to evaluate the rock burst risk of the boringprocess. Experimental and numerical results show that rock burst is prone to occur in the upper, lower, and side areas of the surroundingrock around the tunnel, and risk increases with the lateral pressure coefficient and boring diameter. The optimal boring diameter ratio ofstages 1 to 2 was determined between 0.55 and 0.59. Meanwhile, the ERR of the designed two-stage cutterhead is approximately 60%smaller than that of the flat-face cutterhead.

Numerical and experimental research on the rock-breaking process of tunnel boring machine normal disc cutters

Geng Qi,Wei Zhengying,Meng Hao,Chen Qiao 대한기계학회 2016 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.30 No.4

A common drawback presented by several numerical rock-breaking studies was that the rocks beneath disc cutters were cut off excessively while the rocks between disc cutters remained, which usually resulted in a smaller cutter spacing than the proper value. To overcome this limitation, the constitutive equations of different rock parts were defined separately using VUMAT, an ABAQUS-based material subroutine. The constitutive model of rock was an application of the Drucker-Prager yield criterion coupled with the Lemaitre damage model. Full-scale rock-breaking tests on a rotary cutting machine were conducted, and 25 groups of orthogonal numerical simulations were carried out. By comparing the normal force, rolling force, and specific energy of numerical results with those of experimental results, the optimal values of the defined parameters D c1 , k, and B were determined to be 9 ☓ 10 -4 , 0.1 and 0.8, respectively. With the presented numerical method and the determined parameters, the influences of cutter spacing on normal force, rolling force, and specific energy were studied. Both the normal and rolling forces of the first cutting generally remained constant, whereas the forces of the second cutting generally increased linearly with the cutter spacing. The optimal cutter spacing for the studied rock type (Hard sand rock collected from West Qinling tunnel) was approximately 72 mm, which was in accordance with the cutter spacing of the tunnel boring machine applied in this tunnel project.

SF영화에 나타난 가상공간에 인식론적 특성인 ‘경험적 동시성’의 표현에 관한 연구

겅허치(Geng he-qi),최동혁(Choi, dong-hyeok) 한국콘텐츠학회 2021 한국콘텐츠학회 종합학술대회 논문집 Vol.2021 No.8

An Improved Active Damping Method with Capacitor Current Feedback

Geng, Yi-Wen,Qi, Ya-Wen,Liu, Hai-Wei,Guo, Fei,Zheng, Peng-Fei,Li, Yong-Gang,Dong, Wen-Ming The Korean Institute of Power Electronics 2018 JOURNAL OF POWER ELECTRONICS Vol.18 No.2

Proportional capacitor current feedback active damping (CCFAD) has a limited valid damping region in the discrete time domain as (0, $f_s/6$. However, the resonance frequency ($f_r$) of an LCL-type filter is usually designed to be less than half the sampling frequency ($f_s$) with the symmetry regular sampling method. Therefore, ($f_s/6$, $f_s/2$) becomes an invalid damping region. This paper proposes an improved CCFAD method to extend the valid damping region from (0, $f_s/6$ to (0, $f_s/2$), which covers all of the possible resonance frequencies in the design procedure. The full-valid damping region is obtained and the stability margin of the system is analyzed in the discrete time domain with the Nyquist criterion. Results show that the system can operate stably with the proposed CCFAD method when the resonance frequency is in the region (0, $f_s/2$). The performances at the steady and dynamic state are enhanced by the selected feedback coefficient H and controller gain $K_p$. Finally, the feasibility and effectiveness of the proposed CCFAD method are verified by simulation and experimental results.

A Virtual RLC Active Damping Method for LCL-Type Grid-Connected Inverters

Geng, Yiwen,Qi, Yawen,Zheng, Pengfei,Guo, Fei,Gao, Xiang The Korean Institute of Power Electronics 2018 JOURNAL OF POWER ELECTRONICS Vol.18 No.5

Proportional capacitor-current-feedback active damping (AD) is a common damping method for the resonance of LCL-type grid-connected inverters. Proportional capacitor-current-feedback AD behaves as a virtual resistor in parallel with the capacitor. However, the existence of delay in the actual control system causes impedance in the virtual resistor. Impedance is manifested as negative resistance when the resonance frequency exceeds one-sixth of the sampling frequency ($f_s/6$). As a result, the damping effect disappears. To extend the system damping region, this study proposes a virtual resistor-inductor-capacitor (RLC) AD method. The method is implemented by feeding the filter capacitor current passing through a band-pass filter, which functions as a virtual RLC in parallel with the filter capacitor to achieve positive resistance in a wide resonance frequency range. A combination of Nyquist theory and system close-loop pole-zero diagrams is used for damping parameter design to obtain optimal damping parameters. An experiment is performed with a 10 kW grid-connected inverter. The effectiveness of the proposed AD method and the system's robustness against grid impedance variation are demonstrated.

Numerical and experimental investigation on electromechanical aileron actuation system with joint clearance

Qi Wan,Geng Liu,Yong Zhou,Shangjun Ma,Ruiting Tong 대한기계학회 2019 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.33 No.2

A closed-loop coupling model at the system-level is developed to analyze the effects of joint clearance on the dynamic responses of electromechanical aileron actuation system. The proposed model considers the coupling effects between the electromechanical actuator (EMA) control performance and dynamic characteristics of linkage mechanism with joint clearance. Besides, the experiments are conducted in a test rig, which verifies the effectiveness of the proposed closed-loop coupling model. The nonlinear contact force model and modified Coulomb friction model are adopted in the joint clearance of the linkage mechanism, and the influences of clearance size on the dynamic behaviors of electromechanical aileron actuation system are studied. The numerical and experimental results indicate that the novel closed-loop coupling model, considering the EMA control performance and dynamics of linkage mechanism with joint clearance at the same time, is an effective model to predict the dynamic characteristics of electromechanical aileron actuation with joint clearance, which provides a practical method to analyze the dynamic performance of electromechanical coupling multibody systems with joint clearance.

Study on the dynamic interaction of multiple clearance joints for flap actuation system with a modified contact force model

Qi Wan,Geng Liu,Chunyu Song,Yong Zhou,Shangjun Ma,Ruiting Tong 대한기계학회 2020 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.34 No.7

To analyze the effects of clearance joint number and dynamic interaction on responses of the flap actuation system, a dynamic analysis model is proposed based on a modified contact force model. The modified contact force model can take contact properties with small clearance, heavy load, large contact area and variable contact stiffness coefficient into consideration for the flap actuation system. Numerical results show that the actuation system presents violent fluctuation due to the dynamic interaction between multiple clearance joints, and the clearance joint closest to the input part suffers more serious contact effects. Furthermore, the combination motion modes between the multiple clearance joints are helpful to judge and analyze the motion state and dynamic behaviors of actuation systems. These simulation findings can provide a theoretical foundation for the optimization design, control strategy and engineering experiments of the actuation systems with multiple clearances.

A Virtual RLC Active Damping Method for LCL-Type Grid-Connected Inverters

Yiwen Geng,Yawen Qi,Pengfei Zheng,Fei Guo,Xiang Gao 전력전자학회 2018 JOURNAL OF POWER ELECTRONICS Vol.18 No.5

Proportional capacitor–current–feedback active damping (AD) is a common damping method for the resonance of LCL-type grid-connected inverters. Proportional capacitor–current–feedback AD behaves as a virtual resistor in parallel with the capacitor. However, the existence of delay in the actual control system causes impedance in the virtual resistor. Impedance is manifested as negative resistance when the resonance frequency exceeds one-sixth of the sampling frequency (fs/6). As a result, the damping effect disappears. To extend the system damping region, this study proposes a virtual resistor–inductor–capacitor (RLC) AD method. The method is implemented by feeding the filter capacitor current passing through a band-pass filter, which functions as a virtual RLC in parallel with the filter capacitor to achieve positive resistance in a wide resonance frequency range. A combination of Nyquist theory and system close-loop pole-zero diagrams is used for damping parameter design to obtain optimal damping parameters. An experiment is performed with a 10 kW grid-connected inverter. The effectiveness of the proposed AD method and the system’s robustness against grid impedance variation are demonstrated.

An Improved Active Damping Method with Capacitor Current Feedback

Yi-Wen Geng,Ya-Wen Qi,Hai-Wei Liu,Fei Guo,Peng-Fei Zheng,Yong-Gang Li,Wen-Ming Dong 전력전자학회 2018 JOURNAL OF POWER ELECTRONICS Vol.18 No.2

Proportional capacitor current feedback active damping (CCFAD) has a limited valid damping region in the discrete time domain as (0, fs/6). However, the resonance frequency (fr) of an LCL-type filter is usually designed to be less than half the sampling frequency (fs) with the symmetry regular sampling method. Therefore, (fs/6, fs/2) becomes an invalid damping region. This paper proposes an improved CCFAD method to extend the valid damping region from (0, fs/6) to (0, fs/2), which covers all of the possible resonance frequencies in the design procedure. The full-valid damping region is obtained and the stability margin of the system is analyzed in the discrete time domain with the Nyquist criterion. Results show that the system can operate stably with the proposed CCFAD method when the resonance frequency is in the region (0, fs/2). The performances at the steady and dynamic state are enhanced by the selected feedback coefficient H and controller gain Kp. Finally, the feasibility and effectiveness of the proposed CCFAD method are verified by simulation and experimental results.