Shield tunnel construction cause soil movement to harm the adjacent underground pipelines. This paper, taking Dalian Spring Street subway station as the background, uses the finite difference software to establish 3-D finite element analysis model to simulate the deformation of pipeline with 45* skew angle in the tunnel construction work. The results show: when the left tunnel push towards pipelines, due to the skew of the pipeline and tunnel, vertical displacement of pipelines is a certain shift to the left. When the right tunnel excavation is complete, the pipeline maximum settlement has a return to the center of the two tunnels. The settlement of pipeline is much bigger than horizontal displacement.
To improve the strong dependence of predictive control parameters on finite control set (FCS) models, an improved robust FCS predictive current control (FCS-MPCC) algorithm for permanent magnet synchronous motor (PMSM) drive systems is proposed. First, the problems of complex calculation and inaccurate selection of voltage vectors in traditional FCS-MPCC are analyzed, and an extended voltage vector-based MPCC (EV2-MPCC) based on the deadbeat principle is proposed to improve the steady-state performance of FCS-MPCC and also improve the anti-disturbance performance of the system. Second, the performance of PMSM under parameter mismatch is analyzed, and a sliding mode observer (SMO)-based stator current and disturbance observer is proposed. The observed disturbance term is used to compensate the reference voltage term for quickly selecting the optimal voltage vector, and the estimated current replaces the traditional predicted current. This method further improves the robustness of EV2-MPCC. Finally, the experimental results prove the effectiveness of the scheme.
In order to accurately explore the transmission rattling phenomenon and the influence of different factors on the dynamic characteristics of the gear rattling of the dual-clutch transmission under the condition of preselected gears, this paper establishes the gear rattling dynamics model of the transmission with the 1st gear without preselection and the preselected 4th gear, respectively; The model takes into account factors such as time-varying mesh stiffness, mesh damping, nonlinear oil film force, nonlinear backlash, and the drag torque generated by the clutch in the unengaged state. In addition, the feasibility of the dynamic model was verified by the bench test. On this basis, we took the gear meshing power and system power loss as quantitative indexes to analyze the influence of the preselected gear state and different parameters on the rattle vibration of the transmission. The results show that the pre-selected gear will not have a significant effect on the gears that have been rattled in the non-pre-selected state, and the torque fluctuation of the non-power flow shaft is aggravated by the influence of the transmission power flow branch and transmission ratio at different levels, which makes the overall rattling strength increase. In order to improve the transmission efficiency of the gear, the torque fluctuation of the input end of the system should be reduced as much as possible, and a larger lubricant viscosity can be appropriately selected, the inertia of the empty gear can be properly reduced, and the tooth clearance can be relaxed for selection.
The nonlinear dynamic behaviors of dual-rotor-bearing systems with looseness and rub–impact faults are discussed in this paper. The dual-rotor-bearing system with looseness and rub–impact coupling faults is established by the finite element method. The component mode synthesis (CMS) and proper orthogonal decomposition (POD) methods are introduced. The CMS and POD methods are used to reduce the original rotor system model, and the efficiency of the order reduction method is verified by comparing the dynamic behaviors of the original and reduced systems. The frequency spectrum and amplitude–frequency behaviors of rotor systems are studied. The results can provide qualitative guidance to structural design optimization of large rotating machines and prior information for looseness and rub–impact coupling faults.
Dual-clutch transmissions (DCTs) are very sensitive to torsional vibration and easily produce rattle noise if a single-mass flywheel (SMF) with a conventional torsional damper or a dual-mass flywheel (DMFW) is used in the vehicle. Only a DMFW combined with a centrifugal pendulum vibration absorber (CPVA) can eliminate rattle problem; however, this solution is expensive. Alternatively, a SMF with a CPVA is proposed to eliminate the DCT rattle issue, which could be a feasible and cost-effective solution free of side effects introduced by DMFWs. The vibration absorption principle of different types of pendulums and the rotor dynamic model are investigated to study the feasibility of a SMF with CPVA in a DCT vehicle. A seven-degree-of-freedom nonlinear lumped torsional vibration model is proposed to evaluate the torsional vibration attenuation performance of different configurations of torsional dampers and CPVAs. As per the model calculation results, the bifilar pendulum features the best attenuation performance compared with the circular and cycloid pendulums. The effect of pendulum parameters on attenuation is studied, and the optimized values are obtained. The SMF and optimized bifilar CPVA combination can satisfy the no-rattle requirements in vehicle relative to the DCT in-vehicle no-rattle threshold. A vehicle assessment on roads using physical pendulum prototypes indicates that the SMF with CPVA can be used as an alternative, cost-effective solution for DCTs, instead of the expensive DMFW with CPVA solution.
The interaction of a double-tube parallel tunnel excavation will greatly influence on underground pipeline of its region. This paper, taking Dalian Spring Street subway station as the background, uses the finite difference software to establish 3-D finite element analysis model to simulate the effects of tunnel excavation on underground pipeline, in which different embedment, material properties and diameters are considered. By analyzing of the settlement and deformation law of pipeline, the least affected pipeline conditions are drawn to provide corresponding guidance for subsequent underground projects.
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