Article
Engineering, Mechanical
Heyong Si, Lihua Cao, Pan Li, Dongchao Chen
Summary: A multi-frequency conical whirl model was established to investigate the influence of different rotor whirling motion on seal steam flow excited vibration and dynamic characteristics. The dynamic coefficients have the obvious variation in semi and full conical whirl motion. The expansion profile of seal cavity caused by conical whirl motion makes the fluctuation range of circumferential pressure great.
TRIBOLOGY INTERNATIONAL
(2021)
Article
Engineering, Mechanical
Lipeng Wang, Fengchao Huang, Yuegang Luo, Changzheng Chen
Summary: A dynamic model of a seal-crack rotor system was established using the finite element method, and the vibration characteristics of airflow excitation and single-crack and double-crack coupled faults were analyzed. The results show that the influence of crack damage on the system is closely related to the degree of cracks and sealing parameters.
NONLINEAR DYNAMICS
(2022)
Article
Engineering, Chemical
Baoxing Chen, Chi Yu, Sanpeng Gong, Xinwen Wang
Summary: This paper investigates the dynamic characteristics of the flip-flow screen panel, proposes a dynamic model for analysis with numerical methods, verifies the correctness and accuracy of the theory, and establishes a coupling simulation model to study the impact of screen panel vibration on particle movement and screening efficiency.
CHEMICAL ENGINEERING SCIENCE
(2021)
Article
Engineering, Multidisciplinary
Jun Shao, Jigang Wu, Yuan Zhang
Summary: This paper investigates the dynamic characteristics of an aeroengine rotor subjected to aerodynamic excitation. The dynamic model of the rotor system was established using the finite element method, and critical speeds and mode shapes were determined through calculation, simulation, and experiment. Analysis of the dynamic responses using various tools revealed that the system exhibits stable-periodic motion at low speeds but becomes unstable at higher speeds. The effects of blade-tip clearance, inlet angle, and outlet angle on the dynamic responses were also discussed.
MEASUREMENT SCIENCE AND TECHNOLOGY
(2023)
Article
Energy & Fuels
Chuan Xue, Lihua Cao, Heyong Si
Summary: To investigate the impact of thermal and dynamic loads coupling on steam turbine rotor vibration, a lumped mass method was used to model the anisotropic rotor of a 1000-MW ultra-supercritical steam turbine high-pressure cylinder. The steam flow excited force from the first eight stages was converted into an equivalent gas bearing force and added to the rotor. The Riccati transfer matrix method was then used to analyze the influence of steam flow excited force on rotor vibration characteristics. The results showed that considering thermal and dynamic loads, the ellipse trajectory had smaller amplitudes at the ends and a larger amplitude in the middle. The azimuth of the ellipse trajectory increased with increasing load and nodes before and after coupling. The natural speeds of the rotor changed with load, with the first-order natural speed increasing and the second-order natural speed decreasing. However, the natural speed after coupling was significantly lower than before coupling. The first-order amplitude range decreased with increasing load. Coupling thermal and dynamic loads increased the first-order logarithmic decrement rate under relatively high loads, but the rotor stability margin was insufficient, resulting in instability.
JOURNAL OF ENERGY RESOURCES TECHNOLOGY-TRANSACTIONS OF THE ASME
(2023)
Article
Engineering, Mechanical
Moein Zanjanchi Nikoo, Milad Lezgi, Saeid Sabouri Ghomi, Majid Ghadiri
Summary: This study investigates the dynamic instability and vibration of functionally graded porous sandwich nanobeams resting on a visco-elastic foundation under axial harmonic load based on the nonlocal theory. The Timoshenko and nonlocal continuum theory are used to consider shear deformation, rotational bending, and small-scale effects. The governing equations of motion are derived using the nonlinear Von-Karman and Hamilton approaches, and solved using the method of Galerkin and multiple time scale method. The study finds that the porosity ratio is more influential than porosity distribution and nonlocal parameters on the amplitude response and dynamic instability regions.
PROCEEDINGS OF THE INSTITUTION OF MECHANICAL ENGINEERS PART C-JOURNAL OF MECHANICAL ENGINEERING SCIENCE
(2023)
Article
Engineering, Mechanical
Yuegang Luo, Pengfei Wang, Haifeng Jia, Fengchao Huang
Summary: This study established a finite element model of seal-rubbing rotor system based on various force models, analyzing the vibration characteristics under the coupling faults of airflow excitation and rub-impact. Results showed that airflow excitation exhibits frequency locking and combination frequency when rub-impact fault is absent, while the coupling dynamic responses of airflow-induced vibration and rub-impact fault display nonlinear phenomena closely related to the degree of rub impact.
JOURNAL OF COMPUTATIONAL AND NONLINEAR DYNAMICS
(2021)
Article
Acoustics
Allen Anilkumar, V. Kartik
Summary: The study focuses on the impact of multi-frequency parametric excitation on the stability of an oscillator in a rotating system. Floquet theory is used to develop stability diagrams and explain the reasons for instabilities, finding various resonance scenarios. The investigation aims to identify operating regimes to prevent catastrophic failure in multi-frequency rotating machines.
JOURNAL OF SOUND AND VIBRATION
(2021)
Article
Engineering, Geological
Geng Cao, Xiao Wang, Changdi He
Summary: This study presents a semi-analytical methodology for the dynamic analysis of laterally loaded rectangular piles in multi-layered viscoelastic soils. The governing equations for the pile-soil system are derived using Hamilton's Variation principle and calculus of variations. The dynamic responses are solved analytically and numerically, and the effects of cross-section shapes and soil stratification are investigated.
SOIL DYNAMICS AND EARTHQUAKE ENGINEERING
(2023)
Article
Acoustics
Allen Anilkumar, V. Kartik
Summary: The paper investigates the dynamics of a generic multi-rotor system where the rotor and stator have comparable inertia and compliances. Numerical integration of parametrically-excited equations for a representative dual-rotor case reveals complex frequency spectra and cyclically time-varying eigen-structure. The results suggest that even seemingly simple multi-frequency parametrically excited rotating systems exhibit complicated eigen and temporal characteristics.
JOURNAL OF SOUND AND VIBRATION
(2021)
Article
Astronomy & Astrophysics
P. B. Wiegmann
Summary: In this study, we developed a spacetime-covariant Hamilton principle for the evolution of barotropic flows of a perfect fluid in the presence of an external axial-vector potential. It was found that the axial-current anomaly in quantum field theories with Dirac fermions can be interpreted as a kinematic property of classical hydrodynamics, and interesting effects can occur under the simultaneous actions of the electromagnetic field and the axial-vector potential. By using the Hamilton principle, we obtained the extended Euler equations accounting for the axial potential and derived anomalies in the divergence of the axial and vector currents. Our approach provides a hydrodynamic expression for the vector and axial currents and establishes a platform for studying flows with a chiral imbalance and their associated anomalies.
Article
Engineering, Mechanical
Hongyang Xu, Yang Yang, Hui Ma, Zhong Luo, Xiaopeng Li, Qingkai Han, Bangchun Wen
Summary: This study proposes a novel dynamic model of the bearing-rotor system, considering the inner ring dynamic misalignment and incorporating nonlinearity and axial restraint. The accuracy of the model is verified through experimentation, and the effects of misalignment angle, radial clearance, and rotational speed on system dynamic characteristics are analyzed.
INTERNATIONAL JOURNAL OF MECHANICAL SCIENCES
(2022)
Article
Engineering, Multidisciplinary
Hassan Jalali, Farzad Rafieian, Hamed Haddad Khodaparast
Summary: This work investigates the rotor-armature structure of an exciter rotor used in a steam turbine-generator unit, aiming to create a verified base linear dynamic model for fault diagnosis or nonlinear interactions analysis.
APPLIED MATHEMATICAL MODELLING
(2022)
Article
Chemistry, Physical
Zhen Huang, Xikou He, Kun Chen, Xitao Wang
Summary: The solidification characteristics of C700R-1 alloy were investigated, and it was found that aggravation of segregation led to deterioration of the solidification conditions. The volume fraction of liquid decreased steeply and dendrites formed. The residual liquid solidified slowly, and element segregation resulted in the formation of carbides and eutectic region.
JOURNAL OF ALLOYS AND COMPOUNDS
(2022)
Article
Engineering, Mechanical
Zhong Luo, Lei Li, Fengxia He, Xiaolu Yan
Summary: This paper proposes a scaling method for rotor models that considers gravitational acceleration, which differs from previous studies and can reduce the difficulty and costs of model testing. The results show that neglecting gravitational acceleration can lead to errors in predicting vibration responses.
MECHANISM AND MACHINE THEORY
(2021)
Article
Engineering, Mechanical
Antonella Castellano, Pietro Stano, Umberto Montanaro, Marco Cammalleri, Aldo Sorniotti
Summary: This paper proposes a new control strategy for hybrid electric vehicles, called Model Predictive Control (MPC), and considers the losses in transmission gears. Through a case study on Chevrolet Volt, the results show that the simplified internal model has a minor impact on fuel consumption performance.
MECHANISM AND MACHINE THEORY
(2024)
Article
Engineering, Mechanical
Rui Peng, Gregory S. Chirikjian
Summary: This article introduces a method of designing morphable thick-panel origami structures using reconfigurable linkages, which improves the potential of origami techniques for different tasks and solves the limitations of one-DOF and multiple-DOF folding structures.
MECHANISM AND MACHINE THEORY
(2024)
Article
Engineering, Mechanical
Gaohan Zhu, Weizhong Guo, Yinghui Li, Youcheng Han
Summary: Comprehensive and accurate performance evaluation is crucial for profile synthesis and analysis of higher pair mechanisms. This paper proposes evaluation indices and methods for the transmission performance of planar higher pair mechanisms from different perspectives. It subdivides the transmission performance into element-based performance and joint-based performance and develops novel indices specific to higher pair mechanisms. A graphical mapping method based on element-based performance is also proposed for intuitive analysis. Practical examples validate the effectiveness of the proposed indices and methods for evaluating the performance of higher pair mechanisms.
MECHANISM AND MACHINE THEORY
(2024)
Article
Engineering, Mechanical
Ke Wu, Gang Zheng, Guimin Chen, Shorya Awtar
Summary: Researchers proposed a new modeling method, namely Body-frame Beam Constraint Model (BBCM), to predict and optimize the design of high-precision compliant mechanisms (CMs).
MECHANISM AND MACHINE THEORY
(2024)
Article
Engineering, Mechanical
Youcheng Han, Weizhong Guo, Changjie Zhao, Ziyue Li, Ze Fu, Yinghui Li
Summary: This study proposes a structural synthesis methodology that considers motion, force, and energy characteristics simultaneously to design efficient mechanisms.
MECHANISM AND MACHINE THEORY
(2024)
Article
Engineering, Mechanical
Cristian Enrico Capalbo, Daniel De Gregoriis, Tommaso Tamarozzi, Giuseppe Carbone, Domenico Mundo
Summary: This study proposes a novel flexible multibody formulation that enables efficient updating of models while maintaining small size and high accuracy. Numerical validation demonstrates its wide applicability across various materials and mechanisms, showing promising results in terms of accuracy.
MECHANISM AND MACHINE THEORY
(2024)
Article
Engineering, Mechanical
Weihao Zhao, Junbei Liao, Wei Qian, Haoyong Yu, Zhao Guo
Summary: This paper presents a newly designed compliant actuator using a tensile springs array to address the challenges in achieving linear and consistent elastic properties, low friction, minor hysteresis, and good compliance in series elastic actuators (SEA). The unique geometry of the spring array enables the SEA to have consistent rotary stiffness with minimal friction and hysteresis. The device's performance is evaluated using PID and sliding mode control, demonstrating its constant low rotary stiffness and torque tracking bandwidth, making it suitable for human-robot interaction requirements.
MECHANISM AND MACHINE THEORY
(2024)
Article
Engineering, Mechanical
Mohui Jin, Yukang Luo, Xing Xu, Bowei Xie, Weisheng Wang, Zewei Li, Zhou Yang
Summary: This paper presents a method for evaluating the contact interaction between compliant mechanisms and external objects. By establishing a numerical model and introducing contact springs to describe the contact forces, the deformation and normal contact force/stress can be accurately calculated. The static equilibrium configuration and contact force/stress can be obtained by minimizing the total potential energy function of the system.
MECHANISM AND MACHINE THEORY
(2024)
Article
Engineering, Mechanical
Alejandro G. Gallardo, Martin A. Pucheta
Summary: This paper presents a method for the synthesis of parallel flexure systems using Screw Theory and Linear Algebra. The method is validated through three case studies and offers a simple and precise design with decoupled actuators.
MECHANISM AND MACHINE THEORY
(2024)
Article
Engineering, Mechanical
Xiao Wang, Chenglin Liu, Haoxiang Sun, Hanwen Song
Summary: This paper presents a new decomposition mode for robot-world calibration, which decomposes the Ad(SE(3)) equation using Chasles' motion. A two-step method based on point set matching is proposed. The superiority of this method is verified through simulations and experiments.
MECHANISM AND MACHINE THEORY
(2024)
Article
Engineering, Mechanical
Yanlin Chen, Xianmin Zhang, Yanjiang Huang, Yanbin Wu, Jun Ota
Summary: This study establishes an error model for a 3-RRR+UR spherical parallel mechanism and analyzes the sensitivity of error parameters. A design structure is proposed to reduce input errors based on the analysis. Experimental results show that the multiloop circuit incremental method provides more accurate results.
MECHANISM AND MACHINE THEORY
(2024)
Article
Engineering, Mechanical
Vu Linh Nguyen, Chin-Hsing Kuo, Po Ting Lin
Summary: This paper presents a method for analyzing the performance of gravity-balanced serial robotic manipulators under dynamic loads and uses a three-degree-of-freedom planar serial manipulator as a case study. The significance of this method is demonstrated by evaluating the impact of dynamic loads on gravity-balanced performance and proposing a step-by-step design procedure to improve it.
MECHANISM AND MACHINE THEORY
(2024)
Article
Engineering, Mechanical
Shifeng Rong, Jiange Zhang, Xing Zhang, Keliang Li, Kaibin Rong, Zhenyu Zhou, Han Ding
Summary: This article proposes a data-driven dry cutting tool collaborative optimization model to improve the economic and environmental attributes of facehobbing hypoid gears. An innovative ease-off tooth contact analysis method is introduced to establish accurate relations between ease-off flank and loaded contact performance evaluations. The proposed model significantly improves sustainability in terms of economic and environmental assessments.
MECHANISM AND MACHINE THEORY
(2024)
Article
Engineering, Mechanical
Kemal Eren, Soley Ersoy, Ettore Pennestri
Summary: This research investigates the instantaneous kinematics of the terminal link of a planar two-link open chain using the complex-number technique and higher-order instantaneous invariants.
MECHANISM AND MACHINE THEORY
(2024)
Article
Engineering, Mechanical
Bo Han, Zhantu Yuan, Jiachuan Zhang, Yundou Xu, Jiantao Yao, Yongsheng Zhao
Summary: This paper proposes novel deployable mechanism units with self-limiting position function, and constructs ring truss deployable mechanisms. The degrees of freedom (DOF) of deployable units are analyzed and it is proved that the constructed ring truss deployable mechanisms have only one DOF. The dynamic model of the deployable mechanism unit with passive actuation is established and verified by simulation. The deployable mechanism units proposed in this paper have the advantages of good scalability and stability, and have broad application prospects.
MECHANISM AND MACHINE THEORY
(2024)