Nonlinear Vibration Characteristics With Large Unbalance of Turbogenerators Rotor Systems

1995 ◽  
Author(s):  
Songyuan Lu ◽  
Gao Wei
Keyword(s):  
Nonlinear Vibration ◽  
Power Plants ◽  
Vibration Characteristics ◽  
Accident Analysis ◽  
Operation Condition ◽  
Rotor Systems ◽  
Shaft System ◽  
Time Marching ◽  
Made In China ◽  
Made In

Abstract Some catastrophic vibration failures of turbogenerators shaft system have occurred in China and abroad. But, since the researches on nonlinear vibration characteristics of real engineering rotor-bearing system were not thoroughgoing in the past years, so the accurate and quantity analysis on particular accidents is still impossible. However, to understand the nonlinear vibration characteristics with large unbalance is engineering important for accident analysis, investigation and for precautions against the failures. This paper employed a new transfer matrix-time marching approach, and made researches on calculation for nonlinear vibration caused by large vibration at the generator rotor and low pressure rotor of 200MW turbogenerators made in China. By this study, some new and important conclusions concerned transient process while much mass escaped from turbogenerators rotor at operation condition have been obtained. They can provide valuable suggestions to the accident analysis, the design of large turbogenerators shaft and operation technology of the power plants, and these conclusions will be the foundation for the further researches on the destruction mechanism of turbogenerators forced by nonlinear vibration.

Non-Linear Coupled Dynamics of a Flexible Propeller-Shaft System Supported by Water Film Bearings

2020 ◽  
Vol 142 (3) ◽  
Author(s):  
Chang-Gang Lin ◽  
Ming-Song Zou ◽  
Can Sima ◽  
Li-Bo Qi ◽  
Yue Yu
Keyword(s):  
Nonlinear Vibration ◽  
Damping Ratio ◽  
Water Film ◽  
Vibration Characteristics ◽  
Superposition Method ◽  
Propeller Shaft ◽  
Chaotic Motions ◽  
Mode Superposition Method ◽  
Shaft System ◽  
Slice Method

Abstract A slice method to determine the boundary conditions between the stern bearing and shaft by dividing the journal in the stern bearing into several slice elements along the axial direction is proposed for the first time. A comprehensive finite element model considering the nonlinear force of the water film and the flexibility of the propeller blade is established for a propeller-shaft system. The long bearing approximation is adopted to calculate the pressure distribution around each journal element in the stern bearing. The mode superposition method is employed. The nonlinear equation of motion is solved iteratively using the Newmark method. A parametric study is implemented to analyze the nonlinear vibration characteristics of the system. It is shown that the real motion state of the journal in the stern bearing can be simulated more precisely by the slice method proposed. The responses of the system alternate among period-one, quasi-periodic, multi-periodic, and chaotic motions as the rotating speed increases. The damping ratio has a significant effect on the dynamic characteristics of the propeller-shaft system. The motion of the system is unstable when the damping ratio is very small. At this time, the modes of the flexible propeller blades can be excited readily. The slice method, which can also be extensively used in similar rotor-bearing systems in the engineering field, is very simple and efficient to analyze the nonlinear vibration characteristics of a flexible propeller-shaft system supported by water film bearings.

Made in China [newly made power plants]

2005 ◽  
Vol 19 (6) ◽  
pp. 12
Author(s):  
M. Venables
Keyword(s):  
Power Plants ◽  
Made In China ◽  
Made In

scholarly journals An efficient method for vibration equations with time varying coefficients and nonlinearities

2021 ◽  
pp. 146134842110251
Author(s):  
Jinsong Yang ◽  
Jingsong Xie ◽  
Gaige Chen ◽  
Jinglong Chen
Keyword(s):  
Nonlinear Vibration ◽  
Efficient Method ◽  
Stiffness Matrix ◽  
Time Varying ◽  
Rotor Systems ◽  
Varying Coefficients ◽  
Multistage System ◽  
Shaft System ◽  
Time Varying Coefficients ◽  
Time Required

An efficient method for solving vibration equations is the basis of the vibration analysis of a cracked multistage blade–disk–shaft system. However, dynamic equations are usually time varying and nonlinear, and the time required for solving is greatly increased accompanied by an increase in the model order caused by the multistage system and the nonlinearity caused by cracks. In this article, an efficient method for solving the time varying and nonlinear vibration equation is investigated. In the proposed method, the time varying terms are transformed into constant terms, while the local nonlinear matrix of the cracked blade is separated from the assembly stiffness matrix under the constraint of proper orthogonal decomposition (POD) transformation rules. Furthermore, the POD transformations of the constant terms and the linear assembled stiffness matrix can be implemented in the pretreatment steps to achieve a more efficient POD reduction operation. This research provides a method for efficiently performing the comprehensive and rapid analysis of nonlinear vibration characteristics of rotor systems.

Doctors ’Made in China’ – Locally Trained, Globally Excellent

Praxis ◽  
2020 ◽  
Vol 109 (6) ◽  
pp. 1-2
Author(s):  
Ewelina Biskup ◽  
Feng Li ◽  
Shixian Dong ◽  
Yan Wo
Keyword(s):  
Made In China ◽  
Made In

Made in China: How Chinese Innovation Is Changing the Patent Landscape

2014 ◽  
Author(s):  
Jay P. Kesan ◽  
Alan C. Marco ◽  
Richard Miller
Keyword(s):  
Patent Landscape ◽  
Made In China ◽  
Made In

Made in China, fashioned in Africa: ethnic dress in Ethiopia and Mozambique

Africa ◽  
2021 ◽  
Vol 91 (2) ◽  
pp. 317-336
Author(s):  
Johanna von Pezold ◽  
Miriam Driessen
Keyword(s):  
Design Elements ◽  
Grass Roots ◽  
Made In China ◽  
Made In ◽  
Naming Practices

AbstractThe influx of Chinese-made African ethnic dress has been central to debates about the consequences of the growing Chinese presence in Africa. Exploring the reception of the Chinese-produced capulana in Mozambique and net'ela in Ethiopia, we demonstrate that Mozambican and Ethiopian manufacturers and traders, from the grass roots up to cultural elites, engage with Chinese imports with creativity and verve. While welcoming Chinese materials for their affordability, bold and bright colours and suitability for dressmaking, they fashion them in ways that fit their own tastes and the local fashion trends. We distinguish three practices by which people do this: first, by incorporating Chinese materials or design elements into their own products; second, by co-creating new designs and dress with their Chinese counterparts; and third, by altering the imported fabrics. Apart from fashioning imports, some manufacturers use strategies to distinguish their own products from Chinese counterparts. These strategies include naming practices linked to the stories of their origin and alterations to the material.

Platform Capitalism ‘Made in China’? Intelligent Manufacturing, Taobao Villages and the Restructuring of Work

2019 ◽  
Vol 24 (2) ◽  
pp. 199-217 ◽  
Author(s):  
Boy Lüthje
Keyword(s):  
Intelligent Manufacturing ◽  
Value Chains ◽  
Policy Recommendations ◽  
Employment Policy ◽  
Social Shaping Of Technology ◽  
Social Shaping ◽  
Made In China ◽  
The Impact ◽  
Conditions Of Employment ◽  
Made In

The article examines the development of advanced digital manufacturing (as outlined in the ‘Made-in-China 2025’ government plan) from the perspective of the changing socio-technical paradigms of production. The analysis focuses on the transformations of value chains and work, based on theories of social shaping of technology, regulation theory and regimes of production. Analytically, the author proposes to distinguish between ‘production-driven’ and ‘distribution-driven’ pathways of manufacturing digitalisation. The transformation of semi-rural industrial areas (‘Taobao villages’, named after China’s largest e-commerce platform Taobao) into mass production clusters for e-commerce is depicted as a paradigmatic model of distribution-driven transformation and as a characteristic Chinese strategy in this field. The article examines the impact on industry supply chains and work, leading to ever-more precarious conditions of employment. Policy recommendations focus on local strategies to stabilise supply chain structures and working conditions, as an alternative to the present top-down approaches to manufacturing modernisation in China.

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