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Vibration
Published in M Rashad Islam, A K M Monayem H Mazumder, Mahbub Ahmed, Engineering Dynamics, 2022
M Rashad Islam, A K M Monayem H Mazumder, Mahbub Ahmed
Vibrations can be classified as: Free and Forced Vibration. Free vibration means the system is left to vibrate on its own after the initial disturbance. In forced vibration, the system is subjected to an external repeating type of force, and the system vibrates in response to that. Damped and Undamped. If no energy is lost or dissipated by friction or other resistance during oscillation, the vibration is known as undamped vibration. If any energy is lost in this way, it is called damped vibration. In many physical systems, the amount of damping is so small that it can be disregarded for most engineering purposes. Linear and Nonlinear. If all the basic components of a vibration system such as spring, mass, and the damper behave linearly, then it is called linear vibration. In nonlinear vibration, one or more basic components of a vibration system do not behave in a linear manner. Deterministic or Not. Deterministic means the magnitude of the excitation (force or motion) acting on a vibratory system is known at any given time. In random vibration, the value of the excitation at any given time cannot be predicted. Examples of random vibration are wind velocity, road roughness, and ground motion during an earthquake, etc. Torsional Vibrations. Torsional vibrations are angular vibrations of an object, typically a shaft along its axis of rotation. Torsional vibrations are evaluated as the variation of rotational speed within a rotation cycle.
Vibration and stability analysis of drivelines with self-excitation of non-constant velocity couplings
Published in Mechanics Based Design of Structures and Machines, 2023
Masoud SoltanRezaee, Mohammad-Reza Ghazavi, Asghar Najafi, Wei-Hsin Liao
During the last few decades, parametric resonances of the propeller shaft systems linked via Cardan coupling have attracted a lot of attention. Several studies have been conducted on the lateral and torsional vibrations of propeller shaft systems (Wang and Qi 2018; DeSmidt, Wang, and Smith 2002; Xia et al. 2020; Yao and DeSmidt 2021; Shen and Lu 2021). However, while bending motions have been investigated in detail (DeSmidt, Wang, and Smith 2002; Iwatsubo and Saigo 1984; Saigo and Iwatsubo 1987; Kato and Ota 1990; Browne and Palazzolo 2009; Ganesan and Padmanabhan 2011; Iqbal and Qatu 2010; Feng, Wang, and Zhu 2012), few studies have examined the angular motion of the driving shafts. Torsional vibration in mechanical systems would be destructive since the undesired motion could damage the machine parts (Amer, El-Sayed, and El-Bahrawy 2015; El-Sayed and Bauomy 2015; Saigo and Tanaka 2006). In order to analyze the shaft torsional responses, modeling the shaft system is essential in numerous mechanical systems such as vehicles and machines. On the other hand, resonance conditions of drivelines with more than two shafts have been little studied. Recently, torsional behaviors and dynamic instability of multi-axis driving systems have been considered (Shen and Lu 2021; Wu and Caro 2019; Liu et al. 2019; SoltanRezaee, Ghazavi, and Najafi 2018; SoltanRezaee et al. 2018; Xu, Wan, and Luo 2016; Zlatanov 2016). In all of the studies, the rods were modeled as lumped mass bodies for simplicity. It is possible to obtain more accurate results by considering the shaft as a distributed system or using the finite element method (FEM) (Wu and Caro 2019).
Research on torsional vibration characteristics of reciprocating compressor shafting and dynamics modification
Published in Mechanics of Advanced Materials and Structures, 2020
Jian Liu, Xiaodong Sun, Xiao Zhang, Xiaobing Hou
Shafting is a main part of high-power and high-speed reciprocating compressor which is widely used in ocean engineering field. Its vibration characteristics are closely related to reliability and efficiency of compressors. The vibration of shafting contains transverse vibration and torsional vibration. For high-power, high-speed and multi-column compressors, torsional vibration is the main vibration form of shafting. In case that the torsional vibration is quite intense, it is possible that the shafting and other parts are ruined. Thus, it is of great significance to study the torsional vibration characteristics of compressor shafting.