Influence of elastomeric lag damper modeling on the predicted dynamic response of helicopter rotor systems

Author(s):  
Donald Kunz
Sadhana ◽  
1994 ◽  
Vol 19 (3) ◽  
pp. 427-466 ◽  
Author(s):  
Inderjit Chopra

2014 ◽  
Vol 71 (2) ◽  
Author(s):  
Mohd Shariff Ammoo ◽  
Ziad Abdul Awal ◽  
Norhidayah Mat Sangiti

Balancing is a rotating component is critical in any mechanism. Devoid of proper balancing, any vehicle - be it in air, land or sea, it will affect stability, control and safety. The same goes for rotor crafts. Imbalance of the helicopter tail rotor system leads to vibrations in the entire vehicle and may cause accident. Typically, for the tail rotor of a helicopter, the blade is a source of vibration on the tail boom. This not only causes inconvenience to the pilot but also reduces the life span of the helicopter. There is a certain amount of vibration in the helicopter rotor systems especially the tail rotor. Hence, balancing procedure for rotating mass was conducted to reduce the vibration. This research focuses on balancing of the tail rotor for UTM Single Seat Helicopter. Experiments have been conducted in order to study the vibration level of the tail rotor. Adding and removing masses separately on the tail rotor exhibited different vibration levels. The responses were analyzed and used for balancing the tail of rotor system. The balancing effort was considered successful, although there was still some residual unbalance in the tail rotor.


Author(s):  
Sen Xiao ◽  
FaYong Wu ◽  
YanHong Ma ◽  
Jie Hong

Aiming at the misaligned problems of high-speed flexible multi-supported rotor system, considering the structural characteristics and load characteristics of the rotor, the unbalanced excitation of the rotor with misalignment is presented and quantitatively described. The mechanical model of the high-speed flexible rotor system with multi-support under misaligned excitation is established. Based on the finite element method, the dynamic equation of the rotor system is given and the dynamic response characteristics of rotor systems are studied. The results show that the misalignment for the highspeed multi-support flexible rotor system can not only lead to 2X excitation and support stiffness nonlinearity, but also bring additional unbalanced excitation to the rotor system. The 2X frequency component is one typical feature for the rotor system with bearing misalignment. The vibration response of the rotor showed a trend of “increased slowly first, then reduced quickly as the rotation frequency increased”, and it turns to be more obvious with the increasing of the nonlinear stiffness and unbalance.


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