Quayside container cranes rod of circular cross-section of wind-induced vibration and control
|School||Shanghai Maritime University|
|Course||Mechanical and Electronic Engineering|
|Keywords||vibration control crosswind vibration wind resonance round cross-section rod quayside container crane vortex vibration|
Logistics of the world accelerates the development of shipping greatly. As the main carry tool at the port, the quayside container crane is developing at full speed as well. More and more large-scale quayside container cranes are designed and manufactured so that their size become larger than ever. The influence that the wind cause to crane is heavier and heavier and more and more designing and applying units are paying more attention to this problem. Because of easy-made and cheap, many of the round cross-section rods are applied in the container crane. However, the cross-section rods are easy to occur wind resonance, the strong vibration can cause the rod two-end nodal board fatigue cracking. This dissertation research and analyze the cause of the vibration and the factors influencing their resonant wind velocity, and simulate the wind resonance, try to take some measures to reduce the vibration.The main form of the rod wind vibration is crosswind vibration, called the vortex-induced vibration according to the reason. This kind of vibration is caused by the alternate shedding vortex behind both sides of the rod when wind blow. Besides, in case the vortex shedding frequency is equal to a vibration frequency of structure, the rod will occur the vortex shedding resonance or called vortex resonance. Vortex vibration are forced vibration which basically caused by the vortex, but when the vibration strengthen, the rod vibration control the shedding of vortex, and the vibration appears the characteristic of self-excited vibration.The resonant velocity of wind has directly relation to the structure frequency, and the structure frequency related to many factors of the rod, the dissertation compute the different constrainted rod structure frequency with different axial force and length. With the use of finite element software ANSYS, we created the actual model of the fixed tie link in container crane, compute the model’s structure frequency and analyse the effect of the axial force and length on the frequency and resonant velocity, and use ANSYS dynamic module to simulate the rod crosswind resonance.The main measure we take to control the rod’s wind vibration is structural vibration control, that is fixing some wind interference unit at the surface of rod. The aim is to disturb the regularity of the shedding vortex and reduce the crosswind exciting force. In the dissertation the interference unit is interference rib. We contrast the vibration frequency ^ amplitude and mean square root at the case of no ri^ continuous rib and discontinuous rib of the rod, and put forward some other suggestions of vibration control at actual conditions.