ANALYTICAL APPROACH IN THE ANALYSIS AND OPTIMIZATION OF CRANES DYNAMIC LOADS DURING THEIR START-UP: SWINGING THE LOAD

Abstract

During the operation of the cranes pendulum swings of the load are observed. They cause cranes or cargo carts uneven movement, additional loads on power ele-ments of cranes, create inconvenience during their operation. This must be taken into account during detailed cranes calculations. 
 In bridge, gantry and some other standard types of cranes which move along a rail path, load pendulum oscillations frequency relative to the crane is significantly lower than the elastic oscillations frequency of the crane metal structure and the movement mechanism transmission. Therefore, the load pendulum oscillations can be considered practically independent from the crane elastic oscillations and when cal-culating them, the metal structure and movement mechanism transmission can be taken as absolutely rigid. In this study to determine the dynamic loads acting on the metal structure and the movement mechanism transmission, the law of ropes tension hori-zontal component change, which arises as a result of the load pendulum oscillations, is given in the form of a known time function, which is determined according to the scheme of an absolutely rigid crane. This approach allows to reduce the order of mo-tion equations of the crane dynamic system by two units. In accordance with the above, the calculation of pendulum oscillations of the load on a ropes can be carried out ac-cording to the simplest two-mass scheme. This is exactly the approach implemented in the study. Motion conditions and equations of the “cargo cart − the load on a rope” system analytically determined, at which dynamic loads in the rope/elastic element have the smallest (minimum) values in the starting mode of the bridge-type crane.