Research On Factors Of Lifting Dynamic Coefficient For Offshore Cranes

Since the 21st century, China’s marine economy has developed rapidly, which makes the development of large offshore projects flourish. The offshore crane is special lifting equipment which is used to lift personnel and goods on the platform. When the offshore platform crane works, due to the impact of wind and waves, its working environment is extremely harsh. Therefore, the designer needs to consider the dynamic Load, which usually represented by dynamic coefficients of lifting. In the process of designing the structure of the crane, if the value of dynamic coefficient of lifting is too large, it will cause the value of machine rigidity too large, thus making the structure too heavy; on the contrary, if the value is too small, it will make machine rigidity too small, less than the design equipment. About Lifting dynamic coefficient values, each standardized calculation methods are given, but the calculation process is relatively complicated, and the accuracy to be research, which the bring trouble to designers.From the view of finite element analysis, this paper analyzes the factors which affect the dynamic coefficient of lifting. Firstly, this paper analyzes the factors which affect the dynamic coefficients of lifting using Analytic Method, the theoretical analysis shows that under certain relative velocity, the main factors affect dynamic coefficients of lifting is the rigidity; Therefore, this paper analysis the factors that affect the rigidity, including:diameter of the rope, diameter of the boom and its’thickness, diameter of the cable, diameter of gable frame and its’ thickness and the thickness of the turntable. Then, we process all factors by using the finite element analysis method and successive approximation method, also with the help of MATLAB and Excel to fit the data.Through the analysis of the result, it shows that Rope’s diameter is the most influential factor to the dynamic coefficients of lifting. While the diameter of the base is the second influential factor; diameter of the cable and the thickness of the base are also important influential factors. While the boom, gable frame show little effect on the dynamic coefficients of lifting.Further analysis of the data obtained the following conclusions:Firstly, by analyzing the diameter of the base and its’thickness, we notice the even the same parts, different geometries will produce different effects on the dynamic coefficients of lifting. We also notice that elastic modulus of the material produce some effects on the coefficients by analyzing the effects of the base and rope on the dynamic coefficients of lifting. Finally, we analyze the effects of the cable and rope on the dynamic coefficients of lifting; it shows that different spatial position has different effect on the dynamic coefficients of lifting. In a word, many factors such as geometries, elasticity modulus, and spatial position can affect the dynamic coefficients of lifting.This study provides some useful reference for our offshore crane design.