Dynamic Force Distribution And Design Optimization For Multi-layer Winding Drum

Winding machine is important part of crawler crane,which usually working under high and variable loads in poor operating conditions.Among the system,winch drum and rope are essential parts.If any failure occurs there will be serious consequences.Nowadays,the major reason of the failure of winch drum is the discrepancy between the analysis of drum loads and actual mechanical behavior.The multi-layer winch drum loads calculation based on empirical equations is way too conservative.Because of the mechanical behavior of multi-layer winch drum,the acting loads are not a constant value but variable value which is dependent on the windings in axial direction along the drum and the layers in radial directions.The actual drum loads are sophisticated.If contact method is used for calculation,the massive computational cost to calculate contact and self-contact between each layer will be difficult.So it’s very necessary and important to build up the mechanical model for multi-layer winch drum.The result of dynamic force during the course of spooling into drums in multi-layer winding will be a more sound and accurate basis for the design of drum thickness,strength and stability design.In the thesis,by study and deduction of Euler’s formula,a more accurate method is introduced to study the multi-layer winding drum force.Analytical model of rope is studied to illustrate the loss elimination effect.For a rope drum with Lebus-winding,the compressional force of ropes during parallels section,inclined section and rising section has been taken into account.By using more specific parameters based on design method,correlation factors are counted for the influence of drum and rope deformations depends on the number of layers and the stiffness of rope and drum.Compared to the empirical based calculation,this method is more specific and leads to the realistic pressure pattern on the winch drum.Moreover the analysis of drum shell and rope groove gives more accurate design method for drum thickness,strength and stability.General steps and design methods are reviewed and updated for multi-layer drum strength design under three dimensional stresses.Furthermore the program of dynamic drum loads is developed.And a winch drum and rope system of a 270 T crane is introduced as an application example.The model and method presented in this thesis shows good agreement with the measurement performed.Structural analysis and optimization of drum design according to the model shows the side stress of optimal drum decreases by 24%.It gives good insight in the mechanical behavior of a multi-layer winch and confirms the importance of the research of the dynamic loads.The method can be an effective tool for the estimation of winch pressure and further optimization of the design of multi-layer winches.