Cooperative Optimum Design Of Working Attachment For Backhoe Hydraulic Excavator

Hydraulic excavator plays an important role in mechanical engineering,which is widely used on various occasions.Due to the uncertain object,load uncertainty,uncertain operation,the complexity of movement and stress,overlap and coupling of these uncertainties,the research of hydraulic excavator is complicated.Therefore,it is necessary to adopt the collaborative optimization idea to divide the complex system into a number of relatively simple and independent subsystem to study.As far as excavator working attachment is concerned,its excavation performance and structural strength are the two aspects which reflect the whole performance.In this paper,the structure of the working attachment is analyzed based on parameterized finite element model of the working attachment;the performance of the working attachment is analyzed based on self developing software.Based on the two aspects of analysis,the multi objective optimization design of the integration of structure and performance is realized.The main research contents of this paper are as follows:(1)Through the overall design of the working attachment of the hydraulic excavator,a robust and reliable parameterized model of the Boom,Stick and Bucket is established.The parameterized model lays the foundation for finite element analysis of the whole working attachment.The difficulty of the model is to keep the high roubstness of model restruction when as many as dozens of parameters of the Boom,Stick and Bucket model linkage changes.(2)The parameterized model of the Boom,Stick and Bucket are imported into the finite element analysis software,through the coupling between components to build the finite element model of the whole working attachment,and ultimately the overall finite element analysis of the working attachment is realized.How to meet the requirement to establish the optimal mesh model are the difficulties of this part.Mainly in two aspects: on the one hand,the time required for optimization reduced to an acceptable range with the scale of grid became smaller;on the other hand,the higher quality grid with hexahedron is applied to the main components of working attachment.By doing so,not only reduces the size of the grid,but also improve the accuracy of the calculation.(3)Based on the kinematics and mechanics equations,the excavation resistance model is established to calculate the data of the theoretical digging force and geometric constraints,which lays the foudation for the subsequent optimization.(4)On the basis of the finite element model and the excavation resistance model,the key area method is proposed to investigate the characteristics of the working attachment.Based on this method,the maximum stress value and distribution of the region of the working attachment,Boom,Stick and Bucket are studied,and the corresponding conclusions are obtained.On this basis,the dangerous conditions are obtained and compared with the classical conditions.It is concluded that the new method is more dangerous.(5)Based on the two order regression model,twenty design variables has been selected which have the main influence on the target,and the approximate models of each discipline are establised on the basis above,and finally the collaborative optimization of the working attachment of the hydraulic excavator is realized.