Topology Optimization Design Of Assembled Hub Joints Based On Parametric Level Set Method

The spatial grid structure has the advantages of low material consumption,good permeability and various structural forms.In recent years,it has been widely used by designers in various large-scale public and civil buildings.Joints play an important role in connecting members and transferring loads in spatial structures.The weight of spatial structure fabricated joints usually accounts for about 10%to 30%of the overall reticulated shell,and most of them are semi-rigid nodes.In order to solve the problems of unreasonable material utilization and insufficient stiffness that may exist in the design of prefabricated joints,a parametric level set method that can consider both stress constraints and volume constraints is used to optimize the topology design of prefabricated hub joints.The joins with good mechanical properties and reasonable material distribution are obtained.Chapter 2 introduces a parametric level set topology optimization method,which can consider stress constraints in the optimization of structural stiffness by means of stress penalty.Then,the parametric level set method,which can consider multiple constraints,is integrated in ABAQUS-MATLAB,and the effectiveness of the method is tested and verified through optimization examples of two-dimensional and three-dimensional structures.Chapter 3 takes the K6 reticulated shell as the research object,and uses the parametric level set topology optimization method to optimize the topology of the joints at three key positions.The complex stress state of the joints in the actual structure is fully considered in the optimization process.At the same time,by comparing the optimization results under different volume constraints and Mises stress constraints,the most suitable optimization constraints for each joints are determined.The research results show that the maximum Mises stress in the optimization results is effectively controlled after adding stress constraints.The volume constraints have a significant impact on the compliance of optimization results.In chapter 4,the smoothing of the mesh structure after topology optimization and the method of geometric model reconstruction are explained first.Then,the finite element analysis is carried out on the topology optimization joints and the traditional design joints.And the volume,stress distribution and flexibility of the joints before and after optimization are compared.The research results show that the optimized hub joint has lighter weight and more uniform stress distribution,and the joint stiffness can meet the load conditions of the actual structure.Finally,the manufacturing and processing methods of topology optimization design joints are analyzed and compared,and it is a good choice to combine topology optimization design with metal 3D printing technology.Compared with the traditional single-constraint topology optimization,the topology optimization method proposed in this paper considering multiple constraints has a better optimization effect and has certain reference significance for the topology optimization design of various types of prefabricated joints.