In recent decades, the additive manufacturing technology has made great progress in software and methods in various fields, and gradually explored in a deeper and broader manner. It has changed from the mature homogenized lattice type and model design to a non-uniform direction. It has also started to improve from the aspects of material innovation, additive manufacturing printing technology, etc., to change the additive manufacturing technology and control parameters in the manufacturing process, Furthermore, the model or part can be improved to have better mechanical properties, such as stiffness, strength and wear resistance, which provides an important research methodology for the better development of this direction. These aspects include the software used, the type of structural analysis, the software used and verification, as well as the methods applied in the study of variable density lattices and the application and verification of improved research methods. In addition, there are density design optimization, variable density lattice design and lattice geometric characteristics’ design in geometric topology optimization design. The expected design of the model or part at the design level has reached the ideal model or part, which provides both a framework and ideas for the future research direction of non-uniform lattice design and a broader field of application, and will promote the future research and development prospects of variable density lattices.

Three-dimensional free bending is a new tube forming technology with continuous variable curvature. In order to improve the forming quality of tube, this paper studies the principle of three-dimensional free forming system and the numerical calculation of bending moment in detail, and it uses the finite element simulation to model the mechanism in the bending process. The simulation model is used to simulate the forming process of copper tube, and the influence of key process parameters on the forming process is analyzed,the shape of the inner cavity of the bending die and the gap between the tube and the bending die are studied, the distance between the bending die and the guide column is studied, the axial feed rate on the forming quality of tubular bending parts has also been studied. The optimum process parameters were determined by finite element simulation and analysis.