Modeling And Design Of Lattice Based On Triply Periodic Minimal Surface

In recent years,with the rapid development of additive manufacturing technology,the direct forming of many complex structures has become possible.It makes the lattice which has excellent mechanical properties,functional characteristics of energy absorption and shock absorption,and controllable structure is widely used in aerospace,biomedicine,transportation and other fields.The lattice based on implicit function of Triply Periodic Minimal Surfaces(TPMS)not only has the above advantages,but also makes up for the disadvantages of traditional lattice,which is prone to produce stress concentration at the nodes and difficult to adjust the mechanical property.And the TPMS lattice also has the characteristics of self-supporting,there is no need to add additional support during the forming process of additive manufacturing,which improves the productivity.However,there are still some problems such as tedious steps,slow modeling speed and poor quality in the modeling of TPMS lattice.And limited by the modeling method,there is still great research prospect in the efficient design of TPMS lattice to accommodate more diverse requirements and more complex application scenarios.Thus,this paper optimizes the TPMS lattice modeling method based on the distance field,and aims at the contour distortion problem proposes a TPMS lattice modeling method based on the marching elements.On this basis,the graded TPMS lattice is designed,and the stress adaptive filling method of the graded TPMS lattice is proposed.The main research content of the paper is summarized as follows:(1)The modeling method of TPMS lattice structure based on distance field is explored.Aiming at the time-consuming problem of modeling TPMS lattice with complex contour by this method,a complex contour TPMS lattice modeling method based on voxel distance field is proposed.And the experiment proves that the optimized method can greatly shorten the modeling time when modeling the complex contour TPMS lattice.(2)Aiming at the contour distortion problem of the TPMS lattice modeling method based on the distance field,a method based on the marching elements to modeling the TPMS lattice is proposed.The example shows the TPMS lattice modeling by this method has good surface quality.Then the speed and robustness of the above two modeling methods are analyzed and compared.(3)Taking advantage of the characteristic that the topology of the TPMS lattice can be controlled by function parameters,the relative density graded TPMS lattice,element size graded and structural graded based on sinusoidal function are designed.The relative density graded includes uniaxial linear graded,local relative density graded and TPMS lattice sandwich structure.(4)An adaptive stress filling method for graded TPMS lattice is proposed,and the effectiveness of the method is verified by an example.Network Gyroid lattice(Network Gyroid Lattice,NGL)with different relative densities are fabricated by Stereolithography technology,and the function of allowable stress and TPMS function parameters are obtained by fitting the mechanics experiment data.The stress adaptive filling(stress adaptive NGL)of graded TPMS lattice in quadrangular prism is realized based on the stress cloud and marching elements.Finally,the mechanical properties of stress adaptive NGL,uniaxial relative density gradient NGL and NGL under the same relative density were investigated through compression experiments.The experiments show that the stress adaptive NGL has higher stiffness and can withstand larger loads in the elastic deformation stage.