最小作用量原理对极小曲面点阵结构性能的影响
Influence of the Least Action Principle on Properties of Minimal Surface Lattice Structure
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摘要: 建立了曲面面积及其曲率的数学模型,讨论了最小作用量原理与极小曲面之间的关系,设计了体心立方(BCC)构型下体积分数分别为20%,30%的极小曲面点阵结构,以Ti-6Al-4V合金粉末为原料采用激光选区熔化成形极小曲面点阵结构和传统点阵结构,研究了最小作用量原理对其表面积、曲率特征和力学性能的影响,并利用十字架(cross-cube)构型下的极小曲面点阵结构进行进一步验证。结果表明:极小曲面的平均曲率为0,遵循最小作用量原理;在BCC构型下与传统点阵结构相比,极小曲面点阵结构的表面曲率分布更集中,表面积均更小,刚度、弹性变形阶段的能量吸收和弹性极限更大;cross-cube构型下的极小曲面点阵结构相较于传统点阵结构,其表面积也减小,弹性模量增大。相同拓扑构型下与传统点阵结构相比,极小曲面点阵结构的力学性能更优异是因为极小曲面遵循最小作用量原理,极小曲面点阵结构的表面积更小,表面曲率分布更集中,从而缓解了节点处的应力集中现象。Abstract: The mathematical model of surface area and its surface curvature was established, and the relationship between the least action principle and the minimal surface was discussed. The minimal surface lattice structures in the body-centered cubic (BCC) configuration with volume fraction of 20% and 30% were designed. The minimal surface lattice structures and traditional lattice structures were formed by laser selective melting with Ti-6Al-4V alloy powder as raw materials. The influence of the least action principle on the surface area, curvature characteristics and mechanical properties of lattice structures was studied, and the minimal surface lattice structure in the cross-cube configuration was used for further verification. The results show that the mean curvature of minimal surface was zero, following the least action principle. In the BCC configuration, compared with the traditional lattice structures, the surface curvature distribution of the minimal surface lattice structures was more concentrated. When the volume fraction was 20% and 30%, the surface area of the minimal surface lattice structure was reduced, and the stiffness and the energy absorption and elastic limit during elastic deformation increased. In the cross-cube configuration, compared with the traditional lattice structure, the surface area of the minimal surface lattice structure was reduced and the modulus of elastic increased. Compared with the traditional lattice structure in the same topological configuration, the mechanical properties of the minimal surface lattice structure were better; that was because the minimal surface followed the least action principle, having smaller surface area and more concentrated surface curvature distribution, resulting in alleviation of stress concentration at the nodes.