增材制造八角桁架点阵结构材料的力学行为

Mechanical behavior of the additively manufactured metallic octet-truss lattice materials

基于激光选区熔化增材制造技术(SLM),以GP1不锈钢为母材,制备4种相对密度的八角桁架点阵结构试样,开展了准静态单轴压缩和直接撞击式霍普金森压杆实验,并结合显式有限元计算模拟,研究了相对密度和加载速率对八角桁架点阵结构试样在力学响应、变形模式和吸能特性的影响.结果显示:(1)相对密度是影响八角桁架点阵结构材料力学响应的关键参数,屈服载荷随着相对密度基本呈线性增长,并且表现出明显的应变率强化效应;(2)在准静态压缩下,随着相对密度增大,八角桁架点阵结构的变形模式由弯扭屈曲模式逐渐向稳定屈服模式转变;而在冲击压缩下,八角桁架点阵结构的变形模式随着冲击速度由对称稳定变形模式向非对称逐渐压垮模式转变;(3)八角桁架点阵结构总吸能随着相对密度线性增大,而比吸能随着相对密度呈现双线性变化,在相对密度30%处出现拐折,当相对密度高于30%后,比吸能增大缓慢;(4)与准静态加载相比,冲击加载下八角桁架点阵结构的总吸能和比吸能都显著提升.

Based on selective laser melting(SLM) additive manufacturing technology, octet-truss lattice material with different relative densities were prepared with GP1 stainless steel as the base material. Quasi-static uniaxial compression experiments and direct impact Hopkinson barex periments as well as finite element simulations were carried out to study the influence of relative density and loading rate on the mechanical response,deformation mode and energy absorption foroctet-truss lattice material. Results show that relative density is a key parameter that affects the mechanical response of the octet-truss lattice structure. The critical yield loads increase linearly with the relative density, and it exhibits an obvious strain rate strengthening effect. Under quasi-static compression loading condition, with the increase of relative density, the deformation mode of the octet-truss lattice material changes from an unstable twist mode to a stable buckling mode. But under the impact compression loading condition, with the increase of the impact velocity, the deformation mode of the octet-truss lattice material changes from a symmetrical stable buckling mode to asymmetrical gradually collapsed mode.The total energy absorption of the octet-truss lattice material is a monotonically increasing function of the relative density, but lattice material of relative densities around 0.3 features high specific energy absorption capability. Compared with the results under quasi-static compression loading, the total energy absorption and specific energy absorption of the octet-truss lattice materials are significantly improved under impact compression loading.