Ren Huilan, Shen Haiting, Ning Jianguo
School of Mechatronical Engineering, Beijing Institute of Technology, Beijing 100081, China.
Materials (Basel). 2020 Nov 12;13(22):5094. doi: 10.3390/ma13225094.
In this work, hollow truss structures with different internal microstructure distributions, i.e., basic hollow truss structure (specimen HT), hollow truss structure with internal microstructure at joints (specimen HTSJ), and hollow truss structure with internal microstructure on tube walls (specimen HTSW), were designed and manufactured using a selective laser melting technique. The effect of internal microstructure distribution on quasi-static compressive behavior and energy absorption was investigated by experimental tests and numerical simulations. The experimental results show that compressive strength and specific compressive strength of specimen HTSW increase by nearly 50% and 14% compared to specimen HT, and its energy absorption per volume and mass also increase by 52% and 15% at a strain of 0.5, respectively. However, the parameters of specimen HTSJ exhibit limited improvement or even a decrease in different degrees in comparison to specimen HT. The numerical simulation indicates that internal microstructures change the bearing capacity and structural weaknesses of the cells, resulting in the different mechanical properties and energy absorptions of the specimens. Based on the internal microstructure design in this study, adding microstructures into the internal weaknesses of the cells parallel to the loading direction is an effective way to improve the compressive properties, energy absorption and compressive stability of hollow truss structures.
在这项工作中，采用选择性激光熔化技术设计并制造了具有不同内部微观结构分布的空心桁架结构，即基本空心桁架结构（试样HT）、节点处具有内部微观结构的空心桁架结构（试样HTSJ）以及管壁上具有内部微观结构的空心桁架结构（试样HTSW）。通过实验测试和数值模拟研究了内部微观结构分布对准静态压缩行为和能量吸收的影响。实验结果表明，与试样HT相比，试样HTSW的抗压强度和比抗压强度分别提高了近50%和14%，在应变0.5时其单位体积和单位质量的能量吸收也分别提高了52%和15%。然而，与试样HT相比，试样HTSJ的参数在不同程度上表现出有限的改善甚至下降。数值模拟表明，内部微观结构改变了单元的承载能力和结构弱点，导致试样具有不同的力学性能和能量吸收。基于本研究中的内部微观结构设计，在与加载方向平行的单元内部弱点处添加微观结构是提高空心桁架结构抗压性能、能量吸收和压缩稳定性的有效方法。
