摘要
本文针对四面内凹金字塔型负泊松比点阵结构在有无聚脲涂覆两种情况下的静态力学性能进行了试验研究.采用增材制造方法制作了不同阵列型式的试验模型,实施了点阵模型的准静态压缩试验和点阵夹层结构的三点弯曲和四点弯曲试验.试验结果表明,点阵结构在压缩载荷作用下呈现明显的负泊松比效应.涂覆聚脲后点阵结构的力学性能有明显提升,压缩平台应力约为0.6-1.0 MPa;对于多胞结构,总吸能、单位体积变形能和比吸能显著高于未涂覆聚脲模型1-2个数量级;最大吸能效率和压缩利用率大于未涂覆聚脲模型,最高分别可达40.59%和55.15%.由于未涂覆聚脲点阵结构会发生早期材料脆断,其单位体积变形能、比吸能、最大吸能效率和压缩利用率会随单元数量的增加而减小.涂覆聚脲点阵结构的吸能特性受聚脲涂层的厚度影响较大.在弯曲载荷作用下,未涂覆聚脲点阵夹层结构易出现芯层局部压溃现象,靠近压头部位的芯层最易发生破坏,且芯层破坏程度逐层降低;上面板最终呈现折线型变形,下面板呈现弧形变形模式.涂覆聚脲点阵夹层结构的上面板早期呈现"U"型变形模式,且芯层失效范围大幅减小,下面板变形较无聚脲涂覆点阵夹层结构增大19.61%-42.03%.研究结果可为设计轻质化和高效吸能的舰艇防护结构提供借鉴.
This paper studies the static mechanical properties of four-sided concave pyramid-type lattice structures with a polyurea coating and a negative Poisson’s ratio.Experimental models of different types were made by the additive manufacturing method.Quasi-static compression experiments of lattice structures,and three-point and four-point bending experiments of lattice sandwich structures,were implemented.The lattice structure exhibited a significantly negative Poisson’s ratio effect under compressive load.Under platform stresses of 0.6-1.0 MPa,the polyurea coating obviously improved the mechanical properties of the lattice structures.The total energy absorption,deformation energy per unit volume,and specific energy absorption were significantly higher(by 1-2 orders of magnitude)in the multicellular polyurea-coated models than in the uncoated models.The maximum energy-absorption efficiency and compression utilization in the polyurea-coated models reached 40.59%and 55.15%,respectively.In the lattice structures without polyurea,the deformation energy per unit volume,specific energy absorption,maximum energy-absorption efficiency,and compression utilization decreased with increasing number of units.These trends are attributable to early brittle fracture.Meanwhile,the energy-absorption characteristics of the polyurea-coated lattice structures largely depended on the polyurea thickness.Under a bending load,the polyurea-uncoated lattice sandwich structures were prone to partial core collapse,especially around the indenter.The destruction degree reduced layer by layer outward to the core.The upper and lower panels showed fold-line deformation and a curved deformation mode,respectively.The upper panel developed a"U-shaped"deformation mode at an early stage,and its core failure range was widely reduced.The lower panel was19.61%-42.03%more deformed in the polyurea-coated than in the uncoated lattice sandwich structures.The results provide a reference for the design of lightweight and efficient energy-absorptive structures
作者
黄秀峰
张振华
HUANG XiuFeng;ZHANG ZhenHuar(College of Naval Architecture&Ocean,Naval University of Engineering,Wuhan 430033,China)
出处
《中国科学：物理学、力学、天文学》
CSCD
北大核心
2021年第5期112-130,共19页
Scientia Sinica Physica,Mechanica & Astronomica
基金
国家自然科学基金(编号:51879270)
海军工程大学研究生创新基金资助项目。
关键词
负泊松比
点阵结构
聚脲
压缩试验
多点弯曲试验
增材制造
negative Poisson’s ratio
lattice structure
polyurea
compression experiment
multi-point bending experiment
additive manufacturing
