采用试验与有限元分析相结合的方法研究了变密度多层梯度点阵型金属减振结构的吸能性能.首先,以体心立方(Body-Centered Cubic,BCC)结构为基础单胞,分别设计了变直径 BCC(Diameter BCC,DBCC)和变角度 BCC(Angle BCC,ABCC)两种梯度点阵结构,并采用选择性激光融化工艺实现了 304 不锈钢多层梯度结构的制备.然后,对比研究了梯度点阵结构和均匀点阵结构的压缩和吸能性能.有限元仿真和实验结果均表明,DBCC结构自压缩过程开始,低密度层带动高密度层逐层坍塌,在小应变阶段具有较高的吸能效率,而应力分布不均匀导致其力学性能和整体能量吸收大小较均匀结构大幅降低.ABCC结构小应变阶段抗压性能强,压缩至大应变阶段发生逐层塌陷,一定程度上提升了结构的吸能性能,同时增大ABCC结构梯度率可有效提高结构的弹性模量和吸能特性.
In this paper,the energy absorption performance of the variable density multilayer gradient lattice metal vibration damping structure was studied by experimental and finite element analysis.Firstly,two kinds of gradient lattice structures of variable diameter BCC(DBCC)and variable angle BCC(ABCC)were designed based on the body-centered cubic(BCC)structure,and the multi-layer gradient structures of 304 stainless steel were prepared by selective laser melting process.Then,the compression and energy absorption properties of the gradient lattice structure and the uniform lattice structure were comparatively studied.Both the finite element simulation and the experimental results indicated that for the DBCC structure,the low-density layer drived the high-density layer to collapse layer by layer since the compression was started.A high energy absorption efficiency was obtained in the small strain stage.However,stress distribution was uneven,resulting in a significant decrease in its mechanical properties and overall energy absorption rate compared with the uniform structure.The ABCC structure performed a strong compressive performance in the stage of small strain,and was collapsed layer by layer in the large compression strain stage,thus improved the energy absorption performance to a certain extent.In addition,increasing the gradient rate of the structure effectively improved the elastic modulus and energy absorption characteristics of the ABCC structure.