负刚度蜂窝单胞结构制备及压缩性能

Preparation and compression properties of negative stiffness honeycomb cell structure

基于短切碳纤维增强尼龙复合材料(MarkForged Onyx),采用熔融丝制造工艺(FFF)制备了负刚度蜂窝单胞结构。为分析其打印性能和压缩性能,进行负刚度蜂窝单胞结构试样压缩试验,试验分析了堆叠方式、填充图案及壁厚层数三种打印工艺参数对该结构打印性能和压缩性能的影响机制。结果表明:水平堆叠方式、六边形填充图案、一层壁厚打印工艺参数组合有效减少结构的打印时间、打印成本。水平堆叠方式结构的压缩性能优于侧立和正立方向;与四边形、六边形填充图案相比,三角形填充图案明显提高结构的吸能能力;二层的壁厚层数对结构抗压强度的提高最显著。在加载过程中,单胞结构呈现出显著的负刚度特性,能量吸收效率约达70%,力阈值约为185 N;循环试验后,仅存在6%的压缩变形量,实现了基于MarkForged Onyx短切碳纤维增强尼龙复合材料负刚度蜂窝芯结构的可恢复能量吸收。

Negative stiffness honeycomb cell structures were fabricated by fused filament fabrication(FFF)based on chopped carbon fiber reinforced nylon composites(MarkForged Onyx).In order to analyze the printing properties and compression properties,compression tests for negative stiffness honeycomb cell structure specimens were carried out.The influence mechanism of three process parameters,including building directions,fill patterns and wall layers,on the printing properties and compression properties of the structure was analyzed.The results show that the combination of flat building directions,hexagonal fill pattern and one wall layer can effectively reduce the printing time and cost of the structure.The compression properties of the flat building directions are superior to that of the on-edge and up-right.Compared with quadrilateral and hexagonal fill pattern,triangular fill pattern improves the energy absorption capacity of the structure significantly.Two wall layers have a great impact on the compressive strength of the structure.Cell structures show pronounced negative stiffness behavior during the loading process with percent energy absorbed up to 70%,and force threshold of about 185 N.Through the cycle tests,there is only 6%of the compression deformation,realizing the recoverable energy absorption of negative stiffness honeycomb core structures based on Markforged Onyx chopped carbon fiber reinforced nylon composites.