激光选区熔化成形镍钛基五模超材料力学响应研究

Study on Mechanical Response of Selective Laser Melted Nickel-Titanium Based Pentamode Metamaterials

五模超材料(Pentamode metamaterials,PMs)具有解耦的相对密度和力学性能,在特种声学装备和生物植入物领域具有潜在应用价值。激光选区熔化(Selective laser melting,SLM)技术具有成形复杂精细晶格超材料的能力,可实现定制刚度、单元尺寸和孔隙率。通过五模超材料结构优化设计,利用激光选区熔化成形镍钛形状记忆合金,实现了不同形态的五模超材料结构成形,并开展模拟和性能测试表征研究。微观形貌的观测结果显示,SLM成形的镍钛基五模超材料具有较好的制造保真度。有限元仿真预测结果发现应力集中于杆与杆的连接处。压缩力学试验结果显示,镍钛基五模超材料的强度随着相对密度的增大而增大。通过建立相对密度和相对模量与强度的数学模型,提出了不同相对密度五模超材料的力学性能预测方法。

Pentamode metamaterials(PMs)have uncoupled relative density and mechanical properties,which have potential applications in the field of special acoustic equipments and biological implants.Selective laser melting(SLM)technology has the ability to form complex and fine lattice metamaterials,which can achieve customized stiffness,controllable cell topology,cell size and porosity.In this work,nickel-titanium shape memory alloy(NiTi SMA)powder was used to fabricate pentamode metamaterials with different topological shapes by selective laser melting.The observation results of micro-morphology show that the nickel-titanium based pentamode metamaterials formed by SLM has good manufacturing fidelity.The finite element simulation is used to predict the stress distribution in the compression process of the pentamode metamaterial,and it is found that the stress is concentrated in the joint of the struts.The experimental results of compression mechanics show that the strength of NiTi based pentamode metamaterial increases with the increase of relative density.By establishing the mathematical models of relative density,relative modulus and strength,the mechanical properties of pentamode metamaterials with different relative densities can be well predicted.