芯子间距对激光选区熔化成形AlSi10Mg点阵夹芯板弯曲性能的影响

Influence of core spacing on bending properties of AlSi10Mg lattice sandwich panel formed by selective laser melting

激光选区熔化(selective laser melting,SLM)成形的轻质高刚度金属点阵夹芯结构在航空航天、军工等领域具有重要的应用前景。通过有限元分析(finite element analysis,FEA)和理论方法分析不同芯子间距和芯子排列方向的正方形点阵夹芯板在三点弯曲下的响应,并通过激光选区熔化成形的实验样品对仿真结果进行验证。结果表明:当芯子间距在一定范围内时,芯子间距与柱面弯曲刚度呈现线性关系;当相对密度在一定范围内时,0°正方形点阵夹芯板和45°正方形点阵夹芯板在相同相对密度下的柱面弯曲刚度基本一致;随着芯子间距的增大,应力集中区域由压头下的面板转移到芯子的两端;根据应力分布状态可提出三点弯曲下载荷-挠度曲线的屈服和稳定塑性变形阶段初始载荷预测公式;实验与仿真结果吻合度较高,表明能够通过有限元分析对点阵夹芯板三点弯曲变形和力学性能进行有效预测。

The light-weight and high-stiffness metal lattice sandwich structure formed by selective laser melting has an important application prospect in aerospace,military and other fields.In this study,the response of square lattice sandwich panels with different core spacings under three-point bending was analyzed by finite element analysis,and the results were verified by experimental samples formed by selective laser melting.The results show that there is a linear relationship between the core spacing and cylindrical bending stiffness when the core spacing is within a certain range,the influence of core spacing on cylindrical bending stiffness is very significant and the influence of core spacing on the cylindrical bending stiffness of the square lattice sandwich panel of 45°is greater than that of the square lattice sandwich panel of 0°.The cylindrical bending stiffness of square lattice sandwich panel of 0°and 45°is basically the same under the same relative density when the relative density is within a certain range,which means that they have similar cylindrical bending stiffness under the same weight.When the relative density is less than 5%,the relative density has a significant influence on the cylindrical bending stiffness,and the influence decreases when the relative density exceeds 5%.With the increase of the core spacing,the stress concentration area is transferred from the part of panel under the loading pad to the ends of cores between the support pads due to the reduction of the cylindrical bending resistance of the lattice structure.According to the mechanical analysis,the initial load prediction formula for the yield and plastic stages can be proposed,The comparison between the theoretical results and the FEA results shows that the relative error is less than 13.6%,indicating that the formula is relatively accurate.The experimental results are in good agreement with the FEA results,especially for the cylindrical bending stiffness,the relative error between the FEA value and the experimental value is only less than 6.5%,indicating that the three-point bending deformation and mechanical properties of the lattice sandwich panel can be effectively predicted by FEA.