Hedayati Reza, Sadighi Mojtaba, Mohammadi Aghdam Mohammad, Zadpoor Amir Abbas
Department of Mechanical Engineering, Amirkabir University of Technology (Tehran Polytechnic), Hafez Ave, Tehran 158754413, Iran.
Department of Biomechanical Engineering, Faculty of Mechanical, Maritime, and Materials Engineering, Delft University of Technology (TU Delft), Mekelweg 2, Delft 2628 CD, The Netherlands.
Materials (Basel). 2016 Jul 23;9(8):613. doi: 10.3390/ma9080613.
Honeycombs resemble the structure of a number of natural and biological materials such as cancellous bone, wood, and cork. Thick honeycomb could be also used for energy absorption applications. Moreover, studying the mechanical behavior of honeycombs under in-plane loading could help understanding the mechanical behavior of more complex 3D tessellated structures such as porous biomaterials. In this paper, we study the mechanical behavior of thick honeycombs made using additive manufacturing techniques that allow for fabrication of honeycombs with arbitrary and precisely controlled thickness. Thick honeycombs with different wall thicknesses were produced from polylactic acid (PLA) using fused deposition modelling, i.e., an additive manufacturing technique. The samples were mechanically tested in-plane under compression to determine their mechanical properties. We also obtained exact analytical solutions for the stiffness matrix of thick hexagonal honeycombs using both Euler-Bernoulli and Timoshenko beam theories. The stiffness matrix was then used to derive analytical relationships that describe the elastic modulus, yield stress, and Poisson's ratio of thick honeycombs. Finite element models were also built for computational analysis of the mechanical behavior of thick honeycombs under compression. The mechanical properties obtained using our analytical relationships were compared with experimental observations and computational results as well as with analytical solutions available in the literature. It was found that the analytical solutions presented here are in good agreement with experimental and computational results even for very thick honeycombs, whereas the analytical solutions available in the literature show a large deviation from experimental observation, computational results, and our analytical solutions.
蜂窝结构类似于许多天然和生物材料的结构，如松质骨、木材和软木塞。厚壁蜂窝结构也可用于能量吸收应用。此外，研究蜂窝结构在面内载荷作用下的力学行为有助于理解更复杂的三维镶嵌结构（如多孔生物材料）的力学行为。在本文中，我们研究了使用增材制造技术制造的厚壁蜂窝结构的力学行为，这种技术能够制造出具有任意且精确可控厚度的蜂窝结构。使用熔融沉积建模（一种增材制造技术）由聚乳酸（PLA）制备了具有不同壁厚的厚壁蜂窝结构。对样品进行面内压缩力学测试以确定其力学性能。我们还使用欧拉 - 伯努利梁理论和铁木辛柯梁理论获得了厚壁六边形蜂窝结构刚度矩阵的精确解析解。然后使用刚度矩阵推导出描述厚壁蜂窝结构弹性模量、屈服应力和泊松比的解析关系。还建立了有限元模型，用于对厚壁蜂窝结构在压缩下的力学行为进行计算分析。将使用我们的解析关系获得的力学性能与实验观察结果、计算结果以及文献中可用的解析解进行了比较。结果发现，即使对于非常厚的蜂窝结构，本文提出的解析解与实验和计算结果也非常吻合，而文献中可用的解析解与实验观察结果、计算结果以及我们的解析解有很大偏差。
