Biological structural designs in nature, like hoof walls, horns, and antlers, can be used as inspiration for generating structures with excellent mechanical properties. A common theme in these designs is the small percent porosity in the structure ranging from 1 - 5\%. In this work, the sheep horn was used as an inspiration due to its higher toughness when loaded in the radial direction compared to the longitudinal direction. Under dynamic transverse compression, we investigated the structure-property relations in low porosity structures characterized by their two-dimensional (2D) cross-sections. A diverse design space was created by combining polygonal tubules with different numbers of sides placed on a grid with different numbers of rows and columns. The volume fraction and the orientation angle of the tubules were also varied. The finite element (FE) method was used with a rate-dependent elastoplastic material model to generate the stress-strain curves in plane strain conditions. A gated recurrent unit (GRU) model was trained to predict the structures' stress-strain response and energy absorption under different strain rates and applied strains. The parameter-based model uses eight discrete parameters to characterize the design space and as inputs to the model. The trained GRU model can efficiently predict the response of a new design in as little as 0.16 ms and allows rapid performance evaluation of 128000 designs in the design space. The GRU predictions identified high-performance structures and four design trends that affect the specific energy absorption were extracted and discussed.

翻译：自然界中的生物结构设计（如蹄壁、角和鹿角）可作为生成具有优异力学性能结构的灵感来源。这些设计的共同特点是结构中存在1-5%的小孔隙率。本研究以绵羊角为仿生对象，因其在径向加载时具有比纵向更高的韧性。通过动态横向压缩实验，我们研究了以二维（2D）截面为特征的低孔隙结构中的结构-性能关系。通过将不同边数的多边形微管按不同行数和列数排列在网格上，构建了多样化的设计空间，并改变微管的体积分数和取向角。采用有限元（FE）方法结合率相关弹塑性材料模型，生成平面应变条件下的应力-应变曲线。训练了门控循环单元（GRU）模型来预测结构在不同应变率和施加应变下的应力-应变响应及能量吸收能力。该基于参数的模型使用八个离散参数表征设计空间并作为模型输入。训练后的GRU模型可在低至0.16毫秒内高效预测新设计的响应，并实现对设计空间中128000个设计方案的快速性能评估。GRU预测识别出高性能结构，并提取了影响比能量吸收的四种设计趋势进行了讨论。