Selective Laser Melting (SLM) technology has undergone significant development in the past years providing unique flexibility for the fabrication of complex metamaterials such as octet-truss lattices. However, the microstructure of the final parts can exhibit significant variations due to the high complexity of the manufacturing process. Consequently, the mechanical behavior of these lattices is strongly dependent on the process-induced defects, raising the importance on the incorporation of as-manufactured geometries into the computational structural analysis. This, in turn, challenges the traditional mesh-conforming methods making the computational costs prohibitively large. In the present work, an immersed image-to-analysis framework is applied to efficiently evaluate the bending behavior of AM lattices. To this end, we employ the Finite Cell Method (FCM) to perform a three-dimensional numerical analysis of the three-point bending test of a lattice structure and compare the as-designed to as-manufactured effective properties. Furthermore, we undertake a comprehensive study on the applicability of dimensionally reduced beam models to the prediction of the bending behavior of lattice beams and validate classical and strain gradient beam theories applied in combination with the FCM. The numerical findings suggest that the SLM octet-truss lattices exhibit size effects, thus, requiring a flexible framework to incorporate high-order continuum theories.

中文翻译：

---

增材制造的晶格结构的弯曲行为：数值表征和实验验证

选择性激光熔化（SLM）技术在过去几年中取得了长足的发展，为制造复杂的超材料（例如八角形桁架晶格）提供了独特的灵活性。但是，由于制造过程的高度复杂性，最终零件的微观结构可能会出现明显的变化。因此，这些晶格的机械性能在很大程度上取决于加工引起的缺陷，从而提高了将已制造的几何形状纳入计算结构分析的重要性。反过来，这又对传统的符合网格的方法提出了挑战，从而使计算成本过高。在当前的工作中，将沉浸式图像分析框架应用于有效评估AM晶格的弯曲行为。为此，我们使用有限元方法（FCM）对晶格结构的三点弯曲测试进行三维数值分析，并将设计的有效特性与制造的有效特性进行比较。此外，我们对尺寸减小的梁模型在预测格形梁弯曲行为方面的适用性进行了全面研究，并验证了结合FCM运用的经典和应变梯度梁理论。数值结果表明，SLM八角形桁架晶格表现出尺寸效应，因此，需要一个灵活的框架来合并高阶连续理论。我们对尺寸减小的梁模型在预测格形梁弯曲行为方面的适用性进行了全面研究，并验证了结合FCM应用的经典和应变梯度梁理论。数值结果表明，SLM八角形桁架晶格表现出尺寸效应，因此，需要一个灵活的框架来合并高阶连续理论。我们对尺寸减小的梁模型在预测格形梁弯曲行为方面的适用性进行了全面研究，并验证了结合FCM应用的经典和应变梯度梁理论。数值结果表明，SLM八角形桁架晶格表现出尺寸效应，因此，需要一个灵活的框架来合并高阶连续理论。