Porous structures inspired by porcupine quill: multiscale design optimization approach.

This paper presents a novel approach for designing a fail-safe bending-resistant structure from the combination of explicit discrete component-based topology optimization and the porcupine quill-inspired features. To achieve fail-safe functionalities under classical topology optimization formulations, the method involves constructing discrete components at various scales to imitate the quill's foam-like characteristics. The components are iteratively updated, and the optimization process allows for the grading of quill-inspired features while achieving optimal structural compliance under bending loads. The proposed approach is demonstrated to be effective through the resolution of Messershmitt-Bolkow-Blohm (MBB) beam designs, parameterized studies of geometric parameters, and numerical validation of long-span and short-span quill-inspired beam designs. By examining the von Mises stress distribution, the study highlights the mitigation of material yielding brought by the geometric features of porcupine quills, leading to the potential theory support for the fail-safe capability. The optimized MBB beams are manufactured using the material extrusion (MEX) technique, and three-point bending tests are conducted to explore the failure mitigation capability of the quill-inspired beam under large deformation. Consequently, the study concludes that the proposed quill-inspired component-based topology optimization approach can design a fail-safe structure according to the improved energy absorption as well as increased deformation after reaching 75% peak load.&#xD.