Performance of 3D printing biomimetic conch shell and pearl shell hybrid design composites under quasi-static three-point bending load.

The failure process of biomimetic hybrid design composite composed of layers of conch shell and pearl shell was studied through quasi-static three-point bending experiments and numerical simulations. The biomimetic conch shell structure with inclined angles serves as the upper layer of the hybrid structure, while the biomimetic pearl shell structure with traditional brick and mud structure serves as the lower layer of the hybrid structure, forming a hybrid design structure. Four inclined angles were designed for the structural units of the conch shell, namely 15°, 30°, 45°, and 60°. Twenty-four specimens (six specimens for each inclined angle) were prepared using 3D printing technology using both soft and hard matrix materials. The influence of different inclined angles on the fracture strength, fracture toughness, and energy absorption of hybrid design structures was experimentally studied. The biomimetic hybrid design composite specimen with a notch is placed between two supporting rollers, and a loading indenter acts at mid-span. All twenty-four specimens were notched with a triangular tip and a rectangular bottom. A loading rate of 1 mm/min is used to avoid the viscoelastic effect of the composite materials. Details of the specimens, the experimental set-up and procedure are discussed in this paper. Complementary to the experimental studies, an extensive numerical investigation was carried out to study the influence of the aspect ratio of brick and mud units on the fracture initiation and failure of hybrid design structures. The causes of crack initiation and propagation, and failure modes in biomimetic hybrid design structures were postulated. These numerical findings help in reinforcing the experimental results and provide crucial information to enhance further research in this exciting area.