Light and high-strength structure inspired by the characteristics of double-nutrient foramens in intertarsal joint of ostrich

The ostrich ( Struthio camelus ) is characterized by high speed and heavy load when running. Its intertarsal joint (Fig. 1 A) with double-nutrient foramina (DNF) exhibits excellent ability to withstand high impact during running, and is characterized by lightweight. We investigated the effect of DNF on the biomechanical properties of the intertarsal joints of the ostrich. The intertarsal joint was reconstructed according to computed tomography images, and four models were established to uncover the separate and combined effects of the compositional parameters (geometric features, material properties) on stress concentration reduction. We have revised the formula that can be used to predict the elasticity modulus ( E ) of ostrich bones and verified the accuracy of the formula with nano-indentation equipment. The results were analyzed by t tests, and the p value is less than 0.05. The finite element analysis was performed to evaluate the mechanical properties of the PT and models. Compared to the Filled model (DNF was filled), the maximum stress at the lateral and medial fossa in the Initial model was reduced by 15.4%, although there was no significant difference in the medial maximum stress. Compared with the stress value of models without holes, the models with holes have lower stress, with a reduction of 4.0%. Reasonable design of holes can improve the efficiency of material utilization. This paper investigated the mechanism of high mechanical properties of the intertarsal joints of ostrich and developed four bionic-bearing parts based on the characteristics of DNF and heterogeneity materials, which may provide ideas for the design of aircraft and robot parts with lightweight and high strength. Fig. 1 The intertarsal joint of ostrich and finite element models. a The intertarsal joint of ostrich. b The model which DNF was filled was named Filled model. c The model which DNF was retained was named Initial model Graphic abstract