Study on bio-inspired feet based on the cushioning and shock absorption characteristics of ostrich foot
- 1. Key Laboratory of Bionic Engineering, Ministry of Education, Jilin University, Changchun, P.R. China
- 2. China North Vehicle Research Institute, Beijing, P.R. China
- 3. Beijing Institute of Spacecraft Environment Engineering, Beijing, P.R. China
Description
The African ostrich (Struthio camelus) perennially living in deserts is outstanding with remarkable speed, exceptional endurance and continuous locomotion. As the main actuator of high-speed running, the ostrich feet possess excellent cushioning and shock absorption capabilities. In this study, based on the elastic modulus scales and assembly modes of soft tissues and the functions of the metatarsophalangeal (MTP) joint, eight bio-inspired feet were designed by an engineering method. With the peak acceleration as the index, the cushioning performances of different bio-inspired feet on loose sand or solid ground were compared through impact tests at different heights and verified by simulating the impact processes of the bio-inspired feet on loose sand on the finite element software Abaqus. Meanwhile, the stress distribution and deformation of each component of the bio-inspired feet were also clarified. The 15-15-15 HA (hardness unit) bio-inspired feet showed lower peak acceleration and thereby better cushioning performance, but larger deformation, less-uniform stress distributions and thereby lower stability than the 15-35-55 HA bio-inspired feet. Sensitivity analyses showed the cushioning capacity of the bio-inspired feet was comparable to that of the ostrich foot when the material (elastic modulus) and spring (stiffness coefficient) were properly selected. In fact, the silicon rubbers with different hardness levels which simulate the elasticity modulus scales of the toe pad, fascia and skin, and the spring mechanism which simulates the functions of the MTP joint, work as an “integrated system”of cushioning and shock absorption.