Design and Characterization of a Flexible Self-Inflating Mechanical Structure

Abstract

Inflatable structures are commonly used in a variety of engineering applications such as robotics, space structures, medical devices, and automotive safety devices. However, inflation in these systems often requires a non-flexible external pressurized fluid source. Integration of the pressurized fluid source and the flexible construct sacrifices some of the main advantages of the soft structures such as overall flexibility of the system, weight, and cost of fabrication. In this paper, we introduce a novel design for self-inflating structure with embedded pressurizing module. The design is based on integrating a flexible dome with a cylinder. The pressure inside the cylinder is controlled by subjecting dome to a cyclic compression, causing air exchange between the dome and the cylinder. The performance of this design is fully validated through finite element simulations using fluid structure interactions as well as experimental investigations. The results show that a higher pressure is achieved by having smaller dome height. In addition to controlling internal pressure of the cylinder, the design can be used to control the stiffness of the flexible structure such as soft robotics through pressurization. An application of this conceptual device such as pressurizing a tire is presented. This device is integrated within a tire and tire rotation as well as load on the tire have been shown to pressurize the tire. The final pressure and time to achieve maximum pressure depend on the load to the axel of the tire and tire rotational speed, respectively.