Fatigue strength of laser sintered flexure hinge structures for soft robotic applications

The use of flexure hinges offers significant benefits compared to conventional revolute joints, such as the use for compact monolithic designs of flexural structures, no friction losses and reduced assembly and manufacturing costs. The combination of this design concept with additive manufacturing (AM) techniques provides huge potential for kinematics design, because of the ability to manufacture complex kinematic structures in one part with integrated adjustable functional elements, i.e. flexure hinges. Considering that there is sparse knowledge of thin-walled structures fabricated using additive manufacturing in current literature, it is obvious that the design of flexure hinge mechanisms for soft robotic applications is challenging today. Therefore, this paper describes software for simulation of plane flexure hinge structures based on investigations on the material characteristics of laser sintered polyamide, especially fatigue strength. Furthermore, the software enables automated design of these flexural structures (e.g. manipulator structures) as STL files, representing the standard interface to all additive manufacturing technologies.