geometry of the structure; due to the nature of flexure joints, no purely compliant mechanism can achieve continuous motion such as found in a normal joint. Also, the forces applied by the mechanism are limited to the loads the structural elements can withstand without failure. Due to the shape of flexure joints, they tend to be locations of stress concentration. This, combined with the fact that mechanisms tend to perform cyclic or periodic motion, can cause fatigue and eventual failure of the structure. Also, since some or all of the input energy is stored in the structure for some time, not all of this energy is released back as desired. However, this can be a desirable property to add damping to the system. Applications Some of the oldest uses of compliant structures date back to several millennia. One of the oldest examples is the bow and arrow. Some designs of catapults also made use of the flexibility of the arm to store and release energy to launch the projectile larger distances. Compliant mechanisms are used in a variety of fields such as adaptive structures and biomedical devices. Compliant mechanisms can be used to create self-adaptive mechanisms, commonly used for grasping in robotics. Since robots require high accuracy and have limited range, there has been extensive research in compliant robot mechanisms. Microelectromechanical systems are one of the main applications of compliant mechanisms. These systems benefit from the lack of required assembly and simple planar shape of the structure which can be easily manufactured using photolithography. The flexible drive or resilient drive, often used to couple an electric motor to a machine (for example, a pump), is one example. The drive consists of a rubber "spider" sandwiched between two metal dogs. One dog is fixed to the motor shaft and the other to the pump shaft. The flexibility of the rubber part compensates for any slight misalignment between the motor and the pump. See rag joint and giubo. Image gallery See also Stiffness Remote center compliance Living hinge Flexure bearing Self-adaptive mechanisms References External links Why Machines That Bend Are Better – YouTube video by Veritasium - YouTube video - A Computational Design Tool for Compliant Mechanisms by Disney Research Hub - BYU Compliant Mechanisms Research Compliant Finray gripper for high-speed robotic electrical plug assembly – YouTube video Mechanisms (engineering)