Traditionally, engineers have designed artifacts to be strong and stiff, whereas designs in nature are strong, but not necessarily stiff. Mechanical designers generally tend to treat elastic deformation as an undesirable effect or pretend that it does not exist at least until the design is created and deal with the consequences at a later stage in the product development process. By assuming all functional components to be infinitely rigid, we connect them with different types of joints such as pins and sliders to create intricate, but highly purposeful, mechanical assemblies. Once the device is manufactured, that is after painstakingly assembling various parts, problems due to joint clearances, backlash, wear and noise must be dealt with - not to mention the ‘undesirable’ elastic deformation of certain members either due to unforeseen external loads or due to inertia forces in high-speed applications. Given that nothing is really ‘infinitely rigid’, it is as well to utilise elasticity to provide the desired function by carefully choosing the form and the material. Although the notion of exploiting elasticity is not a common practice in today's engineering world, the idea itself is very old. Researchers at the University of Michigan have developed a systematic procedure to determine an optimal topology and dimensions of compliant mechanisms to meet prescribed functional requirements and performance constraints. Novel designs have been developed including a single piece windshield wiper, an adaptive leading edge and trailing edge for an aircraft wing, displacement amplifiers integrated with various actuators such as micro electrostatic motors (MEMS), piezoactuators and voice-coil motors for a variety of applications.
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