What Are Compliant Systems? Compliant systems are composed of one or more compliant mechanisms integrated or embedded with actuators. What Are Compliant Mechanisms? A compliant mechanism is a flexible structure that elastically deforms without joints to produce a desired functionality, such as force or motion transmission, motion guidance, or energy storage and release. There are simple examples of compliant mechanisms in use all around us. For instance, the flip-top lid on a shampoo bottle is constructed of a single piece of plastic and uses localized flexure hinges to open and shut. Contrast this with a traditional car trunk hinge mechanism comprised of many parts that move relative to one another to accomplish the same task.

An example of a ubiquitous compliant mechanism - the flip-top lid on a shampoo bottle.

Compliance in Nature

Exploiting compliance in design is really nothing new; nature has been doing this for millions of years. Take for example the way that the leaves of a tree curl to lessen drag forces during high winds, or the way fish fins or bird wings flex under loading to maximize propulsion efficiency.

Advantages of Compliant Systems

• Minimize or eliminate assembly requirements
• No joints means no joint friction, need for lubrication, or backlash
• Can easily couple with modern actuators, such as piezoelectric, shape-memory alloy, electro-thermal, electrostatic, fluid pressure, and electromagnetic actuators
• Can create motions not possible with conventional rigid devices
• Scalable: can be micro-, meso-, or macro-sized
• Materials friendly: can be built from any highly resilient material, including steel, aluminum, high-strain nickel-titanium alloys, polysilicon, Delrin, ABS, etc.
• Weight reduction: no need for restoring springs or bulky hinges