In mechanical engineering, a compliant mechanism is a flexible mechanism that achieves force and motion transmission through elastic body deformation. It gains some or all of its motion from the relative flexibility of its members rather than from rigid-body joints alone. These may be monolithic (single-piece) or jointless structures. Some common devices that use compliant mechanisms are backpack latches and paper clips. One of the oldest examples of using compliant structures is the bow and arrow. Design methods Compliant mechanisms are usually designed using two techniques: Kinematics approach Kinematic analysis can be used to design a compliant mechanism by creating a pseudo-rigid-body model of the mechanism. In this model, flexible segments are modeled as rigid links connected to revolute joints with torsional springs. Other structures can be modeled as a combination of rigid links, springs, and dampers. Structural optimization approach In this method, computational methods are used for topology optimization of the structure. Expected loading and desired motion and force transmission are input and the system is optimized for weight, accuracy, and minimum stresses. More advanced methods first optimize the underlying linkage configuration and then optimize the topology around that configuration. Other optimization techniques focus topology optimization of the flexure joints by taking as input a rigid mechanism and replacing all the rigid joints with optimized flexure joints. To predict the behavior of the structure, finite-element stress analysis is done to find deformation and stresses over the entire structure. Other techniques are being conceived to design these mechanisms. Compliant mechanisms manufactured in a plane that have motion emerging from said plane are known as lamina emergent mechanisms. Advantages Compliant structures are often created as an alternative to similar mechanisms that use multiple parts. There are two main advantages for using compliant mechanisms: Low cost: A compliant mechanism can usually be fabricated into a single structure, which is a dramatic simplification in the number of required parts. A single-piece compliant structure can be manufactured through injection molding, extrusion, and 3d printing, among other methods. This makes the manufacturing relatively cheap and accessible. Better efficiency: Compliant mechanisms do not suffer from some issues that affect multi-bodied mechanisms, such as backlash or surface wear. Due to the usage of flexible elements, compliant mechanisms can easily store energy to be released at a later time or transformed into other forms of energy. Disadvantages The full range of a mechanism depends on the material and