**2.2 Distribution of compliance**

The mostly deformable parts of a compliant mechanism are called as compliant joints. Compliant joints can be classified by their distribution of their compliance. The joints with concentrated, local compliance have a small deformable area with the reference to the dimension of a mechanism. In contrast, compliance joints with distributed compliance include a large area of the deformable part. The decision whether a deformable area is small or large, depends on the purpose of the modelling. For example, the installation of a substitute rigid body model for a compliant mechanism, a great role is played by extension of the joint.

two parameters, namely the displacement position and the temperature. In such a case we have compliance of the second degree. The surface F=F(u, T) would reflect the compliance depending on the two parameters, as a value for compliance ∂u/∂F for a definite

The list of such parameters, which influence the compliance, can continue to be developed. If the compliance depends on the N parameter, we deal with the case of the compliance of

Table 1. Compliance of three degrees, from zero till two, for a compliant quarter-circle

The mostly deformable parts of a compliant mechanism are called as compliant joints. Compliant joints can be classified by their distribution of their compliance. The joints with concentrated, local compliance have a small deformable area with the reference to the dimension of a mechanism. In contrast, compliance joints with distributed compliance include a large area of the deformable part. The decision whether a deformable area is small or large, depends on the purpose of the modelling. For example, the installation of a substitute rigid body model for a compliant mechanism, a great role is played by extension

3 2

4

*u R F EI*

3

4

compliance Modelling Figure Compliance

temperature T and a particular displacement u.

the N degree.

N=0 Linear theory

Non-linear theory (large deformations)

Non-linear theory and dependence of

temperature, e.g. E(T)

shaped beam (EI3=100 Nmm2, F=1N)

**2.2 Distribution of compliance** 

the

Degree of

N=1

N=2

of the joint.

In case of a joint with a local compliance, the rigid body joint is introduced in the most cases into the middle of the compliant part. With a compliant joint possessing the distributed compliance, it is important that the position of the rigid body joint is determined for a substitute model. It can be admitted that for the compliant joints the following conditions are available: if the extension of the joint is 10 or more times smaller than the biggest dimension of the whole mechanism, it is classified as a joint with a distributed compliance.

Mechanisms with concentrated compliance behave like classic rigid link mechanisms, where kinematic joints are replaced with flexible hinges, and in consequence methods conceived to design rigid body mechanisms can be modified and applied successfully in this case (Albanesi et al., 2010). Mechanisms with distributed compliance are treated as a continuum flexible mechanism, and Continuum Mechanics design methods are used instead of rigid body kinematics (Albanesi et al., 2010). An overview of calculation methods of compliant mechanisms is indicated in (Albanesi et al., 2010; Shuib et al., 2007).
