Implementation of Self Contact in Path Generating Compliant Mechanisms

Path generating compliant mechanisms with self contact are synthesized using continuum discretization and negative circular masks. Hexagonal cells are employed to represent the design space and negative circular masks are used to remove material beneath them. Each mask is defined by three parameters which constitute the design vector, which is mutated using the Hill-climber search. Hexagonal cells circumvent various geometrical singularities related to single point connections however, many “V” notches get retained on the boundary edges. Self contact is permitted between various subregions of the continuum. To achieve convergence in contact analysis, it is essential to have smooth boundary surfaces for which a smoothing technique is employed. Consequently, many hexagonal cells get modified to six-noded generic polygons. Non-linear finite elements analysis is implemented with Mean Value Coordinates based shape functions. Self contact is modeled between two deformable bodies in association with augmented Lagrange multiplier method. To minimize the error in shape, size and orientation between the actual and specified paths, a Fourier Shape Descriptors based objective is employed. An example of path generating compliant mechanism which experiences self contact is presented and its performance is compared with a commercial software.