Design of compliant mechanisms with selective compliance

Abstract

Conventional mechanisms provide a defined mobility, which expresses the number of degrees of freedom of the mechanism. This allows the system to be driven by a low number of control outputs. This property is virtually retained in the case of compliant mechanisms with lumped compliance, which are obtained by replacing the conventional hinges by solid-state ones. Compliant mechanisms with distributed compliance have, in general, an infinite number of degrees of freedom and therefore cannot guarantee defined kinematics. In this paper the concept of compliant mechanisms with selective compliance is introduced. This special class of compliant mechanisms combines the advantages of distributed compliance with the easy controllability of systems with defined kinematics. The task is accomplished by introducing a new design criterion based on a modal formulation. After this design criterion has been implemented in an optimization formulation for a formal optimization procedure, mechanisms are obtained in which a freely chosen deformation pattern is associated with a low deformation energy while other deformation patterns are considerably stiffer. Besides the description of the modal design criterion and the associated objective function, the sensitivity analysis of the objective function is presented and an application example is shown.

Synthesis of minimum energy adaptive structures

“…Within the context of compliant structures (i.e. joint-less mechanisms) relevant previous work proposed methods for synthesis of structures with selective compliance (Hasse and Campanile 2009). Structures with selective compliance are designed to be stiff against the external loads and flexible relative to the intended deformation pattern for shape control.…”

“…Active tensegrity structures, structures whose stability depends on self-stress, have been used for deployable systems (Tibert 2002) as well as for control of displacements (Fest et al 2003;Veuve and Smith 2015) and of the structure fundamental frequency (Santos and Micheletti 2015;Bel Hadj Ali and Smith 2010). Active compliant structures, which can be thought of as structures working as monolithic mechanisms (Hasse and Campanile 2009) have been investigated for shape control of antenna reflectors (Jenkins 2005), for shape morphing of aircraft wings to improve on manoeuvrability (Previtali and Ermanni 2012;Kota et al 2003) as well as for the control of direct daylight in buildings (Lienhard et al 2011).…”

Model and Parameter Study of a Shape‐Adaptable Beam for Vibration Control

“…The desired effect of the stiffness change is achieved by manipulating the stiffness matrix with respect to a modal target. In [6], an approach for a modal-based stiffness adaption was introduced. Although the aim was to achieve selective compliance by optimizing an inner beam truss, the method can be adapted to change a stiffness matrix based on one or more target modes by an inverse modal transformation.…”

Design and Functional Test of a Morphing High-Lift Device for a Regional Aircraft

“…Some efforts have been spent on the development of kinematical chains (Stubbs, 2003), and others on the development of compliant structures (Monner et al, 1998). Among these, the adoption of a Variable Geometry Truss concept as primary load-carrying structure is quite widespread (Baker and Friswell, 2008;Lesieutre et al, 2008;Hasse and Campanile, 2009). It is within this vibrant scientific framework that motivations were found to address a challenging study oriented to preliminarily investigate the structural feasibility of a variable-camber trailing-edge architecture specifically conceived for a large civil transportation aircraft.…”