A Curved Compliant Differential Mechanism With Neutral Stability

Differential mechanisms are remarkable mechanical elements that are widely utilized in various systems; nevertheless, conventional differential mechanisms are heavy and difficult to use in applications with limited design space. This paper presents a curved differential mechanism that utilizes a lightweight, compliant structure. This...

Compliant variable negative to zero to positive stiffness twisting elements

Compliant mechanisms have the potential to be utilized in numerous applications where the use of conventional mechanisms is unfeasible. These mechanisms have inherent stiffness in their range of motion as they gain their mobility from elastic deformations of elements. In most systems, however, complete control over the elasticity is desired....

Synthesis of Slender Spatial Compliant Mechanisms with application to passive exoskeletons

Industrial passive exoskeletons have been developed for years as a tool to reduce the physical workload of their users. They accomplish this by compensating for the user’s body weight and decreasing fatigue caused by repetitive loads. Despite their advantages, current exoskeletons have drawbacks that make them less convenient for users and thus...

Neutrally stable double-curved shells by inflection point propagation

Elastic structures that can deflect without springback, known as neutrally stable structures, form a remarkable group within their field, since they require the energetic state to remain unchanged during elastic deformation. Several examples in the literature obtain this state of neutral stability by the application of pre-stress, either as a...

Reversible shape morphing of a neutrally stable shell by untethered local activation of embedded Ni-Ti wires

This paper presents a novel shape morphing concept, which exploits neutral stability to achieve reversible shape morphing. The concept is based on actively changing the material stiffness on a local level in order to perturb the neutral stability and thus induce the shell to deform. This concept is realized by embedding Ni-Ti wires in a...

Characterization of spatially curved beams with anisotropically adaptive stiffness using sliding torsional stiffeners

Compliant mechanisms (CM) with adaptive stiffness have been widely used in robotics and machine design applications. This paper proposes adapting the endpoint stiffness of a spatially curved compliant beam using a movable torsional stiffener and a new graphical characterization method for the resulting anisotropic stiffness of the endpoint...

Neutrally stable transition of a curved-crease planar shell structure

Elastic neutral stability in compliant mechanisms is a remarkable appearance since it requires the energetic state of the structure to remain unchanged during a deformation mode. Several examples in literature require either plastic deformation or external constraints to be enforced to obtain a state of pre-stress and often require the use of...

Asymmetric Spatial Beams with Symmetric Kinetostatic Behaviour

A method to achieve symmetric kinetostatic behaviour in an extensive working range at the endpoint of an asymmetric spatial beam, using cross-section optimization, is presented. The objective function of the optimization is defined as expanding the beam working range to the desired region, simultaneously maximizing symmetric behaviour in it....