Synthesis of Nonlinear Torque-angle Profile Using Compliant Helicoidal Shell Joint

Compliant mechanisms, particularly helicoidal shell joints, present intriguing possibilities in mechanical design with applications in medical devices, robotics, automotive, and aerospace engineering. This research focuses on the synthesis of nonlinear torque-angle profiles using a compliant helicoidal shell mechanism such as gravity-balancing...

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...

Neutrally stable shells with embedded actuation

Elastically neutrally stable structures are compelling within the field of compliant mechanisms, since no force is required to deform them. Several examples of this state of elastic neutral stability exist, which often use equal but opposing structures to balance internal forces. This thesis is on the design of an active neutrally stable...

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...

Towards Neutrally Stable Compliant Shells

Elastic neutral stability involves elastic deformation without stiffness or loads. It is a remarkable appearance, since the deformation of materials is normally associated with an increase of potential energy and a resulting opposing reaction force or moment. Neutrally stable mechanisms can be used to overcome unnecessary actuation which makes...

Passive Autonomy: Hygromorphic Rotational Actuators: Design & Evaluation

Inspired by phenomena in the plant world, a<br/>meteoro-sensitive rotational actuator is developed. The design<br/>uses a hygro-active shell, whose water-based swelling is restricted<br/>at selective locations to form a helicoid structure. The influence<br/>of geometrical parameters on the performance is investigated<br/>using a numerical...

Increasing energy storage in compliant tape-spring mechanisms

This thesis studies the possibility of energy increase in tape-spring assemblies through stacking, defined as the practice of placing tape-springs on top of each other in parallel. consists of five chapters. Chapter 2 consists of a paper that presents a theoretical approach to stacking of tape-springs, and studies the potential of energy storage...

Compliant Shell Deformation in Plants: A Designer's Toolbox

The mechanisms that move plants can serve as biological role models for engineers, designers and architects. This practice is slowly being implemented in various engineering fields, with architects often being pioneers. Various methodologies have been written about the subject, but often only from an architectural point of view.<br/>The...

Negative Stiffness in Compliant Shell Mechanisms: To develop a passive stroke rehabilitation device

Present stroke rehabilitation devices for the arm are often difficult to use by the patient himself and cannot be used at home. A compliant shell mechanism could overcome the shortcomings of the current available devices. By the use of monolithic shell mechanisms a simple to use device can be designed, which can be made wearable. It would make...

Scoliosis Brace Design: Utilizing Compliant Shell Mechanisms and Primary Compliance Vector Path Optimization

Existing scoliosis braces preclude spinal movement for activities of daily living, which reduces the willingness to wear the brace and treatment success. This work develops a scoliosis brace that meets corrective requirements while retaining patient mobility.<br/>The primary compliance vector (PCV) captures the predominant kinematic degree of...

Synthesis of mechanisms with prescribed elastic load-displacement characteristics

In this dissertation a collection of concepts to synthesise nonlinear springs is presented. Such springs can be useful in various application domains where, e.g., multi-stability or static balancing is desired. These behaviors are often sought to alleviate the effort required for actuation. The explored concepts are presented by showing the...

Gravity balanced compliant shell mechanisms

The research on compliant shell mechanisms is a new and promising expansion of the well established compliant mechanisms research area. Benefits of compliant shell mechanisms include being spatial and slender, having organic shapes and their high tailorability of the load-displacement response. This work focusses on the design of a shell with...