Field hockey sticks are interesting hand-held sports equipment, due to their duality in preferred stick behaviour. The stick is used for striking, where a high power is desired; but also for stopping, where good control is required. This report aims to identify the properties that influence stick performance and to design a field hockey stick with adaptable properties to improve stick performance; where performance is defined as the ability of the stick to develop a high velocity when hitting a ball, and to provide proper control when stopping the ball.
The stiffness, damping and mass of the stick are properties influencing the stick behaviour; these properties are present locally, at the impact location, as well as over the full length as deflective properties due to the moment originating from the ball impact.
The deflective stiffness and damping properties are identified by applying a disturbance force on the stick tip and measuring the displacement; this shows a range of stick stiffness from 1.4 to 3.0 kN/m and a stick damping from 0.5 to 2.7 Ns/m. Measurements are performed analysing the influence of stiffness, damping, mass and effective mass; this is done by a setup where a stick falls down towards a ball and the ball distance is measured. Additionally, a mathematical model is developed for the analysis of these stick properties. This consists of a collision model, including the coefficient of restitution reflecting the stiffness and damping properties. It can be concluded that the effective stick mass is most influential and the desired properties are opposite for striking and stopping.
A design of a mechanism that fits inside the stick is proposed, this mechanism reacts to the angular acceleration of the stick, and thereby changes its properties between striking and stopping a ball. It adapts the effective mass of the stick, by two weights moving towards the head of the stick when striking a ball. By this increase in effective stick mass, an increase of 7% (compared to the original effective mass) of the ball velocity after hitting the ball is expected.

This thesis presents the state-of-the art gripping literature and the implementation and extension of an existing Pseudo-Rigid Body Modelling (PRBM) method for modelling initially-curved compliant grippers out of which a circular object is extracted. From the existing literature, challenges are found in the design and evaluation of concepts of initially-curved compliant grippers, mainly involving the relevant design parameters, such as the thickness and enclosing angle of the finger.

The main goal of this thesis is therefore to present and validate the pull-out force modelling for these fingers within defined load conditions to provide comprehensive insights into the relation between important design parameters, such as the enclosing angle and thickness of the finger.

This goal is accomplished by extending an existing 3R PRB-model for initially-curved beams with a fifth link that represents the object and analysing the kinematics and kinetics to determine the relation for the pull-out force of a gripper finger with defined dimensions and a known load case.

This model is validated by designing and building an experimental test setup in which the reaction forces of a initially-curved testpiece of PLA and stainless steel material are measured. Errors for the kinetics between 12 and 32 percent were determined, consisting primarily of systematic errors.

The validated model is used for a parametric study, where relations between relevant design parameters, such as the enclosing angle and thickness of an initially-curved compliant gripper finger, are determined and visualized in a design chart that are be applied in the design of an initially-curved enclosing gripper prototype.

The Lunar Zebro is a small moon rover that needs an advanced chassis to endure the harsh environment that the moon brings. To arrive at a solution for such a frame or chassis creativity and hard work are necessary. Whereas hard work is a given, creativity is not and it may need a helping hand. Design synthesis methods, of which brainstorming is a basic example, aid engineers and designers with reaching better solutions. Currently, however, which method works best for a given scenario is unknown. The purpose of this research is to determine which synthesis method works best for concept generation, with the focus lying on generating innovative solutions for frame design. A meta-method is created to evaluate the performance of different synthesis methods when applied to design cases. This meta-method consists of executing fifty case-method combinations, built up from pairing ten design synthesis methods with five design cases, which are focused on frame design primarily. The combinations are then evaluated using a self-made rubric. In the end, it became apparent that different methods apply well at different stages of the design process and at different system levels. Some work well to orient, understand the supersystem and therefore have an positive yet indirect influence on the final outcome. Some work well to generate concepts, bring new ideas at system level. Others apply well after a concept is already generated, only being useful to improve subsystems.

The purpose of this study is to investigate how metamaterials with a negative Poisson ratio, so-called auxetic metamaterials, can be used for conversion of pressure from a fluid to strain in a solid for application in a medical pressure sensor. As a first step, a literature review was carried out to identify the potential of auxetic metamaterials as a solution direction for pressure to strain conversion. From considering three optimal case scenarios for solution directions to create strain in a fiber, the approach of auxetic metamaterials stood out. High axial strains and a linear straining behavior, which is important for the read-out of the sensor, were expected. Auxetic Chiral structures were designed and fabricated and their effective Poisson ratios were experimentally evaluated. It was found that the boundary effects that are introduced during experiments influence the behavior of the auxetic structure, especially on the unit cells close to the boundaries. A region was found where the unit-cells behave as theory describes and the boundary effects are dissipated. Additionally, it was found that for the an-isotropic Meta Tetra Chiral structure the Poisson ratio is influenced by applied strain. The isotropic Anti Tetra Chiral structure did not show strain dependent behavior. The relation between pressure to strain conversion and the effective properties of auxetic structures indicated that an-isotropic effective properties are preferred. Using this finding Re-entrant Honeycomb structures were designed for high pressure to strain conversion. From measuring the force input and output while deforming the structure, the expectations were verified. In this research it was found that auxetic metamaterials with an-isotropic effective properties, such as Re-entrant Honeycomb structures, are an effective intermediate for converting pressure from the fluid domain to strain in a fiber.