Aerostatic bearings are critical components in ultra-precision systems, valued for their near-frictionless motion, high positional accuracy, and clean operation. However, their reliability is compromised by crash events, which occur when the loss of air film separation leads to direct surface contact during relative motion. This thesis presents a parametric finite element model to assess crash resistance by quantifying the impact of surface damage on load-carrying capacity and static stiffness. The model incorporates experimentally observed wear geometries into a coupled Reynolds equation and restriction model, enabling stochastic evaluation through uncertainty quantification and sensitivity analysis. A key contribution is the identification of negative bearing stiffness as a previously unreported failure mechanism, in which a decrease in air film height leads to a drop in load-carrying capacity rather than an increase, creating an unstable condition that can result in surface contact. This behavior is caused by ridge formation, where displaced material accumulates along the damage region and creates protruding features that obstruct local pressure buildup. Experimental analysis using digital microscopy and white light interferometry validates the approximated wear shapes and consistently reveals groove-like damage accompanied by ridge formation. Sensitivity analysis shows that damage location and height have the strongest influence on performance loss, with notable interaction effects. Comparative simulations demonstrate that damage without ridges reduces the impact on bearing performance, highlighting the critical role of damage geometry. The developed framework enables evaluation of crash resistance and supports the design of more robust aerostatic bearings for high-tech applications.

The contactless wafer handling system proposed by He et al. (2024), relies on continuous high-pressure and vacuum flows, leading to energy inefficiencies and limited scalability due to the absence of localized flow control. The research problem addressed in this thesis is how to passively control these flows based solely on wafer presence, without using active sensors or external control systems. To solve this, a passive valve concept was developed, using bistable rubber domes that actuate in response to environmental pressure changes. A design methodology was applied to create and select suitable concepts, followed by detailed modelling of the dome using FEM simulations in COMSOL, which accounted for geometric imperfections and material properties validated through experiments. Prototypes of the high-pressure system were fabricated and tested to assess valve performance. Key findings show that the high-pressure valve design passively reduced airflow by up to 16% when no wafer was present, with performance highly dependent on dome thickness and inlet pressure. The vacuum valve design, however, failed due to excessive membrane deformation and reversed logic. It is concluded that passive high pressure flow control via pressure-responsive domes is feasible and scalable with proper dome design, while vacuum control requires a revised concept. The validated simulation models and developed manufacturing method offer a solid foundation for future iterations aimed at improving efficiency in wafer handling systems.

In laparoscopic surgery, maintaining a pressurised workspace within the intra-abdominal cavity is crucial for the minimally invasive procedure's success. Trocars play an essential role by sealing the cavity during surgery and providing access to surgical instruments. However, conventional trocar seals involve a fundamental trade-off between preventing gas leaks and reducing instrument friction and haptic feedback loss. In response to these challenges, this thesis investigates a novel active trocar sealing system based on the principle of Squeeze Film Levitation (SFL). This approach utilises high-frequency vibrations to create a pressurised gas film at the seal-instrument interface, aiming to achieve both frictionless manipulation and active gas flow control. The primary objective of this numerical investigation was to evaluate the feasibility of employing SFL for dynamic sealing against typical surgical pressure differentials. Initial analyses indicated that while specific SFL configurations effectively generate levitation (indicative of friction reduction), these could, in some instances, intensify gas outflow. However, the research demonstrated that optimised SFL system configurations can potentially achieve net inward gas pumping, actively reversing the direction of gas flow against the pressure difference. This capability represents a significant advancement over traditional sealing methods, moving beyond merely restricting leakage. The study identified distinct operational regimes, governed by the intricate interplay between the system's inherent fluid dynamics and key design parameters, such as geometric configurations and actuation timing. Findings suggest that careful tuning of these parameters fundamentally drives the system's dynamic response, observing outcomes ranging from enhanced flow restriction to substantial inward pumping. This work establishes the SFL system as a promising application for active dynamic sealing. Its demonstrated ability to control the gas flux direction, combined with the inherent low-friction characteristics of SFL, suggests a strong potential for improving pneumoperitoneum stability and surgical instrument interaction, with broader implications for precision fluid and gas control in diverse engineering applications.

Compliant closed-cell joints do not buckle under compression and exhibit a higher axial-to-rotational stiffness ratio than conventional compliant joints by using a fluid encapsulated in a flexible cell as the main load-bearing element. However, the axial and shear stiffness are still insufficient to replace spherical or universal joints in high load-bearing applications. This thesis aims to address this by using a fiber-reinforced cell wall. To make optimal use of the fiber strength, adapted geodesic-isotensoid designs are proposed.
To evaluate the performance of different geodesic-isotensoid designs, an axial mathematical model was developed and validated with a finite element model. Furthermore, both models were used to evaluate the axial, rotational, and shear stiffness, as well as the load-bearing capacity of the joint across a range of designs. The results can be used to guide the design of future fiber-reinforced compliant closed-cell joints. Additionally, it was found that adding extra fibers increases axial stiffness without affecting rotational stiffness, enabling high axial-to-rotational stiffness ratios.

Current wafer handling methods in the high-tech industry rely on mechanical contact to transport and position wafers. This leads to high breakage rates and contamination, ultimately reducing product yield. To overcome these challenges, TU Delft has developed several air-based contactless handling systems. However, stringent thermal requirements in the high-tech industry demand a highly uniform and stable temperature distribution across the wafer, posing significant challenges for such systems. Hence, research is performed on the thermomechanical effects of active air bearings on wafers during contactless handling.

Initially, a comprehensive theoretical analysis is performed on fluid flow and heat transfer phenomena in simplified geometries. Both rectilinear and axisymmetric models are developed to capture essential aspects of laminar thin film flows. Analytical expressions reveal the balance between expansion and viscous dissipation effects, particularly for rectilinear Poiseuille flow. The thesis further advances to complex numerical modelling using COMSOL Multiphysics, refining the geometry to better mirror actual operating conditions and incorporating the influence of mechanical wafer deformation.

In parallel, an experimental test setup is designed and implemented to replicate the operational environment of an air bearing system in a simplified form. This setup enables controlled measurement of temperature profiles and wafer deformation using complementary sensor techniques. One technique provides absolute temperature calibration, while another maps the relative temperature distribution across the wafer surface. Additionally, an optical method inspired by free-surface synthetic schlieren is used to quantify wafer deformation. This experimental setup not only serves to validate the theoretical models and numerical COMSOL simulations but also aims to explore measurement techniques applicable to operational air bearing systems.

This study introduces a novel constraint in linkage mechanism design: the constant-area constraint. Traditional linkage mechanisms rely on constraints of rigidity and joint motion, the constant-area constraint enforces an additional limitation:  the area enclosed by the linkages remains constant throughout its motion. Originating from incompressible fluid mechanics, this concept is adapted for linkage mechanisms. We present computational tools developed for analysing and optimising constant-area linkage mechanisms. These tools are applied to explore their kinematic behaviour and possibilities. This novel concept led to a modification of the Gruebler degrees-of-freedom formula. The constant area concept is applied to five- and six-bar mechanisms and an exploratory analysis of multiple interconnected constant area cells is also conducted.

In the semiconductor and photovoltaic industries, contactless positioning systems are increasingly employed to handle ultra-thin wafers, minimizing the risk of mechanical damage. A suitable and integrated sensor system would make this handling method more attractive in future applications. This Msc. thesis explores a novel concept in planar position measurement for flat, reflective objects using fiber optic sensors distributed across a measurement plane. This sensor configuration creates light profiles via transmitting fibers and utilizes the reflected light detected by receiving fibers to localize the object's position.
A Gaussian-distributed intensity pattern is first applied to the light profiles to validate this concept, establishing the theoretical relationship between brightness and planar positions. A prototype with a single set of fibers is then constructed to verify the proposed brightness model and determine the optimal, sparsest fiber spacing that maintains adequate resolution. In the next phase, algorithms are developed using simulated sensor arrays to calculate planar degrees of freedom based on the actual positions and brightness values from receiving fibers near the object's boundary. These algorithms are then implemented in a fabricated sensor array prototype, forming a complete distributed fiber optic sensor system.
The sensor's performance is evaluated using samples with varying center positions and orientations, resulting in an average error of less than 1 mm in the in-plane directions. In conclusion, the proposed sensor configuration limits planar position errors to sub-millimeter accuracy. The measurement range is significantly extended, and the sensor element no longer needs to be attached to the measured object. As a result, this system offers promising potential for contactless planar positioning of thin, fragile products with specular surfaces.

This research investigates a novel approach to vibration energy harvesting (VEH) using a statically balanced lever mechanism to compress piezoelectric stacks. Current state-of-the-art VEH methods struggle with scaling and harvesting energy efficiently, this proposed prototype addresses these limitations by utilizing the piezoelectric charge constant more efficiently. A prototype was developed and tested, showing a maximal stiffness reduction of 95% and demonstrating the principle's improvement in increasing power output by at most a factor of 116. A model is introduced to predict power output from the response and to estimate the generated power of an unbalanced mechanism. The scalability and improved performance highlight the potential of this approach for future VEH applications.

Contactless handling systems used to accurately position and move substrates in the order of microns can be mechanically driven by actuators. However, these actuators require high actuation forces of up to 140 N due to the high internal stiffness of the contactless handling systems, which can be modeled as stator-mover systems (SMS’s) with a mover capable of moving up to 3 degrees of freedom (DoF). This MSc thesis report shows the development and realisation of a passive stiffness compensation design for a uniform SMS in translational 1 DoF, using only small displacements in the sub micron level. A uniform SMS was created with a mover that was able to displace in the same range of motion as the largest possible displacement of the investigated contactless handling systems: between -65 µm and 65 µm. After classification on stiffness compensation techniques, a concept was developed based on magnetic circuits using C-shaped yokes and air gaps between the yokes and mover. It was found that the the magnetic circuit concept was able to deliver high forces to introduce a negative stiffness and a magnetic force of 74.84 N at maximum displacement was obtained analytically for a 1 DoF translation. A final design was made using an optimisation on the C-shaped yoke, kinetostatic modeling on the SMS and computations on analytical and numerical fields, which together showed promising stiffness compensating behaviour for the SMS design. A 1 DoF SMS demonstrator was developed and manufactured which contained sheet flexures that ensured the translational motion in x-direction and the ability of an adaptable flexure length to adapt the internal stiffness and adaptable air gap length to adapt the magnetic force. The 1 DoF SMS was validated experimentally to show the internal stiffness and stiffness compensation of the SMS. The stiffnesses were measured using a vibration test to find the eigenfrequencies of the system and a static load test to determine the force-displacement relationship. Stiffness compensations were observed for all investigated combinations of
flexure length and air gap length. A maximum passive compensation of 56.7% was obtained in the 1 DoF SMS, which turned out to have smaller internal stiffnesses than the contactless handling system. Nevertheless, the developed stiffness compensation design shows its potential for a next iteration in which an implementation in contactless handling systems could be possible.

In a hydrodynamic journal bearing, the lubricant is pressurized by the relative movement of the bearing surfaces, creating a load-carrying capacity. The load-carrying capacity can be increased by using a lubricant with higher viscosity, at the cost of increased friction. A proposed method to increase the maximum load-carrying capacity, while not increasing the friction at lower loads (or at higher speeds), is by using magnetorheological (MR) fluid as lubricant and electromagnets to generate a magnetic field. MR fluid consists of a carrier fluid with micron-sized magnetic particles suspended. Under the influence of an external magnetic field, the viscosity of the fluid increases as the particles form chain-like structures. Using electromagnets, the magnetic field strength can be adjusted based on the operating conditions of the bearing and the bearing can be semi-actively controlled. The objective of this thesis is to create a visual demonstrator setup, intended for educational purposes, that can be used to investigate the pressure distribution and generated forces in a hydrodynamic half journal bearing using MR fluid and electromagnets. Furthermore, the research objective is to increase the maximum load capacity for a specified minimum film thickness, while not increasing the friction in the hydrodynamic lubrication regime. The test setup was based on an existing setup made by GUNT which is able to show the pressure distribution in a half journal bearing using pressure tubes for various eccentricity ratios. Adaptations to this setup were made to measure the generated forces (horizontal force, vertical force and friction force, defined as the frictional moment divided by the radius of the bearing) and to implement an electromagnet. First, experiments using hydraulic oil were performed to test and improve the performance of the setup. Afterwards, experiments using MR fluid were performed with varying magnetic field strengths. Furthermore, a numerical model based on the two-dimensional Reynolds equation was created and validated with the experimental results. Both the numerical and experimental results showed comparable trends of increasing pressure, horizontal force and vertical force, meaning an increasing load capacity, for increasing eccentricity ratio and applied current. The numerical friction force also increased with increasing eccentricity ratio and applied current, while the experimental friction force only increased with increasing applied current and did not show a clear trend with increasing eccentricity ratio. The magnitude of the forces differed significantly between the experimental and numerical results, where the largest differences were observed for the vertical force and the friction force. Many plausible causes for the differences are identified, such as bearing tolerances, uncertainties in eccentricity and modeling simplifications. A combination of these causes is believed to lead to the observed differences. The increase in pressure, horizontal force and vertical force due to an increase in applied current was found to be much smaller experimentally than numerically. This was thought to be caused by a larger temperature increase in the experimental tests than was modeled and by simplifications used in the numerical model such as neglecting the shearthinning characteristics of MR fluids. The friction force differed even more significantly between the numerical and experimental results. Additionally, this is caused by the small magnitude of the friction force in combination with a test setup that is not accurate enough to measure small forces consistently. The created setup can show the change in pressure distribution when the applied current or eccentricity is changed. It therefore serves as a visual demonstrator setup for an MR lubricated hydrodynamic half journal bearing which can be used for educational purposes. However, demonstrator performance was found to be far from ideal as the changes in fluid column height were very slow because of the high MR fluid viscosity. Performance can potentially be improved by using a different or diluted MR fluid. Despite the large differences between the numerical and experimental results, both can be used to display the potential of semi-active control using MR fluid and electromagnets. It is shown that the maximum load capacity can be increased while not increasing the friction coefficient in the hydrodynamic lubrication regime. Several recommendations have been made for changes to the demonstrator setup to improve performance while keeping the setup simple and elegant. The main recommendations include improving the bearing tolerances, testing with a different or diluted MR fluid, implementing capacitive distance sensors and performing experiments at a more consistent ambient temperature.

The high-tech industry intends to develop many smaller and thinner products, especially in silicon microchips and solar panel manufacturing processes, to enhance the technologies of the world. In these production processes, fabrications are carried out on increasingly thin substrates to create more microchips or enhance the efficiency of solar cells. Current transport methods within these fabrication machines can degrade and break the ever-thinning substrates, especially those less than 200 𝜇𝑚, which are at risk for continuous damage during manufacturing. One solution to this transport issue is a contactless actuation system using the basis of air-bearing physics. The Flowerbed (a deformable surface air actuator) designed by Vuong is proposed as a solution to this issue. Since the Flowerbed is non-operational, a test bench or equivalent system is desired to be created for control law testing for future Flowerbed-type contactless actuation systems. The development of a model for an equivalent system to the Flowerbed could be adapted and used for deformable surface air actuators or similar. The Flowerbed system is studied, and this research determines that the Flowerbed system can be effectively decomposed into two subsystems: the structural base of the Flowerbed with its actuators and a wafer floating on a thin air film. This is done due to the classification of the thin air film as a constant gain. The two subsystems, the Flowerbed Equivalent and Wafer Equivalent subsystems are combined to create a Flowerbed Equivalent system. The ultimate goal is to classify the Flowerbed Equivalent system as a test bench for the Flowerbed and future deformable surface air actuators. Key objectives for the Flowerbed Equivalent system include achieving functional and performance equivalence between the Equivalent system and the Flowerbed to accurately validate potential control strategies. This thesis aims to design, model, and validate a Flowerbed Equivalent system capable of replicating the dynamics and responses of the original Flowerbed. It includes a detailed exploration of design methodologies, manufacturing processes, and experimental validation through system identification techniques. An equivalent system is designed and theoretically modeled, with the manufacturing process completed for the Wafer Equivalent. Subsequent testing of the Wafer Equivalent reveals that while the initial results are not entirely satisfactory, they demonstrate promising trends. These trends suggest that with further refinement, the Wafer Equivalent can accurately model a wafer floating on air, and by extension, the wafer in the Flowerbed system. The findings underline the potential of the Flowerbed Equivalent and Wafer Equivalent as foundational models, future research is needed to further the physical model of the equivalent system before using it in full operation. This work contributes to the validation of complex system modeling and highlights the importance of iterative design and testing.

Model Order Reduction is an essential tool in analysis of structures exhibiting nonlinear dynamic behaviour. In this work the model order reduction method of Modal Derivatives, which is an extension of the linear Modal Truncation method into the nonlinear regime, is implemented in an automated scheme starting from a Finite Element discretization based on a Kirchhoff-Love shell element. After validation of the implementation, multiple thin-walled examples are analyzed and the results of the reduced-order model are compared to results from literature.

High-powered LED arrays have emerged as a viable alternative to halogen lamp-based arrays for heating silicon wafers to 1000C due to their monochromatic radiosity which can be chosen in an efficient bandwidth for high absorption into silicon, removing the requirement for the pre-soak anneal in traditional systems. However, a gap in literature is found as there are only low temperature applications for LED arrays found (max. 400C), on which the research is focussed around improving the control system design. The high-temperature RTP application for LEDs has not yet been studied in literature or implemented in industry. Advancements over the past decades have sharply increased the radiometric flux and efficacy of LEDs, enabling more and more high-powered applications. However, due to the exceptionally small size and high heat fluxes of high-powered LED chips, junction cooling has traditionally been a major bottleneck for implementing LEDs in demanding applications. For the power levels required in 1000C RTP, the feasibility of LEDs in terms of power output, wafer temperature uniformity and cooling of LED-based heater arrays remains unproven. Through a systems-based approach, a multi-domain fundamental analysis and simulation in the fields of linear algebra, heat transfer, optics, electrical engineering, semiconductor physics, CAD and FEM has been performed. Resultingly, feasibility has been demonstrated for 1000C LED RTP.

High-tech systems are subjected to strict temperature requirements. Therefore temperature control using cooling water is vital for thermal stability. Unfortunately, components like pumps and fluid couplings generate flow disturbances, resulting in mechanical vibrations that influence the performance of the system. This research focusses on the propagation of pump induced pressure oscillations to nano-precision instrumentation. A generic vibration isolated precision system has been considered. The system contains a cooling conduit, which is connected to a mechanically isolated pump by viscoelastic tubing. Pressure disturbances are transmitted to the system due to fluid-structure interaction at curved tubes in the cooling conduit. Luckily, viscoelastic tubes are proven to attenuate pressure oscillations. A model has been presented to predict the system disturbance due to pressure oscillations produced by a pump. An experimental setup has been considered to validate the model. The setup represents a simple mechatronic system. Results show that the model provides a decent qualitative description of the spectral disturbance behaviour, however it is only capable of giving an order of magnitude estimation of the overall disturbance. Based on the knowledge gained in this research, possible design improvements can be proposed. These include changing the dimensions of the viscoelastic tubes and altering the mechanical eigenfrequencies of the cooling conduit.

Air bearings are a vital component to high tech machines and have been in widespread use since the 1960s. They provide near frictionless motion, have high stiffness and a near infinite lifetime. When looking at existing literature the influence of the porosity on the dynamic characteristics has not been researched in depth. Especially when looking at porous air bearings with a surface restrictive layer, a discrepancy can be defined between the ideal surface restrictive layers considered in literature and layers that can be realized in reality. This report presents a model to accurately predict the dynamic characteristics of both bearings with and without a surface restrictive layer. An alternative intuitive
approach is presented to explain the dynamic behaviour at low frequencies for these types of bearing based on the amount of stored air inside and underneath the bearing. This model is then used to investigate the influence of the porosity on the dynamic characteristics of a uncoated bearing. Followed by a study on the mechanics behind the surface restrictive layers and the sensitivity of the porosity of the surface restrictive layer. An existing dataset from an experiment is used to asses the viability of the model.

The utilization of CubeSats as a cost-effective solution for satellite missions allows universities to engage in outer space research. Notably, the issue of increased tumbling rates during deployment is highlighted, attributed mainly to propulsion and guiding functions performed by existing contact actuators.
The proposed solution in this thesis employs viscous traction actuators, which manipulate a thin air film to generate both propulsion and guiding forces. The preliminary design of propulsion and guiding functions incorporates these actuators on the inner sides of the deployer case. The design requirements are established as a criterion to evaluate the redesigned propulsion and guiding functions, including minimal exit velocity, maximal tumbling rate, and maximum acceleration. Moreover, the inner envelope accommodates a 3U CubeSat, and estimation for air reservoir volume and pressure ensure adequate space for launch deployment.
Performance simulation is proposed to evaluate whether the design satisfies the design requirements. It consists of the simulation of the viscous traction actuator and the full model simulation of the deployer. For the simulation of the viscous traction actuator, the finite element method is used to calculate load capacity and viscous traction applied by the viscous traction actuator as input to the full model simulation of the deployer. The full model simulation of the deployer assesses CubeSat motion and propulsion force. The successful fulfillment of design requirements and safe deployment are confirmed.
While the preliminary design meets design requirements, a design method is introduced to cater to varied exit velocity and tumbling rate preferences. This approach adjust design parameters based on a propulsion force vs. time plot. Two distinct designs are presented based on this approach, catering to differing preferences.
The selected +EPC design, characterized by low tumbling rates, progresses to a detailed mechanical design encompassing deployer case, actuator, displacement sensor, and air-supplied system. The implementation of the viscous traction actuator follows established research, ensuring structural safety. Other aspects like displacement measurement, air reservoir selection are also discussed in this detailed design.

Nanoimprinting is a manufacturing method to replicate micro- and nanotextures on large-area substrates with ultraviolet-curable resins. Significant potential of large-area nanopatterning lies in its capacity to greatly enhance the performance of an abundance of devices and foster the creation of cutting-edge products. However, current large-area imprinting techniques require improvement in order to achieve high resolution, high throughput and cost-effectiveness, whilst imprinting in a thin uniform resin layer. This work presents the development of a demonstrator to passively control the film thickness in hydrodynamic lubrication on non-flat surfaces in nanoimprinting lithography.
Using low stiffness actuation, it was expected that film thickness uniformity increases during imprinting. In this project a functioning demonstrator is realised, where the film height under a slider bearing is passively controlled. The slider bearing behaviour has been tested on various flat and non-flat surfaces. Film heights of 80-160 micrometer were realised on non-flat substrates of 800 micrometer.

The research objective of this research is to develop a measurement method that can measure thin film thicknesses through a multilayer that consists of both surrounding thick layers and in between thin films. An optical non-contact measurement method is researched and developed to non-destructively measure the thickness of a liquid thin film, which is situated between other layers. The measurement method used in this research is called spectral reflectance. The method works by analyzing the reflectance spectrum from a light beam which is directed perpendicularly and with a wide range of wavelengths on the surface of the layer. The reflectance spectrum that is measured with a spectrometer includes oscillations that result from the interference of light that reflects at the different interfaces in the multilayer. The oscillation contains frequency content which is used to determine the thickness of the layer. This research shows that the spectral reflectance technique can be used to measure the thickness of a stack of thin films with the condition that the thin films are all coherent. It is possible to determine the film thickness of a stack coherent thin films, which are surrounded by incoherently thick layers. The outer layers can be assumed to be incoherently thick based on a combination of factors such as the layer thickness of the thick layer, the measured wavelength range and the resolution of the spectrometer.

Hydrostatic bearings are typically designed to operate on flat, parallel surfaces, but a flexible hydrostatic bearing that can adapt to uneven smooth surfaces would have broader applications. This thesis focuses on the challenges of implementing the whiffletree concept to support a large, deformable hydrostatic bearing on wavy surfaces, which cannot be achieved with the current design due to four significant complications. To overcome these issues, the thesis proposes modifications to the whiffletree concept and introduces the multi-joint suspension system, which has greater potential to support a large, flexible hydrostatic bearing.