This thesis explains the design, fabrication and characterization steps of a high dynamic range CMOS-MEMS capacitive accelerometer array and on-chip environmental sensors for bias drift compensation. Inertial navigation under harsh environments requires a high dynamic range accelerometer that can survive and provide continuous readout accuracy through shock events, while having a large dynamic range to capture fine-scale motions. The dynamic range target is set as 156 dB in accordance with navigation standard macro-electromechanical accelerometers, which corresponds to around 1 mG acceleration resolution in 50 kG input range. The small accelerometer cell design ensures shock survivability (e.g. up to 50 kG) by keeping the stress at the anchors below the fracture strength of thin-film oxide. Arraying multiple accelerometer cells in parallel lowers the fundamental thermomechanical noise limit set by the small mass of the individual accelerometer cells. Resonance frequency staggering between accelerometer cells suppresses ring-down oscillations. Parasitic capacitance of the high-impedance transduction signal is important to mitigate; undercut of the underlying silicon substrate and an aluminum etch of the top metal layer, incorporated in the CMOS-MEMS process flow, reduces the parasitic capacitance and improves sensitivity. PTAT temperature sensors, piezoresistive stress sensors and resonator-oscillators integrated across the accelerometer chip provide high-resolution environmental measurements for the compensation of long-term bias and scale factor drift. Simultaneous measurements from the accelerometer and environmental sensors demonstrate the correlation between environmental variations and long-term drift. Finite-element analysis shows that the scale factor stability of the accelerometer can be improved up to 1 ppm given the sensor array’s measurement resolution. The CMOS-MEMS accelerometer system-on-chip is fabricated in a TowerJazz 0.18 μm CMOS process. The post-CMOS MEMS processing steps are tuned to reduce the top metal milling and sidewall polymer deposition. A reactive ion etch recipe is developed for the removal of the top metal in order to reduce the parasitic capacitance and eliminate the risk of metal creep at spring beam anchors, thereby improve the bias stability. The PTAT temperature sensors have 3.1 mV/K measured sensitivity and 7.1 mK resolution with high repeatability. The compensation of the accelerometer readout for temperature variations down to 7.1 mK translates to 2.6 ppm scale factor stability for the accelerometer. The characterization of the stress sensors through the application of normal stress on the device package leads to an uncertainty in the amount of stress transferred to the stress sensors on the chip surface. The maximum measured stress sensitivity is 36.5 pV/Pa, which leads to 24.7 kPa stress resolution and translates to 1.7 ppm scale factor stability for the accelerometer without taking the stress attenuation into account. The measured sensitivity sets a lower bound on the sensitivity of the stress sensors implying that the stress resolution and the corresponding accelerometer scale factor stability is higher in practice. The measured frequency stability of the resonator-oscillator is 0.4 ppm, thereby the resonance frequency based variations of the accelerometer readout can be compensated to reach up to 0.8 ppm scale factor stability. However, the initial drift in the resonance frequency of the oscillators due to dielectric charging requires a long wait-time before these sensors can be used for accelerometer drift compensation. The accelerometer array is demonstrated to have 23.7 mG/√Hz noise floor and 70 mG bias stability. The maximum input acceleration applied on the device is limited to 4 kG by the split Hopkinson bar test setup. Improvement of the setup to transfer acceleration amplitudes up to 50 kG should validate the designed input range of the accelerometer array and lead to 117 dB dynamic range for the current design. The measurement bandwidth is fundamentally set by the 126 kHz resonance frequency of the accelerometer cells and can be further limited by filtering the readout signal to attenuate the transient oscillations faster. The nonlinearity of the accelerometer response is better than 1.2% in ±10 kG input range; however, it gets up to 19.0% in ±50 kG maximum input range. The long term bias drift of the accelerometer is shown to be correlated with the temperature and stress variations. Compensation of the accelerometer readout based on the stress and temperature sensor measurements leads to an observable improvement in the long term drift. However, the bias stability of the accelerometer is limited by excessive flicker noise in the system, which is believed to result from noise folding from higher frequencies. Suppression of the flicker noise in the system should allow for a more detailed study of the effect of environmental variations on the accelerometer readout and evaluation of more elaborate fitting algorithms for model based prediction and compensation of the bias drift to reach the target bias stability and dynamic range.

The material properties of low stress silicon nitride make it a possible replacement material for beryllium in X-ray windows. In this study, X-ray windows made of LPCVD deposited low stress silicon nitride are fabricated and characterized. The Young's modulus of the LPCVD low stress silicon nitride are characterized and found to be 226±23 GPa. The residual stress is characterized using two different methods and is found to be 127±25 MPa and 141±0.28 MPa. Two support structure geometries for the low stress silicon nitride X-ray windows are used. X-ray windows with thicknesses of 100 nm and 200 nm are suspended on a silicon rib support structure. A freestanding circular geometry is used for a 600 nm thick X-ray window. The 100 nm and 200 nm thick low stress silicon nitride X-ray windows with a silicon support structure are burst tested, cycling tested and leak rate tested. The average burst pressure for the 100 and 200 nm films on a silicon support structure are 1.4 atm and 2.2 atm respectively. Both 100 nm and 200 nm windows are able to withstand a difference in pressure of 1 atm for over 100 cycles with a leak rate of less than 10-10 mbar-L/s.The low stress silicon nitride with 100 nm and 200 nm thicknesses, the 600 nm freestanding low stress silicon nitride windows and freestanding 8 micron thick beryllium windows are mechanical shock resistance tested. The support structure low stress silicon nitride and beryllium windows are tested with an applied vacuum. The freestanding 600 nm thick low stress silicon nitride windows burst at 0.4 atm and are therefore mechanical shock wave tested without an applied vacuum. The support structure low stress silicon nitride windows fractured when subjected to an acceleration of roughly 5,000 g. The 8 micron thick beryllium windows are subjected to accelerations of over 30,000 g without fracturing. A quasistatic model is used to show that for low stress silicon nitride with a freestanding circular geometry, an acceleration of 106 g is required to have the same order of magnitude of stress caused by a pressure differential of 1 atm. Low stress silicon nitride can act as a replacement for beryllium in X-ray windows, but the support geometry, residual stress, and strength of the material need to be optimized.

Filter devices are central elements of radio units utilized for modern-day telecommunication. Leakages of radio waves and passive intermodulation are evolving more prominent as the frequency bands become crowded. The study in this thesis investigates the screw joints in the filter assembly to determine the influential parameters on the connection between the filter lid and its chassis. The clamp and release torque are vital factors in the resulting pre-load force. Besides the geometrical characteristics of the chassis andthe self-threading screw, the friction and surface roughness on the filter lid are significant contributors. Extensive testing revealed that increasing the countersink in the lead holeand applying the lubricant Molykote 1000 Paste increase the consequent clamp torque. After numerous cycles of thermal shock testing, the release torque does not show significant dissimilarities between the tested parameter combinations. A surface roughness test shows that applying a silver coating to the filter lid increases its surface roughness and thereby the friction of the screw head on the surface. In conclusion, the pre-load force will increase by changing the parameters as mentioned above, while it requires further testing to make a suggestion regarding the effect of the silver coating on the filter lid. / Filteranordningar är centrala delar i radioenheter vilka används vid nutida telekommunikation. Läckage av radiovågor och passiv intermodulation blir mer framträdande när frekvensbanden blir trånga. Studien i denna avhandling undersöker skruvförbanden i filtermonteringen för att bestämma de parametrar som har störst inverkan på anslutningen mellan filterlocket och dess chassi. Klämvrid- och lossdragningsmomentet är avgörande faktorer i den resulterande förspänningskraften. Förutom de geometriska egenskaperna hos chassit och den självgängande skruven, är friktionen och ytfinheten på filterlocket starktbidragande orsaker. Omfattande tester visade att en ökning av försänkningen i pilothålet och applicering av smörjmedlet Molykote 1000 Paste ökar det efterföljande klämvridmomentet. Efter talrika cykler av termisk chocktestning visar lossdragningsmomentet inga signifikanta skillnader mellan de testade parameterkombinationerna. Ett ytjämnhetstestvisar att applicering av en silverbeläggning på filterlocket ökar ytans strävhet och därmedfriktionen av skruvhuvudet på ytan. Sammanfattningsvis kommer förspänningskraften att öka genom att parametrarna ändras som nämnts ovan, samtidigt som det krävs ytterligare tester för att komma med ett förslag angående effekten av silverbeläggningen på filterlocket.

The particular study case in this thesis is the shock test performed on the LISA Pathfinder satellite conducted in a laboratory environment on a dedicated test bed: Vega Shock Test Apparatus (VESTA). This test is considered fully representative to study shock levels produced by fairing jettisoning event at Vega Launcher Vehicle, which induces high shock loads towards the satellite. In the frame of this thesis, some transient response analyses have been conducted in MSC Nastran, and a shock simulation tool for the VESTA test configuration has been developed. The simulation tool is based on Nastran Direct Transient Response Analysis solver (SOL 109), and is representative of the upper composite of Vega with the LISA Pathfinder coupled to it. Post-processing routines of transient response signals were conducted in Dynaworks which served to calculate Shock Response Spectra (SRS). The simulation tool is a model of forcing function parameters for transient analysis which adequately correlates with the shock real test data, in order to understand how the effect of shock generated by the launcher is seen in the satellite and its sub-systems. Since available computation resources are limited the parameters for analysis were optimised for computation time, file size, memory capacity,  and model complexity. The forcing function represents a release of the HSS clamp band which is responsible for fairing jettisoning, thus the parameters which were studied are mostly concerning the modelling of this event. Among many investigated, those which visibly improved SRS correlation are radial forcing function shape, implementation of axial impulse, clamp band loading geometry and refined loading scheme. Integration time step duration and analysis duration were also studied and found to improve correlation.  From each analysis, the qualifying shock environment was then derived by linear scaling in proportion of the applied preload, and considering a qualification margin of 3dB. Consecutive tracking of structural responses along shock propagation path exposed gradual changes in responses pattern and revealed an important property that a breathing mode (n = 0) at the base of a conical Adapter translates into an axial input to the spacecraft. The parametrisation itself was based on responses registered at interfaces located in near-field (where the clamp band is located and forcing function is applied) and medium-field with respect to the shock event location. Following shock propagation path, the final step was the analysis of shock responses inside the satellite located in a far-field region, which still revealed a very good correlation of results. Thus, it can be said that parametrisation process was adequate, and the developed shock simulation tool can be qualified. However, due to the nature of shock, the tool cannot fully replace VESTA laboratory test, but can support shock assessment process and preparation to such test. In the last part of the thesis, the implementation of some finite element model improvements is investigated. Majority of the panels in spacecraft interior exhibited shock over-prediction due to finite element model limitation. Equipment units modelled as lump masses rigidly attached with RBE2 elements to the panel surface are a source of such local over-predictions. Thus, some of the units were remodelled and transient responses were reinvestigated. It was found that remodelling with either solid elements, or lump mass connected to RBE3 element and reinforced by RBE2 element, can significantly improve local transient responses. This conclusion is in line with conclusions found in ECSS Shock Handbook.

A construção civil é o maior consumidor de recursos naturais do planeta, apropriando-se atualmente de mais da metade da massa total dos materiais extraídos. Neste contexto, o desenvolvimento de sistemas construtivos que proporcionem uma redução do consumo de materiais, conhecida como o princípio da desmaterialização dos edifícios, pode ser uma estratégia para a redução do impacto que a construção civil exerce sobre o ambiente, e um passo em direção a uma economia mais sustentável. A utilização de placas cimentícias para a produção de vedações vem crescendo em várias partes do mundo, seja para a produção de vedações verticais externas, seja como revestimento não aderido sobre vedos existentes, destinados tanto a melhoria estética quanto o desempenho destas fachadas. Uma vedação com placas cimentícias possui em torno de 25% da massa de uma alvenaria tradicional constituída por blocos de concreto para a execução de uma mesma área de vedação vertical, o que pode contribuir ainda para uma redução dos materiais empregados nas estruturas e fundações de um edifício. Apesar da utilização destas placas cimentícias estar coerente com a estratégia da desmaterialização, algumas experiências de vedações executadas com estes componentes manifestaram problemas de manutenção de suas características ao longo do tempo, apresentando fissuras geralmente nas juntas entre placas. Verificando-se as propriedades dos materiais que constituem esta placa cimentícia, principalmente a variação dimensional em relação à temperatura e umidade, constatou-se uma incompatibilidade entre a amplitude das variações dimensionais resultantes e os sistemas de fixação e juntas empregados para a sustentação das mesmas. A avaliação experimental de choque térmico comprovou a influência destas variações para a deterioração das juntas entre as placas. Com base nesta constatação, e em análises dos processos de fixação de placas cimentícias adotados por fornecedores em diversas partes do mundo, foi desenvolvido neste trabalho um novo sistema de fixação para placas cimentícias e de juntas entre estas com capacidade de atender a esta variação dimensional. Realizaram-se protótipos destes componentes os quais foram submetidos a uma avaliação experimental de choque térmico, resultando em nenhuma alteração visível nas juntas e nas superfícies destas placas. Como resultado concluiu-se que a criação de mecanismos que possibilitem acomodação às variações dimensionais, tanto nos dispositivos de fixação destas à estrutura, quanto nos acabamentos das juntas, podem contribuir significativamente para a durabilidade do sistema de vedações constituída por placas cimentícias. / The construction industry is the largest consumer of natural resources in the planet, currently appropriating more than half of mass of the total material extracted. In this context, the development of building systems that provide their dematerialization can be considered as a strategy to reduce the environmental construction impact, and a step toward a more sustainable economy. The use of fiber cement boards for the building production is growing in many parts of the world, to produce external vertical building enclosure or building envelopes, to improving the aesthetics and performance of these facades. A fiber cement board walls weigh around 25% of the traditional masonry mass made of concrete blocks for the same area of vertical building enclosure which can further contribute to a reduction of the materials used in building structures and foundations. Although the use of fiber cement boards complies with the dematerialization strategy, some experiments carried out with these cladding showed maintenance problems over time, usually cracks in the joints between panels. Checking the properties of materials constituting fiber cement boards, especially the dimensional variation due to changing temperature and humidity, there was an incompatibility between these dimensional variations amplitude and fixing systems and joints used to support them. The thermal shock experimental evaluation proved the influence of these variations on joints deterioration. Based on this observation, and on analyzes of the fiber cement suppliers recommendations over the world, a new system for fixing fiber cement board and joints between them was developed in this work with capacity to adapt to this dimensional variation. Prototypes of these components were made and submitted the thermal shock evaluation, resulting in no visible changes in the joints and on the surfaces of these panels. As a result, it was concluded that the creation of mechanisms that allow accommodating the dimensional variations, both in fixing these panels to the structure, and in the joints finishing can significantly contribute to the vertical building enclosure system durability.

A construção civil é o maior consumidor de recursos naturais do planeta, apropriando-se atualmente de mais da metade da massa total dos materiais extraídos. Neste contexto, o desenvolvimento de sistemas construtivos que proporcionem uma redução do consumo de materiais, conhecida como o princípio da desmaterialização dos edifícios, pode ser uma estratégia para a redução do impacto que a construção civil exerce sobre o ambiente, e um passo em direção a uma economia mais sustentável. A utilização de placas cimentícias para a produção de vedações vem crescendo em várias partes do mundo, seja para a produção de vedações verticais externas, seja como revestimento não aderido sobre vedos existentes, destinados tanto a melhoria estética quanto o desempenho destas fachadas. Uma vedação com placas cimentícias possui em torno de 25% da massa de uma alvenaria tradicional constituída por blocos de concreto para a execução de uma mesma área de vedação vertical, o que pode contribuir ainda para uma redução dos materiais empregados nas estruturas e fundações de um edifício. Apesar da utilização destas placas cimentícias estar coerente com a estratégia da desmaterialização, algumas experiências de vedações executadas com estes componentes manifestaram problemas de manutenção de suas características ao longo do tempo, apresentando fissuras geralmente nas juntas entre placas. Verificando-se as propriedades dos materiais que constituem esta placa cimentícia, principalmente a variação dimensional em relação à temperatura e umidade, constatou-se uma incompatibilidade entre a amplitude das variações dimensionais resultantes e os sistemas de fixação e juntas empregados para a sustentação das mesmas. A avaliação experimental de choque térmico comprovou a influência destas variações para a deterioração das juntas entre as placas. Com base nesta constatação, e em análises dos processos de fixação de placas cimentícias adotados por fornecedores em diversas partes do mundo, foi desenvolvido neste trabalho um novo sistema de fixação para placas cimentícias e de juntas entre estas com capacidade de atender a esta variação dimensional. Realizaram-se protótipos destes componentes os quais foram submetidos a uma avaliação experimental de choque térmico, resultando em nenhuma alteração visível nas juntas e nas superfícies destas placas. Como resultado concluiu-se que a criação de mecanismos que possibilitem acomodação às variações dimensionais, tanto nos dispositivos de fixação destas à estrutura, quanto nos acabamentos das juntas, podem contribuir significativamente para a durabilidade do sistema de vedações constituída por placas cimentícias. / The construction industry is the largest consumer of natural resources in the planet, currently appropriating more than half of mass of the total material extracted. In this context, the development of building systems that provide their dematerialization can be considered as a strategy to reduce the environmental construction impact, and a step toward a more sustainable economy. The use of fiber cement boards for the building production is growing in many parts of the world, to produce external vertical building enclosure or building envelopes, to improving the aesthetics and performance of these facades. A fiber cement board walls weigh around 25% of the traditional masonry mass made of concrete blocks for the same area of vertical building enclosure which can further contribute to a reduction of the materials used in building structures and foundations. Although the use of fiber cement boards complies with the dematerialization strategy, some experiments carried out with these cladding showed maintenance problems over time, usually cracks in the joints between panels. Checking the properties of materials constituting fiber cement boards, especially the dimensional variation due to changing temperature and humidity, there was an incompatibility between these dimensional variations amplitude and fixing systems and joints used to support them. The thermal shock experimental evaluation proved the influence of these variations on joints deterioration. Based on this observation, and on analyzes of the fiber cement suppliers recommendations over the world, a new system for fixing fiber cement board and joints between them was developed in this work with capacity to adapt to this dimensional variation. Prototypes of these components were made and submitted the thermal shock evaluation, resulting in no visible changes in the joints and on the surfaces of these panels. As a result, it was concluded that the creation of mechanisms that allow accommodating the dimensional variations, both in fixing these panels to the structure, and in the joints finishing can significantly contribute to the vertical building enclosure system durability.