This thesis presents a systematic approach to solving the problem of large deflections in the ZBee vehicle, proposing feasible insert solutions while reducing weight and increasing efficiency were possible.An experimental study was done on the structural deformations of a sample ZBee floor using highly advanced measuring instruments. Based on this background a finite element model was developed which simulates the experiment to a good level of correlation. Modifications were then carried out on the model to examine different factors which affect the stiffness and hence deflections experienced by the driver. Based on a systematic selection of alternative solution an insert analysis was done which gives initial design parameters for a new insert implementation.To improve the manufacturability and hence cost of the Zbee floor, a new floor design with simpler geometry was analyzed and further developed based on the stiffness properties studied on the old chassis. / ZBee är ett trehjuligt fordon utformat för att transportera tre personer inklusive föraren. Det är helt elektriskt och nästan helt byggt med kompositmaterial för att möta behovet av lättvikt och energibesparing.I det här arbetet analyseras och föreslås lösningar för ökad strukturell styvhet och insatslösning i fordonets komposit chassi. En alternativ geometri utformad för att minska komplexiteten och därför förenkla produktionen analyseras också och modifieringar föreslås.Den första steget studerar ett existerande provgolv med hjälp av högspecialiserade mätinstrument. Syftet var att studera deformationerna i strukturen vid en given belastning.Baserat på resultaten från strukturprovningarna utvecklades en finit element modell med motsvarande belastningar och gränsvillkor. Flera iterationer utfördes med varierande material, tjocklekar och struktur modifiering. Resultatet av detta var ett optimalt lösning för ett styvare och lättare fordonschassi.Med hjälp av det befintliga golvet som standard bedömdes alternativa geometrin för styvhet och rekommendationer för en bättre struktur, vilket fortfarande bevarar enkelheten i designen föreslogs.En lokaliserad studie utfördes sedan i framhjuls sektion vilket resulterade i utformningen av en genomförbar insatslösning för fastsättning av kompositstrukturen på framgaffeln och styrsystemet.Slutligen gjordes rekommendationer för ytterligare arbete för att tid och resurser inte kunde möjliggöra fortsatt arbete inom denna exjobb.

This report describes the structural design of a wing for a Vertical Take Off  and Landing drone, in which all the structure will be built by fused deposition modeling of polylactic acid (PLA). To perform this de-sign, the material used is first characterized in different orientations using tensile stress tests, Image Correlation and MATLAB. These properties are then input in a MATLAB program specially developed for this project to obtain the optimum skin and spar thickness in the wing for certain fight conditions. Results are finally verified with a 3D model in CAD and scaled wings in bending tests.

The lighter an object is the easier it is to send into space. This principle is what drives the never ending hunt for lighter structures in the space industry. One way to reduce weight is to replace existing materials with lighter ones. Polymer matrix composites are such materials, as their density is lower than both steel and aluminium. The company RUAG Space produces a payload separating system that operates by clamping the payload using a clamp band to the rocket and releasing the payload by releasing the tension in the band. The current band is made in aluminium but RUAG seeks to build them using carbon fiber reinforced epoxy instead. Earlier projects have shown that carbon fiber fulfills the basic requirements, but has insufficient bearing strength to handle the loads at the bolted joints to the release mechanism. Research suggests that making the individual layers of carbon fiber thinner will increase the bearing strength and so in this project test specimen have been manufactured using thick and thin carbon fiber layers. These specimen were then subjected to bearing loads and the response was observed. The result showed that the ultimate bearing strength only increased a small amount with thin plies, but the onset of damage came at 47% higher stress levels compared to thick plies, suggesting a more brittle behavior. Since the onset of damage is the most important factor for RUAG the use of thin plies produced very positive results and could be a viable solution to increase the bearing strength in the clamp band. / Inom rymdindustrin är vikten på olika komponenter en väldigt viktig egenskap, i och med att det är lättare att skjuta upp en lätt produkt i rymden än en tung. På grund av detta finns det en konstantsträvan inom industrin att bygga lättare uppskjutningsriggar. Ett sätt att minska vikten är att använda lättare konstruktionsmaterial. Polymera fiberkompositer är sådana material, de har mekaniska egenskaper som är ungefär lika bra som hos metaller, men har lägre densitet. RUAG Space tillverkar ett klampförband som håller fast nyttolasten vid det sista raketsteget under en uppskjutning. Detta band är tillverkat i aluminium, men det finns intresse av att tillverka det i kolfiberförstärkt epoxy. Tidigare projekt har visat att kolfiberepoxy uppfyller de globala kraven på styrka och styvhet, men att hålkantsstyrkan är otillräcklig vid de skruvförband som finns i släppmekanismen. Forskning tyder på att hålkantsstyrkan kan ökas för kompositmaterial om de individuella lagren i laminatet görs tunnare. I det här projektet tillverkades laminat av tunna och tjocka kolfiberskikt. Av dessa laminat tillverkades provstavar som sedan blev utsatta för hålkantslast. Resultatet från dessa tester visade att provstavarna med tunna skikt kunde utsättas för 47% högre last än de med tjocka skikt innan skada började uppstå. Med detta resultat drogs slutsatsen att kolfiber med tunna skikt är en möjlig ersättare till aluminium i klampförbandet.

Two different numerical tools were considered, the first one is a seakeeping method developed by KTH Ship Dynamics Research Program. It utilizes strip theory and Lewis forms and is further addressed as SMS. The second one, Nemoh is an open source code utilizing three-dimensional panel method for calculating first order hydrodynamic coefficients in the frequency domain.A comprehensive revision of Nemoh and SMS has been performed on behalf of the KTH Ship Dynamics Research Program. The background to the revision was the high interest in accurately capturing a ships dynamic response. The aim was to explore the prospect of making use of the open source code Nemoh for modelling of added mass and damping in terms of modelling, computational efforts and ship motion prediction improvements. Further, the thesis includes a well-described method on how to operate and pre-process data for Nemoh together with a validation study including results from commercial software´s and experimental studies. An approach with the aim to capture the speed-dependency of the hydrodynamic coefficients together with further potential development of Nemoh is addressed.The validation of Nemoh is showing diverse result. For two cases, the Response Amplitude in Heave is insufficiently modelled. In consequence it’s stated that further studies are required in order to establish whether it’s the case of inadequate input from the authors’ side or lack of robustness in Nemoh that is the cause. The approach to capture speed effects in the hydrodynamic coefficients is proven to be fairly accurate and is considered to be of further use for future development of Nemoh.With respect to identified computational efforts, it’s concluded that Nemoh requires much more computational time than SMS while the accuracy of result is lower. No major improvements may therefore be achieved by substituting or implementing parts of Nemoh into SMS. Nemoh is however of use for the KTH Ship Dynamics Research Program and of other users of Lewis Method when establishing whether a hull-geometry is considered to be “too” unconventional for a two-parameter mapping technique or not. The capability to calculate the RAO in surge is also of interest for KTH Ship Dynamics Research Program since it’s not a feature in SMS.

This Master Thesis is about the assessment of the seakeeping performance of different ships subjected to hull parametric variations. The latest version of the potential flow CFD software Shipflow in combination with a CAD platform (CAESES) have been used to carry out the evaluations. Two ships are studied: a simple one that can be mathematically defined, the Wigley hull, and the KVLCC2, a realistic oil tanker. The software is validated, comparing it to experimental results and other CFD solvers, showing a good agreement with the rest of the data; the mesh dependence studies also show only small variations between the used meshes and finer ones. Then, first the performance in calm water is evaluated for both ships by looking at the wave resistance. With the results of the original hulls as a reference, they are parametrically modified in different ways and evaluated as well to see which trends lead to an improved resistance. With the parametrization applied in the Wigley hull big changes can be appreciated, as the variation in wave resistance due to different parametric modifications ranges between -6% and 14%. For the KVLCC2, two different parametrizations are tested. The first one, focusing mainly on the bulb, produces changes that are generally smaller than for the Wigley hull, especially the ones due to bulb modifications; and the negative effects over the wave resistance due to variations affecting the general shape of the hull are larger than the positive effects. The second parametrization mimics the one used for the Wigley hull, focusing on the general forebody: the results obtained with this approach are very similar to the ones of the Wigley hull, also reaching wave resistance reductions of about a 6%. After that, the evaluation is moved to the ships in regular head waves, where the added resistance due to waves is studied; in a range of wavelengths going from 30% to a 200% of the length of the ship for the Wigley hull, while the study of the KVLCC2 is focused around the wavelength where the resistance is higher, at a 120% of the ship’s length and extending to 100% and 140%. Here the differences of the effect a same parametric variation has over the resistance in calm water and waves are assessed. The results of the Wigley hull show many interesting facts: some of the parametrically modified designs that performed worse in calm water have a consistent better behaviour at the wavelengths analysed; while the best designs in calm water exhibit both large positive and negative added resistance variations depending on the wavelength observed. The first KVLCC2 parametrization approach presents again smaller deviations in resistance, frequently even minor than in calm water; despite that, most of the parametric variations that worked well in calm water display also a reduction of added resistance in waves. On the other hand, the results obtained with the second parametrization of the KVLCC2 show the same trends and behaviour as for the Wigley hull.

This study is evaluating Solid-Acoustic Finite Element modelling as a method for calculating structural vibration response in water. When designing for example vehicles, it is important to avoid vibrational resonance in any part of the structure, as this causes additional noise and reduced lifespan. It is known that vibration response can be affected by the surrounding medium, i.e. water for marine applications.Previous studies show that this effect is both material and geometry dependant why it is hard to apply standardised design rules. An alternative approach is direct calculation using full Fluid Structure Interaction (FSI) by Computational Fluid Dynamics (CFD) and Finite Element Methods (FEM) which is a powerful but slow and computationally costly method.Therefore, there exists a need for a faster and more efficient calculation method to predict how structures subjected to dynamic loads will respond when submerged in water. By modelling water as an acoustic medium, viscous effects are neglected and calculation time can be drastically reduced. Such an approximation is a linearization of the problem and can be suitable when all deformations are assumed to be small and there are no other nonlinear effects present.This study consists of experimental tests where vibrational response was measured for rod shaped test specimens which were suspended in a water filled test rig and excited using an electrodynamic shaker. A Solid-Acoustic Finite Element model of the same experiment was created, and the test and simulation results were compared. The numerical results were shown to agree well with experiments up to 450 Hz. Above 450 Hz differences occur which is probably due to a simplified rig geometry in the numerical model.

Products are increasingly judged by their acoustic performance; and during the last decades, sound quality in general has gained a lot of attention, both from academia and companies. An obstacle in the evaluation of the sound quality is that jury testing is time consuming and require human resources. In an attempt to overcome these limitations, neural networks have been applied in this work with the objective to find a relation between human acoustic perception and a quantity possible to physically measure. For this purpose, 30 of 170 sound samples of interior aircraft noise have been subjectively assessed  during jury testing with 40 participators. With extracted psychoacoustic features from the sound samples and the obtained results from the jury testing, a shallow neural network (SNN) with one hidden layer is trained and tested. The prediction performance of the SNN is compared with another alternative method - multiple linear regression. The evaluation of the remaining un-assessed sound samples is predicted by the trained SNN and implemented in the deep learning neural networks, such as Convolutional Neural Network (CNN) and Recurrent Neural Network (RNN).

One of the main issues of cast-iron block brake material is high noise. Nowadays, train operators tend to change the brake block material from cast-iron to composite material. However, composite block brake materials are likely to produce more wear than cast-iron block brakes, degrading the dynamic behavior of the vehicle on the track. Therefore, comparison of the dynamic behavior and the maintenance cost of each block brake material of the train has been performed. The dynamic behavior is analyzed using GENSYS software and the maintenance cost analysis is done by using the Universal Cost Model developed in the EU project Roll2Rail. The iron ore train that operates in Malmbanan has been used as the simulation model. One-wheel profile before changing the block brake material before 2010 and two-wheel profiles after changing the block brake material after 2010 have been used for simulation. Certain radii, cant, vehicle speeds and wheel-rail friction coefficients has been taken into consideration in the simulations. After that, the wheel and track maintenance costs have been taken into consideration for analyzing the Universal Cost Model. The simulation results show that the wheel profiles after changing the block brake material possess higher risk of RCF than wheel profile before changing the brake block material. The UCM calculation show that the wheel profile after changing brake material leads to higher track maintenance costs, 9.3% higher for new1 and 2.8% higher for new2 wheel profiles, compared to the worn wheel profile before changing brake material. Moreover, The UCM calculation show that the wheel profile after changing brake material leads to higher wheel maintenance costs, 1.04% higher for new1 and 4.3% higher for new2 wheel profiles, compared to the worn wheel profile before changing brake material. The total of maintenance cost also shows that the wheel profile after changing brake material leads to higher maintenance costs, around 2-4%, compared to the worn profile before changing brake material.

Dynamic positioning systems have been under development since the first implementation in the early 1960s. The purpose of a dynamic position system is to allow for automatic positioning of a vessel when circumstances do not allow for mooring or anchoring. Historically the development has been driven forward by the offshore industry, while in recent years such systems have been found useful in other parts of the maritime industry as well. However, very few options exist today for jet driven vessels. One of the main parts of a dynamic positioning system is the control allocation. The purpose of this part is to allocate desired actuation to available actuators. It is often desirable to do this while considering a secondary objective, often energy consumption. One allocation algorithm option is direct allocation, which is considered to be quite a basic solution. More advanced options exist in the literature but implementations of them are still uncommon. An example of a more advanced option, allowing for better tuning, is using model-based allocators. Formulating the allocation problem as a linear quadratic problem and using a linear quadratic regulator is one viable option that has been proven to work well for non-jet driven vessels. A general vessel model is developed and used for simulating and testing different allocators. Furthermore, a method for transforming the allocated actuation into parameters that can control the jet engine is also proposed. This is a necessary step in order to be able to implement the allocation onto a vessel. Comparing the allocation options based on step responses with and without disturbances shows that the linear quadratic regulator preforms better than the direct allocator in almost every way. However, the main drawback of model-based controllers is the needed knowledge about the system. This is something that is not required for the direct allocator and is worth taking into account. / Dynamiska positioneringssystem har vart under utveckling sedan den första implementeringen i början av 1960-talet. Syftet med ett dynamiskt positioneringssystem är att möjliggöra automatisk positionering av ett fartyg när omständigheterna inte tillåter förtöjning eller förankring. Historiskt har utvecklingen drivits framåt av behovet inom offshoreindustrin, men under senare år har systemen visat sig vara användbara även i andra delar av den marina industrin. Idag finns dock få alternativ anpassade för jetdrivna fartyg. En av huvuddelarna i ett dynamiskt positioneringssystem är kraftallokering. Syftet med denna del är att fördela önskad styrkraft till tillgängliga ställdon. Ofta är det önskvärt att göra detta samtidigt som ett sekundärt mål tas hänsyn till, vanligtvis energiförbrukning. Ett alternativ för kraftallokering är en direkt allokeringsalgoritm, detta är en ganska enkel algoritm. Mer avancerade alternativ finns i litteraturen, men implementerade exempel är fortfarande ovanliga. Ett exempel på ett mer avancerat alternativ, som möjliggör bättre anpassning, är att använda modellbaserade algoritmer. Att formulera allokeringsproblemet som ett linjärt kvadratiskt problem och använda en linjär kvadratisk regulator är ett alternativ som har visat sig fungera bra för icke jetdrivna fartyg. En generell fartygsmodell utvecklas och anvnnds för att simulera och testa de olika allokeringsalgoritmerna. Vidare föreslås en metod för att omvandla den allokerade styrkraften till parametrar som kan styra jetmotorerna. Detta är ett nödvändigt steg för att, i slutändan, kunna implementera styrkrafterna på ett riktigt fartyg. En jämförelse av allokeringsalgoritmer baserade på stegsvar med och utan störningar visar att den linjära kvadratiska regulatorn hanterar de uppsatta testfallen bättre än den direkta allokeraren. Däremot dras den modellbaserade algoritmen med det problemet att omfattande kunskapen krävs angående systemets dynamik. Detta är något som inte krävs för direktallokeraren och är värt att ta hänsyn till.

The working environment of a high-speed-craft (HSC) can be uncomfortable and hazardous for the crew and passengers on board. This due to the repeated exposure to high levels of vibration and shocks, that can lead to reduced performance and severe injuries to the back and neck. The most common method to reduce the vibration and shock exposure (to the crew) has been to install passive suspension seats. The passive suspension seats have proved to reduce the vibration and shock exposure to the crew aboard HSC’s, by the measures presented in the international standards SS-ISO 2631-5 and SS-ISO 2631-1. The applicability of these measures towards HSC has been debated for a long time, especially the limit values presented in them for maximum vibration and shock exposure. Also, the limit values that are set are often quickly exceeded despite the use of passive suspension seats. The purpose of this thesis is to investigate the possible improvement of reduction of vibrations and shocks by the use of some sort of actively controlled suspension, and to identify what measures are best suited for comparing passive suspension seats with actively controlled suspension seats. A study is conducted where several different measures are evaluated. The measures aim at capturing vibrations and shock aboard HSC’s, the effect they have on the human body from long time exposure and immediate exposure. A semi-active suspension system is chosen as the most suitable suspension system and is compared to a passive system by using several measures that are best suited for evaluating the risks of injuries associated with shocks and vibrations. The semi-active suspension is simulated using Matlab Simulink, where the control method of continuous skyhook control is used for achieving the most efficient damping. Different mechanical set ups for semi-active damping is investigated in order to obtain limitations for the simulation program. The simulation program has seat base acceleration data as the input, and the seat acceleration, that migrate to the human body, as the output. The seat acceleration data of the semi-active seat is compared to recorded and simulated seat acceleration data of passive seats. The result of the comparison is evaluated with the measures presented in ISO 2631-1, ISO 2631-5, BS 1987, and measures that are currently under development. The results show that a semi-active system is more superior than a passive system, but at the cost of a higher travelling distance. / Arbetsmiljön hos ett höghastighetsfartyg (HSC) kan vara obekväm och farlig för besättningen och passagerarna ombord. Detta beror på den upprepade exponeringen för höga vibrationer och stötar som kan leda till minskad prestanda och kraftiga skador hos rygg och nacke. Den vanligaste metoden för att minska vibration och stöt exponering för besättningen har varit att installera passiva stötdämpande stolar. De passiva stötdämpande stolarna har visat att de minskar vibrations och stötexponeringen för besättningen ombord på HSC, enligt de mätningsmetoder som presenteras i de internationella standarderna SS-ISO 2631-5 och SS-ISO 2631-1. Användbarheten av dessa mätmetoder mot HSC har diskuterats under lång tid, särskilt de gränsvärden som presenteras för den maximala vibration och stötexponering. Gränsvärdena överskrids ofta snabbt även med användning passiva stötdämpande stolar. Syftet med denna rapport är att undersöka en möjlig förbättrad reducering av vibrationer och stötar genom användning av någon form av aktivt kontrollerade stötdämpande stolar och bestämma vilka mätmetoder som är bäst lämpade för att jämföra passiva stötdämpande stolar med aktivt kontrollerade stötdämpande stolar. En studie genomförs där flera olika mätningsmetoder utvärderas. Mätningsmetoderna syftar till att fånga accelerationerna ombord på HSC och effekten på människokroppen till följd av långvarig exponering och omedelbar exponering av vibrationer och stötar. Ett semi-aktivt fjädringssystem väljs som det mest lämpliga fjädringssystemet och jämförs med ett passivt system genom att använda flera mätmetoder som är bäst lämpade för att utvärdera riskerna för skador i samband med stötar och vibrationer. De semi-aktiva stötdämpande stolarna simuleras med Matlab Simulink där kontrollmetoden Skyhook kontroll används för att uppnå den mest effektiva dämpningen. Olika tekniker för halvaktiv dämpning undersöks för att få begränsningar för simuleringsprogrammet. Simuleringsprogrammet har accelerationssignaler som inmatning och de reducerade vibrationerna som utmatning, vilket jämfördes med uppmätta och simulerade data för passiva stötdämpande stolar. Resultatet utvärderas med användning av flera mätvärden presenterade i ISO 2631-1, ISO 2631-5 och mätvärden som är under utveckling. Resultaten visar att det semi-aktiva systemet är mer effektivt än ett passivt system, men till kostnad av att stolen förflyttar sig mera under sjögång.