The aim of my master’s thesis was to create models of the damping device and observing their behavior in interaction with the structure. First was the construction separately modeled with Java application named FyDiK2D like a model with one degree of freedom. Model of construction takes form like a high, thin rod with full circular cross section. The lower part was restrained into the subsoil. The design was to verify the correct functionality of the model by comparing the analytical and numerical solutions. For capturing the precise behavior of the structure was converted to a multi-stage model. Then the pendulum damper was applied on this construction and found amplitude lies in highest point of multi-stage model. He was then replaced by tuned mass damper. By comparing these amplitudes from both dampers was found which kind of damper is efficient for multi-stage model.

The transition from internal combustion engine to battery electric cars is accompanied by a shift on the NVH issues damaging the passenger comfort. The rolling noise generated by the wheels and tyres is in particular characterized by an increasing attention from OEMs and car manufacturers. Among the causes of the rolling noise are the vibrations generated at the wheel, which are transmitted to the vehicle interior through its structure. To limit these vibrations at their source, a new innovative concept has been proposed at Stellantis. This idea is based on the use of a specific type of vibration absorber known by the acronym MTMD (Multiple Tuned Mass Damper).First, the existing literature about vibrations absorbers and optimisation techniques has been reviewed. Then, initial simulations on a global model comprising the wheel and beam-like resonators have shown how this system can effectively reduce a resonant peak.Optimisation processes have then revealed an important attenuation of a wheel resonance, even when the peak frequency is shifted. This demonstrated how important the distribution of resonators resonance frequencies are and their damping ratios when designing a robust and efficient MTMD.Finally, local resonators have been designed and modelled by considering the constraints for an integration on a wheel. A satisfactory design for resonators able to vibrate at the wanted frequency has been found. The beam-like resonators used in the first global model have then been replaced by these real resonators, confirming the possible gain with this device in a vehicle. / Övergången från förbränningsmotorer till batterielektriska bilar åtföljs av en övergång till NVH-frågor som kan påverka passagerarnas komfort. Det rullningsljud som genereras av hjul och däck får i synnerhet ökad uppmärksamhet från OEM:er och biltillverkare.Bland orsakerna till rullningsljudet finns de vibrationer som genereras vid hjulet och som överförs till fordonets inre genom dess struktur. För att begränsa dessa vibrationer vid källan har ett nytt innovativt koncept föreslagits av Stellantis. Idén bygger på användningen av en särskild typ av vibrationsdämpare som kallas MTMD (Multiple Tuned Mass Damper).Först har den befintliga litteraturen om vibrationsdämpare och optimeringstekniker gåtts igenom. Därefter har inledande simuleringar på en global modell som omfattar hjulet och balkliknande resonatorer visat hur detta system effektivt kan minska en resonanstopp.Optimeringsprocesserna har sedan bekräftat att hjulresonansen är kraftigt dämpad, även när toppfrekvensen är förskjuten. Detta visade hur viktig fördelningen av resonansfrekvenser och dämpningsförhållanden för resonatorer är när man utformar en robust och effektiv MTMD.Slutligen har lokala resonatorer utformats och modellerats genom att beakta begränsningarna för en integrering i ett hjul. En tillfredsställande utformning av resonatorer som kan vibrera vid den önskade frekvensen har hittats. De balkliknande resonatorer som användes i den första globala modellen har sedan ersatts av dessa riktiga resonatorer, vilket bekräftar den potentiella förbättringen med denna anordning i ett fordon.

A hydraulic damper plays an important role in tuning the handling and comfort characteristicsof a vehicle. Tuning and selecting a damper based on subjective evaluation, by considering theopinions of various users, would be an inefficient method since the comfort requirements of usersvary a lot. Instead, mathematical models of damper and simulation of these models in variousoperating conditions are preferred to standardize the tuning procedure, quantify the comfortlevels and reduce cost of testing. This would require a model, which is good enough to capture thebehaviour of damper in various operating and extreme conditions.The Force-Velocity (FV) curve is one of the most widely used model of a damper. This curve isimplemented either as an equation or as a look-up table. It is a plot between the maximum forceat each peak velocity point. There are certain dynamic phenomena like hysteresis and dependencyon the displacement of damper, which cannot be captured with a FV curve model, but are requiredfor better understanding of the vehicle behaviour.This thesis was conducted in cooperation with Volvo Cars with an aim to improve the existingdamper model which is a Force-Velocity curve. This work focuses on developing a damper model,which is complex enough to capture the phenomena discussed above and simple enough to beimplemented in real time simulations. Also, the thesis aims to establish a standard method toparameterise the damper model and generate the Force-Velocity curve from the tests performedon the damper test rig. A test matrix which includes the standard tests for parameterising andthe extreme test cases for the validation of the developed model will be developed. The final focusis to implement the damper model in a multi body simulation (MBS) software.The master thesis starts with an introduction, where the background for the project is described and then the thesis goals are set. It is followed by a literature review in which fewadvanced damper models are discussed in brief. Then, a step-by-step process of developing thedamper model is discussed along with few more possible options. Later, the construction of a testmatrix is discussed in detail followed by the parameter identification process. Next, the validationof the developed damper model is discussed using the test data from Volvo Hällered ProvingGround (HPG). After validation, implementation of the model in VI CarRealTime and Adams Caralong with the results are presented. Finally the thesis is concluded and the recommendations forfuture work are made on further improving the model. / En hydraulisk stötdämpare spelar en viktig roll för att fordonets hantering och komfort. Attjustera och välja en stötdämpare baserat på subjektiv utvärdering, genom att beakta olika användares åsikter, skulle vara en ineffektiv metod eftersom användarnas komfortkrav varierarmycket. Istället föredras matematiska modeller av stötdämpare och simulering av dessa modellerunder olika driftsförhållanden för att standardisera inställningsförfarandet, kvantifiera komfortnivåerna och minska testkostnaden. Detta skulle kräva en modell som är tillräckligt bra för attfånga upp stötdämparens beteende under olika drifts- och extrema förhållanden.Force-Velocity (FV) -kurvan är en av de mest använda stötdämparmodellerna. Denna kurvaimplementeras antingen som en ekvation eller som en uppslagstabell. Det är ett diagram somredovisar den maximala kraften vid varje maxhastighetspunkt. Det finns vissa dynamiskafenomen som hysteres och beroende av stötdämparens förskjutning, som inte kan fångas med enFV-kurvmodell, men som krävs för att bättre förstå fordonets beteende.Denna avhandling genomfördes i samarbete med Volvo Cars i syfte att förbättra den befintligastötdämparmodellen som är en Force-Velocity-kurva. Detta arbete fokuserar på att utveckla enstötdämparmodell, som är tillräckligt komplex för att fånga upp de fenomen som diskuteratsovan och tillräckligt enkel för att implementeras i realtidssimuleringar. Avhandlingen syftarockså till att upprätta en standardmetod för att parametrisera spjällmodellen och generera ForceVelocity-kurvan från de test som utförts på stötdämpartestriggen. En testmatris som innehållerstandardtest för parametrisering och extrema testfall för validering av den utvecklade modellenkommer att utvecklas. Det sista fokuset är att implementera stötdämparmodellen i en multi-bodysimulation (MBS) programvara.Examensarbetet inleds med en introduktion, där bakgrunden för projektet beskrivs ochdärefter definieras målen med arbetet. Det följs av en litteraturöversikt där några avanceradestötdämparmodeller diskuteras i korthet. Därefter diskuteras en steg-för-steg-process för attutveckla stötdämparmodeller tillsammans med några fler möjliga alternativ. Senare diskuteraskonstruktionen av en testmatris i detalj följt av parameteridentifieringsprocessen. Därefterdiskuteras valideringen av den utvecklade stötdämparmodellen med hjälp av testdata från VolvoHällered Proving Ground (HPG). Efter validering presenteras implementeringen av modellen iVI CarRealTime och Adams Car tillsammans med resultaten. Slutligen avslutas rapporten medslutsatser från arbetet och rekommendationer för framtida arbete görs för att ytterligare förbättramodellen.

Denna slutrapport beskriver projektarbetet Funktionsbeskrivning av Brandlarms-styrningen av Ventilationssystemet ombord Korvett av Göteborgsklass som beställdes av divisionsingenjören vid 41.korvettdivisionen. Bakgrunden till projektets beställning var att fartygens dokumentation över ventilationssystemets funktion vid brand var bristfällig vilket försvårade underhåll, felsökning och utbildning av och på systemet. Den ofullständiga dokumentationen var ett resultat av att individerna i fartygs­klassen modifierats i flera olika omgångar utan att dokumentationen uppdaterats på ett tillfredsställande sätt. Det hade även framkommit att det fanns olikheter i konfigurationen av fartygsindividernas system. Projektet genomfördes dels genom studier av den befintliga dokumentation som fanns att tillgå ombord och på divisionen, dels genom praktiska under­sökningar ombord på fartygen. Under de praktiska undersökningarna framkom behov av ytterligare utredningar än de som ursprungligen framgick av det erhållna uppdraget. Projektet påvisade skillnader mellan fartygens system, vissa förmodat felaktiga styr­ningar av fläktar och spjäll samt fastställde att dokumentationen var bristfällig. Projektet resulterade i ett antal beskrivande dokument som sammanställdes i en pärm för respektive fartyg. Dessa uppfyller det givna uppdraget och målen med projektet. En större modifiering av fartygen i klassen med syfte att förlänga deras operativa livslängd är under planeringsstadiet. Under modifieringen skall bland annat fartygens dokumen­tation uppdateras, något som resultaten från detta projekt kommer underlätta. / This is the final report regarding the project A Functional Description of the Fire Alarm Con­trol in the Ventilation System aboard the Swedish Navy’s Gothenburg-class Corvettes, wh­­ich was commissioned by the Senior Marine Engineer Officer of the 41st Corvette Sq­­ua­d­ron of the 4th Naval Warfare Flotilla. The reason for the commission was that the set of documentation concerning the function of the ventilation system in case of a fire was insufficient. This caused problems, both during maintenance work done to en­­­su­re that the system was operating in accordance with the design parameters, as well as when trouble-shooting the system. The insufficient set of documentation was a result of a number of upgrades done to the ships over the ye­ars without any corr­e­s­p­on­ding up­date of the documentation. During the project it has also been made clear that there were non-documented differences existing be­­tween the ships in the class. The project was fulfilled by a combination of studies of the existing set of do­cumen­tation and practical surveys aboard the ships. During the surveys, more short­comings in the existing set of documentation became evident. The project demonstrated differences between the individual ships, assumed inaccuracies in the control of fans and dampers and determined the shortage in the set of documentation. The project has resulted in a number of describing documents that are collected in one unique file for each ship. These documents fulfil the commission and the objectives of the project. A major upgrade of the ships in the class with the purpose of extending their operational lifetime is now being planned. The ships’ set of documentation will be simultaneously updated, a task that will be simplified with the support of the results of this project.

A study on shape memory alloy materials as vibration dampers is reported. An important component is the strain rate-dependent and temperature-dependent constitutive behavior of shape memory alloy, which can significantly change its energy dissipation capacity under cyclic loading. The constitutive model used accounts for the thermo-mechanical strain rate-dependent behavior and phase transformation. With increasing structural flexibility, the hysteretic loop size of shape memory alloy dampers increases due to increasing strain rates, thus further decreasing the response of the structure to cyclic excitation. The structure examined is a beam, and its behavior with shape memory alloy dampers is compared to the same beam with conventional dampers. Parametric studies reveal the superior performance of the shape memory alloy over the conventional dampers even at the resonance frequency of the beam-damper system. An important behavior of the shape memory alloy dampers is discovered, in that they absorb energy from the fundamental and higher vibration modes. In contrast, the conventional dampers transfer energy to higher modes. For the same beam control, the stiffness requirement for the shape memory alloy dampers is significantly less than that of the conventional dampers. Response quantities of interest show improved performance of the shape memory alloy over the conventional dampers under varying excitation intensity, frequency, temperature, and strain rate.

Aero-engine assemblies are complex structures typically involving two or three nested rotors mounted within a flexible casing via squeeze-film damper (SFD) bearings. The deployment of SFDs into such structures is highly cost-effective but requires careful calculation since they can be highly nonlinear in their performance, particularly if they are unsupported (i.e. without a retainer spring). The direct study of whole-engine models with nonlinear bearings has been severely limited by the fact that current nonlinear computational techniques are not well-suited for complex large-order systems. The main contributions of this thesis are: • A procedure for unbalance response computation, suitable for generic whole-engine models with nonlinear bearings, which significantly extends the capability of current finite element packages. This comprises two novel nonlinear computational techniques: an implicit time domain integator referred to as the Impulsive Receptance Method (IRM) that enables rapid computation in the time domain; a whole-engine Receptance Harmonic Balance Method (RHBM) for rapid calculation of the periodic response in the frequency domain. Both methods use modal data calculated from a one-off analysis of the linear part of the engine at zero speed.• First-ever analyses on real twin-spool and three-spool engines. These studies illustrate the practical use of these solvers, provide an insight into the nonlinear dynamics of whole-engines and correlate with a limited amount of industrial experimental data. Both IRM and RHBM are directly formulated in terms of the relative response at the terminals of the nonlinear bearings. This makes them practically immune to the number of modes that need to be included, which runs into several hundreds for a typical engine. The two solvers are extensively tested on two/three-shaft engine models (with 5-6 SFDs) provided by a leading engine manufacturer using an SFD model that is used in industry. The tests show the IRM to be many times faster than an established robust conventional implicit integrator while achieving a similar level of accuracy. It is also shown to be more reliable than another popular implicit algorithm. The RHBM enables, for the first time, the frequency domain computation of the nonlinear response of whole-engine models. Its use is illustrated for both Single-Frequency Unbalance (SFU) excitation (unbalance confined to only one shaft) and Multi-Frequency Unbalance (MFU) excitation (unbalance located on two or more shafts, rotating at different speeds). Excellent correlation is demonstrated between RHBM and IRM.The parametric studies compare and contrast the frequency spectra for SFU and MFU cases. They also reveal the varying degree of lift at the unsupported SFDs. The sensitivity of the response to end-sealing and bearing housing alignment is also illustrated. It is demonstrated that the use of suitably preloaded vertically oriented “bump-springs” at the SFDs of heavy rotors produces a significant improvement in journal lift. It is also shown that the consideration of a slight amount of distributed damping in the structure significantly affects the predicted casing vibration levels, bringing them closer to measured levels, while having little effect on the SFD orbits.

Este trabalho aborda a aplicação de uma máquina elétrica síncrona do tipo tubular linear de ímãs permanentes em um sistema de suspensão semiativa. O uso de amortecedores eletromagnéticos lineares em sistemas de suspensão não é uma ideia nova, mas a maioria dos trabalhos publicados sobre este assunto concebem soluções ativas e negligenciam as semiativas, sobretudo com estudos experimentais. Nesta pesquisa é discutido um modelo dinâmico eletromecânico acoplado de um sistema de suspensão semiativa, considerando um amortecedor eletromagnético linear e também apresentando dados experimentais. Leis da mecânica clássica e do eletromagnetismo são aplicadas para descrever o sistema que combina teoria de vibrações e máquinas elétricas. Um modelo virtual com vários subsistemas foi implementado no ambiente MATLABR /Simulink/Simscape para associar equações e simular o desempenho global. Para o caso passivo, os resultados numéricos e experimentais validam os parâmetros e confirmam a funcionalidade do sistema e a metodologia proposta. Simulações e testes experimentais para o caso semiativo são consistentes, mostrando uma melhoria na transmissibilidade de deslocamento, em relação ao modo passivo, e a possibilidade de regeneração de energia. / This work addresses the application of a tubular linear permanent magnet synchronous machine working as a damper for a semi-active suspension system. The use of linear electromagnetic dampers in suspension systems is not a new idea. However, most published papers on this subject outline active solutions and neglect semi-active ones, above all, with experimental studies. Here a dynamic mechanicalelectromagnetic coupled model for a semi-active suspension system is reported. This is in conjunction with a linear electromagnetic damper and also presents experimental data. Classical laws of mechanics and electromagnetics are applied to describe a dynamic model combining vibration and electrical machines theories. A multifaceted MATLABR /Simulink/Simscape model was implemented to incorporate equations and simulate global performance. For the passive case, numerical and experimental results validate the parameters and confirm system function and the proposed methodology. Simulation and practical results for the semi-active case are consistent, showing an improvement in the displacement transmissibility and the possibility of energy regeneration.

<p>Denna slutrapport beskriver projektarbetet <em>Funktionsbeskrivning av Brandlarms-styrningen av Ventilationssystemet ombord Korvett av Göteborgsklass</em> som beställdes av divisionsingenjören vid 41.korvettdivisionen. Bakgrunden till projektets beställning var att fartygens dokumentation över ventilationssystemets funktion vid brand var bristfällig vilket försvårade underhåll, felsökning och utbildning av och på systemet. Den ofullständiga dokumentationen var ett resultat av att individerna i fartygs­klassen modifierats i flera olika omgångar utan att dokumentationen uppdaterats på ett tillfredsställande sätt. Det hade även framkommit att det fanns olikheter i konfigurationen av fartygsindividernas system.</p><p>Projektet genomfördes dels genom studier av den befintliga dokumentation som fanns att tillgå ombord och på divisionen, dels genom praktiska under­sökningar ombord på fartygen. Under de praktiska undersökningarna framkom behov av ytterligare utredningar än de som ursprungligen framgick av det erhållna uppdraget.</p><p>Projektet påvisade skillnader mellan fartygens system, vissa förmodat felaktiga styr­ningar av fläktar och spjäll samt fastställde att dokumentationen var bristfällig. Projektet resulterade i ett antal beskrivande dokument som sammanställdes i en pärm för respektive fartyg. Dessa uppfyller det givna uppdraget och målen med projektet.</p><p>En större modifiering av fartygen i klassen med syfte att förlänga deras operativa livslängd är under planeringsstadiet. Under modifieringen skall bland annat fartygens dokumen­tation uppdateras, något som resultaten från detta projekt kommer underlätta.</p> / <p>This is the final report regarding the project <em>A Functional Description of the Fire Alarm Con­trol in the Ventilation System aboard the Swedish Navy’s Gothenburg-class Corvettes,</em> wh­­ich was commissioned by the Senior Marine Engineer Officer of the 41st Corvette Sq­­ua­d­ron of the 4th Naval Warfare Flotilla. The reason for the commission was that the set of documentation concerning the function of the ventilation system in case of a fire was insufficient. This caused problems, both during maintenance work done to en­­­su­re that the system was operating in accordance with the design parameters, as well as when trouble-shooting the system. The insufficient set of documentation was a result of a number of upgrades done to the ships over the ye­ars without any corr­e­s­p­on­ding up­date of the documentation. During the project it has also been made clear that there were non-documented differences existing be­­tween the ships in the class.</p><p>The project was fulfilled by a combination of studies of the existing set of do­cumen­tation and practical surveys aboard the ships. During the surveys, more short­comings in the existing set of documentation became evident.</p><p>The project demonstrated differences between the individual ships, assumed inaccuracies in the control of fans and dampers and determined the shortage in the set of documentation. The project has resulted in a number of describing documents that are collected in one unique file for each ship. These documents fulfil the commission and the objectives of the project.</p><p>A major upgrade of the ships in the class with the purpose of extending their operational lifetime is now being planned. The ships’ set of documentation will be simultaneously updated, a task that will be simplified with the support of the results of this project.</p>

Automotive engine mounts are used to support engine weight, protect engine from road inputs and isolate transmission of vibrations created by the engine, which has a drastic effect on the noise generated inside the passenger cabin. Most common types of engine mounts are elastomeric and hydraulic mounts, the former having better vibration isolation characteristics whereas the latter displays better shock isolation. Elastomeric mounts are widely used for their low initial cost, while hydraulic mounts with inertia track and decoupler are chosen for their good vibration isolation and shock excitation characteristics. However, hydraulic mounts with inertia track and decoupler are not appropriate for small segment and commercial vehicles due their high initial cost. In this thesis, the effect of the addition of a dry friction damper on the performance of elastomeric automobile engine mounts is investigated. Friction dampers are used to attenuate vibration amplitudes in many applications such as gas turbine engines, railway vehicles, space structures and civil buildings. In this study, a friction element is added to the engine mount at its axial direction and its effect is studied. Results show that, the addition of dry friction damping to the original system increases vibration isolation performance significantly at low frequencies / whereas, due to the increased stiffness of the system, at high frequencies dry friction damper has a mitigating effect on performance. In order to overcome this problem, original system parameters are modified. In the modified system a softer mount that increase vibration isolation performance at high frequencies / but, which might cause excessive static deflection due to reduced stiffness of the system is used. On the other hand, addition of dry friction damping prevents excessive static deflections due to the increased stiffness effect and also increases the performance at high frequencies due to the soft mount. Final results showed that vibration isolation performance at low frequencies increases considerably while vibration isolation performance at high frequency is similar and even slightly better than the original system with addition of dry friction damping.

The traveling wave ultrasonic motor is considered for use in haptic devices where a certain input-output relation is desired between the applied force and the resulting motion. Historically, DC motors have been the standard choice for this purpose. Owing to its unique characteristics, the ultrasonic motors have been considered an attractive alternative. However, there are some limitations when using the ultrasonic motor for force-feedback applications. In particular, direct torque control is difficult, and the motor can only supply torque in the direction of motion. To accommodate these limitations we developed an indirect control approach. The experimental results demonstrate that the model reference control method was able to approximate a second order spring-damper system.