Platinautvinning är antagligen en av the farligaste gruvindustrierna. På följd av det har gruvmaskiner som Slotborer utvecklats för att göra utvinningsprocessen säkrare. Slotborern är ett ganska nytt koncept och har problem med vibrationer i borrsträngen när den blir längre.Den här rapporten föreslår fyra koncept för att dämpa/stabilisera dessa vibrationer och ett av dessa koncept var sedan vidare utvecklat efter en evaluering. Det koncept som vidareutvecklats använder sig av massdämpare för att dämpa/stabilisera borrsträngen. Massdämparna är justerbara vilket gör dem effektiva över ett större frekvensområde. Några mätvärden från riktiga borrningar var analyserade och analytiska och matematiska modeller var utvecklade att ha ett liknande beteende som det från mätningarna. Modellerna var sedan utvidgade och massdämparna var implementerade in i modellerna för att analysera deras effekt på systemet. När de analytiska modellerna för massdämparna vara klara nog, började konstruktions- och dimensioneringsarbetet av projektet. Dämparen/stabilisatorn var från början konstruerad för att direkt dämpa vibrationer på 2 – 5 Hz, men på grund av väldigt höga spänningar i massdämparna var frekvensspannet ändrat till 3,5 – 6-7 Hz. Ingen verifiering genom empiriska studier var gjorda men några bra analytiska resultat åstadkoms. / Platinum excavation is probably one of the most dangerous mining businesses. Because of that machines like the Slotborer has been developed to make the excavation process much safer. The Slotborer is a pretty new concept and has problems with oscillations in the drill string when it gets extended.This paper suggests four concepts for dampening/stabilizing these oscillations and one of these concepts was then further developed after an evaluation. The further developed concept uses mass dampers to dampen/stabilize the drill string. The mass dampers are adjustable making them effective for a wider range of frequencies. Some measurements from actual drilling operations was analyzed and analytical and mathematical models were developed to have a similar behavior of that from the measurements. The models was then extended and the mass dampers was applied into the models to analyze their impact of the system. When the analytical models for the mass dampers where done enough, the construction and dimensioning of the project took place. The damper/stabilizer was initially design to directly dampen oscillations between 2 – 5 Hz, but due to very high stresses in the mass dampers the dampening frequency span was changed to 3,5 – 6,7 Hz. No verification through empirical studies was made but some good analytical results of damping was achieved.

The aim of this thesis is to design crankshaft for in-line six-cylinder diesel engine and to design viscous torsional vibration damper for the cranktrain of specified parameters. The thesis includes the creation of a dynamic torsional model of cranktrain and calculation of forced vibrations of mechanism with and without damper. Part of this thesis is also strength analysis of the designed crankshaft with damper using the Finite Element Method (FEM).

<p>Detta examensarbete handlar om utveckling och konstruktion av ett spjäll och spjällblad till en plattvärmeväxlare som ingår i Fläkt Woods AB:s produktsortiment.</p><p>Bakgrunden till utvecklingen berodde på två problem med det nuvarande spjället. Ett problem var att det fanns vissa hygienproblem med befintlig konstruktion som behövde rättas till och ersättas mot en bättre lösning. Detta för att produkten ska kunna certifieras enligt normen VDI 6022. Det andra problemet var att den befintliga konstruktionen kändes gammal och behövde förbättras.</p><p>Examensarbetet omfattar två stycken huvuddelar/mål. Den första delen är att finna ett material för att kunna täta i spjället på ett effektivt sätt. På grund av konflikt mellan låg friktion och bra tätning genomfördes en stor materialundersökning och en lista på tänkbara material togs fram och analyserades. Olika typer av behandling har även stötts på för att minska friktionen ännu mer. De material som var mest intressanta var gummi och andra elastomerer. Nitrilgummi, behandlad EPDM-gummi och behandlat SBR-gummi uppfyllde de önskade kraven bäst. De olika behandlingsmetoderna är bland annat lackering med speciallack och klorering av materialet.</p><p>Den andra delen är konstruktionsdelen. Här presenteras ett flertal olika produktidéer på spjäll och spjällblad som har tagits fram. Idéerna är framtagna genom tillämpning av flera verktyg och metoder för produktutveckling som till exempel TIPS/TRIZ och QFD. Patentsökning, benchmarking och en simulering av bladens utböjning är några ingående delar på vägen till den slutliga produkten.</p><p>Resultatet blev tre produkter som ska fungera som förslag till Fläkt Woods AB. Produkterna skiljer sig från varandra i både konstruktion, tillverkningsmetod och kostnad för att erbjuda flera möjligheter. Den första idén bygger på att två plåtar bockas och fliknitas ihop, vilket ger en stabil och robust konstruktion. Den andra idén innehåller formade profiler av stålplåt, som tillverkas genom rullformning. Metoden ger dem en lämplig form och enkel hantering, till exempel väger de inte så mycket. Den tredje idén skall tillverkas av strängpressad aluminium, är gjord i ett stycke och innehåller flera gynnsamma funktioner. Bland annat så finns det förstärkningar integrerade, ett spår för en axel samt spår för gummilister.</p> / <p>This thesis work concerns a development of a damper and damper blades for a plate heat exchanger. The plate heat exchanger is included in Fläkt Woods AB’s product programme.</p><p>The background for this development was caused by two problems with the existing damper. One of the problems was that it had some problems with the hygiene. This needed to be corrected and the product needed to be replaced with a better solution, allowing it to be certified according to VDI 6022. The second problem was that the design felt rather old and it needed to be improved.</p><p>The thesis work is divided into two main parts/main goals. The first of them is to find a material to seal the product in an effective way. Because there is a conflict regarding low friction and a good sealing there was a large material investigation done and a list of possible materials was done and analysed. Different types of treatments were also found to reduce the friction. The type of materials that was most interesting was rubber and elastomers. Nitrile rubber, treated EPDM rubber and treated SBR rubber was the ones to fulfil the wanted requirements in the best way. The different types of treating a rubber material are among other things, painting the material with a special type of lacquer or chlorination of the rubber.</p><p>The second part of the thesis work is about the design. Several product ideas on dampers and damper blades will here be presented. These were developed by applying tools and methods for product development, like TIPS/TRIZ and QFD. Searching for patents, benchmarking of competing products and a simulation of the blades bending are some of the parts on the way to find the final product.</p><p>The result of this is three products, which will work as suggestions to Fläkt Woods AB. The products differs both in design, way of manufacture and in cost to offer many options. The first idea has a design of two metal sheets which is bended and joined together. This is a stable and robust design. The second idea contains forming sheets of steel which is then made into profiles. This is made in the method of roll forming. This gives the product an appropriate shape and the product is easy to handle. The third idea is made in the method of aluminium extrusion. It is made in one piece and contains several functions. Among other things, it has integrated reinforcement, a hole for the axle and two holes for rubber profiles (sealing).</p>

Current seismic design practice promotes inelastic response in order to reduce the design forces. By allowing the structure to yield while increasing the ductility of the structure, the global forces can be kept within the limited bounds dictated by the yield strength. However, during severe earthquakes, the structures undergo significant inelastic deformations leading to stiffness and strength degradation, increased interstory drifts, and damage with residual drift. The research presented in this thesis has three components that seek to address these challenges. To prevent the inelastic effects observed in yielding systems, a new concept “apparent weakening” is proposed and verified through shake table studies in this thesis. “Apparent weakening” is introduced in the structural system using a complementary “adaptive negative stiffness device” (NSD) that mimics "yielding” of the global system thus attracting it away from the main structural system. Unlike the concept of weakening and damping, where the main structural system strength is reduced, the new system does not alter the original structural system, but produces effects compatible with an early yielding. Response reduction using NSD is achieved in a two step sequence. First the NSD, which is capable of exhibiting nonlinear elastic stiffness, is developed based on the properties of the structure. This NSD is added to the structure resulting in reduction of the stiffness of the structure and NSD assembly or “apparent weakening”-thereby resulting in the reduction of the base shear of the assembly. Then a passive damper, designed for the assembly to reduce the displacements that are caused due to the “apparent weakening”, is added to the structure-thereby reducing the base shear, acceleration and displacement in a two step process. The primary focus of this thesis is to analyze and experimentally verify the response reduction attributes of NSD in (a) elastic structural systems (b) yielding systems and (3) multistory structures. Experimental studies on 1:3 scale three-story frame structure have confirmed that consistent reductions in displacements, accelerations and base shear can be achieved in an elastic structure and bilinear inelastic structure by adding the NSD and viscous fluid damper. It has also been demonstrated that the stiffening in NSD will prevent the structure from collapsing. Analogous to the inelastic design, the acceleration and base shear and deformation of the structure and NSD assembly can be reduced by more than 20% for moderate ground motions and the collapse of structure can be prevented for severe ground motions. Simulation studies have been carried on an inelastic multistoried shear building to demonstrate the effectiveness of placing NSDs and dampers at multiple locations along the height of the building; referred to as “distributed isolation”. The results reported in this study have demonstrated that by placing a NSD in a particular story the superstructure above that story can be isolated from the effects of ground motion. Since the NSDs in the bottom floors will undergo large deformations, a generalized scheme to incorporate NSDs with different force deformation behavior in each storey is proposed. The properties of NSD are varied to minimize the localized inter-story deformation and distribute it evenly along the height of the building. Additionally, two semi-active approaches have also been proposed to improve the performance of NSD in yielding structures and also adapt to varying structure properties in real time. The second component of this thesis deals with development of a novel device to control the response of structural system using adaptive length pendulum smart tuned mass damper (ALP-STMD). A mechanism to achieve the variable pendulum length is developed using shape memory alloy wire actuator. ALP-STMD acts as a vibration absorber and since the length is tuned to match the instantaneous frequency, using a STFT algorithm, all the vibrations pertaining to the dominant frequency are absorbed. ALP-STMD is capable of absorbing all the energy pertaining to the tuned-frequency of the system; the performance is experimentally verified for forced vibration (stationary and non-stationary) and free vibration. The third component of this thesis covers the development of an adaptive control algorithm to compensate hysteresis in hysteretic systems. Hysteretic system with variable stiffness hysteresis is represented as a quasi-linear parameter varying (LPV) system and a gain scheduled controller is designed for the quasi-LPV system using linear matrix inequalities approach. Designed controller is scheduled based on two parameters: linear time-varying stiffness (slow varying parameter) and the stiffness of friction hysteresis (fast varying parameter). The effectiveness of the proposed controller is demonstrated through numerical studies by comparing the proposed controller with fixed robust H∞ controller. Superior tracking performance of the LPV-GS over the robust H∞ controller in different displacement ranges and various stiffness switching cases is clearly evident from the results presented in this thesis. The LPV-GS controller is capable of adapting to the parameter changes and is effective over the entire range of parameter variations.

Detta examensarbete handlar om utveckling och konstruktion av ett spjäll och spjällblad till en plattvärmeväxlare som ingår i Fläkt Woods AB:s produktsortiment. Bakgrunden till utvecklingen berodde på två problem med det nuvarande spjället. Ett problem var att det fanns vissa hygienproblem med befintlig konstruktion som behövde rättas till och ersättas mot en bättre lösning. Detta för att produkten ska kunna certifieras enligt normen VDI 6022. Det andra problemet var att den befintliga konstruktionen kändes gammal och behövde förbättras. Examensarbetet omfattar två stycken huvuddelar/mål. Den första delen är att finna ett material för att kunna täta i spjället på ett effektivt sätt. På grund av konflikt mellan låg friktion och bra tätning genomfördes en stor materialundersökning och en lista på tänkbara material togs fram och analyserades. Olika typer av behandling har även stötts på för att minska friktionen ännu mer. De material som var mest intressanta var gummi och andra elastomerer. Nitrilgummi, behandlad EPDM-gummi och behandlat SBR-gummi uppfyllde de önskade kraven bäst. De olika behandlingsmetoderna är bland annat lackering med speciallack och klorering av materialet. Den andra delen är konstruktionsdelen. Här presenteras ett flertal olika produktidéer på spjäll och spjällblad som har tagits fram. Idéerna är framtagna genom tillämpning av flera verktyg och metoder för produktutveckling som till exempel TIPS/TRIZ och QFD. Patentsökning, benchmarking och en simulering av bladens utböjning är några ingående delar på vägen till den slutliga produkten. Resultatet blev tre produkter som ska fungera som förslag till Fläkt Woods AB. Produkterna skiljer sig från varandra i både konstruktion, tillverkningsmetod och kostnad för att erbjuda flera möjligheter. Den första idén bygger på att två plåtar bockas och fliknitas ihop, vilket ger en stabil och robust konstruktion. Den andra idén innehåller formade profiler av stålplåt, som tillverkas genom rullformning. Metoden ger dem en lämplig form och enkel hantering, till exempel väger de inte så mycket. Den tredje idén skall tillverkas av strängpressad aluminium, är gjord i ett stycke och innehåller flera gynnsamma funktioner. Bland annat så finns det förstärkningar integrerade, ett spår för en axel samt spår för gummilister. / This thesis work concerns a development of a damper and damper blades for a plate heat exchanger. The plate heat exchanger is included in Fläkt Woods AB’s product programme. The background for this development was caused by two problems with the existing damper. One of the problems was that it had some problems with the hygiene. This needed to be corrected and the product needed to be replaced with a better solution, allowing it to be certified according to VDI 6022. The second problem was that the design felt rather old and it needed to be improved. The thesis work is divided into two main parts/main goals. The first of them is to find a material to seal the product in an effective way. Because there is a conflict regarding low friction and a good sealing there was a large material investigation done and a list of possible materials was done and analysed. Different types of treatments were also found to reduce the friction. The type of materials that was most interesting was rubber and elastomers. Nitrile rubber, treated EPDM rubber and treated SBR rubber was the ones to fulfil the wanted requirements in the best way. The different types of treating a rubber material are among other things, painting the material with a special type of lacquer or chlorination of the rubber. The second part of the thesis work is about the design. Several product ideas on dampers and damper blades will here be presented. These were developed by applying tools and methods for product development, like TIPS/TRIZ and QFD. Searching for patents, benchmarking of competing products and a simulation of the blades bending are some of the parts on the way to find the final product. The result of this is three products, which will work as suggestions to Fläkt Woods AB. The products differs both in design, way of manufacture and in cost to offer many options. The first idea has a design of two metal sheets which is bended and joined together. This is a stable and robust design. The second idea contains forming sheets of steel which is then made into profiles. This is made in the method of roll forming. This gives the product an appropriate shape and the product is easy to handle. The third idea is made in the method of aluminium extrusion. It is made in one piece and contains several functions. Among other things, it has integrated reinforcement, a hole for the axle and two holes for rubber profiles (sealing).

[pt] No presente trabalho estuda-se a aplicação do controle estrutural na proteção de estruturas submetidas a carregamentos dinâmicos contra níveis de vibração indesejáveis que possam causar desconforto e, até mesmo, comprometer a segurança e integridade da edificação. Os três tipos de controle estrutural, passivo, ativo e híbrido, são analisados de forma a evidenciar as vantagens do uso do controle híbrido. O mecanismo de controle utilizado é o denominado amortecedor de massa sintonizado (AMS), devido à sua vasta aplicação na Engenharia Civil, tendo uma grande quantidade sido instalada em edifícios, pontes e chaminés industriais para controle de vibrações causadas pelo vento. Verifica-se a influência da não- linearidade da rigidez do AMS no comportamento do sistema principal. A utilização de amortecedores de massa sintonizados múltiplos é também estudada como uma forma de vencer certas limitações quanto à robustez deste tipo de sistema e melhorar sua performance. Analisa-se por fim o comportamento e eficiência do amortecedor de massa híbrido (AMH), em relação ao AMS passivo. Para cálculo da força de controle são utilizados os seguintes algoritmos: controle ótimo linear clássico, controle ótimo instantâneo e controle ótimo não-linear. Uma estratégia para definição das matrizes de ponderação, utilizadas no algoritmo de controle ótimo instantâneo, que minimizem a amplitude da resposta harmônica permanente é apresentada. Exemplos numéricos são apresentados ao longo de todo o trabalho. Verifica-se que a utilização do controle híbrido é mais eficiente que os controles passivo e ativo isolados, requerendo forças de magnitude inferiores, o que reduz bastante o custo deste tipo de sistema. O sistema de controle híbrido se mostrou eficiente na redução de vibrações causadas por carregamentos cujas freqüências eram diversas das consideradas no projeto do sistema de controle passivo. Verificou-se, ainda que o mesmo se comportou de forma satisfatória no caso de discrepância na freqüência natural da estrutura. / [en] In this work the use of structural control is studied to protect dynamically loaded building structures against undesirable vibration levels, which can cause human discomfort and, even more, compromise the building safety and integrity. The three types of structural control, passive, ative and hybrid, are analysed to show the advantages of hybrid control in reducing undesirable vibration levels. The chosen control mechanism is the so called tuned mass damper (TMD), due to its large application in Civil Engineering, having a great number of these devices been installed in buildings, bridges and industrial chimneys to control structural vibrations induced by wind loads. It is also verified the influence of TMD non linear stiffness on the main system behaviour. The use of multiple tuned mass dampers is studied as a possible way of improving the TMD robustness and performance. The hybrid mass damper (HMD) behaviour and efficiency comparing to the passive mass damper is analysed in detail. To calculate the control force the following control algorithms are used: classical optimum linear control, instantaneous optimum control and non-linear optimum control. A strategy to define the weighting matrices used in the instantaneous optimum control algorithm that minimizes the harmonic response amplitude is presented. Several numerical examples are presented aalong the work. The results show that the hybrid control is more efficient that the passive or active control used separately, requiring smaller forces reducing in this way the cost of the control system. The hybrid control system showed to be more efficient in reducing vibrations caused by loadings which had different frequencies from that considered on the passive control design. Moreover it was shown that hybrid control has a satisfactory perfomance when discrepancies in natural frequency occur.

Magnetorheological (MR) dampers are adaptive devices whose properties can be adjusted through the application of a controlled voltage signal. A semi-active suspension system incorporating MR dampers combines the advantages of both active and passive suspensions. For this reason, there has been a continuous effort to develop control algorithms for MR-damped vehicle suspension systems to meet the requirements of the automotive industry. The overall aims of this thesis are twofold: (i) The investigation of non-parametric techniques for the identification of the nonlinear dynamics of an MR damper. (ii) The implementation of these techniques in the investigation of MR damper control of a vehicle suspension system that makes minimal use of sensors, thereby reducing the implementation cost and increasing system reliability. The novel contributions of this thesis can be listed as follows: 1- Nonparametric identification modelling of an MR damper using Chebyshev polynomials to identify the damping force from both simulated and experimental data. 2- The neural network identification of both the direct and inverse dynamics of an MR damper through an experimental procedure. 3- The experimental evaluation of a neural network MR damper controller relative to previously proposed controllers. 4- The application of the neural-based damper controller trained through experimental data to a semi-active vehicle suspension system. 5- The development and evaluation of an improved control strategy for a semi-active car seat suspension system using an MR damper. Simulated and experimental validation data tests show that Chebyshev polynomials can be used to identify the damper force as an approximate function of the displacement, velocity and input voltage. Feed-forward and recurrent neural networks are used to model both the direct and inverse dynamics of MR dampers. It is shown that these neural networks are superior to Chebyshev polynomials and can reliably represent both the direct and inverse dynamic behaviours of MR dampers. The neural network models are shown to be reasonably robust against significant temperature variation. Experimental tests show that an MR damper controller based a recurrent neural network (RNN) model of its inverse dynamics is superior to conventional controllers in achieving a desired damping force, apart from being more cost-effective. This is confirmed by introducing such a controller into a semi-active suspension, in conjunction with an overall system controller based on the sliding mode control algorithm. Control performance criteria are evaluated in the time and frequency domains in order to quantify the suspension effectiveness under bump and random road excitations. A study using the modified Bouc-Wen model for the MR damper, and another study using an actual damper fitted in a hardware-in-the-loop- simulation (HILS), both show that the inverse RNN damper controller potentially gives significantly superior ride comfort and vehicle stability. It is also shown that a similar control strategy is highly effective when used for a semi-active car seat suspension system incorporating an MR damper.

In recent years, an increase to design slender and aesthetically-pleasing structures have resulted in some structures having a low natural frequency. This is because the design calculation did not meet the requirement of serviceability performance. Structures can experience excessive vibrations when they are subjected to different types of dynamic loading. A device can be installed to prevent these vibrations.In this thesis, we study the response of buildings and lateral vibrations of footbridges equipped with Tuned Liquid Damper. The aim is to mitigate the first mode of vibration. Tuned Liquid Damper consists of a container in rectangular, cylindrical or arbitrary shape partially filled with shallow liquid, most often water is used as a regulating device system. The design properties of Tuned Liquid Damper is introduced and it is based on the analogyof the most popular damper, Tuned Mass Damper.An experimental study of a building frame model with four floors is conducted to validate the numerical results obtained from the simulation of the model in ANSYS. The linear and non-linear analysis are performed through a system coupling between Ansys mechanical and Fluent solver. The simulation results obtained are in good agreement with the experimental results.A parametric study is conducted with a simply supported steel footbridge. It is a 45 m long span with 3 m width and the flexural rigidity is modified to get the lateral vibration mode. The first lateral natural frequency obtained is 0.713 Hz. The load case for the study considered is according to Sétra guide. The variable parameters studied is the Tuned Liquid Damper water mass ratios: 0.7%, 1.0%, 2.0%, 3.0% and 4.0%. The results show a satisfactory performance of the footbridge model equipped with Tuned Liquid Damper. The accelerations are below 0.1 m/s2 which satisfied the requirement of 0.15 m/s2.

No description available.

Since their invention in the early 1900s, Tuned Vibration Absorbers (TVAs) have shown to be effective in suppressing vibrations of machines and structures. A vibration absorber is a vibratory subsystem attached to a primary system. It normally consists of a mass, a spring, and a damper. Mounted to the primary system, a TVA counteracts the motions of the primary system, "absorbing" the primary structure's vibrations. A conventional passive TVA, however, is only effective when it is tuned properly, hence, the name "tuned" vibration absorber. In many practical applications, inevitable off-tuning (or mistuning) of a TVA occurs because of the system's operating conditions or parameter changes over time. For example, the mass in a building floor could change by moving furnishings, people gathering, etc., which can "off-tune" TVAs. When TVAs are off-tuned, their effectiveness is sharply reduced. Moreover, the off-tuned TVAs can excessively amplify the vibration levels of the primary structures; therefore, not only rendering the TVA useless but also possibly causing damage to the structures. Off-tuning is one of the major problems of conventional passive TVAs. This study proposes a novel semiactive TVA, which strives to combine the best features of passive and active TVA systems. The semiactive TVA in this study includes a Magneto-Rheological (MR) damper that is used as a controllable damping element, for providing the real-time adjustability that is needed for improving the TVA performance. This study is conducted in two phases. The first phase provides a numerical investigation on a two-degree-of-freedom (2-DOF) numerical model in which the primary structure is coupled with a TVA. The numerical investigation considers four semiactive control methods for the MR TVAs, in addition to an equivalent passive TVA. These numerical models are optimally tuned using numerical optimization techniques to compare each TVA system. These tuned systems then serve as the basis for numerical parametric studies for further evaluation of their dynamic performance. The parametric study covers the effects of damping, as well as system parameter variations (off-tuning). The results indicates that semiactive TVAs are more effective in reducing the maximum vibrations of the primary structure and are more robust when subjected to off-tuning. Additionally, the numerical study identifies the "On-off Displacement-Based Groundhook control (on-off DBG)" as the most suitable control method for the semiactive TVA among control methods considered in this study. For the second phase of this study, an experimental study is performed on a test setup, which represents a 2-DOF structure model coupled with an MR TVA. Using this setup, a series of tests are conducted in the same manner as the numerical study to evaluate the performance of the semiactive TVA. The primary purposes of the experiment are to further evaluate the most promising semiactive control methods and to serve as a "proof-of-concept" of the effectiveness of this MR TVA for floor vibration applications. The results indicate that the semiactive TVA with displacement-based groundhook control outperforms the equivalent passive TVA in reducing the maximum vibrations of the primary structure. This confirms the numerical result that identifies on-off DBG control method as the "best" control method for the MR TVA among four semiactive control schemes considered. The experimental robustness study is also conducted, focusing on the dynamic performance of both the passive and the semiactive TVAs when the mass of the primary system changes (mass off-tuning). The mass of the primary system varied from -23 % to +23 % of its nominal value by adding and removing external masses. The experimental results show that the semiactive TVA is more robust to changes in the primary mass than the passive TVA. These results justify the benefits of the use of semiactive MR TVAs in structures, such as building floor systems. The off-tuning analysis further suggests that, in practice, semiactive TVAs should be tuned slightly less than their optimum in order to compensate for any added masses to the structure. Additionally, the lessons learned from the experimental study have paved the way for implementing the semiactive MR TVA on a test floor, which is currently in progress under a separate study. / Ph. D.