This report is the result of a study performed as a master thesis. The study involves different noise encapsulations intended for Scania trucks. The work was performed at the Marcus Wallenberg Laboratory for Sound and Vibration Research, MWL. The study consists of two parts. The first part is a comparison survey concerning the sound reduction qualities of different types of noise encapsulations. The second part is a modal survey of the standard noise encapsulation currently employed by Scania. The report is divided into two chapters each treating one of the surveys. Both chapters start with a short theoretical deduction and description of the method that is being used. Thereafter follows a practical description of how the survey was executed. The main results are given last in each chapter.

The high voltage power network in Sweden consists mainly of overhead power lines, that is conductors suspended in the air by supports. Ideally when projecting a power line, all supports should be placed equidistantly and the conductors should be suspended at equal height. When this is not applied, the support placement may have consequences, such as uplifting forces in a support, which should be avoided. The objective of this thesis was to investigate both what in　uences the support placement, and what consequences that may come out of it. This was investigated using mainly analytical calculations on poles and conductors, but was also implemented on a specic case. When solving the case, support placement and FEM software were also used and compared with the analytical calculations. It was found that the support placement is in　uenced by both environmental factors; such as terrain, obstacles and solidity of the ground, as well as how long spans that are possible to construct. The span length is the distance between two nearby supports and is limited by sag, that is the de　ection of the conductors, and the strength of the supports. The sag is dependent on the tension in the conductor, which is dependent on wind and ice loads, temperature and creep; a permanent elongation that for certain materials occur over time even if the load is constant. Since the sag will increase over time, and especially at high temperatures, the distance between the conductors and the ground will decrease. This extra de　ection must be accounted for when designing the power line and determining the span length. When it comes to support designing, both bending and buckling should be accounted for. The greatest loads the supports are in　uenced by are transferred from the conductors, and therefore are dependent of the span length. An analysis of buckling and bending as function of span length was therefore conducted on non-guyed timber pole supports. It was concluded that bending stresses; due to wind loads on the support and especially on the conductors, are usually the critical aspect when designing standard power line supports.

In the truck industry, it is crustal to test components against fatigue to make sure that the trucks stand up to the high demands on durability. Today’s testing methods have some disadvantages; it is quite a time-consuming process, but more important, similar tested components cannot easily be compared due to the load spread the components are subjected to. It is therefore desirable to test the components in a standardized way. One way to do this is to use a synthetic signal which is a large number of unique truck measurements combined. The synthetic signal only contains information of the frame’s vibration and not any components. The purpose of this project was to create a model that uses the synthetic signal to describe the motion of components.   Two approaches were used, the first was to base the model on previous measurements, the second one was to base the model on analytical equations. These models were experimentally tested in a 4 channel shake rig, and a silencer was the component chosen to be tested. For the model based on measurements, the load was shown to have a large spread which was hard to control due to the spread in the measurements. The second model was easier to control where the damping factor can be chosen and varied. A promising model was the analytical model using 10% damping applied to the synthetic signal, it covers most measurements without overestimate the load of the component. However, the model was only developed for the silencer acceleration in the z-direction, and it is recommended to develop it for the x-direction as well. The method used in this project could also be used to develop models for other components. / Inom lastbilsindustrin är det viktigt att prova komponenter mot utmattning för att säkerställa att produkterna håller de höga krav som ställs på tillförlitlighet. Dagens provmetoder har några svagheter, dels är det en tidsödande process. En ännu viktigare svaghet är dock att liknande komponenter som provats kan inte på ett enkelt sätt jämföras med varandra, eftersom belastningen på en komponent kan skilja sig rejält beroende på vilken fordonskonfiguration som väljs att studera. Det är därför önskvärt att prova komponenterna på ett standardiserat sätt. Detta kan göras genom att använda den syntetiska signalen, som är en kombination av ett antal unika lastbilsmätningar. Men den syntetiska signalen innehåller bara information om ramens vibrationer och inte komponenten. Syftet med det här projektet är att ta fram en modell som använder den syntetiska signalen för att beskriva en komponentens rörelse. Två angreppssätt användes, det första var att basera modellen på tidigare mätningar, det andra var att basera modellen på analytiska ekvationer. Dessa modeller var experimentellt provade i en skakrigg med fyra kanaler, och en ljuddämpare blev det valda testobjektet. Modellen baserad på mätningar resulterade i en stor spridning av last, som var svårkontrollerad till följd av spridningen från mätningarna. Modellen baserad på de analytiska ekvationerna var däremot lättare att kontrollera där dämpningen kunde väljas och varieras. En lovande modell verkar vara att använda modellen med 10% dämpning på den syntetiska signalen, den täcker in dem flesta mätningarna utan att överskatta komponentbelastningen. Modellen är dock bara utvecklad för komponentens acceleration i z-riktning och det är rekommenderat att utveckla en liknande modell för x-riktningen också. Metoden kan även användas för andra utveckla modeller för andra komponenter än ljuddämparen.

Corrugated board and other paper products are widely used in product packaging due to good mechanical properties, recyclability, price etc. Due to the growing e–commerce industry the dynamical behaviour of corrugated board is of particular interest. Paper exhibits an orthotropic behaviour and is a non–linear material. In this work, corrugated board is analyzed from mechanical point of view,when subjected to a short timespan impactload. Edgecrushtest (ECT),flatcrusttest(FCT),bending stiffness and static deflectiontests which are part of standards used in the industry are performed. Both experimental and numerical approaches are used in the analysis and the results are compared and discussed. The elastic part of a corrugated board material model predicts the physical behaviour well and provides reliable results. Bending stiffness model results have approximately 1% difference from physical experiments and the static deflection test together with FCT has a 6% difference. Dynamicaldroptest gives13%,11% and 27% relative error for different drop heights. Elastic–plastic behaviour requires further investigations, especially in ECT test which has around 45% discrepancy from physical experiment. The possible difference in the dynamical model might arise from the boundary conditions which were not fully controlled during the physical experiment and the difference in the ECT can be possibly explained by layer thickness approximations together with glue line width assumptions between fluting and the liners in the numerical models. Results suggest that the finite element approach is a reliable way to model corrugated board but it poses challenges especially in complex loading conditions. The elastic behaviour of the corrugated board is well predicted by assuming an orthotropical material model. The dynamic behaviour when subjected to an impulse force was well predicted for low drop heights. but requires more investigation for high impulse impacts.

The Swedish armed forces, Försvarsmakten (FM), is the governing body in charge of defending the sovereignty of Sweden. In FM, a large part of the personnel is exposed to high levels of noise as part of their work with machines and weaponry. The Swedish authority on workplace related hazards, Arbetsmiljöverket, has set out limitations for noise exposure during work in the publication: AFS 2005:16. To reduce the total noise exposure of the employees, FM have implemented multiple changes in their work. These changes include the use of hearing protection devices (HPD) but also include changes in routine and equipment. Multiple versions of the hearing protectors include radio communications to facilitate communication while maintaining a high level of noise reduction. The methods set out in AFS 2005:16 to measure noise exposure are not applicable when sound is generated inside the ear canal. Therefore, the total noise exposure cannot be determined accurately with regards to the set limitations. The thesis aims to determine a method to measure the total noise exposure in representative conditions and how the use of this method along with other objective measures of sound to set system settings. The method of choice is to use a HATS or MIRE measurement in accordance with ISO11904- 1:2002 or ISO11904-2:2004 to properly capture the influence of the operator and calculate the contribution from the communication systems. The contribution from external sources need to be evaluated separately as the attenuation of hearing protection devices may not be properly measured when using MIRE or HATS. When such contribution is calculated, insertion loss (IL) determined using the REAT method should be used. The exposure using three weapon systems was measured using a HATS at representative head position and a selection of HPD. The resulting IL was compared to other methods of measuring IL and total exposure using these results. The IL in in-situ measurements was influenced by the presence of a disturbance in the HATS and consequently overestimated exposure. IL was also measured in a reverberation chamber and an echo-free chamber using a HATS. The resulting IL seems to differ from REAT measurements and did in some cases severely overestimate the IL. The thesis also simulated the influence of three idealized types of noise on the Speech Transmission Index (STI), an objective measure of speech intelligibility. To measure STI using HATS or MIRE measurements, a transfer function like the one from ISO11904-2:2004 needs to be applied if noise or HPD:s will be used. Previous work recommends a speech-to-noise ratio of at least 12dB to achieve good speech intelligibility. The rule of thumb seems to have some advantages when using a simulated Matrix Transfer Function but does overestimate the required level for low noise levels. For higher levels, excellent STI (0,75) does not seem to be achievable. The required signal-to- noise is dependent on both the spectral content of the noise as well as the level, which both is influenced by the use of hearing protection devices. To select a proper signal to noise level, a representative recording of speech using relevant equipment is required. The influence of noise can be added separately using the methods in IEC60268-16 and REAT measured attenuation.

In this master thesis a method for optimizing welds has been investigated. The method was developed by the use of a finite element (FE)-model of a silencer. The silencer is exposed to both dynamic and thermal loads. Focus has been on using topology optimization for the welds. The main driver for developing a method for weld optimization is to investigate whether the stresses close to the welds could be decreased if some weld material were to be removed. Another motive for conducting the study is to understand the potential for decreased computation time for modeling welds (continuous welds) should the component have more intermittent welds. Given the loads that the component is subjected to, a plastic material model would be preferable. However as of today, a material model in an optimization is limited to being linear elastic and hence it is not possible to use a plastic material model in an optimization, even though that would better to capture the real conditions of the silencer. Thus, as part of this thesis an investigation aiming to find a transfer function between a plastic material model and an elastic material model was conducted. An important part of an optimization is to have a relevant requirement to optimize against. This requirement could be calculated from the transfer function and then be used in an optimization.Summarizing the findings, a transfer function between a plastic and elastic material model was identified, but only for a specific model and position. The identified function can translate and enable the stricter conditions used in a plastic material model to be adapted to an elastic material model. To get a functional transfer function the Super Neuber needs to be calculated for every element in a time efficient way. This might be done by finding a relation of the geometry and the Super Neuber parameter but this will require more investigations. If the Super Neuber parameters for the model are found then the fatigue requirement can be translated to an elastic stress constraint which will give a more accurate optimization.The method for weld optimization has been evaluated but without a requirement calculated from the transfer function. By changing from continuous to intermittent welds the stresses caused by the thermal load can be decreased.

Today the European energy grid contains more renewable energy sources than ever before, yet there is little to no research on how the increased amount affects the cost structure of the remaining energy sources of the grid. A consequence of phasing more renewable energy sources into the power grid, is a reduction of the overall balancing capacity of the grid. Thus, the demand for balancing services from the remaining dispatchable energy sources increases. Hydropower is currently frequently used to balance the grid, and thus, the increased demand for balancing services offers a large opportunity for the hydropower segment. Furthermore, as the operating patterns become increasingly aggressive, the structural integrity is reduced, and the maintenance costs are increased. This thesis finds and elucidates the magnitude of the reduced lifetime and increased maintenance costs. This master's thesis finds that the reduction of the structural integrity comes at a large cost, and greatly impacts the overall financial feasibility. In that regard, it is presented market solutions that further incentives balancing services. Balancing services are in markets sold as system services, which includes frequency response, black start capacity, reactive power, and reserve capacity. The thesis presents operating patterns for Francis turbines that seek to fulfill the various system services. The thesis predicts the lifetime of five unique operating patterns, one is assumingly the status quo of operations today, and another is an analogy of operating the turbine like a battery. The results show that low part load and startup are the most damaging operating points, and that the lifetime is lower for flexible operations, than the currently expected lifetime. Despite greatly reducing the lifetime of the turbine, the evaluated cases are financially feasible if they are adequately rewarded. The exact power price that provides adequate rewards differs for all five cases. Financially feasible power prices are in the interval 0.257 to 0.0533 NOK/kWh, where the lowest price refer to current operations and the highest price refers to the aggressive extreme case. The analyses conducted in this thesis are utilizing the numerical software ANSYS mechanical to predict the stress state, the Palmgren-Miner method to predict the lifetime, the rothalpy relationship to predict the pressure in the runner and net present value calculations to evaluate the financial feasibility. In addition, the thesis utilizes, and post-processes previously conducted numerical fluid analyses and pressure measurements from the Waterpower Laboratory at NTNU.

High-chromium cast irons are used in certain applications where the demand on abrasion resistance is high. Such applications can be found in the milling industry and in pumps for transport of abrasive particles in liquid suspension. Soft annealed high-chromium cast iron containing 2.6 % C and 24.7 % Cr was supplied by Xylem Water Solutions, Sundbyberg, and investigated by dilatometry. The heat treatments were inspired by induction hardening procedures. The purpose of the investigation was to evaluate the effect of maximum temperature reached during heat treatment on the final length of the test specimen. The aim with this was to find the treatment yielding the maximum possible length which should be profitable to create desirable compressive stresses in the surface hardened area. The experimental results were used to create a finite element model in COMSOL Multiphysics accommodating for the maximum temperature, simulating the phase changes occurring in a geometry based on the experimental test specimen. The experimental results did not reveal any clear correlation between the maximum temperature and the final length change. The hardness, however, increased with the increasing temperature in the treatment interval 900-1150 °C. The, by light optical microscopy, observed amount of secondary precipitated carbides decreased with increasing temperature. Martensite transformation was also affected; the transformation temperature decreased for increased treatment temperatures. From dilatometry it was also seen that the thermal strains were greatly affected by the direction of which the material was cut from the original cast material. Samples taken perpendicular to the mainly investigated direction showed lower coefficients of thermal expansion and the final strain was clearly positive compared to the slightly negative values found for the main direction. This phenomenon could possibly be explained by different macrostructures created during solidification of the melt causing anisotropy in the eutectic. The implementation in COMSOL by describing the phase transformation as ordinary differential equations did show partially good results in the simulation of thermal expansion. The difference in original material is noticeable in the dilatometry and the simulated martensite transformation deviates from the experimental results. The model needs to be validated against new intermediate test temperatures and the martensite transformation kinetics must be investigated further to yield better results to be able to combine the phase transformations with mechanical calculations.

The purpose of this thesis project is to develop a methodology that can be used to minimize the number of spot-welds in a mechanical structure, this is done in a reliable manner via optimization methods. The optimization considers fatigue life in spot-welds and also stiffness and eigenfrequency values. The first chapter of this thesis presents a spot-weld fatigue model proposed by Rupp (1995), common FEmodels of spot-welds and also important aspects about structural optimization in general. The second chapter further describes how topology optimization and size (parameter) optimization are applied on a simple multi-weld model with respect to the aforementioned structural constraints. The topology optimization is later used on a full-size car model, while the size optimization is used to optimize the multiweld model by adding an non-linear structural constraint - a crash indentation constraint. The spot-weld fatigue model proposed by Rupp (1995), is also verified by comparing FE results using different FE-models of spot-welds compared to fatigue data by Long and Khanna (2007). Both optimization methods successfully minimize the total amount of spot-welds on the multi-weld model. The topology optimization,accompanied with thegradient based MFD algorithm,minimizes th etotal spot-welds with around 15% and 3% on the multi-weld model and car body respectively. The size optimization, using design of experiments and response surfaces, manage storeduce the number of welds in the multi-weldmodel by 25%. However, with the size optimization the computational time is several orders of magnitude longer-even without the formulation of the crash constraint. The fatiguespot-weld model fares reasonably well compared to the experimental fatigue data, regardless of the FE model of the spot-weld. It is concluded that the ACM model would be recommended based on its compatibility with fatigue and optimization methods, mesh-independence and also other studies have shown its ability to represent stiffness and eigenfrequency correctly.

Additive manufacturing is a technique allowing the building of complex geometries in a layerby-layer approach. These layers lead to an anisotropic material behaviour. In this report a material description for selective laser sintered (SLS) PA12, which is a common 3D-printing plastic, is investigated. First material tests are carried out on ISO 3167 multipurpose test specimens and a transversely isotropic material model with plasticity is fitted to the test results. The material model is then used to topology optimise the pylon and support of a lower leg prosthesis to lower their weight with respect to the printing directions. Two of the designs where then printed, together with additional material test specimens in order to validate the used material model. It is found that the model gives a reasonable estimation of the material behaviour, but that there is very large variation of the material parameters, something also observed in other studies. The conclusion is that more material tests would need to be conducted to fit a probabilistic material model to the material, and thus better account for the large variations.