Material damping in a structure is well defined and documented. However, dissipation due to mechanical contact (surface contact) in a complex built-up structure is not as well represented, in particular in large scale noise and vibration simulations. The present work is dealing with the understanding of the physical behaviour of losses that take place at such complex interfaces. The objective is to investigate, if, these mechanical loss phenomena can be modelled using linear response simulation techniques and implemented using commercially available finite element software. In a first step, the losses at the interfaces were experimentally investigated using an experimental setup capable of in-vacuo conditions. Following this, the second step was aimed at different ways of representing the proposed boundary conditions in a linear response simulation of a built-up structure. Two different approaches were studied, one using a continuous surface approach and one using a discrete element method. / <p>QC 20120424</p>

The structural damping is of importance to suppress the vibration amplitude of compressor blades rotating at high angular velocity under a high cycle impact. To avoid the appearance of the high cycle fatigue (HCF), damping materials may be applied to the compressor blades. To quantify the effect while using damping materials, a numerical tool needs to be developed for the damping prediction of a dynamic rotating blade. This thesis is divided into two parts: Paper A develops a dynamic model of a rotating blade and Paper B a damping structure model including measurements. In Paper A, a dynamic rotating blade model is developed by using a plate model at an arbitrary stagger angle. Hamilton’s principle is applied to derive a system of equations of motion and the corresponding boundary conditions. Numerical simulation is implemented to perform eigenfrequency analysis by the Extended Galerkin method. In addition, parametric analysis is performed with respect to rotation speed and stagger angle, respectively. Results show a good agreement with those of the finite element method. Finally, forced response analysis is determined for two cases; a point force and a distribution force, using a proportional damping model. In Paper B, unconstrained and constrained damping techniques are applied to increase the structural damping of the blades, including measurement and modeling results. Two specimens, titanium and stainless steel, are treated by aluminum oxide and epoxy coating material. Measurement results show that both treatments give damping increase, where aluminum oxide is more effective for damping improvement than the corresponding epoxy treatment. The unconstrained damping layer model is used to predict the total material damping of the combined structure as well as the material damping of coating layer. Furthermore, the constrained-layer model is used to optimize the damping configuration. Two compressor blades in titanium and stainless steel are tested in air and vacuum. One reason is being that the radiation loss factor increases the total damping comparing with that under vacuum condition. The calculation of radiation loss factor is performed to match the measurement data. Finally, increased material damping decreases peak stress and therefore increases the life time of the compressor blades. / <p>QC 20110311</p>

The production processes of porous materials introduce an inherent geometric anisotropy in the material at micro scale, which influences the material properties at macro scale. In this thesis, the focus is turned to one of these macroscopic properties, the flow resistivity, which is a measure of the resistance felt by the sound pressure waves as they propagate through a porous space. In the current work, two different porous materials have been studied, a fibrous glass wool and a Melamine foam. The two materials are expected to show different degrees of anisotropy with respect to flow resistivity. Glass wool is assumed to be transversely isotropic, as a result of the stacking of layers of fibres. The level of anisotropy in Melamine foam is not as obvious, and might be related to production specific aspects, such as the rise-direction, and the position of the injection nozzles. The thesis begins by giving an introduction to porous materials in general, and to glass wool and Melamine foam in particular, followed by an introduction to flow resistivity, together with two methods to measure the flow resistivity. The full anisotropic flow resistivity of glass wool and Melamine foam samples is determined by means of measurements and inverse estimation. An eigenvalue and eigenvector decomposition of the flow resistivity tensor provides an insight into the connection between the directionality of the flow resistivity in each material, and its production process. A study of the homogeneity in density and flow resistivity for the two materials shows that these properties vary within the block of material. However, for each material, there seems to be no connection between the variation in the two properties, investigated at the macroscopic scale. / QC 20110311

The pantograph - catenary interaction is one of the most important features in high speed trains, and to guarantee a reliable current collection is the target that every railway system must take into consideration in order to speed up trains. The problem that goes against this direction is mainly the variation of the overhead equipment's stiness. To understand the phenomenon a lumped mass model of the pantograph with a rigid body attached to the ground representing the contact wire were built up; in this way a complete lumped mass model is developed. All information regarding both wire and pantograph set up is introduced as lumped parameters. Creating the model, dierent active control strategies as ideal control, PID control and optimal control are introduced. All simulations are made in GENSYS, while the control part is made inSIMULINK; a connection between those two softwares was created as part of the thesis using TCP/IP protocol. Results compared to experimental acquisition are satisfactory in terms of contact force representation. The standard deviation and average value's errors of the contact force are lower than 10%; regarding the control system, typically 20% of reduction of the standard deviation compared to the passive case is achieved. Also a comparison with a nite element program is done in order to better understand the limits of the model compared with a more sophisticated one. The comparison shows a good accordance up to 60 % of the average speed of the wave propagation in the catenary. The last feature analyzed is how the behavior of the controlled system changes introducing a real actuator: results shows that the performance is reduced in dierent ways considering dierent speeds, but no instabilities occur.

This thesis project focuses on the verification method of a safety function called PICthat stands for Post-Impact Control which controls the vehicle motion of passengercars after being exposed to external disturbances produced by a 1st impact, aiming atavoiding or mitigating secondary events.The main objective was to select a promising method, among several candidates, todevelop further for testing the function and the interaction with the driver. To do thisis was first necessary to map the real destabilized states of motion that are targeted bythe function. These states are referred as Post-Impact problem space and are acombination of variables that describes the host vehicles motion at the instant thedestabilizing force has ceased. Knowing which states are requested by the solutioncandidates, it is possible to grade the rig candidates based on the capability ofcovering the problem space. Then, simulating the proposed rig solutions withMatlab/Simulink models to investigate which candidate fulfils best the problem space.The result of the simulations and other criteria is that a moving base simulator(Simulator SIM4) is most fitted to research verification. The second mostadvantageous solution is the rig alternative called Built-in Actuators.

In an effort to reduce physical testing during the development process of a new vehicle, the automotive industries develop methods that can facilitate the recreation of the physical testing scenarios in virtual environments using simulation software. This thesis aims to develop a method which would help evaluate the vehicle’s dynamic properties without it being subjected to physical testing. The goal is to develop a tool that can be used in an early development phase by the industry and that would allow for modifications and calibration to take place. A vehicle model as well as an electronic stability control implementation is built, and the model’s performance to an ISO3888 part-2 double lane change test is evaluated. Since the handling potentials of the vehicle are rated by its entry speed in that test, the model was subjected to an optimization process where its steering action was controlled in order to achieve the highest possible entry speed to the test in an effort to isolate the vehicle’s dynamic potential from the influence of a human driver when conducting this test. The vehicle modelling procedure is done in steps, from a simple implementation of a linear bicycle model to a more complex implementation of a four-wheel vehicle including roll, tire relaxation and suspension compliance properties as well as a simplified ESC implementation. The results of the steering input optimization process were physically tested on a test track, where the correspondence of the model to the real vehicle was evaluated. By further promoting the vehicle dynamics modelling, this tool can facilitate study more testing scenarios and options and it can serve as a step toward the reduction of the physical testing when the vehicle’s dynamic and handling performance need to be studied and evaluated. / Under utvecklingsprocessen av nya fordon sker en strävan mot att reducera fysiska tester, bilindustrier utvecklar därför metoder för att återskapa fysiska testscenarier i virtuella miljöer med hjälp av simuleringsmjukvara. Denna studie har som målsättning att utveckla en metod, med vilken fordonets dynamiska egenskaper kan utvärderas utan att utföra fysiska tester. Målet är att utveckla ett simuleringsverktyg som, i en tidig utvecklingsfas, kan användas av fordonsindustrin och som skulle införa både modifikations- och kalibreringsmöjligheter i detta skede. Såväl en fordonsmodell som ett anti-sladd system är konstruerat och modellens prestanda i ett dubbelt filbyte, specificerat i ISO3888 del 2, är utvärderad. Då bilens dynamiska prestanda klassificeras utifrån ingångshastigheten i detta test utfördes en optimeringsprocess där hjulens styrvinklar reglerades för att uppnå högsta möjliga hastighet vid testets startposition, detta för att separera fordonets dynamiska klassificering från mänsklig inverkan. Processen att konstruera fordonsmodellen utfördes med succesivt ökande antal av fordonsegenskaper, från en enkel implementering av en linjär cykel-modell till en tvåspårs-modell med krängning, transienta däckegenskaper, hjulupphängningsegenskaper samt ett anti-sladd system. Resultatet av den optimerade styrregleringen testades i motsvarande fordon på en testbana varefter modellen kunde utvärderas med det verkliga testet som referens. Genom en utökad möjlighet till simulering kan detta verktyg ge möjligheten att studera fler scenarier såväl som alternativa modelleringskonfigurationer; det kan reducera fysiska tester då fordons dynamiska prestanda ska klassificeras, studeras samt utvärderas.

This report is written as part of the thesis requirements for a bachelor of science in Automotive systems at Luleå University of Technology. BAE systems Hägglunds was in need of improved user interface and standardization of their test rigs for drivelines. There was a lack of a naming system for the sensors, formulas for efficiency and heating power as well as the absence of graphical view of the test objects with associated sensors. All of this is important for an efficient development procedure. Also a suggestion on suitable replacement of the mechanical water flow sensor was requested. This report presents the theory around the components and sensors regarding the test rigs, methods for making the decision and finished results. By developing an understanding of the test cell and test subjects, graphical recreations could be created with belonging calculations and documentation. Reading of analog signals and digital CAN-messages made it possible to collect and use the data from the sensors that was requested. By comparing the different flow sensors a of that the inductive flow sensor is most suitable for BAE System Hägglunds was made. The thesis resulted in a chosen naming system which is according to(Element)(Material)_(High/LowTemperature)_(Subject)_(In/Out). Formulas for efficiency and heating power, as well as 6 graphical views, 6 implemented views and 6 Excel documents was made and implemented in the DewesoftX software. The graphical views strongly improved the user interface of the test cell. Because some of the objects are classified they can also be used when presenting the data from testing without giving out more information than necessary. Also to make it easy to see where the sensors are placed and how to install the object in the test cell. This is very useful for BAE Systems Hägglunds that are now expanding their personal that will need basic knowledge of the test cell.

Underground mining machines play a critical role in the mining industry, enablingexcavation of valuable minerals from subterranean deposits. The efficiency of mining op-erations relies heavily on the effectiveness of these machines. Path and trajectory opti-mization techniques are important for improving the effectiveness by reducing the timeand resources required to excavate minerals while ensuring the safety of miners.This thesis explores the application of Model Predictive Control (MPC) in optimizingLoad-Haul-Dump (LHD) routes in underground mining operations. The research ques-tions focus on the utilization of MPC, considerations of dynamic vehicle behaviors, in-tegration of constraints and comparison of optimized routes in terms of cycle times andoverall mining process efficiency.The thesis adopts a two-controller approach, comprising longitudinal and lateral con-trollers, to effectively control the steering angle and optimize the vehicles path. The er-ror dynamics model accurately describes the vehicles position and orientation, enablingprecise route planning and execution. By developing and implementing an MPC-basedalgorithm, the routes are optimized, resulting in improvements in travel time.Dynamic vehicle behaviors, including position, orientation, longitudinal speed andsteering rate, are considered through the kinematic model of the articulated vehicle. Thisensures accurate representation and control of the vehicles movements.Constraints on the admissible state and control input, such as speed limitations, accel-eration limitations and steering angle limitations, are integrated into the MPC-based pathplanning algorithm. Collision avoidance with mine walls is also addressed through sim-ulation in MATLAB, incorporating the mine map. This analysis ensures the safety of thevehicles trajectory and highlights the importance of balancing optimization objectives withoperational constraints and safety requirements.Comparing the optimized LHD routes generated by the MPC-based algorithm revealsdifferences in travel time, with reductions ranging from 1-3 seconds. However, the specificmine conditions and constraints considered in this study may limit significant improve-ments in travel time.The findings of this research have implications for the mining industry, researchersand practitioners in autonomous vehicle control and optimization. The proposed methodenhances the efficiency and productivity of underground mining operations.Future work could explore alternative optimization approaches, refine the existingMPC-based algorithm and consider a more comprehensive vehicle dynamics model. Addi-tionally, investigating different mine environments and incorporating realistic sensor data,uncertainties and noise would improve the reliability and applicability of the method inreal-world mining scenarios.In conclusion, this study contributes to the understanding of applying MPC in LHDroute optimization, paving the way for further research. The utilization of a two-controllerapproach, error dynamics model and careful consideration of weighting parameters en-ables more effective route planning and execution. Continued advancements in au-tonomous vehicle control and optimization in the mining industry will lead to increasedproductivity, efficiency and indirectly safety in underground mining operations.

An increasing amount of sensors is being placed in cars in order to monitor their vicinities, which performance is highly dependant on the driving conditions, in which weather has a big role, and thus water contamination is a topic that will increase its importance in the future of the car industry. One of these sources of contamination is self-soiling: how cars get dirty because of their own tires. Thus, historically speaking this phenomena has been treated computationally by the use of droplet rakes in the tires which do not consider how this water has been picked up, or how it detaches from the tire itself. In this thesis the method to apply results obtained from Smoothed-particle Hydrodynamics (SPH) simulations of the tire droplet adhesion and release, to vehicle soiling simulations in order to improve the accuracy of these studies has been developed. In order to develop the method, first the SPH simulation data has been treated by filtering it according to the droplet location and the tire characteristics which has lead to the development of a geometrical and a kinematical filter for the data set.  Afterwards, the results for the coarsest data set have been applied in the external aerodynamics simulation of a DrivAer bluff car model, as a proof-of-concept simulation, in which a Lagrangian Multiphase + Fluid film simulation has been developed for three different regimes: an unsteady injection with data extracted from the SPH simulations (USPH), a steady injection (SSPH) with the same data set origin and eventually a variable mass flow rake simulation (VMFR), with particles being injected in a rake pattern following the classic method which has been the most extended method in industry and academia to simulate vehicle soiling. These three simulations have been compared among each other so that the main similarities and differences are presented in the report. It has been seen that the injection pattern of USPH and SSPH is similar compared to the classic VMFR simulation, which differs notably both in injection and wake. Moreover, the pattern of fluid film generated in the sides of the car is also similar in both USPH and SSPH, being more intense in the former. Nevertheless, the results from VMFR indicate that the pattern covers more of the side of the car, even though the intensity of the film generated is lower compared to the SPH cases.

Artificial satellites play a vital role throughout the world today. They providea broad range of services ranging from navigation to communication and reconnaissance. As antenna technology is evolving and ground based antennas are getting smaller and smaller, the demand for on-the-move solutions is growing.These antennas can be used whilst mounted on for example, a moving vehicle,where the mechanical performance of the antenna must be sufficient for thecurrent conditions. During this project, a computer based tool that can helpengineers when iterating and optimizing a two-axis gimbal type antenna designwas created. The tool uses simulated and recorded data from road vehicles andboats to calculate the required torque on the two axes necessary to sustain communication with a geostationary satellite. When completed, the tool was easy to use and configure whilst not requiring much computational power. / Artificiella satelliter har en viktig roll i dagens samhälle. De gör att en radtjänster så som navigation, kommunikation och spaning är tillgängliga på ettsätt som annars ej vore möjligt. Samtidigt som antenner blir mindre och lättareså ökar efterfrågan på så kallade on-the-move-lösningar. Dessa antenner kananvändas under färd och ofta på fordon av olika slag. För sådana antenner är detviktigt att den mekaniska prestandan är tillräcklig för de rådande förhållandena.I detta projekt har ett datorbaserat verktyg som kan hjälpa ingenjörer att itereraoch optimera en tvåaxlig inpekare utvecklats. Verktyget använder simulerad ochinsamlad data från markfordon och båtar för att beräkna de vridmoment sombehövs på vardera axel for att bibehålla kommunikation med en geostationärsatellit. Det färdiga verktyget är enkelt att använda och konfigurera utan attkräva stor beräkningskraft.