The ever growing demand on reduced fuel consumption in modern aircrafts puts high requirements on manufacturers to reduce weight in all parts of the aircraft. With a total weight of up to one fifth of an aircraft’s total operating weight, ways to decrease the weight of the engine systems are continuously sought. The containment structure that surrounds the fan and turbine in larger commercial aircrafts is designed to prevent any debris to escape and damage any other systems such as fuel tanks or fuselage in the event that a blade should come off. This structure adds considerable bulk to the engine and because of the importance of the containment structure any redesign needs to be thoroughly tested. The high costs associated with containment testing means industry is looking into the feasibility of substituting parts of the expensive experimental testing with more economical numerical simulations. In this thesis modelling of the plastic behaviour of the nickel based super alloy, called Alloy 718, is investigated in an effort to correctly model the material in numerical simulations. This material is one of the most widely used materials in the parts of an aircraft engine subjected to elevated temperatures due to its retained strength and resistance to corrosion and creep. The material models chosen to model the plastic behaviour were the widely used Johnson-Cook and Zerilli-Armstrong models, because of their proven applicability for wide ranges of strain rates. The models were calibrated using data collected from tensile testing performed in a high speed VHS machine from Instron. Tensile tests were performed at quasi-static conditions and raised strain rates up to 1000 s-1. With an induction coil testing was also performed at temperatures up to 650 oC. Fitting the models to the data gave models valid from quasi-static to high rate conditions. In order to test the accuracy of the models they need to be validated. For this purpose a reverse impact experiment using free flying discs impacting a long slender rod was designed. This design enables the force history to be accurately monitored throughout the impact, while still achieving high strain rates. An investigation into producing additional data for use in validation was also performed. This investigation utilized a series of high speed photographs on which shape measurements were carried out in order to find parameters such as plate velocity and average strain without interfering with the experimental results

Due to the requirements of higher strength components and lower carbon dioxide emission, press hardening becomes prevalent in the automotive industry. Heating a boron alloyed steel blank to obtain the austensite phase at high temperature and quenching it to martensitic phase enhances the strength of the products and still allows complex shapes. However, the stamping tool has to endure severe temperature changes, impacts of the counterpart and sliding processes. The wear including material transfer, surface scuffing and complicated reactions between coatings and superficial oxide layers not only shortens the service-life of tools but also decreases the productivity and the quality of the manufacturing process. Furthermore, the harsh contact conditions between the stamping tools and the work-piece, regarded as the reason for the wear, are difficult to measure in situ. The fundamental study on the tool wear in the press hardening receives insufficient attention. The present work aims at establishing an understanding of tribological characteristics in press hardening and at developing a predictive wear model by establishing a relationship between the contact conditions and the wear process. Based on these results, the extension of the service life of stamping tools through adjustment of process parameters can be possible. Sliding wear, as the dominant wear phenomenon taking place during press hardening processes, causes formation of wear particles and transfer of material fragments to the tool surface. Since the wear process is dependent on the contact conditions, finite element (FE) simulations based on thermo-mechanical calculations are used to investigate the contact conditions in a given press hardening process. Based on the results from the FE--simulations, reciprocating tests and tribolgical tests are conducted respectively under press hardening conditions to evaluate the wear coefficients of the Archard's wear model. A modified wear model is implemented in the FE--simulations to predict wear depths on the stamping tools. It is noted that most wear concentrates on the tool radius and that it correlates with the sliding distance. The correlation between the experimental set-ups and the wear predictions are analysed. An industrial experimental set-up for validation of the wear model predictions has been developed. The future work on this study is outlined.

Within the sheet metal industry, different shear cutting technologies are commonly used in several processing steps, e.g. in cut to length lines, slitting lines, end cropping etc. Shearing has speed and cost advantages over competing cutting methods like laser and plasma cutting, but involves large forces on the equipment and large strains in the sheet material.Numerical models to predict forces and sheared edge geometry for different sheet metal grades and different shear parameter set-ups are desirable. For new sheet metal grades, numerical shear models are efficient for finding appropriate shear parameters without the need for time consuming and expensive live tests in the production. In order to allow for validation of numerical models, accurate experimental data is wanted.Many industrial equipments for shearing give some measure of applied force, but due to machinery friction losses, measured forces are always higher than the forces acting on the sheet. Shearing also generates a force that attempts to separate the two shear tools with changed shear conditions through increased clearance between the shear tools as result. Clearance is also the most common shear parameter to adjust, depending on material grade and sheet thickness, in order to moderate the required force and to control the final sheared edge geometry.Sheared edges have four characteristic zones, rollover, shear, fracture and burr zones. Burrs and rough fracture zones complicate the following processing through inadequate tolerances that may imply additional machining and sharp edges that may damage equipment or even cause injuries. Well defined shears and accurate measurements are important for the understanding of shear parameters. In this work, an experimental procedure with high measurability and consistent and predictable output, is designed, built and evaluated. Important shear parameters and demands on the experimental set-up are identified in a perturbation analysis performed with use of finite element method.Considering the perturbation analyses results, experimental set-up requirements are formulated. Based on magnitude of the force changes obtained as result of perturbed input parameters in the analyses, force measurements with one percent accuracy are considered necessary. Since a clearance change of one percentage point results in approximately one percent change in forces, the target experimental clearance stability is an order of magnitude lower, i.e. the clearance should remain within 0.1% or 5μm at the sheet thicknesses sheared.With respect to high clearance stability and accurate force measurements, a symmetric experiment with two simultaneous shears and internal balancing of forces attempting to separate the shear tools, is constructed. Besides a stable clearance, the experiment features high accuracy force measurements without external friction losses through 20 strain gauges mounted on the set-up.Since clearance and clamping of the sheet are identified as important to the shear results, these parameters are selected for further experimental studies through shearing of three material grades with various strength. Judging by the result, shear tool penetration before fracture decreases with increased material strength. When one side of the sheet is left unclamped and free to move, the required shear force decreases but instead the force attempting to separate the two shear tools increase. Further, the maximum shear force increases and the rollover decreases with decreased clearance. In general terms, results from the study are promising for use in validation of numerical shear models.

Abrasive wear is largely involved in many industrial processes, and has far reaching economic consequences which involve not only the costs of replacement, but also the costs involved in machine downtime and lost production. Constructions and machines like conveyers, chutes and dumper truck bodies are often exposed to abrasive wear during handling of industrial raw granular material flow e.g. sand, rocks, pebbles etc.Different theoretical models and numerical models have been establishedto study wear phenomena in different cases. However, simulation andprediction of wear at large scale are seldom presented.In order to effectively predict abrasive wear in large scale applications,models for solid structure, material flow and wear behaviour have to becoupled together. To effectively study sliding abrasive wear of steel platesfrom interaction with granular material, numerical simulations can be anoption. In this work both smoothed particle hydrodynamics (SPH) anddiscrete element method (DEM) is used to mimic the granular materialflow behaviour. The finite element method (FEM) represents thesurrounding solid material. To create models that reproduce interactionbetween solid and granular material both SPH and DEM are one at thetime coupled to FEM. This gives a new opportunity to study abrasive wear insteel structures and also a possibility to estimate the absolute wear in large scale applications. In this work, simulation and field measurements has beendone on tipper and dumper trucks working with rock material. Wearpattern from dumper bodies obtained from numerical simulation showsa reasonably good correspondence to experimental measurements. Anadvanced analysis tool that takes into account both the actual materialflows, wear calculation and optimize equipment against wearis developed. This is done within the multi-physics software LS-DynaIn paper A the SPH/FEM interaction is used to describe an unloading ofa dumper truck. In this paper the “load intensity” is found and used todescribe the areas in the structure that is subjected to the highest wear.Paper Buses the DEM/FEM interaction to find the load intensity in thestructure of a tipper body. Paper Cis a continuation of paper B, were the Archard’s sliding wearlaw is applied on the load intensity to find the absolute sliding wear inthe structure.In summary, numerical methods used to calculate localwear in industrial raw material handling systems is developed.

In hydropower systems, it is essential to avoid catastrophic failures that leads to human and economic losses. Unfortunately, the rotor can behave abnormally since several nonlinear effects occur during start-up, shut downs or when running at nominal speed. Weak nonlinear interaction in the tilting pad bearings, electromagnetic interaction between the generator and rotor or fluid-structure interaction in turbines are typical nonlinear effects that appear. Moreover, strong nonlinearities can also occur due to blade contacts and assembly errors. These types of nonlinearities can be strong in case of bad design of the rotor, and it could even lead to catastrophes in the worst case. Due to the complexity of the blade contact nonlinearity, it is first necessary to evaluate the general properties of the system using a simple model such as the Jeffcott rotor. Studies of nonlinearities are performed using common tools such as Poincare sections, bifurcation diagrams, Maximum Lyapunov Exponent, Lyapunov Spectrum and 3-dimensional plots of the Fast Fourier Transform . The results obtained are also compared with an experimental rig to validate the models proposed. The second part of the thesis is dedicated to real hydropower systems with complex geometry. A focus is made on the numerical methods to employ as well as reduction methods to gain computation time. The aim is to verify that the inherent properties of simple bladed are also present in complex systems. Further numerical simulations of the system at nominal speed will be studied as function of unbalance forces and damping properties. In this case, the tools used in simple rotors system can help us evaluate under which conditions a catastrophic failure can be avoided in any hydropower system.

When it comes to handling of food grade products in an industrial setting, consumer safety is a bigconcern. Therefore, most national, and international food agencies around the world haveimplemented strict rules regarding the level of contaminants from the manufacturing process thatare allowed in the food we consume.The company Nicoccino produces and sells a polymer based film as a substitution for cigarettes andother nicotine products. The company recently established a new factory and have invested in newproduction line but are having problems with one of their machines.The problem stems from the lack of ability to keep a certain number of films in ordered stacks alonga conveyor belt, and the aim of this report is to find a technical solution to that problem.To try and find a suitable solution, a simplified version of a product development workflow was usedwhich included the development of different concepts, refining a selected idea and then thedevelopment of a 3D model with technical drawings. Through interviews with the manufacturer ofthe machine, a suitable spot for the solution was identified and with help from the Swedish FoodAgency, EU compliant construction materials were selected.The result of this work is a fully developed design proposal that doesn’t require a redesign of themachines existing layout and is design with materials to fully EU regulations regarding contaminationin consumable, food grade goods.

The continuous development of the press hardening technology has led to stronger, lighter and more environmentally friendly components. Utilising the varying properties of boron steel at different temperatures enables great design freedom, while also attaining high strength in the final component. This is achieved by heating the initial material to an austenitic state, where it has good formability, followed by forming and quenching using pressing tools. However, in order to simulate this thermo-mechanical process the microstructure evolution must be understood. Research has been performed using various initial material states, evaluating possible effects on the final mechanical properties. Studies have also been performed to evaluate the grain growth during austenitisation. The influence of the initial material and the evolution of the austenite morphology during austenitisation has previously been less researched compared to other parts of the process. In this work, samples from commercially available materials have been heat treated to create test specimens, which subsequently have been used for mechanical testing and microstructure analysis. Digital image correlation was used to determine local fracture strains and anisotropic properties during plastic deformation. Samples were also heat treated using varying process parameters in order to study the grain growth during austenitisation. It was found that if hot rolled, cold rolled and soft annealed cold rolled samples were compared after hardening, their mechanical properties only exhibited minor variations. However, all samples displayed anisotropic properties during plastic deformation. There is therefore some microstructural trace from the production which is unaffected by soft annealing, austenitisation and subsequent quenching. The grain growth observed during the austenitisation was consistent within a temperature range not exceeding 930 ◦C. Using data retrieved from isothermal experiments a model could be fitted which described the growth using the temperature and current grain size. At 960 ◦C the microstructure was irregular, with large single grains and considerable variations in the average grain size within the same sample. The bending performance was not affected in a major way by the austenitisation temperature. The lack of variation of the mechanical properties due to the initial microstructure or parent austenite grain size is a testament to the robustness of the process. It should be noted however, that all samples were rapidly quenched. If the microstructure is formed through diffusion dependent phase transformations, the final mechanical properties could be more sensitive to process parameters. Further research is needed to fully understand the microstructural evolution and thus the mechanical properties where a more general thermal cycle can be used.

Handling of granular material occurs all over the world for different reasons and under different conditions. In the mining industry, granular material handling is present in almost all processes. The machinery that deals with the granular material is typically subjected to significant wear. The loading process is a very crucial task in any mine. During the loading process, fragmented material is loaded with large rope- or hydraulic shovels. In open-pit mines, machines capable of loading more than 100 tonnes of fragmented rocks per bucket are often used. Maximizing the availability and increasing the productivity of these enormous machines are two challenges that are crucial in order to maintain the production. The work in this thesis is divided up into two parts, where the first part is to develop a numerical model to simulate granular material handling for full-scale applications, and the second part is to develop a wear model suitable for the prediction of abrasive sliding and impact wear for full-scale industrial use. A numerical model utilizing the discrete element method (DEM) in combination with rigid-finite element (FE) is used to obtain a realistic granular material model of copper ore. A multi rigid body dynamics model is utilized to model a realistic dynamic model of a rope shovel. Novel full-scale in-situ experiments are used for calibration and validation of the granular material model. A wear model, with the basis of the traditional Finnie's wear model is developed. The model enables the calculation of wear for different impact angles varying between sliding to vertical impacts. Calibration of the wear model is performed by measuring the wear on steel plates belonging to a vibratory feeder. A sensitivity analysis is performed to investigate how the particle size distribution (PSD) and the FE grid size influences the numerical wear. Furthermore, the model is validated by comparing predicted wear from simulations with experimentally measured wear on a rope shovel bucket. Validation of the granular material model from drone video recordings, and measurements of mass in the bucket confirms that the granular material model is able to capture the main phenomenon during the loading process. Validation of the wear simulation model agrees exceptionally well between the predicted wear when compared to the experimentally obtained wear data. In conclusion, numerical models including prediction of wear are developed and demonstrated for the loading process. Calibration and validation approaches for full-scale industrial use are also presented. The presented model can be used as a tool for industries to make better decisions regarding e.g. how to increase productivity and reduce wear.

Comminution is one of the highest energy-consuming processes in the mining and mineral processing industry by consuming around 2% of the global generated energy with an overall efficiency of 1-3%. Different approaches to the optimization of processes have been developed, but there is still room for improvement. The macro events where energy is mostly spent require numerical methods, so an overall optimization of the system is performed by the analysis and optimization of individual subsystems, such as machines and material to be crushed. The challenge when applying numerical analysis lies on the calibration of the models with mechanical parameters inherent to the constitutive laws and physics of the system. It has been seen that mineral material is exposed to a great variety of time dependent forces within the process. A baseline to understanding the interaction of the material with the machines is the analysis of fracture processes under different loading conditions. This thesis focuses on the mechanical characterization of manganese slag core material for the development, calibration and validationof constitutive models via direct and indirect measurements of the strength and fracture behavior. Diametrial and axial compressive tests under quasi-static and dynamic conditions were used by the hand of optical techniques to obtain information about the evolution of damage. Digital image correlation in 2D and 3D was implemented, considering that it is a method virtually independent ofthe geometry, size, material and deformation rate. Quasi-static tests on both Brazilian disc and unconfined axial compression configurations exposed a mechanical behavior of composite-like material where random failure of the components caused high variability of the elastic parameters. Irreversible damage was perceived globally as non-linearities in load-strain curves, while cyclic loading revealed a degradation of the material affecting the elastic modulus where a weakening of the matrix and dominant behavior of the inclusions on the mechanical response is perceived. Dynamic tests were performed in an in-house built Split Hopkinson Pressure Bar which follows the wave propagation theory in the material generated by the impact of a pressure driven projectile. 2D high speed imaging was performed in order to obtain informationabout the crack initiation and fracture process so that a sampling frequency of 380,000 fps and 663,200 fps was obtained for axially and diametrically loaded samples, respectively. Full-field deformations showed a staggered fracture process were on set failure points vary due to the internal events happening in the material. Localized frictional occurrences and inertial effects acting in the pre-cracked matrix have a strong effect on the global mechanical response and, therefore, a great variability of ultimate compressive and tensile strengths was found. The overall strain/loading rate dependency of the material was perceived as a general increase of the UCT and maximum load compared to quasi-static values. In general, the objective of this work was to study the effect of different loading conditions on the mechanical behavior and material parameters of unprocessed slag for the future development of numerical models of large-scale comminution processes.

Modeling the dynamics of hydropower generators has been the aim pursued by many studies, as providing a reliable model would lead to more cost-effective designs. Hydropower generators comprise many parts, tilting-pad bearings, shaft, rotor rim, and stator among them, that contribute to the system's nonlinearities. In this thesis, the dynamics of hydropower generator is studied first by characterizing tilting-pad bearings. Multiple pad bearings are common in the industry; an eight-pad tilting-pad bearing has been studied on vertical rotors. Previous studies have shown that multiple pad bearings display stiffness and damping coefficients dependent on eccentricity and position. A model for eight-pad tilting pad bearings has been proposed and compared to experiments. The effect of cross-coupled phenomena was also investigated. On the other hand, the generators are not rigid bodies, and the flexibility of either rotor rim or stator influences the distribution of the magnetic field, thus the force distribution. An uneven force distribution endangers the integrity of the machine. This thesis also proposes a model for a generator with flexible rotor rims and rigid stators using Lagrange equations, considering the centrifugal and Coriolis effects, the electromagnetic interaction between rotor and stator, and static and dynamic eccentricities. This model was tried on a generator prototype, discussing the impact of the connecting plates and the magnetic forces on the natural frequencies and the effect of static eccentricity. / Swedish Hydropower Centre - SVC