Technical textiles are increasingly being engineered and used in challenging applications, in areas such as safety, biomedical devices, architecture and others, where they must meet stringent demands including excellent and predictable load bearing capabilities. They also form the bases for one of the most widespread group of composite materials, fibre reinforced polymer-matrix composites (PMCs), which comprise materials made of stiff and strong fibres generally available in textile form and selected for their structural potential, combined with a polymer matrix that gives parts their shape. Manufacturing processes for PMCs and technical textiles, as well as parts and advanced textile structures must be engineered, ideally through simulation, and therefore diverse properties of the textiles, textile reinforcements and PMC materials must be available for predictive simulation. Knowing the detailed geometry of technical textiles is essential to predicting accurately the processing and performance properties of textiles and PMC parts. In turn, the geometry taken by a textile or a reinforcement textile is linked in an intricate manner to its constitutive behaviour. This thesis proposes, investigates and validates a general numerical tool for the integrated and comprehensive analysis of textile geometry and constitutive behaviour as required toward engineering applications featuring technical textiles and textile reinforcements. The tool shall be general with regards to the textiles modelled and the loading cases applied. Specifically, the work aims at fulfilling the following objectives: 1) developing and implementing dedicated simulation software for modelling textiles subjected to various load cases; 2) providing, through simulation, geometric descriptions for different textiles subjected to different load cases namely compaction, relaxation and shear; 3) predicting the constitutive behaviour of the textiles undergoing said load cases; 4) identifying parameters affecting the textile geometry and constitutive behaviour under evolving loading; 5) validating simulation results with experimental trials; and 6) demonstrating the applicability of the simulation procedure to textile reinforcements featuring large numbers of small fibres as used in PMCs. As a starting point, the effects of reinforcement configuration on the in-plane permeability of textile reinforcements, through-thickness thermal conductivity of PMCs and in-plane stiffness of unidirectional and bidirectional PMCs were quantified systematically and correlated with specific geometric parameters. Variability was quantified for each property at a constant fibre volume fraction. It was observed that variability differed strongly between properties; as such, the simulated behaviour can be related to variability levels seen in experimental measurements. The effects of the geometry of textile reinforcements on the aforementioned processing and performance properties of the textiles and PMCs made from these textiles was demonstrated and validated, but only for simple cases as thorough and credible geometric models were not available at the onset of this work. Outcomes of this work were published in a peer-reviewed journal [101]. Through this thesis it was demonstrated that predicting changes in textile geometry prior and during loading is feasible using the proposed particle-based modelling method. The particle-based modelling method relies on discrete mechanics and offers an alternative to more traditional methods based on continuum mechanics. Specifically it alleviates issues caused by large strains and management of intricate, evolving contact present in finite element simulations. The particle-based modelling method enables credible, intricate modelling of the geometry of textiles at the mesoscopic scale as well as faithful mechanical modelling under load. Changes to textile geometry and configuration due to the normal compaction pressure, stress relaxation, in-plane shear and other types of loads were successfully predicted. During simulation, particles were moved randomly until a stable state of minimum strain energy in the system was reached; as particles moved upon iteration, the configuration of fibres in the textile changed under constant boundary conditions. Then boundary conditions were altered corresponding to strains imposed on the textile, and the system was iterated again towards a new state of minimum strain energy. The Metropolis algorithm of the Monte Carlo method was adopted in this specific implementation. The method relies on a statistical approach implemented in computational algorithms. In addition to geometrical modelling, the proposed particle-based modelling method enables the prediction of major elements of the constitutive behaviour of textiles and textile reinforcements. In fact, prediction of the constitutive behaviour is integral to the prediction of the meso-scale geometry. Simulation results obtained from the proposed particle-based modelling method were validated experimentally for yarns, single-layer textiles and multi-layer textiles undergoing compaction. Validation work showed that the particle-based modelling method replicates reality very faithfully, and it also showed the suitability of including Gutowski's function along with Hertz' function for representing lateral compaction of yarns. The procedure and results were accepted in final form for publication in a peer reviewed journal [104]. The capability of the proposed particle-based modelling method towards replicating the time-dependent relaxation and reconfiguration of woven textiles subjected to compaction loading was investigated. The capability, which was demonstrated for single and double-layers of plain woven textiles, is intrinsic to the modelling method. The method is unique in the fact that in contrary to work previously reported in the literature, it models the compaction and the relaxation seamlessly in the same simulations and environment. This work is being finalised towards submission for publication in a peer reviewed journal [103]. The proposed particle-based modelling method was also used for modelling in-plane shear in woven textiles. Simulation results were validated experimentally for a single-layer plain woven textile. Validation work showed that the particle-based modelling method reproduces experimental data and published trends very well. A novel algorithm for modelling friction was introduced, leading to results being obtained from a significantly less computationally demanding procedure in these simulations. This work was submitted for publication in a peer reviewed journal [102]. Finally the thesis discusses early work towards the application of the method to carbon fibre fabrics through the description of expansion algorithm (EA) to be used in modelling textiles made of yarns featuring very large numbers of fibres. Furthermore, additional modelling work is presented towards further manufacturing process involving technical textiles, namely textile bending and punching. The latter part is presented as early steps towards future work.

Carbon fibre reinforced polymer matrix composites (CF PMCs) are increasingly used in state-of-the-art aerospace applications. Aerospace manufacturers favour components made of CF PMCs over those made of traditional metallic alloys because of their light weight and corrosion resistance, which lead to significant improvements in fuel consump- tion, increased payload capability, and reduced maintenance and inspection costs. How- ever, manufacturing of CF PMC components is performed differently than traditional material in all stages – design, prototyping and production – and therefore, many com- mercial manufacturers have only recently begun producing components with CF PMCs. The first half of this thesis was written as a contribution to the CRIAQ COMP-501 project, which focusses on investigating the cost-effective procurement of airframe com- ponents that are manufactured from final-thickness, net-shaped, and through-thickness reinforced CF preforms. Reinforcement preforms were assembled from commercial 2D woven fabric using stacks of various configurations of structural through-thickness CF stitch. The contribution herein provides the results obtained from investigations into the mechanical behaviour of the relevant reinforcements, when subjected to pre-infusion op- erations typical to RTM VARTM; mechanical behaviour in compaction, shear (draping) and bending (forming). The second half of this thesis presents the major developments which were made to an alternative process for producing thick 3D preforms with great versatility, a process originally proposed as a candidate for supplying preforms to the COMP-501 project. This process interfaces a proprietary kinematic drape optimization (CAD) software with proprietary automated dry fibre placement assembly (CAM) machinery to produce vari- able or final-thickness reinforcements which are highly-drapable and can lay steered tow yarns.

Cette étude porte sur les matériaux graveleux latéritiques utilisés dans de nombreux pays pour la construction des couches de fondation et de base des chaussées routières. Au Sénégal, les matériaux sont sélectionnés par référence aux règles du CEBTP de 1972, révisées en 1980. Les graveleux latéritiques doivent respecter des fuseaux granulométriques avant ou après compactage. Des conditions sont aussi imposées à l'indice CBR, à l'indice de plasticité et à l'optimum Proctor. Les recherches présentées dans ce rapport concernent différentes questions :- quel est l'effet du compactage à différentes énergies sur la fragmentation des particules solides et la modification de la courbe granulométrique ? Comment en tenir compte dans la sélection des matériaux et donc leur classification ? Comment se comportent ces matériaux dans les chaussées sous l'effet du compactage à la mise en œuvre puis de la circulation ?- peut-on trouver une corrélation entre l'indice CBR et les paramètres granulométriques ou géotechniques du sol ? Les corrélations sont-elles valables pour tous les sites ou seulement à l'échelle d'une carrière ?- comment réagit le sol graveleux latéritique lorsqu'on le mélange avec un autre matériau dépourvu de particules fines pour améliorer sa plasticité et sa résistance ?- comme une partie des recherches a eu lieu au Brésil, le rapport compare les procédures expérimentales utilisées au Brésil et au Sénégal. La pertinence de l'utilisation des coefficients de fragmentabilité et dégradabilité, introduits dans la classification des sols latéritiques de Rodrigues et al. pour caractériser l'évolution des graveleux latéritiques, a été évaluée par des essais de laboratoire sur le matériau de la carrière de Lam-Lam et le même matériau mis en œuvre en couche de base sur deux routes du Sénégal. Le coefficient de dégradabilité ne différencie pas les matériaux et le coefficient de fragmentabilité semble être un meilleur paramètre. L'étude de l'évolution des classes granulaires des latérites de deux carrières du Sénégal et deux carrières du Brésil sous compactage CBR confirme l'importance de la fragmentation des particules les plus grandes et le décalage des courbes granulométriques vers les sols plus fins, mais ces changements dépendent de la nature des latérites testées. Il en résulte que l'étude des matériaux graveleux latéritiques doit continuer de se faire à l'échelle de la carrière. La méthode de régression linéaire multiple a été appliquée à la prévision de l'indice CBR des matériaux prélevés dans deux carrières sénégalaises (40 prélèvements à Sindia et 46 à Dougar). Cette étude a montré que l'on peut trouver des approximations acceptables à l'échelle de chaque carrière pour calculer l'indice CBR à partir des courbes granulométriques et à partir de six paramètres choisis pour leur influence potentielle sur cet indice : le passant au tamis 80µm, les caractéristiques de courbure et d'étendue de la courbe granulométrique, l'indice de plasticité et les caractéristiques Proctor. Mais les formules établies sur un site sont inadaptées à la prévision de l'indice CBR sur d'autres sites, ce qui confirme que les analyses doivent se faire à l'échelle de la carrière. La lithostabilisation des latérites de Lam-Lam et de Sindiapar mélange avec 30% et 10% de sable de KeurMassar pour abaisser leur indice de plasticité naturel a eu l'effet attendu sur la plasticité, tout en respectant les critères granulométriques. Mais l'effet de l'ajout du sable sur l'indice CBR est inattendu et devra être étudié : diminution pour la latérite de Lam-Lam et augmentation pour la latérite de Sindia. La comparaison des normes françaises et brésiliennes a montré que, malgré de légères différences, les résultats sont globalement équivalents. La plus grande différence concerne l'indice CBR, qui est déterminé avec des énergies de compactage différentes et donne des résultats plus faibles au Brésil. Mais les conditions imposées aux matériaux sont adaptées à ces valeurs / This study is devoted to the gravelly lateritic soils used in many countries as foundation and base layers of road structures. In Senegal, road materials are selected according to the CEBTP 1972 rules, which were revised in 1980. Lateritic gravel grain size curves must lay between lower and upper limit curves before or after compaction. Additional conditions are put on CBR index, plasticity index and modified Proctor optimum. The researches presented in this report concern various aspects of the use of lateritic soils:- what is the influence of compaction at different energy levels on the fragmentation of solid particles and the changes in the grain-size curve? How can particle fragmentation be taken into account in the selection and classification of materials? What is the behaviour of lateritic gravels in road pavements once they have been compacted then submitted to traffic?- can a relation be found between CBR index and grain size curve and other geotechnical properties of the soil? Are correlations valid for all sites or only for a particular quarry?- what is the evolution of a gravelly lateritic soil when it is mixed with another material without fines to improve its plasticity and resistance?- since part of the research was made in Brazil, experimental procedures used in Brazil and Senegal, where French standards are used, are compared. The relevance of fragmentability and degradability coefficients, which are used in the classification for lateritic soils proposed by Rodriguez et al., to characterize the evolution of lateritic gravels was assessed by means of laboratory tests on samples from Lam-Lam quarry and samples of the same material taken from the base layer of two roads sections in Senegal. The degradability coefficient does not differentiate the materials and the coefficient of fragmentability seems to be a better parameter. The evolution of granular classes of laterites taken from two quarries in Senegal and two quarries in Brazil, which were submitted to CBR compaction, confirms the importance of the fragmentation of the bigger particles and the shift of grain size curves towards finer soils, but these changes depend on the nature of the tested laterites. As a consequence, the study of gravelly lateritic materials must still be done at the scale of a quarry. Multilinear regression techniques were applied to the prediction of CBR index of materials taken from two Senegalese quarries (40 samples from Sindia quarry and 46 from Dougar quarry). It was shown that acceptable approximations can be found for each quarry to calculate CBR index from grain size curves, on one side, and from the values of six parameters, which were deemed to influence the CBR index value: mass percentage of particles finer that 80µm (C0,08mm), curvature and extension coefficients of the grain size curve (CUL et CCL), plasticity index (IP) and Proctor characteristics (wOPM et ρdOPM). Nevertheless, the formula established for a given site cannot be used for predicting CBR index on another site. This confirms that analyses should be made at the scale of a quarry. Lithostabilisation of Lam-Lam and Sindia laterites by adding 30% and 10% of sand from KeurMassar quarry, which aimed at reducing the plasticity index of these laterites, had the expected effect on plasticity, while conforming to granularity criteria. But the addition of sand on CBR index had contradicting effects, which should be further studied: decrease of CBR index for Lam-Lam laterite and increase of CBR index for Sindia laterite. The comparison of French and Brazilian standards showed that, despite slightly differing procedures, the results are globally equivalent. The biggest difference concerns CBR index, which is determined using different compaction energies and yields smaller values in Brazil. But the conditions put on materials are adapted to these values

Orientadores: Zigomar Menezes de Souza, Edson Eiji Matsura / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Agrícola / Made available in DSpace on 2018-08-22T04:49:55Z (GMT). No. of bitstreams: 1 Araujo_FernandoSilva_D.pdf: 5020372 bytes, checksum: af978a8271ef4c982fd82d0d223e486b (MD5) Previous issue date: 2012 / Resumo: É crescente a demanda global por fontes de energia renováveis, tais como o etanol, o qual no Brasil, possui como principal matriz energética a cultura da cana-de-açúcar. Neste contexto faz-se necessário a incorporação de novas tecnologias, como a mecanização da colheita, para o uso racional das áreas manejadas com cana-de-açúcar. O acúmulo superficial de resíduos vegetais da cana-de-açúcar na superfície do solo promove o enriquecimento das camadas superficiais com matéria orgânica bem como o incremento do intervalo hídrico ótimo, mitigando os efeitos da compactação do solo causados pelo tráfego de máquinas no sistema de cana colhida mecanicamente sem queima. Portanto, o objetivo deste trabalho foi estudar as alterações no comportamento físico e mecânico de um Latossolo Vermelho produzido pelo enriquecimento do conteúdo de matéria orgânica e, ainda, a capacidade dos resíduos vegetais acumulados na superfície do solo dissiparem cargas aplicadas sobre o mesmo, em áreas cultivadas com cana-de-açúcar colhidas com e sem queima. O projeto foi desenvolvido em três áreas cultivadas com cana-de-açúcar: 1- cana-de-açúcar sem queima e corte mecanizado, desde 1996 (com 16 anos de implantação do sistema de cana crua); 2- cana-de-açúcar sem queima e corte mecanizado, desde 2004 (com 8 anos de implantação do sistema de cana crua); 3- cana-de-açúcar com queima e corte manual, desde 1973 (cana queimada). Os atributos físicos avaliados foram: análise granulométrica, consistência do solo, densidade do solo, estabilidade de agregados, porosidade do solo e resistência do solo à penetração nas profundidades de 0,00-0,10 m, 0,10-0,20 m e 0,20-0,30 m. Determinou-se ainda o intervalo hídrico ótimo para desenvolvimento das plantas. Foram avaliadas as relações entre o teor de matéria orgânica e a compressibilidade do solo, as relações entre teor de matéria orgânica do solo e a umidade crítica para a compactação e as relações entre quantidade de resíduos vegetais na superfície e a densidade do solo obtida pelo teste Proctor. Os atributos de solo estudados apresentam estrutura de dependência espacial. O intervalo hídrico ótimo e ?p mostraram-se sensíveis as alterações ocorridas no solo em detrimento dos sistemas de manejo estudados. A área sob colheita manual da cultura da cana-de-açúcar apresentou menor valor de densidade crítica para o intervalo hídrico ótimo, sendo que a maior produtividade da cultura concentrou-se nas regiões de maior amplitude do intervalo hídrico ótimo e maior capacidade suporte de carga do solo / Abstract: An increasing global demand for renewable energy sources such as ethanol, which in Brazil, has as its primary energy matrix culture of sugar cane. In this context it is necessary to incorporate new technologies, mechanization of the harvest, for the rational use of managed areas with cane sugar. The accumulation of surface plant residues of sugar cane on the soil surface promotes the enrichment of the surface layers with organic matter as well as increasing the optimal water, mitigating the effects of soil compaction caused by machinery traffic on the system cane mechanically harvested without burning. Therefore, the aim of this work was to study the changes in physical and mechanical behavior of soil produced by enriching the content of organic matter, and also the ability of plant debris accumulated on the soil surface dissipate loads applied on it, in cultivated areas sugar cane harvested with and without burning. The project was developed in three areas cultivated with sugar cane: 1 - harvested with manual cutting and burning since 1973; 2 - mechanically harvested without burning since 2004 (8 years of implantation of sugarcane), 3 - mechanically harvested unburned since 1996 (16 years of implantation of sugarcane). The physical attributes were: particle size analysis, soil consistency, soil bulk density, and aggregate stability, soil porosity and soil resistance to penetration depths of 0.00 to 0.10 m, 0.10-0.20 me 0.20-0.30 m. It was determined the optimal water yet to identify the critical limits of soil density where resistance to penetration and aeration porosity are restrictive to plant development. We evaluated the relationship between the organic matter content and soil compressibility, the relationships between organic matter content and soil moisture critical for the compression and the relationship between the amount of crop residue on the surface and soil density obtained by the Proctor test. The soil attributes have studied the spatial dependence structure. The least limiting water range and ?p were sensitive to changes in the soil instead of studied treatments. The area under cultivation of manual harvesting cane sugar showed a lower value of the critical density for optimal water, and the greater crop concentrated in regions of higher altitude and lower load-bearing capacity / Doutorado / Agua e Solo / Doutor em Engenharia Agrícola

No description available.

Test generation procedures for large VLSI designs are required to achieve close to 100% fault coverage using a small number of tests. They also must accommodate on-chip test compression circuits which are widely used in modern designs. To obtain test sets with small sizes one could use extra hardware such as test points or use software techniques. An important aspects impacting test generation is the number of specified positions, which facilitate the encoding of test cubes when using test compression logic. Fortuitous detection or generation of tests such that they facilitate detection of yet not targeted faults, is also an important goal for test generation procedures. At first, we consider the generation of compact test sets for designs using on-chip test compression logic. We introduce two new measures to guide automatic test generation procedures (ATPGs) to balance between these two contradictory requirements of fortuitous detection and number of specifications. One of the new measures is meant to facilitate detection of yet undetected faults, and the value of the measures is periodically updated. The second measure reduces the number of specified positions, which is crucial when using high compression. Additionally, we introduce a way to randomly choose between the two measures. We also propose an ATPG methodology tailored for BIST ready designs with X-bounding logic and test points. X-bounding and test points used to have a significant impact on test data compression by reducing the number of specified positions. We propose a new ATPG guidance mechanism that balances between reduced specifications in BIST ready designs, and also facilitates detection of undetected faults. We also found that compact test generation for BIST ready designs is influenced by the order in which faults are targeted, and we proposed a new fault ordering technique based on fault location in a FFR. Transition faults are difficult to test and often result in longer test lengths, we propose a new fault ordering technique based on test enumeration, this ordering technique and a new guidance approach was also proposed for transition faults. Test set sizes were reduced significantly for both stuck-at and transition fault models. In addition to reducing data volume, test time, and test pin counts, the test compression schemes have been used successfully to limit test power dissipation. Indisputably, toggling of scan cells in scan chains that are universally used to facilitate testing of industrial designs can consume much more power than a circuit is rated for. Balancing test set sizes against the power consumption in a given design is therefore a challenge. We propose a new Design for Test (DFT) scheme that deploys an on-chip power-aware test data decompressor, the corresponding test cube encoding method, and a compression-constrained ATPG that allows loading scan chains with patterns having low transition counts, while encoding a significant number of specified bits produced by ATPG in a compression-friendly manner. Moreover, the new scheme avoids periods of elevated toggling in scan chains and reduces scan unload switching activity due to unique test stimuli produced by the new technique, leading to a significantly reduced power envelope for the entire circuit under test.

The widespread use of titanium and its alloys in structural applications has been limited to few highend applications. The dominant reason for this being cost implications. These high costs arise from extracting titanium from its mineral form as well as that of the manufacturing processes to develop a final product. Since producing titanium products includes expensive starting stock, high machinability costs and high wastage, a need for a process that may minimize one or more of these factors is necessary. One such technology that exists is a branch of powder metallurgy (PM), direct powder rolling (DPR) which allows for a continuous approach to produce strip or sheet metal. Products developed by this process are however known to possess inferior properties to its wrought counterpart. The present study comprises of a parametric study observing how two different blends of powder differ in the development of Ti-6Al-4V strip by employing the blended elemental (BE) approach to direct powder rolling. The objectives of this work include predicting the compaction behavior of the two respective blends during powder rolling to inform the production of high density green strip and to compare the outcomes of the prediction method to experimentally determined results using a gravity-fed laboratory-scale rolling mill with roll diameter of 265 mm and roll width of 150 mm. Johanson’s rolling theory was applied to predict rolling outcomes and a fixed set of rolling parameters were implemented for the simulation and experimental segment of this dissertation. The two blends being investigated include blending titanium powder with an elemental blend consisting of aluminium and vanadium powders (B1) and a master alloy blend of a 60Al-40V master alloy (B2). These two blends were used to validate the Johanson simulated rolling data. Fixed parameters applied to the rolling mill included using a roll speed of 14 rpm, roll face width of 65 mm and gravity-fed hopper outlet diameter of 25 mm. Variable roll gaps of 0.5, 1 and 1.5 mm were studied. Average relative green densities of B1 and B2 strips achieved at a roll gap of 1 mm were 77% and 73% respectively. Rolling performance of the B1 powder blend were higher than that of B2, reaching higher green densities and showing superior formability, as rolling at smaller roll gaps was achievable for B1 and not B2. Green strength of B1 and B2 strips at a roll gap of 1 mm reflected similar outcomes where B1 strips required a greater breaking load to fracture samples when compared to B2 indicating a stronger self-supporting compact. Furthermore, the Johanson rolling model proved to overestimate reasonable roll pressure values, although, the general trend of compactibility between B1 and B2 powder blends was reasonably predicted showing B1 to be more compressible than B2 during powder rolling. iv Subsequent sintering at 1200 °C for 3 hours in a vacuum environment was applied to green strips to further densify and homogenize strips. Average relative sintered densities achieved for B1 and B2 strips rolled at a roll gap of 1 mm were 78% and 87% respectively. While green densities of B1 strips were higher than that of B2 strips, it was evident that the addition of the 60Al-40V master alloy to blend B2 resulted in superior sinterability as final sintered densities surpassed that of B1, even when starting at a lower green density after rolling. SEM/EDX was used to evaluate what effect sintering had on homogenization. A standard wrought Ti-6Al-4V specimen was used as the benchmark to compare homogenization results. B2 strips homogenized more than B1 strips when comparing to the baseline wrought sample. It was concluded that both B1 and B2 powders used to create Ti-6Al-4V strip by direct powder rolling (DPR) exhibited high levels of porosity and a subsequent step is necessary to fully densify the material. While B1 strips exhibit superior rollability with higher green densities and green strength; after applying a sintering practice to both B1 and B2 strips, B2 sintered densities surpassed those of B1 and prove to homogenize to a greater degree than B1 strips. The superior roll compaction ability and inferior sinterability for B1 powders was attributed to the elemental powder, aluminium. While the addition of ductile aluminium to B1 aids roll compaction, its low melting point results in large pores evolving at sintering temperatures almost twice its melting point.

Purpose: Compaction is one of the fundamental pillars of construction, without a proper compaction of ground material deformation may occur shorty after completed construction. A flaw of the traditional method of compaction control is that only point sources are obtained. This means that you can easily miss weak points of the compaction. This becomes significant when dealing with compaction of larger areas. The purpose of this study is to investigate how digital technology can ensure the compaction quality compared to traditional methods, and to expand the company’s knowledge of the application of the compaction computer MCA-3000. Method: The method chosen to gather data for this study were literature study, case study and interviews. Findings: The findings show how the compaction computer can be used to ensure compaction quality. An important factor is to know the conditions of the ground material in order to ensure a credible result. The case study suggest that the compaction computer can be used to visually show the compaction quality of an area. However, I cannot be used as a separated method to ensure compaction quality. The compaction computer needs test surfaces to be calibrated with assistance of traditional methods. This means that it cannot replace the traditional method. However, it can be used as a complementary tool to support the traditional methods. In the interviews, both the respondents pointed out that the compaction computer cannot be used as a separate method but can be used as a complementary tool for the contractors.  Implications: Our conclusions are as followed: ·         The compaction computer cannot be used as a single method to ensure compaction quality. ·         The compaction computer implies that it can be used as a complementary tool to support the traditional methods to ensure compaction quality of lager areas.  ·         The compaction computer allows the user to detect faults in real time during the compaction prosses. Our results indicate that the compaction computer can be uses as a complementary tool to support the traditional methods but not as its own method. To ensure the reliability of the compaction computer MCA-3000 further studies needs to be conducted to see how it preform with different ground material condition.  Limitations: Our result was limited by access of data. We were only able to collet data from a single project in a relatively small area, this means we only were able to get three data sources of compaction quality conducted with a tradition method. Another limitation was that the entire area had the same ground condition which means the result is only applicable in our case.

The master thesis deals with the design of a light tandem roller with an electric drive. The final design of the machine is designed in regard to the knowledge from design and technical analysis and the shortcomings of current rollers. The purpose of this work is to design a tandem roller which will respect the ergonomic requirements of the operator.

<p><a>Voids in the mineral aggregate (VMA), as a main volumetric design parameter in the Superpave mixture design method, is an important factor to ensure asphalt mixture durability and rutting performance. Moreover, an asphalt mixture’s aggregate skeleton, related to VMA, is another important factor that affects critical asphalt mixture properties such as durability, workability, permeability, rutting, and cracking resistance. The objective of this study is to evaluate the effects of aggregate size distribution and shape parameters on aggregate packing characteristics (volumetric and compaction properties) of asphalt mixtures. Three tasks were undertaken to reach this goal. </a></p> <p>The first task was to propose an analytical approach for estimating changes in voids in the mineral aggregate (VMA) due to gradation variation and determining the relevant aggregate skeleton characteristics of asphalt mixtures using the linear-mixture packing model, an analytical packing model that considers the mechanisms of particle packing, filling and occupation. Application of the linear-mixture packing model to estimate the VMA of asphalt mixtures showed there is a high correlation between laboratory measured and model estimated values. Additionally, the model defined a new variable, the central particle size of asphalt mixtures that characterized an asphalt mixture’s aggregate skeleton. Finally, the proposed analytical model showed a significant potential to be used in the early stages of asphalt mixture design to determine the effect of aggregate gradation changes on VMA and to predict mixture rutting performance.</p> <p>As the second task, a framework to define and understand the aggregate structure of asphalt mixtures was proposed. To develop this framework, an analytical model for binary mixtures was proposed. The model considers the effect of size ratio and air volume between the particles on the aggregate structure and packing density of binary mixtures. Based on this model, four aggregate structures, namely coarse pack (CP), coarse-dense pack (CDP), fine-dense pack (FDP) and fine pack (FP), were defined. The model was validated using a series of 3D discrete element simulation. Furthermore, the simulation of multi-sized aggregate blends using two representative sizes for fine and coarse stockpiles was carried out to apply the proposed analytical model to actual aggregate blends. The numerical simulations verified the proposed analytical model could satisfactorily determine the particle structure of binary and multi-sized asphalt mixture gradations and could, therefore, be used to better design asphalt mixtures for improved performance. </p> <p>The third task virtually investigated the effect of shape characteristics of coarse aggregates on the compactability of asphalt mixtures using a discreet element method (DEM). The 3D particles were constructed using a method based on discrete random fields’ theory and spherical harmonic and their size distribution in the container was controlled by applying a constrained Voronoi tessellation (CVT) method. The effect of fine aggregates and asphalt binder was considered by constitutive Burger’s interaction model between coarse particles. Five aggregate shape descriptors including flatness, elongation, roundness, sphericity and regularity and, two Superpave gyratory compactor (SGC) parameters (initial density at N_ini and compaction slope) were selected for investigation and statistical analyses. Results revealed that there is a statistically significant correlation between flatness, elongation, roundness, and sphericity as shape descriptors and initial density as compaction parameter. Also, the results showed that the maximum percentage of change in initial density is 5% and 18% for crushed and natural sands, respectively. The results of analysis discovered that among all particle shape descriptors, only roundness and regularity had a statistically significant relation with compaction slope, and as the amount of roundness and regularity increase (low angularity), the compaction slope decreases. Additionally, the effect of flat and elongated (F&E) particles percentage in a mixture using a set of simulations with five types of F&E particles (dimensional ratios 1:2, 1:3, 1:4 and 1:5) and ten different percentage (0, 5, 10, 15, 20, 30, 40, 50, 80 and 100) with respect to a reference mixture containing particles with flatness and elongation equal to 0.88 was conducted. Results indicated that increase of F&E particles in a mixture (more than 15%) results in a significant reduction in the initial density of the mixture especially for lower dimensional ratio (1:4 and 1:5). <b><i></i></b></p> <br> <p> </p>