O conhecimento da resistência ao dano por choque térmico de materiais refratários é uma das características mais importantes para determinar seu desempenho em muitas aplicações, pois quando os refratários são submetidos a abruptas e severas variações de temperatura, estes podem sofrer danos. A resistência ao dano por choque térmico de um material pode variar com o tamanho de grão, com o tipo e valor da tensão, com a taxa de carregamento e com outras condições de aplicação da tensão, ou seja, não é uma propriedade intrínseca do material. Os métodos correntemente utilizados para prever o comportamento da resistência ao dano por choque térmico são baseados nos trabalhos de Hasselman, responsável pelo estudo da determinação dos parâmetros de resistência ao choque térmico, R (oC), o parâmetro de resistência ao dano por choque térmico R\'\'\'\' (m), e o parâmetro de estabilidade da trinca sob tensão térmica Rst (m1/2.oC). As equações previstas por ele levam em consideração o módulo de Young, o módulo de ruptura, a energia de fratura e o coeficiente de expansão térmica do material a ser analisado. A resistência ao dano por choque térmico pode ser avaliada por meio de ciclos térmicos, isto é, sucessivos testes de aquecimento e subseqüente resfriamento, com análise da queda do módulo de Young a cada ciclo. Para prever e avaliar a resistência ao dano por choque térmico, amostras de um concreto refratário comercial fornecido pela IBAR (Indústrias Brasileiras de Artigos Refratários), foram sinterizadas a 1000ºC e 1450ºC por cinco horas. Essas temperaturas foram definidas em virtude de o concreto em questão apresentar agregados de andaluzita, que sofrem mulitização após 1280ºC. Logo esse concreto exibe um comportamento distinto em função da temperatura de tratamento térmico, pois seu agregado pode se transformar em mulita e sílica. Para esse estudo, amostras prismáticas sinterizadas a 1000ºC e 1450ºC, foram submetidas a ciclos de choque térmico, permanecendo 20 minutos no forno com temperatura de 1000ºC e subseqüente resfriamento em água circulante a 25ºC. Também foram realizadas análises de porosidade aparente, de absorção de água, de massa específica aparente, de difração de raios X e microscopia eletrônica de varredura. Foi verificado que os parâmetros de Hasselman previram que o refratário sinterizado a 1450ºC apresentaria menor resistência ao choque térmico, previsão esta confirmada pelos testes experimentais. Sendo assim é importante avaliar o comportamento do concreto refratário desde a temperatura ambiente até a temperatura de trabalho, a fim de que se conheçam todas as mudanças envolvidas, e que sejam evitados problemas que possam gerar prejuízos na instalação industrial e ao processo pertinente à sua aplicação. / The thermal shock resistance of refractory materials is one of the most important characteristics that determine their performance in many applications, since abrupt and drastic differences in temperature can damage them. A material1s thermal shock resistance may vary according to grain size, the type and intensity of the stress to which it is subjected, the loading rate, and other loading conditions; hence, this resistance is not an intrinsic property of the material. The method currently employed to predict thermal shock behavior is based on the work of Hasselman, whose studies involved the determination of the parameters of thermal shock resistance, R (ºC), thermal shock damage resistance, R\"\" (m), and thermal stress crack stability, Rst (m1/2.ºC). Hasselman\'s equations take into consideration Young\'s modulus, the modulus of rupture, the energy at fracture and the coefficient of thermal expansion of the material under analysis. Resistance to thermal shock damage can be evaluated based on thermal cycles, i.e., successive heating and cooling cycles followed by an analysis of the drop in Young\'s modulus occurring in each cycle. In the present study, samples of a commercial refractory produced by IBAR (Indústrias Brasileiras de Artigos Refratários) were sintered at 1000ºC and 1450ºC for 5 hours to predict and evaluate their thermal shock resistance. These temperatures were chosen because this refractory contains andalusite aggregates that become mullitized at temperatures above 1280ºC. Therefore, this castable displays a particular behavior as a function of the heat treatment temperature, since its aggregates can transform into mullite and silica. In this study, prismatic samples from each sintering temperature were subjected to thermal shock cycles, soaking in the furnace for 20 minutes at a temperature of 1000ºC, and subsequent cooling in circulating water at 25ºC. Apparent porosity, water absorption, apparent density, X-ray diffraction and scanning electron microscopy analyses were also performed. It was found that Hasselman\'s parameters predicted that the refractory sintered at 1450ºC would show lower thermal shock resistance than the refractory sintered at 1000ºC, a prediction that was confirmed by the results of the thermal shock tests. Hence, is important to evaluate the behavior of refractory castables from ambient temperature to working temperature in order to be aware of all the changes that occur, thus avoiding problems leading to losses in industrial installations and in the processes involved in the specific applications of these refractories.

O conhecimento da resistência ao dano por choque térmico de materiais refratários é uma das características mais importantes para determinar seu desempenho em muitas aplicações, pois quando os refratários são submetidos a abruptas e severas variações de temperatura, estes podem sofrer danos. A resistência ao dano por choque térmico de um material pode variar com o tamanho de grão, com o tipo e valor da tensão, com a taxa de carregamento e com outras condições de aplicação da tensão, ou seja, não é uma propriedade intrínseca do material. Os métodos correntemente utilizados para prever o comportamento da resistência ao dano por choque térmico são baseados nos trabalhos de Hasselman, responsável pelo estudo da determinação dos parâmetros de resistência ao choque térmico, R (oC), o parâmetro de resistência ao dano por choque térmico R\'\'\'\' (m), e o parâmetro de estabilidade da trinca sob tensão térmica Rst (m1/2.oC). As equações previstas por ele levam em consideração o módulo de Young, o módulo de ruptura, a energia de fratura e o coeficiente de expansão térmica do material a ser analisado. A resistência ao dano por choque térmico pode ser avaliada por meio de ciclos térmicos, isto é, sucessivos testes de aquecimento e subseqüente resfriamento, com análise da queda do módulo de Young a cada ciclo. Para prever e avaliar a resistência ao dano por choque térmico, amostras de um concreto refratário comercial fornecido pela IBAR (Indústrias Brasileiras de Artigos Refratários), foram sinterizadas a 1000ºC e 1450ºC por cinco horas. Essas temperaturas foram definidas em virtude de o concreto em questão apresentar agregados de andaluzita, que sofrem mulitização após 1280ºC. Logo esse concreto exibe um comportamento distinto em função da temperatura de tratamento térmico, pois seu agregado pode se transformar em mulita e sílica. Para esse estudo, amostras prismáticas sinterizadas a 1000ºC e 1450ºC, foram submetidas a ciclos de choque térmico, permanecendo 20 minutos no forno com temperatura de 1000ºC e subseqüente resfriamento em água circulante a 25ºC. Também foram realizadas análises de porosidade aparente, de absorção de água, de massa específica aparente, de difração de raios X e microscopia eletrônica de varredura. Foi verificado que os parâmetros de Hasselman previram que o refratário sinterizado a 1450ºC apresentaria menor resistência ao choque térmico, previsão esta confirmada pelos testes experimentais. Sendo assim é importante avaliar o comportamento do concreto refratário desde a temperatura ambiente até a temperatura de trabalho, a fim de que se conheçam todas as mudanças envolvidas, e que sejam evitados problemas que possam gerar prejuízos na instalação industrial e ao processo pertinente à sua aplicação. / The thermal shock resistance of refractory materials is one of the most important characteristics that determine their performance in many applications, since abrupt and drastic differences in temperature can damage them. A material1s thermal shock resistance may vary according to grain size, the type and intensity of the stress to which it is subjected, the loading rate, and other loading conditions; hence, this resistance is not an intrinsic property of the material. The method currently employed to predict thermal shock behavior is based on the work of Hasselman, whose studies involved the determination of the parameters of thermal shock resistance, R (ºC), thermal shock damage resistance, R\"\" (m), and thermal stress crack stability, Rst (m1/2.ºC). Hasselman\'s equations take into consideration Young\'s modulus, the modulus of rupture, the energy at fracture and the coefficient of thermal expansion of the material under analysis. Resistance to thermal shock damage can be evaluated based on thermal cycles, i.e., successive heating and cooling cycles followed by an analysis of the drop in Young\'s modulus occurring in each cycle. In the present study, samples of a commercial refractory produced by IBAR (Indústrias Brasileiras de Artigos Refratários) were sintered at 1000ºC and 1450ºC for 5 hours to predict and evaluate their thermal shock resistance. These temperatures were chosen because this refractory contains andalusite aggregates that become mullitized at temperatures above 1280ºC. Therefore, this castable displays a particular behavior as a function of the heat treatment temperature, since its aggregates can transform into mullite and silica. In this study, prismatic samples from each sintering temperature were subjected to thermal shock cycles, soaking in the furnace for 20 minutes at a temperature of 1000ºC, and subsequent cooling in circulating water at 25ºC. Apparent porosity, water absorption, apparent density, X-ray diffraction and scanning electron microscopy analyses were also performed. It was found that Hasselman\'s parameters predicted that the refractory sintered at 1450ºC would show lower thermal shock resistance than the refractory sintered at 1000ºC, a prediction that was confirmed by the results of the thermal shock tests. Hence, is important to evaluate the behavior of refractory castables from ambient temperature to working temperature in order to be aware of all the changes that occur, thus avoiding problems leading to losses in industrial installations and in the processes involved in the specific applications of these refractories.

The finite element method (FEM) has been widely applied to various medical imaging applications over the past two decades. The remarkable progress in high-resolution imaging techniques has allowed FEM to draw great research interests in computing trabecular bone (TB) stiffness from three-dimensional volumetric imaging. However, only a few results are available in literature on applying FEM to multi-row detector CT (MDCT) imaging due to the challenges posed by limited spatial resolution. The research presented here develops new methods to preserve TB structure connectivity and to generate high-quality mesh representation for FEM from relatively low resolution images available at MDCT imaging. Specifically, it introduced a space-variant hysteresis algorithm to threshold local trabecular structure that preserves structure connectivity. Also, mesh generation algorithms was applied to represent TB micro-architecture and mesh quality was compared with that generated by traditional methods. TB stiffness was computed using FEM simulation on micro-CT (µ-CT) and MDCT images of twenty two cadaveric specimens of distal tibia. Actual stiffness of those specimens were experimentally determined by mechanical testing and its correlation with computed stiffness was analyzed. The observed values of linear correlation (r2) between actual bone stiffness and computed stiffness from µ-CT and MDCT imaging were 0.95 and 0.88, respectively. Also, reproducibility of the FEM-based computed bone stiffness was determined from repeat MDCT scans of cadaveric specimens and the observed intra-class correlation coefficient was a high value of 0.98. Experimental results demonstrate the feasibility of application of FEM with high sensitivity and reproducibility on MDCT imaging of TB at distal tibia under in vivo condition.

Nanoindentation is a method of contacting a material whose mechanical properties are unknown with another material whose properties are known. Nanoindentation has the advantage of being able to probe a material’s microstructure while being sensitive enough to detect variations in mechanical properties. However, nanoindentation has some limitations as a testing technique due to the specific formation and structure of some biomaterials. The main objective of this research is to identify any factors that influence the nanoindentation measurement of wood cell walls (a typical biomaterial). The function of the embedding media in describing the properties of wood cells is poorly understood. This research demonstrated that Spurr’s resin, when diffused into wood cell wall during the embedding process, enhanced both the Young’s modulus and hardness of the cell walls. A substitute sample preparation method was developed to avoid this resin penetration into cell wall and was determined to be both effective and easy to perform. The nanoindentation procedure involves the application of a monitor and an analysis of the load-displacement behavior and the response in the material. It can be anticipated that various ways of loading, including the maximum force, the loading time, and others, will cause a variety of mechanical properties. Thus, our second aim was to study the effect of load function on nanoindentation measurement in wood. It was discovered that a fast loading rate contributed to greater contact depth and lower hardness. Increasing the holding time decreased measured values for both Young’s modulus and hardness. However, no significant difference of Young’s modulus and hardness among three loading functions with different unloading rates. The final part of the research was to study the effect of moisture content on the micromechanical properties of wood material. Several nanoindentations were performed on the wood cell wall while varying the moisture content of wood. Results indicated that both the Young’s modulus and hardness decreased significantly with an increase of moisture content. A rheology model was developed to describe the nanoindentation behaviors of wood cell walls at different moisture contents. Five parameters were extracted from Burger’s model, and the relationships among those five parameters were quantified.

Materials derived from chicken feathers could be used advantageously in composite building material applications. Such applications could potentially consume the five billion pounds of feathers produced annually as a by-product of the U.S. poultry industry. To aid the development of successful applications for chicken feather materials (CFM), the physical and mechanical properties of processed CFM have been characterized in this research. Results describing the moisture content, aspect ratio, apparent specific gravity, chemical durability, Youngs modulus, and tensile strength for processed CFM and specifically their fiber and quill components are presented herein. Processed chicken feather fiber and quill samples were found to have similar moisture contents in the range of 16 - 20%. The aspect ratio (i.e., length/diameter) of samples were found to be in the range of 30 - 50, and the fiber material was found to have a larger aspect ratio than the quill material. A comparison with values in the literature suggests that different processing regimes produce CFM with higher aspect ratios. Samples were found to have apparent specific gravities in the range of 0.7 - 1.2, with the fiber material having a higher apparent specific gravity than the quill material. A comparison with values in the literature suggests that apparent specific gravity results vary with fiber length and approach the value for keratin as fiber length decreases and internal voids become increasingly accessible. Chemical durability results showed that CFM rapidly degrade in highly alkaline (pH=12.4) environments and are, thus, likely incompatible with cement-based materials without special treatment. The Youngs modulus of processed chicken feather materials was found to be in the range of 3 - greater than 50 GPa and, thus, comparable to the Youngs moduli of other natural fibers. The tensile strength of oven-dried samples was found to be in the range of 10 - greater than 70 MPa. In agreement with results in the literature, the fiber material was found to have a greater tensile strength than the quill material. Finally, a simplified approach for comparing the effective Youngs moduli and effective tensile strengths of various processed CFM samples was introduced.

Nanoindentation is a method of contacting a material whose mechanical properties are unknown with another material whose properties are known. Nanoindentation has the advantage of being able to probe a material’s microstructure while being sensitive enough to detect variations in mechanical properties. However, nanoindentation has some limitations as a testing technique due to the specific formation and structure of some biomaterials. The main objective of this research is to identify any factors that influence the nanoindentation measurement of wood cell walls (a typical biomaterial).The function of the embedding media in describing the properties of wood cells is poorly understood. This research demonstrated that Spurr’s resin, when diffused into wood cell wall during the embedding process, enhanced both the Young’s modulus and hardness of the cell walls. A substitute sample preparation method was developed to avoid this resin penetration into cell wall and was determined to be both effective and easy to perform.The nanoindentation procedure involves the application of a monitor and an analysis of the load-displacement behavior and the response in the material. It can be anticipated that various ways of loading, including the maximum force, the loading time, and others, will cause a variety of mechanical properties. Thus, our second aim was to study the effect of load function on nanoindentation measurement in wood. It was discovered that a fast loading rate contributed to greater contact depth and lower hardness. Increasing the holding time decreased measured values for both Young’s modulus and hardness. However, no significant difference of Young’s modulus and hardness among three loading functions with different unloading rates.The final part of the research was to study the effect of moisture content on the micromechanical properties of wood material. Several nanoindentations were performed on the wood cell wall while varying the moisture content of wood. Results indicated that both the Young’s modulus and hardness decreased significantly with an increase of moisture content. A rheology model was developed to describe the nanoindentation behaviors of wood cell walls at different moisture contents. Five parameters were extracted from Burger’s model, and the relationships among those five parameters were quantified.

The liquefaction resistance of undisturbed soil samples collected from a selected location in Carbondale, Southern Illinois was evaluated by conducting cyclic triaxial tests. Index property tests were carried out on the sample for identification and classification of the soil. Cyclic triaxial tests were conducted on undisturbed sample after saturation, undisturbed sample at natural water content and remolded samples prepared by compaction in the lab. The results were used to evaluate the effect of saturation and remolding on liquefaction resistance of the local soil. Effect of effective confining pressure on dynamic properties of soil (Young's Modulus and Damping ratio) was also studied. Forty five stress controlled cyclic triaxial tests were performed. Three different values of initial effective confining pressure (5 psi, 10 psi and 15 psi) were used and cyclic stress ratio was varied from 0.1 to 0.5 in order to apply different cyclic shear stresses. The results show that the cyclic load resistance of soil decreases as a result of remolding. Saturated undisturbed samples show increase in resistance to liquefaction with increase in initial confining pressure. Remolded samples were prepared by compaction in the lab keeping unit weight and water content equal to that of undisturbed samples. Remolded samples show increase in liquefaction resistance with increase in confining pressure. Undisturbed samples at natural water content show increase in resistance to develop axial strain with increase in confining pressure. Both the rate of excess pressure development and axial strain development increase significantly as a result of remolding. While investigating the effect of saturation of undisturbed samples on liquefaction resistance of soil, interesting observations were made. The excess pressure buildup rate was faster in case of saturated undisturbed samples compared to that in samples with natural water content. On the other hand, rate of strain development was significantly high in case of sample with natural water content compared to that in saturated sample. Also, results obtained from cyclic triaxial tests on saturated undisturbed samples were compared with results obtained from similar tests on Ottawa Sand (Lama 2014) sample. The comparison shows that the saturated undisturbed soil samples of the selected local soil have very high resistance to liquefaction both in terms of initial liquefaction and development of 2.5% and 5% axial strain. Modulus of Elasticity and damping ratio were studied as important dynamic properties of soil. Young's Modulus was observed to decrease significantly at higher strain levels for all three types of samples. Young's modulus increased with increase in effective confining pressure, the effect of confining pressure being large at low strain level and almost insignificant at higher strain level. Damping ratio was highest in undisturbed sample at natural water content and smallest in remolded sample and damping ratio for saturated undisturbed sample falls in between. The damping ratio did not show any definite correlation with strain and confining pressure at lower strain level. But, for strain higher than 1% double amplitude axial strain, damping ratio significantly decreases with increase in strain. Damping ratio increases with increase in confining pressure as observed at high strain for all samples.

Microfibrillated cellulose (MFC) is an alternative material that has been widely studied to enhance the mechanical properties of a polymer matrix due to a number of perceived advantages over traditional plant fibre forms. Mechanical properties of MFC networks were found to depend on parameters such as the modulus of fibrils, bonding strength, porosity, degree of crystallinity, contact area of fibrils and possibly the modulus of the cellulose crystals of the raw materials (cellulose I or II). Even though the longer processing time used to produce MFC was found to yield networks with fewer fibre aggregates, finer fibrils and higher density, some properties, for instance thermal stability and degree of crystallinity, decreased due to the degradation of fibrils caused by the harsh treatment. The aims of this thesis were to assess the mechanical properties and interfaces of composites produced using of a range of MFC materials, prepared using different treatments and from different sources. Raman spectroscopy has been used to detect the molecular orientation of cellulose chains within an MFC network, and to monitor the deformation micromechanics of MFC networks. The Raman band initially located at ~1095 cm-1 obtained from MFC networks was observed to shift towards a lower wavenumber position upon the application of tensile deformation. The intensity of this band as a function of rotation angle of MFC networks was similar, indicating randomly oriented networks of fibrils. From the Raman band shift rate data, the effective moduli of MFC single fibrils produced from pulp were estimated to be in the range of 29-41 GPa. Poly(lactic acid) (PLA) composites reinforced with MFC networks were prepared using compression moulding. Enhanced mechanical properties of MFC reinforced composites were reported, compared to neat PLA films. The mechanical properties of these composites were found to mainly depend on the interaction of the PLA matrix and the reinforcement phase. The mechanical properties of the composites reinforced with dense networks were shown to be dominated by the network properties (fibril-fibril interactions), while matrix-fibril interactions played a major role where more opened networks were used to reinforce a polymer matrix. The penetration of the matrix into the network was found to depend on the pore sizes, fibre width and porosity within the network. It was found that the matrix easily penetrates into the network with a range of mean fibril dimensions, rather than for networks with only fine fibrils present. The stress-transfer process in MFC reinforced PLA composites was monitored using Raman spectroscopy. Greater Raman band shift rates with respect to tensile deformation for the composites were observed compared to pure MFC networks. This indicates that stress is transferred from the PLA matrix to MFC fibrils, supporting the enhancement of the mechanical properties of the composites.

A pavement construction designed to cope with the different type of traffic loads; it is exposed to and at the same time it can resist the effect of the climate. A road structure consists of sub- and superstructure which is divided by a boundary known as terrace. During the construction of unbound layers (base course and sub-base course) in the superstructure, it is always ensured that the material meet the requirements for bearing capacity and the degree of compaction. These parameters are controlled by various laboratory tests and control methods. To obtain increased knowledge of the material and improve the quality of the compaction in the field, it is necessary to perform laboratory tests in order to determine material properties. A base course material 0/ 32 mm limestone from Gotland (Hejdeby) was investigated in this study. To determine properties of the material various laboratory tests such as proctor compaction test, Micro-Deval, Los Angeles, and grain distribution curve are conducted. To investigate how grain size distribution affects technical properties of the material, the 0/32 mm material was modified with two different samples; grain size distribution of 2/32 mm excluding superior material content, and 0+/32 mm with enhanced superior material content. The purpose of this study was to examine changes in material behavior during proctor compaction. Two aspects of changes in material behavior were emphasized in this study; the optimal water content and maximum dry density, as well as changes of both. As a reference for the limestone features, a traditional 0/32 mm tonalite material (granite) from Vällstaverket was used relating to proctor investigation. Material's resistance to abrasion and fragmentation was investigated by two methods: Micro-Deval and Los Angeles. The results were compared with other rock materials. Furthermore the bearing capacity of the material was verified by examination of the Young's modulus and degree of compaction, as well as properties of water content and dry density, at three trial areas on Gotland. This is performed with various methods such as static plate loading test, light weight deflectometer, density gauge/SDG200, and water/sand volume meter measurement test. By comparing results from different methods of measurement, it may indicate a relationship between these. Test area 3 consists of two smaller test areas which have different water content. The bearing capacity (Young's modulus) and the degree of compaction were measured after each roller passage. Different relationships were obtained between the amount of roller overpass, with Young's modulus of material; as well as degree of compaction. It was found in this study that limestone from Gotland (Hejdeby) maintain its position as construction material for the unbound layers of the road. The result from static plate load which indicated high E V2 values (Young's modulus) was obtained from the field, and it suggests that a fine bearing capacity can be achieved in the use of limestone.

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