This paper presents results on experimental research for concrete produced using recycled coarse aggregates (RCA). Five types of coarse aggregates were used in this study, four of which were RCA. The main purpose of this research was to examine how different types and properties of coarse aggregate affected compressive strength, modulus of elasticity, and shrinkage in concrete when natural coarse aggregates were replaced with RCA. Concrete batches were made with water-cement (w/c) ratios of 0.30, 0.45, and 0.60, and substitution percentages ranged from 0% to 100% of natural aggregate with RCA. Test results clearly show that compressive strength, modulus of elasticity, and shrinkage greatly depend on the quality and type of coarse aggregate used. In addition to testing of hardened concrete, predictive models for elasticity and ultimate shrinkage were developed to formulate and reinforce proposed conclusions about the properties and performance for the different RCA.

Exploring the expressive abilities of overspunnen woollen-based knits . This project focused on the influence of over-spun woollen yarns in knitted material and the overall material quality. The use of over-twisted yarns focuses on the reactionary design and explores the colour rituals and patterns of the Igbo tribe in Nigeria. This exploration of heritage opened up new patterns and expressive material development methods with a regenerative alternative to fossil fuel-based elastics. The exploration was focused on the transformative possibilities of knitted textile tubes that interact with elasticity activated by the body. Furthermore, it is defined through technical knits and sensitivity to poetic aesthetics. This artistic and poetic expression is researched using colour and patterns. The colours used are based on the original colours utilized in Uli, a practice of body painting. The texture is inspired by the concept of ritual pollution, which is closely linked to the earth. The patterns are developed through drawings on the body employed in the Nigerian practice of Uli and then translated into jacquard knits. Close attention is paid to in conveying dynamics and movement by utilizing opaque and non-opaque areas, focusing on elastic and non-elastic properties. The results show a great range in conveying adaptive colour, textures, and interactive patterns for the body through woollen-based elastic yarns. This project showcases the great potential and encourages rethinking of elastic materials.

We work with two different mechanisms to generate geometric frustration on thin elastic sheets; isotropic differential growth and folding. We describe how controlled growth and prescribing folding patterns are useful tools for designing three-dimensional objects from information printed in two dimensions. The first mechanism is inspired by the possibility to control shapes by swelling polymer films, where we propose a solution for the problem of shape formation by asking the question, ``what 2D metric should be prescribed to achieve a given 3D shape?'', namely the reverse problem. We choose two different types of initial configurations of sheets, disk-like with one boundary and annular with two boundaries. We demonstrate our technique by choosing four examples of 3D axisymmetric shapes and finding the respective swelling factors to achieve the desired shape. Second, we present a mechanical model for a single curved fold that explains both the buckled shape of a closed fold and its mechanical stiffness. The buckling arises from the geometrical frustration between the prescribed crease angle and the bending energy of the sheet away from the crease. This frustration increases as the sheet's area increases. Stiff folds result in creases with constant space curvature while softer folds inherit the broken symmetry of the buckled shape. We extend the application of our numerical model to show the potential to study multiple fold structures.

We develop a coarse-grained model of lipids and proteins in which the lipids are modelled as diblock copolymers and the proteins as rigid cylinders. The generic protein model allows the possibility of amphipathic proteins with intrinsic curvature. Self-consistent field theory (SCFT) is used to determine the morphology of the lipid bilayer in the vicinity of the proteins. In particular, we focus on the case of a long transmembrane protein inserted perpendicular to the bilayer. For this system we use SCFT to determine the mechanical properties of the membrane and the thickness profile as a function of distance from the protein inclusion. The mechanical constants are also used in an elastic theory to predict the thickness profile. Good agreement between the full SCFT and elastic theory is obtained. We also use SCFT to determine systematic trends of the boundary conditions for the thickness profile at the protein interface. Such results could be used as boundary conditions for the description of bilayers using elastic theory. We show that this system undergoes a second order wetting transition as the interaction strength between the protein and membrane is varied. / Thesis / Master of Science (MSc)

Over the last 50 years significant advancements have been made in the southern yellow pine (SYP) forests in the U.S. south. Due to silvicultural changes and large scale reforestation efforts the US south has seen significant increases in standing volume (more than 120% over the period). Landowners that grow SYP plantations largely manage for trees that are harvested to produce dimensional lumber. With the changes in growth patterns it is of interest if there have been any changes in structural properties of the lumber that is produced from timber grown today. Landowners desire confirmation that what they are doing in terms of management is maintaining the quality and strength of lumber that the market demands. This information is critical because timberland owners’ plant and manage trees that will ultimately be brought to market at lumber 25-40 years into the future. In an effort to provide clarity to this topic this dissertation investigates: 1) The extent to which the specific gravity (SG), bending strength (modulus of rupture, MOR), and bending stiffness (modulus of elasticity, MOE) of small clear specimens of SYP have changed, particularly with respect to reduction(s), during the interval from approximately 1965 to 2015. 2) The extent to which the compression parallel to grain and perpendicular to grain strength of small clear specimens of SYP have changed, particularly with respect to reduction(s), during the interval from approximately 1965 to 2015. Use statistical analysis of variance to investigate potential differences among data from a historical 1966 data set, a 2014 in-grade data set, and a 2018 staircase material data set. 3) The nature of the relationship between and among SG, MOE, and MOR of small clear specimens of SYP and how these relationships may have changed, during the interval from approximately 1965 to 2015. Use statistical regression analysis to explore changes to the interrelationships of SG, MOE, and MOR among the three samples, with particular interest toward how these may impact or influence non-destructive evaluation. This work consists of 3 independent chapters using varying appropriate statistical methods and is accompanied by an introduction and conclusion.

This investigation focuses on the production, strength properties, and marketability of a new ultra stiff wood composite. The basis of the examination is to compare strength properties such as, Modulus of Rupture, Modulus of Elasticity, Work to Max Load, and Density with currently available products. The final analysis of the ultra stiff product suggested that this product would compete favorably in today’s market due to the strength properties of the product. Although the current hot-pressing method is not economical for mass production, other ways of pressing can be utilized. It is noted in this research that the wood moisture content can influence MOE, MOR, and density properties. By manipulating and controlling the press cycle and the moisture content, a competitive product was produced.

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<p>This thesis is composed of six chapters. First MRE is briefly introduced together with some relevant literature in Chapter one. The second chapter is about the principles and theory of magnetic resonance imaging, with the MRE theory, software and hardware addressed in Chapter 3. Chapters 4 and 5 describe the hardware design, software programming, experimental setup and elasticity reconstruction. Chapter 6 is a general discussion, introducing challenges and future directions.</p> <p>A vibration actuator and coil was designed and constructed, then combined with the necessary hardware required to induce the motion in the actuator. A Gradient Echo pulse sequence was modified using the Siemens IDEA environment for MRE application. A phantom was made with concentrations of 1%, 2%, and 3% agar gel.</p> <p>The phantom was scanned using the MRE sequence while inducing the propagating waves. Waves were selected to have frequencies of 125 Hz and 250 Hz. Magnitude and phase images acquired at these frequencies were used to construct the elasticity map using the MRE/Wave reconstruction software. Mean Shear Modulus measured in 1% gel cylinder is 10 kPa and standard deviation (SD) is 6 kPa. Mean elasticity value measured in 3% gel is 49 kPa and SD is 9 kPa. Mean value measured in the background which is 2% gel is 28 kPa and SD is 6 kPa. The results obtained are comparable to the values calculated in literature.</p> / Master of Applied Science (MASc)

PhD Thesis / In this thesis, experiments are described which study the elastocapillary interactions between liquids and taut solid films. The research employs contact angle measurements to elucidate how capillary forces deform compliant solid structures, but also to attain fundamental insight into the energy of interfaces involving amorphous solids. The majority of the work focuses on how capillary deformations of compliant elastic membranes introduce modifications to descriptions of common wetting phenomena. Particular focus is given to studying partial wetting in the presence of compliant membranes in various geometries: droplet on a free-standing membrane, droplet capped by a membrane but sessile on a rigid substrate, and droplet pressed between two free-standing membranes. The mechanical tension in these membranes is found to play an equivalent role as the interfacial tensions. As such, the mechanical tension is incorporated into Young-Dupre's law (capped droplet on a rigid substrate) or Neumann's triangle (droplet on free-standing membrane), leading to departures from the classical wetting descriptions. In addition, one study is conducted investigating how viscous dewetting is affected by the liquid film being capped by an elastic film. The results of this study show that the dewetting rate and rim morphology are dictated by the elastic tension. Another important aspect of the work is demonstrating the utility of anisotropic membrane tension for liquid patterning. A biaxial tension is shown to produce droplets and dewetting holes which are elongated along the high tension direction. The compliant membrane geometry can also be designed to produce droplets and holes with square morphology. In the final project, the surface energy of strained glassy and elastomeric solids is studied. Glassy solids are shown to have strain-dependent surface energies, which implies that surface energy (energy per unit area) and surface stress (force per unit length) are not equivalent for this class of materials by virtue of the Shuttleworth equation. On the other hand, this study provides strong evidence that surface energy and surface stress are equivalent for elastomeric interfaces. / Thesis / Doctor of Philosophy (PhD)