The goal of this project is to contribute to the development of design values for cross-laminated timber (CLT) diaphragms in the seismic load-resisting system for buildings. Monotonic and cyclic tests to determine strength and stiffness characteristics of 2.44 m (8 ft) long shear connections with common self-tapping screws were performed....
Prepreg is widely used in composite manufacturing with advanced composites such as carbon and aramid. The material is characterized by a degree of flexibility (drape) and stickiness (tack), which allows an efficient layup on molds with complex shapes. However, axial instability of compressed fibers during the molding process may occur,...
This thesis explores the use of human kinesthetic input to advance robotic grasp planning. It specifically focuses on identification of human heuristics of grasp similarity by extensive human-subject experiments. This heuristic is then utilized to develop a robust metric for identifying similar robotic grasps. The central hypothesis of this work...
CSS-1H is the most commonly used slow-setting emulsion grade in Oregon. “New” engineered emulsions were recently developed in Oregon to reduce tracking, the pick-up of tack coats by construction vehicle tires during construction activities, and increase interlayer shear strength (ISS), the amount of adhesive bond present between layers of asphalt...
Most of existing commercial unsaturated polyester (UPE) resins are typically composed of a UPE and a high amount of highly volatile, flammable, and toxic styrene. The emission of hazardous styrene in the handling of the UPE resins and the preparation and use of fiber-reinforced UPE composites poses severe hazards to...
Duplex stainless steels (DSS) are an attractive potential material in nuclear power generation systems due to an excellent combination of corrosion resistance, strength, toughness, and affordability. Thermal embrittlement caused by phase instability in the temperature range of ~300-550°C severely limits the service temperature of DSS. The rate of embrittlement varies...
Concrete is the most widely used construction material in the world. When constructing large concrete structures, concrete may have to be placed in multiple lifts. In these cases, fresh concrete is placed on hardened concrete. The interface that is formed between these two lifts of concrete is known as a...
Variations in heat treatments have significant effects on the microstructure of tool steels. For CPM-M4 tool steel, the changes in microstructure and mechanical properties were observed based off of variations in temperature. Five heat treatments with constant exposure time and variable austenitizing and tempering temperatures were performed on samples of...
Mechanical property degradation due to isothermal ageing is of potential concern for alloys based on the Ni-Cr binary system (e.g., Inconel 690, 625), particularly in nuclear power applications where component lifetimes can exceed 40 years. In the present research, the disorder-order phase transformation, which is the primary mechanism of ageing,...
Today nano scale materials are being used for wide range of applications. One promising topic in nano scale materials is using them for reinforcement of different polymeric materials to reach desirable stiffness properties. The stiffness of these materials is mostly found experimentally because the nanocomposite community lacks a decent analytical...
Metal-organic frameworks (MOFs) represent an exciting, new class of porous materials. Their hybrid organic-inorganic structure opens up near infinite possibilities to tune and design their structure for specific properties and applications. A new generation of flexible MOFs, following a generation of stiff MOFs, has created additional design space and complexity....
Polylactic acid (PLA), a renewable material, is used widely in a variety of commercial and specialty applications. However, certain limitations such as high temperature stability and brittleness limit its applicability. This problem is addressed by reinforcing PLA with a variety of materials but the process gives rise to different issues...
Total US lumber production in 2011 was 77.9 million cubic meters. Its primary use was for housing and construction. There is a growing concern that the structural properties for wood are being reduced as trees are harvested at much younger ages as the wood supply shifts from older to younger...
Anterior cruciate ligament injuries are relatively common in female athletes with greater frontal plane knee motion and loading during a landing task predictive of injury. As a result, decreasing knee abduction motion and loading is important for ACL injury prevention. While increased strength of the hip abductors, extensors, and external...
Understanding the effect on the materials mechanical properties from the perspective of interfacial interaction between the filler and the polymer matrix has become an important criterion in polymer nanocomposites field. Cellulose nanocrystals (CNCs) are renewable materials that can be extracted from natural sources, such as wood, cotton, and tunicates. In...
As people learn new concepts, they experience a process termed conceptual change. There are several theories that attempt to explain conceptual change, and this paper uses the framework theory to explain how students learn mechanics of materials. Semi-structured interviews with ninety students were qualitatively analyzed for this research in an...
Wheat (Triticum aestivum) is a globally traded staple food crop. The diverse and pleasing nature of wheat-derived products is a result of the complex interactions of the polymeric components from the wheat endosperm. Changes in the functionality of these polymeric components, as a result of changes in growing conditions or...
Anterior cruciate ligament injuries are common in a wide variety of sports and most frequently occur during activities requiring rapid deceleration such as landing and cutting. Deceleration of the body's center of mass during movement results primarily from eccentric muscle contraction. This type of contraction serves to absorb energy from...
Cast-in-drilled-hole (CIDH) piles are often constructed to depths that are inaccessible to internal vibration of the concrete. Internal vibration is necessary to consolidate the concrete and, if not performed, then typically inspection pipes are necessary to detect the presence of voids in CIDH piles. Void detection is critical to assessing...
The development and some applications of holographic optical tweezers (HOT) are presented. Our HOT system uses a spatial light modulator (SLM) to control the location and properties of the optical trap. We have developed a method for optimizing the diffraction efficiency of a SLM that can be applied in situ...
This thesis explores the development of biomechanical models for evaluating a new class of passive mechanical implants for orthopedic surgery. The proposed implants take the form of passive engineered mechanisms and will be used to improve the functional attachment of muscles to tendons and bone by modifying the transmission of...
CPM-M4 tool steel is a commonly used knife blade material due to its high strength and wear resistance. The goal of this thesis is to understand how heat treatment parameters affect blade performance and microstructure.Five heat treatments were applied to CPM-M4 steel by varying austenitizing and tempering temperatures. The microstructures...
Bipedal locomotion is a complex phenomenon to understand and control, making it difficult for legged robots to achieve the speed, agility, efficiency, and robustness of their animal counterparts. This thesis argues for the use of numerical optimization to investigate and implement bipedal control as it applies to biology, dynamical models,...
The ability to engineer stiffness and strength in any desired direction make composites an ideal material candidate for various applications when compared to their traditional isotropic counterparts. In spite of this, the ability to model the material response in composites has yet to be fully explored. Composite research largely focuses...
The collapse of the I-35W Bridge in Minneapolis, MN in 2007 prompted an investigation into the design and inspection of the steel truss bridges. Further investigation into the collapse revealed that a gusset plate experienced sway buckling, causing the bridge failure. This bridge failure motivated research into the analysis and...
The mechanical performance of composite materials is determined by the mechanical properties of their individual components and the effective load transfer between these components. Binders are commonly used to bond composite components together and to provide effective load transfer between them. In wood-based composites the binder-component load transfer occurs at...
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Lech Muszyński
The mechanical performance of composite materials is determined by the
Most specifications for ready-mix concrete (RMC) limit mixing time to 90 minutes and/or truck drum revolution counts (DRC) to 300 before discharge. These specifications have been in place for many years with the objective of ensuring the quality and performance of the finished concrete product. However, limited research has been...
Dental resin composites are widely used in modern dentistry due to their aesthetic appearance. However, resin based restorations have inferior mechanical properties (fracture is the second reason for restorations replacement) in comparison to alloy based composites and their antimicrobial properties still remain poor, leading to secondary tooth decay development on...
This thesis presents the results of quantum-mechanical first principles calculations
of optical, electronic and mechanical properties of organic molecules and solids, which have
diverse potential applications such as photovoltaics, flexible electronics, and mechanical
catalysts with applications in force sensors and self-healing materials.
The electronic and optoelectronic properties of organic thin...
Whale blubber is the insular tissue layer located between the dermis and the superficial fascia layer which sheathes the whale's musculature. It is made up of a lipid matrix ramified with strong, structural collagen and elastic fiber bundles, but little is known of its mechanical properties. Knowing these properties adds...
Development of micro air vehicles has led to a strong interest in the biomechanics of flapping fliers such as bats, birds, and insects, due to their ability to perform extreme unsteady maneuvers and fly in confined spaces. Determining the methods and mechanisms used by these fliers is a valuable source...
Identifying material characteristics of composites is important in designing any
structural system. The aerospace industry relies on these material properties not only to
design a functional aircraft, but also a safe and reliable one. Since carbon fiber
composites are relatively new materials, little is known about its characteristics under
certain...
Bulk metallic glasses (BMGs) offer a great deal of potential through their near-theoretical strength, potentially high toughness and unique forming and molding traits. However, there are still a number of outstanding issues that bar their widespread use. This thesis describes the investigation of three research questions each designed to further...
In the field of civil infrastructure, bridge desks are typically constructed using high performance concrete (HPC). Concrete bridge decks demand qualities such as low permeability, high abrasion resistance, superior durability, and long design life. Over decades of field and laboratory experience, many HPC bridge decks have been found to be...
A lightweight carbon fiber reinforced polymer (CFRP) c-channel beam was previously designed using analytical theory and finite element analysis and subsequently manufactured through a pultrusion process. Physical testing revealed the prototype did not meet the bending and torsional stiffness of the beam model. An investigation revealed that the manufactured prototype...
Favorable properties of Balsa wood make it an interesting alternative in a number of
applications including thermal insulation or as a lightweight core material in
sandwich composites. Increasing use in construction necessitates a better
understanding of its mechanical and failure properties. In the present work, mode I
and mode II...
Identifying material parameters in composite plates is a necessary first step in a variety of structural applications. For example, understanding the material parameters of carbon fiber composite is important in investigating sensor and actuator placement on micro-air-vehicle wings for control and wing morphing purposes. Knowing the material parameters can also...
Polymeric composites reinforced with bio-materials have advantages over composites with synthetic reinforcements. Bio-based composites use low-cost and renewable reinforcements, have nonabrasive properties for machining, have improved damping characteristics, and have potential for energy recycling. However, the limited use of bio-based composites is because their mechanical properties are typically much lower...
Engineers, in practice, are often faced with the challenge of evaluating a fire-damaged structure and developing a rehabilitation and retrofit plan. In order to decide on a rehabilitation and retrofit plan, information on thermal degradation of building materials and connections are vital. A critical knowledge gap exists in terms of...
Moisture intrusion in residential structures can lead to substantial fungal decay and this damage costs billions in repair/replacement costs. The extent of damage and the rate at which it occurs are primarily dependent on the wood moisture content and temperature in the structure. Determining the risk of decay for various...
Different specimen preparation methods such as moist tamping, dry funnel deposition, slurry deposition, dry air pluviation have been reported in the literature to investigate the undrained behavior of silty sands. Similarly, different means have been used to densify the soils prepared with such methods. However, the influence of the densification...
To compete with other building materials, the wood products industry must
find a way to increase value and lower costs. Wood stiffness is important for most
wood uses. Value can be increased and costs can be lowered by sorting logs for
stiffness in the woods using acoustic devices mounted on...
In wood-based composites, the glue-line (interface) between wood-strands affects the stress transfer from one member to the next. The glue-line properties determine the rate of load transfer between phases and these properties depend on wood species, surface preparation, glue properties, glue penetration into wood cells, and moisture content of the...
Large numbers of reinforced concrete deck girder bridges that were constructed during the
interstate system expansion of the 1950s have developed diagonal cracking in the stems.
Compared to the present AASHTO-LRFD standards, the provisions of the 1950s allowed
for higher shear stress in the concrete, thus reducing the amount of...
The overall goal of this project was to design a wood frame shear wall that could withstand greater displacement before damage occurred to the Gypsum Wall Board (GWB). More specifically, the objectives of the study were: (1) to evaluate damage to the GWB in alternative shear wall designs at 1%,...
Hygro-mechanical effect is a general term applied to all phenomena that involves interaction between moisture content and mechanical characteristics of hygroscopic materials by analogy to thermo-mechanical effects. The hygromechanical effects include (but are not limited to) free shrinkage/swelling, effect of moisture on elastic modulus, strength, creep, failure mechanisms, and mechano...
Epoxy resin is a thermosetting resin that is commonly used as composite matrix. Epoxy composite materials are well utilized in industries, such as aerospace, due to their good mechanical properties. Nano-scale filler reinforced polymer composite materials have been intensively researched in recent decades. Cellulose nanocrystals (CNXLs) are a type of...
Society uses massive quantities of wood fiber in production of paper, and demand for fiber is projected to increase further as production of biofuels from fermentation of plant cellulosic materials increases. Because these end uses generally require the costly step of removing of lignin, wood with reduced or more easily...
Ever since composite laminate technology was introduced into the aerospace and automotive industry, there has been a need to fully understand the damage progression experienced by composite laminated plates in the presence of a notch. While numerous research studies have been conducted on this matter when subjected to in-plane loads,...