This thesis presents two major sections with the objective of introducing a new cold-formed steel (CFS) shear wall system with corrugated steel sheathings. The work shown herein includes the development of an optimal shear wall system as well as an optimal slit configuration for the CFS corrugated sheathings which result in a CFS shear wall with high ductility, high strength, high stiffness and overall high performance. The conclusion is based on the results of 36 full-scale shear wall tests performed in the structural laboratory of the University of North Texas. A variety of shear walls were the subject of this research to make further discussions and conclusions based on different sheathing materials, slit configurations, wall configurations, sheathing connection methods, wall dimensions, shear wall member thicknesses, and etc. The walls were subject to cyclic (CUREE protocol) lateral loading to study their deformations and structural performances. The optimal sit configuration for CFS shear walls with corrugated steel sheathings was found to be 12×2 in. vertical slits in 6 rows. The failure mode observed in this shear wall system was the connection failure between the sheathing and the framing members. Also, most of the shear walls tested displayed local buckling of the chord …

The HVAC&R industry is looking to transition from copper-aluminum heat exchangers to all-aluminum microchannel technology. The want for the transition stemmed from seeing the performance improvement of all-aluminum microchannel radiators in the automotive industry. Applications differ between the two industries; therefore, applying this technology for HVAC&R use must be validated. Research towards operating modes of an all-aluminum heat exchanger in a defined corrosive environment will provide the industry with a better understanding of heat exchanger design and heat exchanger material selection. The worth in this is preventing overdesign and producing more efficient heat exchangers. Furthermore, ASHRAE members and the corrosion community will find value in a defined corrosion system and corrosion test procedure. The information gained through past research has progressed assessment of material performance; however, the methods improperly simulate and expedite natural weathering. The most common method being used is the ASTM (American Society of Testing Materials) Sea Water Acetic Acid Test. The research discussed in this paper was focused on improving a standard corrosion system by implementing system modifications to simulate heat exchanger operation while performing a modified wet-dry cyclic test (e.g. ASTM G85 Annex 5). The goal is to produce results that are more representative of natural …

Materials selection processes have been the most important aspects in product design and development. Knowledge-based system (KBS) and some of the methodologies used in the materials selection for the design of aircraft cabin metallic structures are discussed. Overall aircraft weight reduction means substantially less fuel consumption. Part of the solution to this problem is to find a way to reduce overall weight of metallic structures inside the cabin. Among various methodologies of materials selection using Multi Criterion Decision Making (MCDM) techniques, a few of them are demonstrated with examples and the results are compared with those obtained using Ashby's approach in materials selection. Pre-defined constraint values, mainly mechanical properties, are employed as relevant attributes in the process. Aluminum alloys with high strength-to-weight ratio have been second-to-none in most of the aircraft parts manufacturing. Magnesium alloys that are much lighter in weight as alternatives to the Al-alloys currently in use in the structures are tested using the methodologies and ranked results are compared. Each material attribute considered in the design are categorized as benefit and non-benefit attribute. Using Ashby's approach, material indices that are required to be maximized for an optimum performance are determined, and materials are ranked based on the …

Two-phase spray cooling has been an emerging thermal management technique offering high heat transfer coefficients and critical heat flux levels, near-uniform surface temperatures, and efficient coolant usage that enables to design of compact and lightweight systems. Due to these capabilities, spray cooling is a promising approach for high heat flux applications in computing, power electronics, and optics. Two-phase spray cooling inherently depends on saturation temperature-pressure relationships of the working fluid to take advantage of high heat transfer rates associated with liquid-vapor phase change. When a certain application requires strict temperature and/or pressure conditions, thermo-physical properties of the working fluid play a critical role in attaining proper efficiency, reliability, or packaging structure. However, some of the commonly used single-component working fluids have relatively poor properties and heat transfer performance. For example, water is the best coolant in terms of properties, yet in certain applications where the system operates at low temperature ambient, it cannot be implemented due to freezing risk. The common solution for this problem is to use the antifreeze mixtures (binary mixtures of water and alcohol) to reduce the freezing point. In such cases, utilizing binary mixtures to tune working fluid properties becomes an alternative approach. This study has …