Matching Items (52)
Filtering by
- All Subjects: Materials Science
- All Subjects: Sustainability
- All Subjects: chemical engineering
Description
Advanced composites are being widely used in aerospace applications due to their high stiffness, strength and energy absorption capabilities. However, the assurance of structural reliability is a critical issue because a damage event will compromise the integrity of composite structures and lead to ultimate failure. In this dissertation a novel homogenization based multiscale modeling framework using semi-analytical micromechanics is presented to simulate the response of textile composites. The novelty of this approach lies in the three scale homogenization/localization framework bridging between the constituent (micro), the fiber tow scale (meso), weave scale (macro), and the global response. The multiscale framework, named Multiscale Generalized Method of Cells (MSGMC), continuously bridges between the micro to the global scale as opposed to approaches that are top-down and bottom-up. This framework is fully generalized and capable of modeling several different weave and braids without reformulation. Particular emphasis in this dissertation is placed on modeling the nonlinearity and failure of both polymer matrix and ceramic matrix composites.
ContributorsLiu, Guang (Author) / Chattopadhyay, Aditi (Thesis advisor) / Mignolet, Marc (Committee member) / Jiang, Hanqing (Committee member) / Li, Jian (Committee member) / Rajadas, John (Committee member) / Arizona State University (Publisher)
Created2011
Description
This study investigates how well prominent behavioral theories from social psychology explain green purchasing behavior (GPB). I assess three prominent theories in terms of their suitability for GPB research, their attractiveness to GPB empiricists, and the strength of their empirical evidence when applied to GPB. First, a qualitative assessment of the Theory of Planned Behavior (TPB), Norm Activation Theory (NAT), and Value-Belief-Norm Theory (VBN) is conducted to evaluate a) how well the phenomenon and concepts in each theory match the characteristics of pro-environmental behavior and b) how well the assumptions made in each theory match common assumptions made in purchasing theory. Second, a quantitative assessment of these three theories is conducted in which r2 values and methodological parameters (e.g., sample size) are collected from a sample of 21 empirical studies on GPB to evaluate the accuracy and generalize-ability of empirical evidence. In the qualitative assessment, the results show each theory has its advantages and disadvantages. The results also provide a theoretically-grounded roadmap for modifying each theory to be more suitable for GPB research. In the quantitative assessment, the TPB outperforms the other two theories in every aspect taken into consideration. It proves to 1) create the most accurate models 2) be supported by the most generalize-able empirical evidence and 3) be the most attractive theory to empiricists. Although the TPB establishes itself as the best foundational theory for an empiricist to start from, it's clear that a more comprehensive model is needed to achieve consistent results and improve our understanding of GPB. NAT and the Theory of Interpersonal Behavior (TIB) offer pathways to extend the TPB. The TIB seems particularly apt for this endeavor, while VBN does not appear to have much to offer. Overall, the TPB has already proven to hold a relatively high predictive value. But with the state of ecosystem services continuing to decline on a global scale, it's important for models of GPB to become more accurate and reliable. Better models have the capacity to help marketing professionals, product developers, and policy makers develop strategies for encouraging consumers to buy green products.
ContributorsRedd, Thomas Christopher (Author) / Dooley, Kevin (Thesis advisor) / Basile, George (Committee member) / Darnall, Nicole (Committee member) / Arizona State University (Publisher)
Created2012
Description
Ecolabels are the main driving force of consumer knowledge in the realm of sustainable product purchasing. While ecolabels strive to improve consumer's purchasing decisions, they have overwhelmed the market, leaving consumers confused and distrustful of what each label means. This study attempts to validate and understand environmental concerns commonly found in ecolabel criteria and the implications they have within the life cycle of a product. A life cycle assessment (LCA) case study of cosmetic products is used in comparison with current ecolabel program criteria to assess whether or not ecolabels are effectively driving environmental improvements in high impact areas throughout the life cycle of a product. Focus is placed on determining the general issues addressed by ecolabelling criteria and how these issues relate to hotspots derived through a practiced scientific methodology. Through this analysis, it was determined that a majority the top performing supply chain environmental impacts are covered, in some fashion, within ecolabelling criteria, but some, such as agricultural land occupation, are covered to a lesser extent or not at all. Additional criteria are suggested to fill the gaps found in ecolabelling programs and better address the environmental impacts most pertinent to the supply chain. Ecolabels have also been found to have a broader coverage then what can currently be addressed using LCA. The results of this analysis have led to a set of recommendations for furthering the integration between ecolabels and life cycle tools.
ContributorsBernardo, Melissa (Author) / Dooley, Kevin (Thesis advisor) / Chester, Mikhail (Thesis advisor) / Fox, Peter (Committee member) / Arizona State University (Publisher)
Created2012
Description
Composite materials are increasingly being used in aircraft, automobiles, and other applications due to their high strength to weight and stiffness to weight ratios. However, the presence of damage, such as delamination or matrix cracks, can significantly compromise the performance of these materials and result in premature failure. Structural components are often manually inspected to detect the presence of damage. This technique, known as schedule based maintenance, however, is expensive, time-consuming, and often limited to easily accessible structural elements. Therefore, there is an increased demand for robust and efficient Structural Health Monitoring (SHM) techniques that can be used for Condition Based Monitoring, which is the method in which structural components are inspected based upon damage metrics as opposed to flight hours. SHM relies on in situ frameworks for detecting early signs of damage in exposed and unexposed structural elements, offering not only reduced number of schedule based inspections, but also providing better useful life estimates. SHM frameworks require the development of different sensing technologies, algorithms, and procedures to detect, localize, quantify, characterize, as well as assess overall damage in aerospace structures so that strong estimations in the remaining useful life can be determined. The use of piezoelectric transducers along with guided Lamb waves is a method that has received considerable attention due to the weight, cost, and function of the systems based on these elements. The research in this thesis investigates the ability of Lamb waves to detect damage in feature dense anisotropic composite panels. Most current research negates the effects of experimental variability by performing tests on structurally simple isotropic plates that are used as a baseline and damaged specimen. However, in actual applications, variability cannot be negated, and therefore there is a need to research the effects of complex sample geometries, environmental operating conditions, and the effects of variability in material properties. This research is based on experiments conducted on a single blade-stiffened anisotropic composite panel that localizes delamination damage caused by impact. The overall goal was to utilize a correlative approach that used only the damage feature produced by the delamination as the damage index. This approach was adopted because it offered a simplistic way to determine the existence and location of damage without having to conduct a more complex wave propagation analysis or having to take into account the geometric complexities of the test specimen. Results showed that even in a complex structure, if the damage feature can be extracted and measured, then an appropriate damage index can be associated to it and the location of the damage can be inferred using a dense sensor array. The second experiment presented in this research studies the effects of temperature on damage detection when using one test specimen for a benchmark data set and another for damage data collection. This expands the previous experiment into exploring not only the effects of variable temperature, but also the effects of high experimental variability. Results from this work show that the damage feature in the data is not only extractable at higher temperatures, but that the data from one panel at one temperature can be directly compared to another panel at another temperature for baseline comparison due to linearity of the collected data.
ContributorsVizzini, Anthony James, II (Author) / Chattopadhyay, Aditi (Thesis advisor) / Fard, Masoud (Committee member) / Papandreou-Suppappola, Antonia (Committee member) / Arizona State University (Publisher)
Created2012
Description
I present a new framework for qualitative assessment of the current green purchasing practices of U.S. state governments. Increasing demand from citizens for green public purchasing has prompted state governments to adopt new, and improve existing, practices. Yet there has been little assessment of public green purchasing in academic research; what has been done has not provided the conceptual support necessary to assess green purchasing practices as a single component of the procurement process. My research aims to fill that gap by developing a conceptual framework with which to assess the status of green purchasing practices and by applying this framework to determine and describe the status of green purchasing in the five most populous U.S. states. The framework looks at state purchasing practices through the lenses of policy, policy implementation, and transparency.
ContributorsSharma, Lucky (Author) / Melnick, Rob (Thesis advisor) / Dooley, Kevin (Thesis advisor) / Basile, George (Committee member) / Arizona State University (Publisher)
Created2012
Description
Derived from the idea that the utilization of sustainable practices could improve small business practice, this honors thesis offers a full business assessment and recommendations for improvements of a local, family-owned coffee shop, Gold Bar. A thorough analysis of the shop's current business practices and research on unnecessary expenses and waste guides this assessment.
ContributorsSorden, Clarissa (Co-author) / Boden, Alexandra (Co-author) / Darnall, Nicole (Thesis director) / Dooley, Kevin (Committee member) / Barrett, The Honors College (Contributor) / School of Sustainability (Contributor) / W. P. Carey School of Business (Contributor) / Department of Management (Contributor) / Department of Supply Chain Management (Contributor)
Created2015-05
Description
The goal of this project is to gain and use knowledge of sustainability topics as a value-adding function for a business in the Tempe, AZ area and to develop the skills to approach and consult with business owners and staff about sustainable business options. Sustainability searches for a balance between society, economy and the environment where all three can thrive; therefore, the ideal project partner was a business that values the wellbeing of mankind, is locally owned and operated and promotes environmental stewardship. The Original Chop Shop Co in Tempe Arizona was appropriately selected. Throughout the duration of our partnership, I observed their daily routine, interviewed employees and managers and used the collected information to identify three areas of focus that have the largest potential to reduce The Original Chop Shop Company's impact on the environment. Information on the areas of recycling, composting, and food sourcing was researched and synthesized to make suggestions for ecofriendly changes to business practices. The scope of the project includes small changes in daily practices such as implementing a recycling and composting program and employee training sessions and minor investments such as purchasing a micro washer and silverware in order to eliminate nonrenewable plastic utensils. The scope does not include major renovations or investments in technology. The suggestions offered position The Original Chop Shop to conduct business in a way that does not compromise the health of the environment, society, or economy.
ContributorsFerry, Brianna Aislinn (Author) / Dooley, Kevin (Thesis director) / Darnall, Nicole (Committee member) / Barrett, The Honors College (Contributor) / W. P. Carey School of Business (Contributor) / School of Politics and Global Studies (Contributor)
Created2015-05
DescriptionAn examination of ways the pet retail industry can integrate sustainability into their internal operations by pursuing initiatives surrounding associate engagement, logistics/transportation, packaging/certifications, and water and energy conservation.
ContributorsSuch, Emily Marie (Author) / Dooley, Kevin (Thesis director) / Byers, Reynold (Committee member) / Mars, Carole (Committee member) / Barrett, The Honors College (Contributor) / W. P. Carey School of Business (Contributor) / Department of Supply Chain Management (Contributor)
Created2013-05
Description
This thesis conducts research into the emissions from ocean going vessels and the ports that they dock at and current methods that are being pursued to help reduce the environmental impact of the ocean shipping industry. The main emissions from the industry analyzed are particulate matter, oxides of nitrogen, oxides of sulfur and greenhouse gases. One method of reducing the environmental impact of the industry is through the improvement of the vessels. The vessels are currently being improved through the exploration of using liquefied natural gas (LNG) instead of bunker fuel. It has been found that LNG takes up less space, costs less, and has fewer emissions compared to bunker fuel, making it an ideal replacement as a fuel source. In addition to changing fuel sources, the International Maritime Organization (IMO) has created emission control areas around the United States and its territories mandating the use of ultra-low sulfur diesel within a certain range of land. There are two emission control areas with one being for the United States, Canada, and the French Territories of North America and the other for Puerto Rico and the U.S. Virgin Islands. For the North American nations it is 200 nautical miles, while for Puerto Rico and the U.S. Virgin Islands it is 50 nautical miles. This is an external pressure encouraging current shipping companies to switch to LNG as a fuel source. A second method of reducing the environmental impact of the ocean shipping industry is to improve the ports. The ports are being improved by utilizing alternative maritime power, reducing the emissions of vehicles at the ports, and engaging all of the stakeholders of a port. Alternative maritime power (AMP) is the use of shore-side power sources to power the auxiliary engines of vessels while they are hotelling, at dock. AMP is also referred to as cold-ironing and is effective in reducing emissions from vessels because the auxiliary engines are powered by electricity as opposed to fuel. This is an expensive option to pursue because of the high investment costs, but the Carl Moyer Program provides analysis for the cost-effectiveness of projects to justify the high costs. The second facet of port improvements is decreasing the emissions from all vehicles at the ports. The Port of Los Angeles has gradually been phasing out trucks with old engines and even banning them from entering the port. Cargo handling equipment has seen similar restrictions to reduce emissions. Finally locomotives have seen requirements implemented causing them to improve their engines while implementing idling restriction technologies as well. These improvements have yielded tangible and effective results for the Port of Los Angeles. These initiatives have resulted in a decrease in emissions from the port since their inception in 2005 to 2011 (2011 being the last year that data is available). In that time frame diesel particulate matter has been reduced by 71% at 634 tons, NOx has been reduced by 51% at 8,392 tons and SOx has been reduced by 76% at a total of 4,038 tons. The final part of port improvements this paper looks into is the integration and engagement of all stakeholders. The Port of Los Angeles has all but approved the Southern California International Gateway Project (SCIG) by Burlington Northern Santa Fe (BNSF) Railway. This project included the cooperation of BNSF, local unions, and local politicians to create a new rail yard that contains the highest sustainability standards for any rail yard. SCIG will employ numerous local people, require trucks to take alternative routes, reduce the amount of trucks on the highway, and help get products to consumers more competitively and efficiently. This will result in reduced emissions, decreased noise pollution, and less traffic congestion on Los Angeles highways. In conclusion it was found that real, effective, and cost-effective projects are being undertaken to improve the environmental impacts of the ocean shipping industry.
ContributorsAlbright, Joe Todd (Author) / Maltz, Arnold (Thesis director) / Dooley, Kevin (Committee member) / Brown, Steven (Committee member) / Barrett, The Honors College (Contributor) / Department of Supply Chain Management (Contributor) / W. P. Carey School of Business (Contributor)
Created2013-05
Description
Non-Destructive Testing (NDT) is integral to preserving the structural health of materials. Techniques that fall under the NDT category are able to evaluate integrity and condition of a material without permanently altering any property of the material. Additionally, they can typically be used while the material is in active use instead of needing downtime for inspection.
The two general categories of structural health monitoring (SHM) systems include passive and active monitoring. Active SHM systems utilize an input of energy to monitor the health of a structure (such as sound waves in ultrasonics), while passive systems do not. As such, passive SHM tends to be more desirable. A system could be permanently fixed to a critical location, passively accepting signals until it records a damage event, then localize and characterize the damage. This is the goal of acoustic emissions testing.
When certain types of damage occur, such as matrix cracking or delamination in composites, the corresponding release of energy creates sound waves, or acoustic emissions, that propagate through the material. Audio sensors fixed to the surface can pick up data from both the time and frequency domains of the wave. With proper data analysis, a time of arrival (TOA) can be calculated for each sensor allowing for localization of the damage event. The frequency data can be used to characterize the damage.
In traditional acoustic emissions testing, the TOA combined with wave velocity and information about signal attenuation in the material is used to localize events. However, in instances of complex geometries or anisotropic materials (such as carbon fibre composites), velocity and attenuation can vary wildly based on the direction of interest. In these cases, localization can be based off of the time of arrival distances for each sensor pair. This technique is called Delta T mapping, and is the main focus of this study.
The two general categories of structural health monitoring (SHM) systems include passive and active monitoring. Active SHM systems utilize an input of energy to monitor the health of a structure (such as sound waves in ultrasonics), while passive systems do not. As such, passive SHM tends to be more desirable. A system could be permanently fixed to a critical location, passively accepting signals until it records a damage event, then localize and characterize the damage. This is the goal of acoustic emissions testing.
When certain types of damage occur, such as matrix cracking or delamination in composites, the corresponding release of energy creates sound waves, or acoustic emissions, that propagate through the material. Audio sensors fixed to the surface can pick up data from both the time and frequency domains of the wave. With proper data analysis, a time of arrival (TOA) can be calculated for each sensor allowing for localization of the damage event. The frequency data can be used to characterize the damage.
In traditional acoustic emissions testing, the TOA combined with wave velocity and information about signal attenuation in the material is used to localize events. However, in instances of complex geometries or anisotropic materials (such as carbon fibre composites), velocity and attenuation can vary wildly based on the direction of interest. In these cases, localization can be based off of the time of arrival distances for each sensor pair. This technique is called Delta T mapping, and is the main focus of this study.
ContributorsBriggs, Nathaniel (Author) / Chattopadhyay, Aditi (Thesis director) / Papandreou-Suppappola, Antonia (Committee member) / Skinner, Travis (Committee member) / Mechanical and Aerospace Engineering Program (Contributor) / School of Mathematical and Statistical Sciences (Contributor) / Barrett, The Honors College (Contributor)
Created2019-05