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Description
Multiaxial mechanical fatigue of heterogeneous materials has been a significant cause of concern in the aerospace, civil and automobile industries for decades, limiting the service life of structural components while increasing time and costs associated with inspection and maintenance. Fiber reinforced composites and light-weight aluminum alloys are widely used in aerospace structures that require high specific strength and fatigue resistance. However, studying the fundamental crack growth behavior at the micro- and macroscale as a function of loading history is essential to accurately predict the residual fatigue life of components and achieve damage tolerant designs. The issue of mechanical fatigue can be tackled by developing reliable in-situ damage quantification methodologies and by comprehensively understanding fatigue damage mechanisms under a variety of complex loading conditions. Although a multitude of uniaxial fatigue loading studies have been conducted on light-weight metallic materials and composites, many service failures occur from components being subjected to variable amplitude, mixed-mode multiaxial fatigue loadings. In this research, a systematic approach is undertaken to address the issue of fatigue damage evolution in aerospace materials by:
(i) Comprehensive investigation of micro- and macroscale crack growth behavior in aerospace grade Al 7075 T651 alloy under complex biaxial fatigue loading conditions. The effects of variable amplitude biaxial loading on crack growth characteristics such as crack acceleration and retardation were studied in detail by exclusively analyzing the influence of individual mode-I, mixed-mode and mode-II overload and underload fatigue cycles in an otherwise constant amplitude mode-I baseline load spectrum. The micromechanisms governing crack growth behavior under the complex biaxial loading conditions were identified and correlated with the crack growth behavior and fracture surface morphology through quantitative fractography.
(ii) Development of novel multifunctional nanocomposite materials with improved fatigue resistance and in-situ fatigue damage detection and quantification capabilities. A state-of-the-art processing method was developed for producing sizable carbon nanotube (CNT) membranes for multifunctional composites. The CNT membranes were embedded in glass fiber laminates and in-situ strain sensing and damage quantification was achieved by exploiting the piezoresistive property of the CNT membrane. In addition, improved resistance to fatigue crack growth was observed due to the embedded CNT membrane.
(i) Comprehensive investigation of micro- and macroscale crack growth behavior in aerospace grade Al 7075 T651 alloy under complex biaxial fatigue loading conditions. The effects of variable amplitude biaxial loading on crack growth characteristics such as crack acceleration and retardation were studied in detail by exclusively analyzing the influence of individual mode-I, mixed-mode and mode-II overload and underload fatigue cycles in an otherwise constant amplitude mode-I baseline load spectrum. The micromechanisms governing crack growth behavior under the complex biaxial loading conditions were identified and correlated with the crack growth behavior and fracture surface morphology through quantitative fractography.
(ii) Development of novel multifunctional nanocomposite materials with improved fatigue resistance and in-situ fatigue damage detection and quantification capabilities. A state-of-the-art processing method was developed for producing sizable carbon nanotube (CNT) membranes for multifunctional composites. The CNT membranes were embedded in glass fiber laminates and in-situ strain sensing and damage quantification was achieved by exploiting the piezoresistive property of the CNT membrane. In addition, improved resistance to fatigue crack growth was observed due to the embedded CNT membrane.
ContributorsDatta, Siddhant (Author) / Chattopadhyay, Aditi (Thesis advisor) / Liu, Yongming (Committee member) / Jiang, Hanqing (Committee member) / Marvi, Hamidreza (Committee member) / Tang, Pingbo (Committee member) / Yekani Fard, Masoud (Committee member) / Iyyer, Nagaraja (Committee member) / Arizona State University (Publisher)
Created2018
Description
Sustainable Materials Management and Circular Economy are both frameworks for considering the way we interact with the world's resources. Different organizations and institutions across the world have adopted one philosophy or the other. To some, there seems to be little overlap of the two, and to others, they are perceived as being interchangeable. This paper evaluates Sustainable Materials Management (SMM) and Circular Economy (CE) individually and in comparison to see how truly different these frameworks are from one another. This comparison is then extended into a theoretical walk-through of an SMM treatment of concrete pavement in contrast with a CE treatment. With concrete being a ubiquitous in the world's buildings and roads, as well as being a major constituent of Construction & Demolition waste generated, its analysis is applicable to a significant portion of the world's material flow. The ultimate test of differentiation between SMM and CE would ask: 1) If SMM principles guided action, would the outcomes be aligned with or at odds with CE principles? and conversely 2) If CE principles guided action, would the outcomes be aligned with or at odds with SMM principles? Using concrete pavement as an example, this paper seeks to determine whether or not Sustainable Materials Management and Circular Economy are simply different roads leading to the same destination.
ContributorsAbdul-Quadir, Anisa (Author) / Kelman, Candice (Thesis director) / Buch, Rajesh (Committee member) / Barrett, The Honors College (Contributor)
Created2017-05
Description
Shape Memory Polymers (SMPs) are smart polyurethane thermoplastics that can recover their original shape after undergoing deformation. This shape recovery can be actuated by raising the SMP above its glass transition temperature, Tg. This report outlines a process for repeatedly recycling SMPs using 3D printing. Cubes are printed, broken down into pellets mechanically, and re-extruded into filament. This simulates a recycling iteration that the material would undergo in industry. The samples are recycled 0, 1, 3, and 5 times, then printed into rectangular and dog-bone shapes. These shapes are used to perform dynamic mechanical analysis (DMA) and 3-point bending for shape recovery testing. Samples will also be used for scanning electron microscopy (SEM) to characterize their microstructure.
ContributorsSweeney, Andrew Joseph (Author) / Yekani Fard, Masoud (Thesis director) / Chattopadhyay, Aditi (Committee member) / W.P. Carey School of Business (Contributor) / Mechanical and Aerospace Engineering Program (Contributor) / Barrett, The Honors College (Contributor)
Created2018-05
Description
Filament used in 3D printers can vary by size, color, and material. Most commonly thermoplastics are used for rapid prototyping by industry. Recycled filament has the potential to reduce cost and provide a more sustainable and energy efficient approach to 3D printing. This can be a viable option if recycled parts show comparable mechanical characteristics to non-recycled material. This report focuses on the development of a methodology to efficiently characterize recycled filament for application in industry. A crush sample in the shape of a hollow cube and a dog-bone shaped specimen will be created using a filament extruder and 3D printer. The crush sample will be broken and extruded to produce a recycled filament. The crush sample will undergo a varying number of recycles (i.e. breakings) per sample group to simulate mechanical degradation; 0, 1, 2, and 5 recycling loops. The samples will undergo micro mechanical (microscopy analysis) and macro mechanical (tensile) characterization.
ContributorsPalermo, Marissa Nicole (Author) / Chattopadhyay, Aditi (Thesis director) / Yekani Fard, Masoud (Committee member) / Mechanical and Aerospace Engineering Program (Contributor) / Barrett, The Honors College (Contributor)
Created2016-12
Description
While the term sustainability is commonly used in 2019, in 1950, it was sparsely uttered. To understand how Contento Recycling LLC became Central New York’s leader in sustainable development, you must go back to Gerald Contento Sr, and the year 1950. This was the year my grandfather started our family’s vehicle dismantling and scrap metal recycling business. Over the course of the next 70 years, Contento’s and now, Contento Recycling, has evolved into a leader in recycling and environmental work in Central New York. To see how I created a sustainable business enterprise, you must analyze my family’s past. My family’s history provides a roadmap to a more sustainable future.
When I established Contento Recycling LLC in 2017, it was poised to be Central New York’s first ever construction and demolition debris recycling business. I was tasked with the challenge that many sustainability professionals are tasked with and that was to show the community why they should stop taking their construction debris to the landfill, and instead bring it to my recycling center for processing, recycling, and landfill diversion. Over the last several years I applied for state grant funding, spread awareness about my new business, designed and constructed a material recovery facility, outfitted equipment, and trained staff. I now have a facility that accepts about 40 tons of mixed C&D debris per day, and diverts about 20% of that from the landfill.
On a more personal level, I learned a tremendous amount about dealing with change management. I’ve learned a lot about business development, and some keys to success when building a business. I’ve figured out how to help my employees and customers grow. I’ve learned to be more patient and flexible with my business endeavors. I have a much clearer vision of what I want for my business and for myself. I have developed a rousing optimism on the impact that my business, and myself can have on the sustainable development of Central New York. I will be a leader in environmental stewardship and partner with other people and organizations who want to work towards a more sustainable future.
When I established Contento Recycling LLC in 2017, it was poised to be Central New York’s first ever construction and demolition debris recycling business. I was tasked with the challenge that many sustainability professionals are tasked with and that was to show the community why they should stop taking their construction debris to the landfill, and instead bring it to my recycling center for processing, recycling, and landfill diversion. Over the last several years I applied for state grant funding, spread awareness about my new business, designed and constructed a material recovery facility, outfitted equipment, and trained staff. I now have a facility that accepts about 40 tons of mixed C&D debris per day, and diverts about 20% of that from the landfill.
On a more personal level, I learned a tremendous amount about dealing with change management. I’ve learned a lot about business development, and some keys to success when building a business. I’ve figured out how to help my employees and customers grow. I’ve learned to be more patient and flexible with my business endeavors. I have a much clearer vision of what I want for my business and for myself. I have developed a rousing optimism on the impact that my business, and myself can have on the sustainable development of Central New York. I will be a leader in environmental stewardship and partner with other people and organizations who want to work towards a more sustainable future.
ContributorsContento, Anthony (Author, Project director)
Created2019-05-15