Matching Items (4)
Filtering by
- All Subjects: Mechanical Engineering
- All Subjects: Flexible
- Creators: Jiang, Hanqing
- Member of: Barrett, The Honors College Thesis/Creative Project Collection
Description
The data and results presented in this paper are part of a continuing effort to innovate and pioneer the future of engineering. The purpose of the following is to demonstrate the mechanical buckling characteristics in stiff thin film and soft substrate systems, and the importance of controlling them. In today's engineering research, wrinkling in systems in beginning to be viewed as a means for engineering innovation rather than failure. This research is important to further progress the possible applications the technology proposes, such as flexible electronics and tunable adhesives. This work utilizes a cost efficient and relatively easy method for generating and analyzing buckled systems. Ultra violate oxidation at ambient temperatures is exploited to create a stiff thin surface on rubber like polydimethylsiloxane, and couple with strain induction wrinkles are generated. Wrinkle characteristics such as amplitude, wavelengths and wetting properties were investigated. In simple cases, trends were confirmed that increased oxidation relates to increased buckle wavelengths, and increase in strain corresponds to a decrease in wavelength. Hierarchical buckles were produced in one-dimensional systems treated with a multi-step method; these were the first to be generated in the ASU labs. Unique topographic changes were produced in two-dimensional systems treated with the same method. Honeycomb or dome like structures were noted to occur, important as they undergo a different energy-reliving configuration compared to traditional parallel buckles. The information provided characterizes many aspects of the buckle phenomena and will allow for further inquiry into specific functions utilizing the technology to continue advancements in engineering.
ContributorsValacich, Michael James (Author) / Jiang, Hanqing (Thesis director) / Yu, Hongyu (Committee member) / Teng, Ma (Committee member) / Barrett, The Honors College (Contributor) / Mechanical and Aerospace Engineering Program (Contributor)
Created2013-05
Description
This thesis research project seeks to provide an investigation to find the most appropriate organogel serving as a lithium ion battery separator that is compatible with stretchable electronics. Separators play a key role in all batteries. Their main function is to keep the positive and negative electrodes apart to prevent electrical short circuits and at the same time allow rapid transport of ionic charge carriers that are needed to complete the circuit during the passage of current in an electrochemical cell [1].Li-ion batteries have become important in the field of electronic industry due to their advantages like compactness, lightweight, high operational voltage and providing highest energy density. Typical Li-ion battery has a cathode (LiCoO2, LiMnO2, LiFePO4 etc.), an anode (graphite, graphene, carbon nanotubes, carbon nanofibers, lithium titanium oxides etc.) and a separator [1]. The separator provides an electrical insulation between anode and cathode and allows ion transfer during operation. It also plays a significant role in determining battery performance. The performance of the Li-ion battery separator is determined by several factors such as permeability, porosity, electrolyte uptake capacity, mechanical, thermal and chemical stability. Several commercially available polymers have been used as separators and the most common polymers are poly(ethylene), poly(propylene), poly (ethylene oxide), poly(acrylonitrile), poly (methyl methacrylate) and poly (vinylidene fluoride) (PVDF) [3]. In this project, organogels were chosen because of their flexible, semi-permeable and reliable bendable characteristics which becomes useful in stretchable batteries. The first part is to use Polydimethylsiloxane (PDMS) which belongs to a group of polymeric organosilicon compounds that are commonly referred to as silicones, then mixed with hexane and sucrose solvents to make the required organogel. Different organogels from PDMS and Dragon skin in different amounts and conditions were created and tested to see what works best in stretchable lithium batteries, thus improving the battery’s efficiency and life cycle. Ion conductivity values were obtained after running the Electrochemical Impedance Spectroscopy Test. Graphs produced after this test proved that the most effective combination to use was at a porosity of 0.8, at a ratio of Sucrose: PDMS wt Ratio of 5: 0.764 respectively. The future endeavors of this project will involve working with reduced cell thickness so as to reduce the overall distance traveled by the ions, which also reduces the overall cost of making each separator.
ContributorsMatsika, Clive (Author) / Jiang, Hanqing (Thesis director) / Phelan, Patrick (Committee member) / Mechanical and Aerospace Engineering Program (Contributor, Contributor, Contributor) / Barrett, The Honors College (Contributor)
Created2019-05
Description
The purpose of this project focuses on analyzing how a typically brittle material, such as PLA, can be manipulated to become deformable, through the development of an origami structure, in this case—the Yoshimuri pattern. The experimental methodology focused on creating a base Solidworks model, with varying hinge depths, and 3D printing these various models. A cylindrical shell was also developed with comparable dimensions to the Yoshimuri dimensions. These samples were then tested through compression testing, with the load-displacement, and thus the stress-strain curves are analyzed. From the results, it was found that generally, the Yoshimuri samples had a higher level of deformation compared to the cylindrical shell. Moreover, the cylindrical shell had a higher stiffness ratio, while the Yoshimuri patterns had strain rates as high as 16%. From this data, it can be concluded that by changing how the structure is created through origami patterns, it is possible to shift the characteristics of a structure even if the material properties are initially quite brittle.
ContributorsSundar, Vaasavi (Author) / Jiang, Hanqing (Thesis director) / Kingsbury, Dallas (Committee member) / Mechanical and Aerospace Engineering Program (Contributor) / School of Social Transformation (Contributor) / Barrett, The Honors College (Contributor)
Created2016-12
Description
This research project will test the structural properties of a 3D printed origami inspired structure and compare them with a standard honeycomb structure. The models have equal face areas, model heights, and overall volume but wall thicknesses will be different. Stress-deformation curves were developed from static loading testing. The area under these curves was used to calculate the toughness of the structures. These curves were analyzed to see which structures take more load and which deform more before fracture. Furthermore, graphs of the Stress-Strain plots were produced. Using 3-D printed parts in tough resin printed with a Stereolithography (SLA) printer, the origami inspired structure withstood a larger load, produced a larger toughness and deformed more before failure than the equivalent honeycomb structure.
ContributorsMcGregor, Alexander (Author) / Jiang, Hanqing (Thesis director) / Kingsbury, Dallas (Committee member) / Mechanical and Aerospace Engineering Program (Contributor) / Barrett, The Honors College (Contributor)
Created2018-05