View All Items
(1 - 5 of 5)
- Title
- Characterization of Dynamic and Static Mechanical Behavior of Polyetherimide.
- Creator
-
Mutter, Nathan, Gordon, Ali, Raghavan, Seetha, Xu, Chengying, University of Central Florida
- Abstract / Description
-
Polymers are increasingly being used in engineering designs due to their favorable mechanical properties such as high specific strength, corrosive resistance, manufacturing flexibility. The understanding of the mechanical behavior of these polymers under both static and dynamic loading is critical for their optimal implementation in engineering applications. One such polymer utilized in a wide variety of applications from medical instrumentation to munitions is Polyetherimide, referred to as...
Show morePolymers are increasingly being used in engineering designs due to their favorable mechanical properties such as high specific strength, corrosive resistance, manufacturing flexibility. The understanding of the mechanical behavior of these polymers under both static and dynamic loading is critical for their optimal implementation in engineering applications. One such polymer utilized in a wide variety of applications from medical instrumentation to munitions is Polyetherimide, referred to as Ultem. This thesis characterizes both the static and dynamic mechanical behavior of Ultem 1000 through experimental methods and numerical simulations. Standard compression experiments were conducted on and MTS test frame to characterize the elastic-plastic behavior of Ultem 1000 under quasi-static conditions. The dynamic response of the material was investigated at very high strain rates using a custom built miniaturized Kolsky bar apparatus. The smaller Kolsky bar configuration was chosen over the conventional Kolsky device to increase the maximum capable strain rates and to reduce common experimental problems such as wave dispersion, friction, and stress equilibrium. Since a universal test standard for this apparatus is not available, the details of the design, construction, and experimental procedures of this device are provided. The results of the high strain rate testing revealed a bilinear relationship between the material yield stress and strain rate. This relationship was modeled using the Ree-Eyring two stage activation process equation.
Show less - Date Issued
- 2012
- Identifier
- CFE0004238, ucf:49533
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0004238
- Title
- CHARACTERIZATION OF POLYETHERIMIDE UNDER STATIC, DYNAMIC, AND MULTIPLE IMPACT CONDITIONS.
- Creator
-
Zuanetti, Bryan, Gordon, Ali, University of Central Florida
- Abstract / Description
-
The application of polymers in robust engineering designs is on the rise due to their excellent mechanical properties such as high fracture toughness, specific strength, durability, as well as, thermal and chemical resistances. Implementation of some advanced polymeric solids is limited due to the lack of available mechanical properties. In order for these materials to endure strenuous engineering designs it is vital to investigate their response in multiple loading rates and conditions. In...
Show moreThe application of polymers in robust engineering designs is on the rise due to their excellent mechanical properties such as high fracture toughness, specific strength, durability, as well as, thermal and chemical resistances. Implementation of some advanced polymeric solids is limited due to the lack of available mechanical properties. In order for these materials to endure strenuous engineering designs it is vital to investigate their response in multiple loading rates and conditions. In this thesis, the mechanical response of polyethermide (PEI) is characterized under quasi-static, high strain rate, and multiple impact conditions. Standard tension, torsion, and compression experiments are performed in order to distinguish the multi-regime response of PEI. The effects of physical ageing and rejuvenation on the quasi-static mechanical response are investigated. The strain softening regime resulting from strain localization is eliminated by thermal and mechanical rejuvenation, and the advantages of these processes are discussed. The dynamic fracture toughness of the material in response to notched impact via Charpy impact test is evaluated. The high strain-rate response of PEI to uniaxial compression is evaluated at rates exceeding 104/s via miniaturized Split Hopkinson Pressure Bar (MSHPB), and compared to the quasi-static case to determine strain-rate sensitivity. The elastic response of the aged material to multiple loading conditions are correlated using the Ramberg-Osgood equation, while the elastoplastic response of rejuvenated PEI is correlated using a both the Ramberg-Osgood equation and a novel model. The strain-rate sensitivity of the strength is found to be nominally bilinear and transition strains are modeled using the Ree-Erying formulation. Finally, multiple impact experiments are performed on PEI using the MSHPB and a model is proposed to quantify damage as a result of collision.
Show less - Date Issued
- 2013
- Identifier
- CFH0004531, ucf:45166
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFH0004531
- Title
- THE EFFECTS ADVERTISING PLAYS ON COLLEGE STUDENTS' MORAL INTENTIONS BEYOND PURCHASE BEHAVIOR.
- Creator
-
Crockett, William, Massiah, Carolyn, University of Central Florida
- Abstract / Description
-
Advertisements affect our daily lives and as technology and the practice of marketing has developed over the course of history, we have become exposed to greater amounts of product and service campaigns. The purpose of advertisements is to educate the consumer with the goal of ultimately selling the product, and many companies and organizations would not be able to survive without the use of advertisements. Ultimately, it is a necessity for a business to prosper in a competitive market, but...
Show moreAdvertisements affect our daily lives and as technology and the practice of marketing has developed over the course of history, we have become exposed to greater amounts of product and service campaigns. The purpose of advertisements is to educate the consumer with the goal of ultimately selling the product, and many companies and organizations would not be able to survive without the use of advertisements. Ultimately, it is a necessity for a business to prosper in a competitive market, but there are possible side-effects for the consumer that are beyond the intentions to buy. The purpose of this thesis is to explore the effects advertisements play on the college student in particular. Different static/multi media advertisements have been shown to various college students ranging in gender and background to discover the comprehensive ramifications of specific promotions to study the moral and ethical impact that advertisements play on students' moral intent. An analysis and conclusion will be given, along with ideas for possible future studies. Recommendations will also be stated for marketers to be morally responsible for the advertisements they portray so the audience is not effected in a way that can lead to unwanted consequences. Ultimately, the results did not support the original hypotheses, leading to thought- provoking questions concerning our current marketing practices and the effectiveness of static and multimedia advertisements on college students. Future studies need to take place to reveal the accuracy of the study and to ultimately answer the question, "Are current advertisements influencing the audience at hand?"
Show less - Date Issued
- 2012
- Identifier
- CFH0004250, ucf:44899
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFH0004250
- Title
- A Place in the Sunshine State : Community, Preservation, and the Parliament House.
- Creator
-
Montgomery, Erin, Lester, Connie, Gannon, Barbara, Pineda, Yovanna, University of Central Florida
- Abstract / Description
-
A Place in the Sunshine State, is a thesis project focused on the Parliament House Motor Inn in Orlando, Florida. This project nominated the Parliament House Motor Inn for inclusion on the National Register of Historic Places. This nomination was completed using both oral histories and more traditional historical source material. The Parliament House Motor Inn was evaluated using National Register Bulletins and the Secretary of the Interior's Standards for Preservation. This nomination was...
Show moreA Place in the Sunshine State, is a thesis project focused on the Parliament House Motor Inn in Orlando, Florida. This project nominated the Parliament House Motor Inn for inclusion on the National Register of Historic Places. This nomination was completed using both oral histories and more traditional historical source material. The Parliament House Motor Inn was evaluated using National Register Bulletins and the Secretary of the Interior's Standards for Preservation. This nomination was presented to give voice to a long-underrepresented community within the national narrative of the United States, along with giving the Parliament House the recognition it deserves as an integral institution within the gay community. This nomination sheds new light onto early gay life in Orlando and concludes that Parliament House is a significant historic and cultural resource. This conclusion is vital to the preservation of LGBT history; it allows for a more complex interpretation of Orlando and central Florida history and helps to recognize LGBT history and the sites associated with them. This thesis also discusses Parliament House and its role as a site of the intersections between gay community and identity creation, place making, and the intricate history of the southern United States. ?
Show less - Date Issued
- 2017
- Identifier
- CFE0007128, ucf:52319
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0007128
- Title
- Nano-Particles in Multi-Scale Composites and Ballistic Applications.
- Creator
-
Gibson, Jason, Gou, Jihua, Raghavan, Seetha, Bai, Yuanli, Zhai, Lei, University of Central Florida
- Abstract / Description
-
Carbon nanotubes, graphene and nano sized core shell rubber particles have all been extensively researched for their capability to improve mechanical properties of thermoset resins. However, there has been a lack of research on their evaluation for energy absorption in high velocity impact scenarios, and the fundamental mechanics of their failure mechanisms during highly dynamic stress transfer through the matrix. This fundamental research is essential for laying the foundation for...
Show moreCarbon nanotubes, graphene and nano sized core shell rubber particles have all been extensively researched for their capability to improve mechanical properties of thermoset resins. However, there has been a lack of research on their evaluation for energy absorption in high velocity impact scenarios, and the fundamental mechanics of their failure mechanisms during highly dynamic stress transfer through the matrix. This fundamental research is essential for laying the foundation for improvement in ballistic performance in composite armor. In hard armor applications, energy absorption is largely accomplished through delamination between plies of the composite laminate. This energy absorption is accomplished through two mechanisms. The first being the elongation of the fiber reinforcement contained in the resin matrix, and the second is the propagation of the crack in between the discreet fabric plies. This research aims to fundamentally study the energy absorption characteristics of various nano-particles as reinforcements in thermoset resin for high velocity impact applications. Multiple morphologies will be evaluated through use of platelet, tubular and spherical shaped nano-particles. Evaluations of the effect on stress transfer through the matrix due to the combination of nano sized and micro scale particles of milled fiber is conducted. Three different nano-particles are utilized, specifically, multi-walled carbon nanotubes, graphene, and core shell rubber particles. The difference in surface area, aspect ratio and molecular structure between the tube, platelet and spherical nano-particles causes energy absorption through different failure mechanisms. This changes the impact performance of composite panels enhanced with the nano-particle fillers. Composite panels made through the use of dispersing the various nano-particles in a non-contact planetary mixer, are evaluated through various dynamic and static testing, including unnotched cantilever beam impact, mixed mode fracture toughness, split-Hopkinson bar, and ballistic V50 testing.The unnotched cantilever beam testing showed that the addition of milled fiber degraded the impact resistance of the samples. Addition of graphene nano platelets unilaterally degraded impact resistance through the unnotched cantilever beam testing. 1.5% loading of MWCNT showed the greatest increase in impact resistance, with a 43% increase over baseline.Determining the critical load for mixed mode interlaminar shear testing can be difficult for composite panels that bend without breaking. An iterative technique of optimizing the coefficient of determination, R2, in linear regression is developed for objectively determining the point of non-linearity for critical load. This allows for a mathematical method of determination; thereby eliminating any subjective decision of choosing where the data becomes non-linear. The core shell rubber nano particles showed the greatest strain energy release rate with an exponential improvement over the baseline results.Synergistic effects between nano and micro sized particles in the resin matrix during transfer of the stress wave were created and evaluated. Loadings of 1% milled carbon fiber enhanced the V50 ballistic performance of both carbon nanotube and core shell rubber particles in the resin matrix. However, the addition of milled carbon fiber degrades the impact resistance of all nano-particle enhanced resin matrices. Therefore, benefits gained from the addition of micro-sized particles in combination with nano-sized particles, are only seen in high energy impact scenarios with micro second durations.Loadings of 1% core shell rubber particles and 1% milled carbon fiber have an improvement of 8% in V50 ballistic performance over the baseline epoxy sample for 44 mag single wad cutter gas check projectiles. Loadings of 1% multi-walled carbon nanotubes with 1% milled carbon fiber have an improvement of 7.3% in V50 ballistic performance over the baseline epoxy sample.The failure mechanism of the various nano-particle enhanced resin matrices during the ballistic event is discussed through the use of scanning electron microscope images and Raman spectroscopy of the panels after failure. The Raman spectroscopy data shows a Raman shift for the fibers that had an enhancement in the V50 performance through the use of nano-particles. The Raman band for Kevlar(&)#174; centered at 1,649 cm-1 stemming from the stretching of the C==O bond of the fiber shows to be more sensitive to the residual axial strain, while the Raman band centered at 1,611 cm-1 stemming from the C-C phenyl ring is minimally affected for the CSR enhanced panels due to the failure mechanism of the CSR particles during crack propagation.
Show less - Date Issued
- 2013
- Identifier
- CFE0004849, ucf:49714
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0004849
