Matching Items (14)
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- All Subjects: Mechanical Engineering
- Genre: Masters Thesis
- Creators: Nian, Qiong
Description
Polymer fibers have broad applications in wearable electronics, bulletproof vests, batteries, fuel cells, filters, electrodes, conductive wires, and biomedical materials. Polymer fibers display light density and flexibility but are mostly weak and compliant. The ceramic, metallic, and carbon nanoparticles have been frequently included in polymers for fabricating continuous, durable, and functional composite fibers. Nanoparticles display large specific areas, low defect density and can transfer their superior properties to polymer matrices. The main focus of this thesis is to design, fabricate and characterize the polymer
anocarbon composite fibers with unique microstructures and improved mechanical/thermal performance. The dispersions and morphologies of graphene nanoplatelets (GNPs), the interactions with polyvinyl alcohol (PVA) molecules and their influences on fiber properties are studied. The fibers were fabricated using a dry-jet wet spinning method with engineered spinneret design. Three different structured fibers were fabricated, namely, one-phase polymer fiber (1-phase), two-phase core-shell composite fiber (2-phase), and three-phase co-axial composite fiber (3-phase). These polymer or composite fibers were processed at three stages with drawing temperatures of 100˚C, 150˚C, and 200˚C. Different techniques including the mechanical tester, wide-angle X-Ray diffraction (WAXD), scanning electron microscope (SEM), thermogravimetric analysis (TGA), and differential scanning calorimeter (DSC) have been used to characterize the fiber microstructures and properties.
anocarbon composite fibers with unique microstructures and improved mechanical/thermal performance. The dispersions and morphologies of graphene nanoplatelets (GNPs), the interactions with polyvinyl alcohol (PVA) molecules and their influences on fiber properties are studied. The fibers were fabricated using a dry-jet wet spinning method with engineered spinneret design. Three different structured fibers were fabricated, namely, one-phase polymer fiber (1-phase), two-phase core-shell composite fiber (2-phase), and three-phase co-axial composite fiber (3-phase). These polymer or composite fibers were processed at three stages with drawing temperatures of 100˚C, 150˚C, and 200˚C. Different techniques including the mechanical tester, wide-angle X-Ray diffraction (WAXD), scanning electron microscope (SEM), thermogravimetric analysis (TGA), and differential scanning calorimeter (DSC) have been used to characterize the fiber microstructures and properties.
ContributorsVerma, Rahul (Author) / Song, Kenan (Thesis advisor) / Jiang, Hanqing (Committee member) / Nian, Qiong (Committee member) / Arizona State University (Publisher)
Created2018
Description
Stereolithography (SLA) is an innovative additive manufacturing technique that has gained immense popularity in recent times due to its ability to produce complex and precise three-dimensional objects. However, the quality of the final product depends on the stability and homogeneity of the photocurable metallic ink used, which is crucial for manufacturing high-quality parts with good surface finish and higher density. To achieve homogeneity in the photocurable metallic resin, the study conducted on optimizing the printing ink for ultrafast layer less fabrication of 3D metal objects investigated the effectiveness of different dispersants such as KH 560, Triton X-100, BYK 2013, BYK 2030, and BYK 111. The use of dispersants plays a vital role in optimizing the ink and enhancing the surface finish and density of the final product. The rheology results showed that the appropriate dispersant has the potential to improve the properties of the printing ink and benefit the integrity of the printed green bodies and their surface finish. By using the optimized suspension, the study was able to fabricate parts with high metallic loading at an ultrafast speed using the Continuous Liquid Interface Production technique. FTIR analysis, sedimentation testing, and rheology study has been carried out which demonstrates the effects of the utilization of various dispersants optimally to improve the homogeneity and manufactured part’s integrity. Power law has been used to understand the viscosity behavior of dispersants in a photocurable ink with copper sulfate keeping the parameters such as shearing rate, stress, and torque intact. The microscopic images of the sintered parts showed high precision and an extremely smooth surface finish, which underscores the technique's potential to produce high-quality 3D metal objects. The solubility of dispersants significantly influenced the structural quality after washing and debinding processes. This study provides valuable information to design photocurable metallic suspensions for metal salts like copper sulfate pentahydrate.
ContributorsVerma, Harsh Pyarelal (Author) / Li, Xiangjia (Thesis advisor) / Nian, Qiong (Committee member) / Xie, Renxuan (Committee member) / Arizona State University (Publisher)
Created2023
Description
Polylactic Acid (PLA), a thermoplastic polymer is well-known for its biocompatibility, making it ideal for the manufacturing of biomedical devices. However, the current applications of PLA are commonly limited by its intrinsic polymer characteristics, such as low modulus, mechanical strength, and thermal conductivity. To enhance these physical properties, a biocompatible nanodiamond enhanced PLA filament has been studied. Thermogravimetric analysis was performed to unveil the composition of nanodiamond in the composite. Four printing parameters: nozzle temperature, layer height, infill pattern and printing speed were considered and the Taguchi L9 orthogonal array was implemented for the design of experiments. Fused deposition modeling (FDM) technique was utilized to 3D print the PLA/Nanodiamond samples by altering the four printing parameters considered and were tested according to the standards for tensile strength, flexural strength, and thermal conductivity. Using the Taguchi optimization approach and analysis of variance (ANOVA), the generated experimental data was used to find the optimum set of printing parameters. Finally, cell studies were performed to demonstrate the biocompatibility of PLA/Nanodiamond. All these results could aid in determining the working ranges for FDM fabrication of PLA/Nanodiamond for biomedical applications.
ContributorsPoornabodha, Nikhitha (Author) / Nian, Qiong (Thesis advisor) / Kang, Wonmo (Committee member) / Zhuang, Houlong (Committee member) / Arizona State University (Publisher)
Created2022
Description
Fatigue fracture is one of the most common types of mechanical failures seen in structures. Considering that fatigue failures usually initiate on surfaces, it is accepted that surface roughness has a detrimental effect on the fatigue life of components. Irregularities on the surface cause stress concentrations and form nucleation sites for cracks. As surface conditions are not always satisfactory, particularly for additively manufactured components, it is necessary to develop a reliable model for fatigue life estimation considering surface roughness effects and assure structural integrity. This research study focuses on extending a previously developed subcycle fatigue crack growth model to include the effects of surface roughness. Unlike other models that consider surface irregularities as series of cracks, the proposed model is unique in the way that it treats the peaks and valleys of surface texture as a single equivalent notch. First, an equivalent stress concentration factor for the roughness was estimated and introduced into an asymptotic interpolation method for notches. Later, a concept called equivalent initial flaw size was incorporated along with linear elastic fracture mechanics to predict the fatigue life of Ti-6Al-4V alloy with different levels of roughness under uniaxial and multiaxial loading conditions. The predicted results were validated using the available literature data. The developed model can also handle variable amplitude loading conditions, which is suggested for future work.
ContributorsKethamukkala, Kaushik (Author) / Liu, Yongming (Thesis advisor) / Jiao, Yang (Committee member) / Nian, Qiong (Committee member) / Arizona State University (Publisher)
Created2022
Description
Non-Destructive Testing (NDT) is a branch of scientific methods and techniques
used to evaluate the defects and irregularities in engineering materials. These methods
conduct testing without destroying or altering material’s structure and functionality. Most
of these defects are subsurface making them difficult to detect and access.
SONIC INFRARED (IR) is a relatively new and emerging vibrothermography
method under the category of NDT methods. This is a fast NDT inspection method that
uses an ultrasonic generator to pass an ultrasonic pulse through the test specimen which
results in a temperature variation in the test specimen. The temperature increase around
the area of the defect is more because of frictional heating due to the vibration of the
specimen. This temperature variation can be observed using a thermal camera.
In this research study, the temperature variation in the composite laminate during
the SONIC IR experimentation using an infrared thermal camera. These recorded data are
used to determine the location, dimension and depth of defects through SONIC IR NDT
method using existing defect detection algorithms. Probability of detection analysis is
used to determine the probability of detection under specific experimental conditions for
two different types of composite laminates. Lastly, the effect of the process parameters
such as number of pulses, pulse duration and time delay between pulses of this technique
on the detectability and probability of detection is studied in detail.
used to evaluate the defects and irregularities in engineering materials. These methods
conduct testing without destroying or altering material’s structure and functionality. Most
of these defects are subsurface making them difficult to detect and access.
SONIC INFRARED (IR) is a relatively new and emerging vibrothermography
method under the category of NDT methods. This is a fast NDT inspection method that
uses an ultrasonic generator to pass an ultrasonic pulse through the test specimen which
results in a temperature variation in the test specimen. The temperature increase around
the area of the defect is more because of frictional heating due to the vibration of the
specimen. This temperature variation can be observed using a thermal camera.
In this research study, the temperature variation in the composite laminate during
the SONIC IR experimentation using an infrared thermal camera. These recorded data are
used to determine the location, dimension and depth of defects through SONIC IR NDT
method using existing defect detection algorithms. Probability of detection analysis is
used to determine the probability of detection under specific experimental conditions for
two different types of composite laminates. Lastly, the effect of the process parameters
such as number of pulses, pulse duration and time delay between pulses of this technique
on the detectability and probability of detection is studied in detail.
ContributorsDarnal, Aryabhat (Author) / Liu, Yongming (Thesis advisor) / Zhuang, Houlong (Committee member) / Nian, Qiong (Committee member) / Arizona State University (Publisher)
Created2019
Description
With the advancement of the Additive Manufacturing technology in the fields of metals, a lot of interest has developed in Laser Powder Bed (LPBF) for the Aerospace and Automotive industries. With primary challenges like high cost and time associated with this process reducing the build time is a critical component. Being a layer by layer process increasing layer thickness causes a decrease in manufacturing time. In this study, effects of the change in layer thickness in the Laser Powder Bed Fusion of Inconel 718 were evaluated. The effects were investigated for 30, 60 and 80 μm layer thicknesses and were evaluated for Relative Density, Surface Roughness and Mechanical properties, for as-printed specimens not subjected to any heat treatment. The process was optimized to print dense pasts by varying three parameters: power, velocity and hatch distance. Significant change in some properties like true Ultimate Tensile Testing (UTS), %Necking and Yield Stress was observed.
ContributorsPatil, Dhiraj Amar (Author) / Bhate, Dhruv (Thesis advisor) / Azeredo, Bruno (Committee member) / Nian, Qiong (Committee member) / Arizona State University (Publisher)
Created2019
Description
This thesis intends to cover the experimental investigation of the propagation of laser-generated optoacoustic waves in structural materials and how they can be utilized for damage detection. Firstly, a system for scanning a rectangular patch on the sample is designed. This is achieved with the help of xy stages which are connected to the laser head and allow it to move on a plane. Next, a parametric study was designed to determine the optimum testing parameters of the laser. The parameters so selected were then used in a series of tests which helped in discerning how the Ultrasound Waves behave when damage is induced in the sample (in the form of addition of masses). The first test was of increasing the mases in the sample. The second test was a scan of a rectangular area of the sample with and without damage to find the effect of the added masses. Finally, the data collected in such a manner is processed with the help of the Hilbert-Huang transform to determine the time of arrival. The major benefits from this study are the fact that this is a Non-Destructive imaging technique and thus can be used as a new method for detection of defects and is fairly cheap as well.
ContributorsRavi Narayanan, Venkateshwaran (Author) / Liu, Yongming (Thesis advisor) / Zhuang, Houlong (Committee member) / Nian, Qiong (Committee member) / Arizona State University (Publisher)
Created2019
Description
Corrosion fatigue has been of prime concern in railways, aerospace, construction industries and so on. Even in the case of many medical equipment, corrosion fatigue is considered to be a major challenge. The fact that even high strength materials have lower resistance to corrosion fatigue makes it an interesting area for research. The analysis of propagation of fatigue crack growth under environmental interaction and the life prediction is significant to reduce the maintenance costs and assure structural integrity. Without proper investigation of the crack extension under corrosion fatigue, the scenario can lead to catastrophic disasters due to premature failure of a structure. An attempt has been made in this study to predict the corrosion fatigue crack growth with reasonable accuracy. Models that have been developed so far predict the crack propagation for constant amplitude loading (CAL). However, most of the industrial applications encounter random loading. Hence there is a need to develop models based on time scale. An existing time scale model that can predict the fatigue crack growth for constant and variable amplitude loading (VAL) in the Paris region is initially modified to extend the prediction to near threshold and unstable crack growth region. Extensive data collection was carried out to calibrate the model for corrosion fatigue crack growth (CFCG) based on the experimental data. The time scale model is improved to incorporate the effect of corrosive environments such as NaCl and dry hydrogen in the fatigue crack growth (FCG) by investigation of the trend in change of the crack growth. The time scale model gives the advantage of coupling the time phenomenon stress corrosion cracking which is suggested as a future work in this paper.
ContributorsKurian, Bianca (Author) / Liu, Yongming (Thesis advisor) / Nian, Qiong (Committee member) / Zhuang, Houlong (Committee member) / Arizona State University (Publisher)
Created2019
Description
Traditionally, for applications that require heat transfer (e.g. heat exchangers),metals have been the go-to material for manufacturers because of their high thermal as
well as structural properties. However, metals have some notable drawbacks. They are
not corrosion-resistant, offer no freedom of design, have a high cost of production, and
sourcing the material itself. Even though polymers on their own don’t show great
prospects in the field of thermal applications, their composites perform better than their
counterparts. Nanofillers, when added to a polymer matrix not only increase their
structural strength but also their thermal performance. This work aims to tackle two of
those problems by using the additive manufacturing method, stereolithography to solve
the problem of design freedom, and the use of polymer nanocomposite material for
corrosion-resistance and increase their overall thermal performance. In this work, three
different concentrations of polymer composite materials were studied: 0.25 wt%, 0.5
wt%, and 1wt% for their thermal conductivity. The samples were prepared by
magnetically stirring them for a period of 10 to 24 hours depending on their
concentrations and then sonicating in an ice bath further for a period of 2 to 3 hours.
These samples were then tested for their thermal conductivities using a Hot Disk TPS
2500S. Scanning Electron Microscope (SEM) to study the dispersion of the nanoparticles
in the matrix. Different theoretical models were studied and used to compare
experimental data to the predicted values of effective thermal conductivity. An increase
of 7.9 % in thermal conductivity of the composite material was recorded for just 1 wt%
addition of multiwalled carbon nanotubes (MWCNTs).
well as structural properties. However, metals have some notable drawbacks. They are
not corrosion-resistant, offer no freedom of design, have a high cost of production, and
sourcing the material itself. Even though polymers on their own don’t show great
prospects in the field of thermal applications, their composites perform better than their
counterparts. Nanofillers, when added to a polymer matrix not only increase their
structural strength but also their thermal performance. This work aims to tackle two of
those problems by using the additive manufacturing method, stereolithography to solve
the problem of design freedom, and the use of polymer nanocomposite material for
corrosion-resistance and increase their overall thermal performance. In this work, three
different concentrations of polymer composite materials were studied: 0.25 wt%, 0.5
wt%, and 1wt% for their thermal conductivity. The samples were prepared by
magnetically stirring them for a period of 10 to 24 hours depending on their
concentrations and then sonicating in an ice bath further for a period of 2 to 3 hours.
These samples were then tested for their thermal conductivities using a Hot Disk TPS
2500S. Scanning Electron Microscope (SEM) to study the dispersion of the nanoparticles
in the matrix. Different theoretical models were studied and used to compare
experimental data to the predicted values of effective thermal conductivity. An increase
of 7.9 % in thermal conductivity of the composite material was recorded for just 1 wt%
addition of multiwalled carbon nanotubes (MWCNTs).
ContributorsGide, Kunal Manoj (Author) / Nian, Qiong (Thesis advisor) / Kwon, Beomjin (Committee member) / Li, Xiangjia (Committee member) / Arizona State University (Publisher)
Created2020
Description
Additive manufacturing (AM) has been extensively investigated in recent years to explore its application in a wide range of engineering functionalities, such as mechanical, acoustic, thermal, and electrical properties. The proposed study focuses on the data-driven approach to predict the mechanical properties of additively manufactured metals, specifically Ti-6Al-4V. Extensive data for Ti-6Al-4V using three different Powder Bed Fusion (PBF) additive manufacturing processes: Selective Laser Melting (SLM), Electron Beam Melting (EBM), and Direct Metal Laser Sintering (DMLS) are collected from the open literature. The data is used to develop models to estimate the mechanical properties of Ti-6Al-4V. For this purpose, two models are developed which relate the fabrication process parameters to the static and fatigue properties of the AM Ti-6Al-4V. To identify the behavior of the relationship between the input and output parameters, each of the models is developed on both linear multi-regression analysis and non-linear Artificial Neural Network (ANN) based on Bayesian regularization. Uncertainties associated with the performance prediction and sensitivity with respect to processing parameters are investigated. Extensive sensitivity studies are performed to identify the important factors for future optimal design. Some conclusions and future work are drawn based on the proposed study with investigated material.
ContributorsSharma, Antriksh (Author) / Liu, Yongming (Thesis advisor) / Nian, Qiong (Committee member) / Jiao, Yang (Committee member) / Arizona State University (Publisher)
Created2020