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Description
With the increasing focus on developing environmentally benign electronic packages, lead-free solder alloys have received a great deal of attention. Mishandling of packages, during manufacture, assembly, or by the user may cause failure of solder joint. A fundamental understanding of the behavior of lead-free solders under mechanical shock conditions is

With the increasing focus on developing environmentally benign electronic packages, lead-free solder alloys have received a great deal of attention. Mishandling of packages, during manufacture, assembly, or by the user may cause failure of solder joint. A fundamental understanding of the behavior of lead-free solders under mechanical shock conditions is lacking. Reliable experimental and numerical analysis of lead-free solder joints in the intermediate strain rate regime need to be investigated. This dissertation mainly focuses on exploring the mechanical shock behavior of lead-free tin-rich solder alloys via multiscale modeling and numerical simulations. First, the macroscopic stress/strain behaviors of three bulk lead-free tin-rich solders were tested over a range of strain rates from 0.001/s to 30/s. Finite element analysis was conducted to determine appropriate specimen geometry that could reach a homogeneous stress/strain field and a relatively high strain rate. A novel self-consistent true stress correction method is developed to compensate the inaccuracy caused by the triaxial stress state at the post-necking stage. Then the material property of micron-scale intermetallic was examined by micro-compression test. The accuracy of this measure is systematically validated by finite element analysis, and empirical adjustments are provided. Moreover, the interfacial property of the solder/intermetallic interface is investigated, and a continuum traction-separation law of this interface is developed from an atomistic-based cohesive element method. The macroscopic stress/strain relation and microstructural properties are combined together to form a multiscale material behavior via a stochastic approach for both solder and intermetallic. As a result, solder is modeled by porous plasticity with random voids, and intermetallic is characterized as brittle material with random vulnerable region. Thereafter, the porous plasticity fracture of the solders and the brittle fracture of the intermetallics are coupled together in one finite element model. Finally, this study yields a multiscale model to understand and predict the mechanical shock behavior of lead-free tin-rich solder joints. Different fracture patterns are observed for various strain rates and/or intermetallic thicknesses. The predictions have a good agreement with the theory and experiments.
ContributorsFei, Huiyang (Author) / Jiang, Hanqing (Thesis advisor) / Chawla, Nikhilesh (Thesis advisor) / Tasooji, Amaneh (Committee member) / Mobasher, Barzin (Committee member) / Rajan, Subramaniam D. (Committee member) / Arizona State University (Publisher)
Created2011
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Description
Concrete columns constitute the fundamental supports of buildings, bridges, and various other infrastructures, and their failure could lead to the collapse of the entire structure. As such, great effort goes into improving the fire resistance of such columns. In a time sensitive fire situation, a delay in the failure of

Concrete columns constitute the fundamental supports of buildings, bridges, and various other infrastructures, and their failure could lead to the collapse of the entire structure. As such, great effort goes into improving the fire resistance of such columns. In a time sensitive fire situation, a delay in the failure of critical load bearing structures can lead to an increase in time allowed for the evacuation of occupants, recovery of property, and access to the fire. Much work has been done in improving the structural performance of concrete including reducing column sizes and providing a safer structure. As a result, high-strength (HS) concrete has been developed to fulfill the needs of such improvements. HS concrete varies from normal-strength (NS) concrete in that it has a higher stiffness, lower permeability and larger durability. This, unfortunately, has resulted in poor performance under fire. The lower permeability allows for water vapor to build up causing HS concrete to suffer from explosive spalling under rapid heating. In addition, the coefficient of thermal expansion (CTE) of HS concrete is lower than that of NS concrete. In this study, the effects of introducing a region of crumb rubber concrete into a steel-reinforced concrete column were analyzed. The inclusion of crumb rubber concrete into a column will greatly increase the thermal resistivity of the overall column, leading to a reduction in core temperature as well as the rate at which the column is heated. Different cases were analyzed while varying the positioning of the crumb-rubber region to characterize the effect of position on the improvement of fire resistance. Computer simulated finite element analysis was used to calculate the temperature and strain distribution with time across the column's cross-sectional area with specific interest in the steel - concrete region. Of the several cases which were investigated, it was found that the improvement of time before failure ranged between 32 to 45 minutes.
ContributorsZiadeh, Bassam Mohammed (Author) / Phelan, Patrick (Thesis advisor) / Kaloush, Kamil (Thesis advisor) / Jiang, Hanqing (Committee member) / Arizona State University (Publisher)
Created2011
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Description
Pb-free solders are used as interconnects in various levels of micro-electronic packaging. Reliability of these interconnects is very critical for the performance of the package. One of the main factors affecting the reliability of solder joints is the presence of porosity which is introduced during processing of the joints. In

Pb-free solders are used as interconnects in various levels of micro-electronic packaging. Reliability of these interconnects is very critical for the performance of the package. One of the main factors affecting the reliability of solder joints is the presence of porosity which is introduced during processing of the joints. In this thesis, the effect of such porosity on the deformation behavior and eventual failure of the joints is studied using Finite Element (FE) modeling technique. A 3D model obtained by reconstruction of x-ray tomographic image data is used as input for FE analysis to simulate shear deformation and eventual failure of the joint using ductile damage model. The modeling was done in ABAQUS (v 6.10). The FE model predictions are validated with experimental results by comparing the deformation of the pores and the crack path as predicted by the model with the experimentally observed deformation and failure pattern. To understand the influence of size, shape, and distribution of pores on the mechanical behavior of the joint four different solder joints with varying degrees of porosity are modeled using the validated FE model. The validation technique mentioned above enables comparison of the simulated and actual deformation only. A more robust way of validating the FE model would be to compare the strain distribution in the joint as predicted by the model and as observed experimentally. In this study, to enable visualization of the experimental strain for the 3D microstructure obtained from tomography, a three dimensional digital image correlation (3D DIC) code has been implemented in MATLAB (MathWorks Inc). This developed 3D DIC code can be used as another tool to verify the numerical model predictions. The capability of the developed code in measuring local displacement and strain is demonstrated by considering a test case.
ContributorsJakkali, Vaidehi (Author) / Chawla, Nikhilesh K (Thesis advisor) / Jiang, Hanqing (Committee member) / Solanki, Kiran (Committee member) / Arizona State University (Publisher)
Created2011
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Description

Animals encounter information from different resources simultaneously, integrating input from multiple sensory systems before responding behaviorally. When different cues interact with one another, they may enhance, diminish, or have no impact on their responses. In this project, we test how the presence of chemical cues affect the perception of visual

Animals encounter information from different resources simultaneously, integrating input from multiple sensory systems before responding behaviorally. When different cues interact with one another, they may enhance, diminish, or have no impact on their responses. In this project, we test how the presence of chemical cues affect the perception of visual cues. Zebrafish (Danio rerio) often use both chemical cues and visual cues to communicate with shoal mates, to assess predation risk, and to locate food. For example, zebrafish rely on both olfactory cues and visual cues for kin recognition, and they frequently use both chemical and visual cues to search for and to capture prey. In zebrafish, the terminal nerve (TN) constitutes the olfacto-visual centrifugal pathway and connects the olfactory bulb with the retina, thus allowing olfactory perception also to activate visual receptors. Past studies have found that the presence of an olfactory cue can modulate visual sensitivity in zebrafish through the terminal nerve pathway. Alternatively, given that zebrafish are highly social, the presence of social chemical cues may distract individuals from responding to other visual cues, such as food and predator visual cues. Foraging and predator chemical cues, including chemical food cues and alarm cues, may also distract individuals from responding to non-essential visual cues. Here, we test whether the response to a visual cue either increases or decreases when presented in concert with alanine, an amino acid that represents the olfactory cues of zebrafish prey. We found that the presence of chemical cues did not affect whether zebrafish responded to visual cues, but that the fish took longer to respond to visual cues when chemical cues were also present. These findings suggest that different aspects of behavior could be affected by the interaction between sensory modalities. We also found that this impact of delayed response was significant only when the visual cue<br/>was weak compared to the strength of the chemical cue, suggesting that the salience of interacting cues may also have an influence on determining the outcomes of the interactions. Overall, the interactive effects of chemicals on an animal’s response to visual cues may also have wide-ranging impacts on behavior including foraging, mating, and evading predators, and the interaction of cues may affect different aspects of the same behavior.

ContributorsPuffer, Georgie Delilah (Author) / Martins, Emilia (Thesis director) / Suriyampola, Piyumika (Committee member) / Gerkin, Richard (Committee member) / School of Life Sciences (Contributor) / Department of Psychology (Contributor) / Barrett, The Honors College (Contributor)
Created2021-05
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Description

Exploratory Play is a universal experience that occurs throughout different kinds of childhoods. This study investigates how children’s vocabulary and exploratory play are influenced by how the caregiver responds to the child’s communicative bids. We hypothesize that if caregivers use more open-ended questions in response to their child’s communicative bids,

Exploratory Play is a universal experience that occurs throughout different kinds of childhoods. This study investigates how children’s vocabulary and exploratory play are influenced by how the caregiver responds to the child’s communicative bids. We hypothesize that if caregivers use more open-ended questions in response to their child’s communicative bids, children will show higher rates of exploration during free play.

ContributorsMccollum, Shani Monifa (Author) / Lucca, Kelsey (Thesis director) / Spinrad, Tracy (Committee member) / Department of Psychology (Contributor) / Barrett, The Honors College (Contributor)
Created2021-05
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Description

Laminated composites are increasingly being used in various industries including <br/>automotive and aerospace. Under a variety of extreme loading conditions such as low and <br/>high-velocity impacts and crash, laminated composites delaminate. To understand how and<br/>when delamination occurs, two types of laboratory tests are conducted - End-notched <br/>Flexure (ENF) test and

Laminated composites are increasingly being used in various industries including <br/>automotive and aerospace. Under a variety of extreme loading conditions such as low and <br/>high-velocity impacts and crash, laminated composites delaminate. To understand how and<br/>when delamination occurs, two types of laboratory tests are conducted - End-notched <br/>Flexure (ENF) test and Double Cantilever Beam (DCB) test. The ENF test is designed to <br/>find the mode II interlaminar fracture toughness, and the DCB test, the mode I interlaminar <br/>fracture toughness. In this thesis, thermopressed Honeywell Spectra Shield® 5231 <br/>composite specimens made of ultra-high molecular weight polyethylene (UHMWPE), <br/>manufactured under two different pressures (3000 psi and 6000 psi), are tested in the <br/>laboratory to find its delamination properties. The test specimen preparation, experimental <br/>procedures, and data reduction to determine the mode I and mode II interlaminar fracture <br/>properties are discussed. The ENF test results show a 15.8% increase in strain energy <br/>release rate for the 6000 psi specimens when compared to the 3000 psi specimens. <br/>Conducting the DCB tests proved to be challenging due to the low compressive strength <br/>of the material and hence required modifications to the test specimens. An estimate of the <br/>mode I interlaminar fracture toughness was found for only two of the 6000 psi specimens.

ContributorsRyder, Chandler (Author) / Rajan, Subramaniam (Thesis director) / Khaled, Bilal (Committee member) / Neithalath, Narayanan (Committee member) / Mechanical and Aerospace Engineering Program (Contributor) / Barrett, The Honors College (Contributor)
Created2021-05
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Description

In this thesis I will explore deficits in Theory of Mind (ToM) in autistic people due to new evidence that they do not completely lack a ToM. A new theory is proposed, claiming that autistic people use a Hyper Theory of Mind (HyperToM) which has some application and processing differences

In this thesis I will explore deficits in Theory of Mind (ToM) in autistic people due to new evidence that they do not completely lack a ToM. A new theory is proposed, claiming that autistic people use a Hyper Theory of Mind (HyperToM) which has some application and processing differences from typical ToM. The HyperToM test will be administered as an online questionnaire that includes a self-reported Autism Quotient (AQ) section. The study is done in low support needs autistic (LSA) adults, which should have a developed ToM due to age and ability. Results showed some correlations with the AQ symptoms and HyperToM, but not enough diagnosed autistic people (9) participated in this study for significant results.

ContributorsMarkov, Vlada A (Author) / Fabricius, William (Thesis director) / Philips, Ben (Committee member) / Department of Psychology (Contributor) / Dean, W.P. Carey School of Business (Contributor) / School of Life Sciences (Contributor) / Barrett, The Honors College (Contributor)
Created2021-05
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Description

Appearance ideals are standards of beauty imposed by a culture or society, that are unrealistic and impossible to achieve. Research documents the existence of three appearance ideals, thin, muscular and hourglass ideals. The thin ideal is the pursuit of a very thin and low body weight. The muscular ideal is

Appearance ideals are standards of beauty imposed by a culture or society, that are unrealistic and impossible to achieve. Research documents the existence of three appearance ideals, thin, muscular and hourglass ideals. The thin ideal is the pursuit of a very thin and low body weight. The muscular ideal is the pursuit of a toned and fit body. The hourglass ideal is the pursuit of a shapely body with bigger breasts and hips/buttocks than waist. These ideals are associated with disordered eating. However, no current study has examined the prevalence of all three ideals, or how the combination of ideals relates to dietary restraint, one example of a disordered eating behavior. This study was conducted on 505 undergraduate women at Arizona State University, who were completing research credit for a psychology course. The women participated in an online survey that assessed their demographics, each ideal, and dietary restraint. Results show that all combinations of ideals exist. Specifically, 41.5% of the sample endorse high levels of all three ideals, while 12.5% report thin and muscular ideals, 9.5% report thin and hourglass ideals, 9.9% report hourglass and muscular ideals, 8.4% report low levels of all three ideals, 6.4% report muscular ideal only, 6.4% report hourglass ideal only, and 5.6% report thin ideal only. Endorsing more than one ideal significantly associated with dietary restraint. Findings fulfill an important gap in the literature, suggest future directions for research, and have important clinical implications.

ContributorsByrd, Jordyn (Author) / Perez, Marisol (Thesis director) / Hernández, Juan (Committee member) / Department of Psychology (Contributor) / Barrett, The Honors College (Contributor)
Created2021-05
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Description

Long distance travel around the globe can potentially be revolutionized with the use of an intercontinental rocket that uses low earth orbit as its medium. This transport system can increase growth in many new businesses like tourism travel between the continents. This research evaluates the technical and non-technical possibilities

Long distance travel around the globe can potentially be revolutionized with the use of an intercontinental rocket that uses low earth orbit as its medium. This transport system can increase growth in many new businesses like tourism travel between the continents. This research evaluates the technical and non-technical possibilities of using a double-stage reusable rocket, where the second stage is also a reusable, rocket-powered passenger vehicle using a low earth orbit space journey with a stabilized re-entry method that ensures passenger comfortability. A potential network of spaceports spanning the globe is postulated within a range of 4,000 km to 8,000 km(2,160 nm to 4,320 nm) of each other, and each located within an hour by any other means of ground transport to population hubs greater than four million. This will help further connect the world as the journey from one major city to another would take at most an hour, and no point on the habited continents would be more than 4,000 km(2,160 nm) from a spaceport. It is assumed that the costs of an international first class flight ticket are in the thousands of dollars range showing how there is a potential market for this type of travel network. The reasoning and analysis, through a literature review, for an intercontinental rocket vehicle is presented along with the various aspects of the possibility of this kind of travel network coming to fruition in the near future.

ContributorsRanganathan, Anirudh (Co-author) / Karthikeyan, Sayish (Co-author) / Takahashi, Timothy (Thesis director) / Niemczyk, Mary (Committee member) / Mechanical and Aerospace Engineering Program (Contributor, Contributor) / Barrett, The Honors College (Contributor)
Created2021-05
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Description

Mayer-Rokitansky-Küster-Hauser (MRKH) is a rare Disorder of Sexual Development (DSD) that results in the lack of a uterus and vagina in women. Receiving this diagnosis during adolescence can cause various forms of psychological distress in patients and families.<br/>Specifically, this condition could affect a women’s gender identity, body image, romantic relationships,

Mayer-Rokitansky-Küster-Hauser (MRKH) is a rare Disorder of Sexual Development (DSD) that results in the lack of a uterus and vagina in women. Receiving this diagnosis during adolescence can cause various forms of psychological distress in patients and families.<br/>Specifically, this condition could affect a women’s gender identity, body image, romantic relationships, family relationships, and psychological wellbeing. Parents are also put in a stressful<br/>position as they now have to navigate the healthcare system, disclosure, and the relationship with their child. This study aims to expand the knowledge of psychosocial adjustment by studying body<br/>image, gender identity, and mental health in individuals living with MRKH as well as parental disclosure, parental support systems, and parental perceptions of their child’s mental health.

ContributorsLaloudakis, Vasiliki (Author) / Wilson, Melissa (Thesis director) / Fontinha de Alcantara, Christiane (Committee member) / Baimbridge, Erica (Committee member) / Department of Psychology (Contributor) / School of Life Sciences (Contributor) / Barrett, The Honors College (Contributor)
Created2021-05