Browsing by Subject "Failure"
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Item Durability and waterproofing investigations of the building envelope(2015-05) Feero, Beth Anne; Fowler, David W.; Novoselac, AtilaDurability of the building envelope is an important characteristic to monitor and test on a structure to ensure it does not fail prematurely from water penetration. Due to the building envelop failures existing today, the described testing herein aims to evaluate different building components in an effort to express deficiencies in testing or products so as to better influence the building envelope product market and lessen the possibility of future failures. This thesis describes the background and protocol for testing water resistive barrier full-scale mockups for long-term durability. An auxiliary study of the product nail sealability testing was also conducted, providing supporting visibility into inconsistencies between manufacturer and test results. Elastomeric sealants were also tested according to a new standard, ASTM C1589, which evaluates products for the long term based on both movement and weathering--a much needed standardized testing scenario. Initial results show the need for primed, silicone, and SWR Institute validated products. The water penetration characteristics of concrete masonry units were also analyzed using both ASTM C90 and RILEM tube testing. The results emphasized the need for redundancy in water repellents for porous units and the significant leniency of ASTM C90. Lastly, masonry veneer anchor guidelines were discussed, and it was found that the prescriptive nature of the MSJC code does not provide adequate guidance on installation of anchors for unique architectural or structural details. Suggestions for placement in these instances are given. Much of the testing described in this thesis represents best practice suggestions and initial product evaluation. Since this testing has been developed as long-term experiments, the next few years will provide the needed information on failure mechanisms and methods to prevent these failures.Item Fail forward : an examination of failure and the director's practice(2017-05-04) Phipps, Cara Marie; Dietz, Steven; Sanchez, K. J.This thesis is about failure and its role in the director’s practice. I will define failure, its function in three of my production experiences at the University of Texas at Austin, and how this understanding of failure has become part of my artistic practice moving forward into the professional world. I seek to emphasize failure as an integral part of the director’s practice.Item From failure to flourishing: a cognitive, emotional, and behavioral model(2010-05) North, Rebecca Jeanne; Holahan, Charles J.; Carlson, Caryn L.; Pennebaker, James W.; Swann, William B.; Wong, Patrick P.Two studies were conducted to examine if and how failure can lead to subsequent psychological flourishing. Both studies used the context of individuals’ biggest job-related failure or most significant challenge to test a proposed model of adaptive response to failure. Specifically, it was proposed that, at a cognitive/emotional level, an adaptive response to failure is characterized by acceptance of negative emotions and self-acceptance. Further, it was proposed that at a behavioral level, an adaptive response to failure involves goal disengagement coupled with goal reengagement, including reengaging with new goals that are intrinsically meaningful. These complementary studies both examined the relationship between individuals’ response to failure and psychological flourishing. Studies were conducted with different participant samples and used complementary designs to provide converging evidence for the proposed model. Using a random sampling process to recruit participants, Study 1 (N = 50) consisted of semi-structured interviews with individuals from the Austin community. Study 2 (N = 101) was an online study and consisted of a series of questionnaires and a writing task. Analyses were conducted on interviews, questionnaires, and writings to examine the relationships between response to failure, including acceptance of negative emotions, self-acceptance, goal disengagement, and goal reengagement, and psychological flourishing. Overall, findings underscored the significance of acceptance and goal reengagement in predicting psychological flourishing after failure. Goal reengagement, in particular, consistently predicted subsequent flourishing. Results also indicated that in response to failure, both persistence toward meeting established goals and moving beyond established goals can lead to subsequent flourishing. These findings imply that flexibility, rather than adherence to a singular response, may be adaptive in responding at a behavioral level to failure. Furthermore, results showed that failures characterized by higher emotional distress can lead to greater subsequent psychological flourishing than failures characterized by low levels of emotional distress. Overall, both studies demonstrate that failure, when responded to in an adaptive way, can lead to a broad range of positive psychological outcomes.Item Localization and failure of Aluminum 6061-T6 under biaxial loading(2019-06-19) Scales, Martin Filipp; Kyriakides, S.; Kovar, Desiderio; Liechti, Kenneth; Mear, Mark; Ravi-Chandar, KrishnaswamyThe adoption of new materials for light-weighting purposes in the automotive industry has been hindered by these materials’ limited ductility and more-complicated constitutive models. Establishing the onset of failure through experiment is challenging, and numerical predictions depend strongly on the adopted material model. With this in mind, a series of experiments was developed with the goal of providing directly-measurable strains and stresses at failure. Custom-designed Al 6061 T6 tubular specimens with a thin-walled test section are loaded in radial stress paths in the nominal axial-shear stress space. Stereo digital image correlation is used to monitor the specimen surface throughout the experiment. The stress and deformation within the test section are uniform until a load maximum is reached, beyond which deformation localizes into a circumferential band with width the order of the wall thickness. The series of experiments shows that the strain at failure monotonically increases as the triaxiality decreases, a result that is contrary to previously-reported results for this alloy. The strains at failure are also significantly larger than previously-reported values, with equivalent strains around 1.5 at low triaxialities. This experimental methodology provides a robust means of directly establishing failure strains that can be employed as failure criteria in numerical simulations. In support of a separate effort to numerically reproduce the responses and localization in these tension-torsion experiments, a series of combined tension and internal pressure experiments on the same tube stock was conducted. In these experiments, the tubes are loaded in radial paths in the nominal axial-hoop stress space. The data obtained proved sufficient for calibrating the non-quadratic, 18-parameter, anisotropic constitutive model of Barlat and coworkers. With the calibrated constitutive model, a large-deformation material stress-strain curve was inversely extracted from the post-necking response in a uniaxial tension test. The pressure-tension experiments were then studied numerically through a finite element (FE) model that incorporated the calibrated constitutive model and hardening response. The analysis shows that properly-calibrated plasticity with an accurate stress-strain curve and suitable FE mesh is capable of reproducing the measured responses as well as the localized deformations that developed prior to burst.Item Methods for mud motor failure prevention : stall detection and temperature advisory(2022-05-09) De Saint Germain, Alexandre; Oort, Eric vanMud motor failure should be avoided where possible and a lot of research has gone into understanding potential mitigation strategies. Previous research performed for the RAPID group at the University of Texas at Austin identified stalls as a leading cause for mud motor damage and failure, yet very little research has been done to investigate them. Temperature is known to be leading factor in reducing mud motor life and will likely be more important now than it was in the past as drilling operations increase in complexity. In this work, we present two different algorithms designed to run while drilling. The first is a statistics-based stall detection algorithm designed to run on surface data. Where stall detection has previously based itself only on the Differential Pressure, our approach requires three simultaneous peaks in MSE, WOB and Differential Pressure. The second is a temperature model for the estimation of bottomhole temperature which can serve as a real-time advisory alerting if the temperature exceeds the motor rating. Both could be implemented in a damage index for the estimation of mud motor degradation at any timeItem On the axial crushing and failure of aluminum alloy tubes : experiments and numerical simulations(2020-05-01) Haley, Jake Andrew; Kyriakides, S.The use of aluminum alloys for light-weighting purposes in energy absorbing components of automobiles is hindered by the relatively low ductility and more complicated constitutive behavior of these alloys. This study presents results from series of quasi-static and dynamic axial crushing experiments on extruded Al-6061-T6 circular tubes of varying D/t ratios. A custom drop-weight testing facility was used to perform the dynamic experiments. Crushing led to axisymmetric, mode-2, and mode-3 concertina folding. In the quasi-static experiments, the folding was monitored using time-lapse photography; dynamic crushing was monitored using high-speed photography. The crushing responses and energy absorption capacities are evaluated and failures were recorded. Failure was observed in most of the experiments with the severity depending on the D/t and mode of folding. The experiments are simulated with three-dimensional, nonlinear finite element analysis using the von Mises, the non-quadratic Hosford, and the calibrated anisotropic Yld04-3D models. The Yld04-3D model was found to most accurately reproduce the structural response under both quasi-static and dynamic loadings. This model was used to the monitor the strains induced in two example cases: axisymmetric folding under quasi-static loading, and mode-2 folding under dynamic loading. The analysis predicted maximum strains to develop at locations on the model tube where failure is observed on the specimen in the experiments. It is concluded that the Yld04-3D constitutive model is most suitable for the prediction of the structural response and failure in tube crushing of this aluminum alloy.Item On the implosion of underwater composite shells(2011-12) Leduc, Mathieu; Liechti, K. M.; Kyriakides, S.The aim of this study was to investigate the dynamic collapse of composite shells in a constant external pressure water environment that is representative of a naval underwater structure. Laminated carbon/epoxy composite shells with diameters of 1.735 in., wall thickness of 0.041 in, length-to-diameter ratios ranging for 2.8 to 12 and [55/-55/(90)3/-55/55] layup were collapsed in a custom pressure testing facility that provided a constant pressure water environment. Buckling was sudden, dynamic, led to failure and fragmentation of the shells; the whole event lasted only a couple of ms. The dynamic collapse of the shells was recorded using high-speed digital imaging and dynamic pressure sensors synchronized with the camera were used to monitor the emanating pressure waves. All shells buckled in mode 2 at pressure levels predicted by models adopted. Collapse led to a localization zone in the central section of the shells, approximately spanning on a 4D length for the longer ones, and shorter for the shorter shells. A single axial crack developed in the collapsing section, which propagated 2 to 4 diameters depending on the length of the specimen. The axial crack was located on the extrados for long shells, and on the intrados for shorter ones. Helical cracks initiated from the tips of the axial crack, propagated outwards, and were responsible for the collapse and fragmentation of the two outer sections. The receding walls of the central localizing zone caused a dynamic drop in pressure that lasted until the inward motion was arrested by contact. This was followed by a sharp, short duration positive pressure pulse associated with an outward expansion wave. The pressure pulse varied to some degree around the circumference with the highest peak occurring opposite the initial crack. The final result of such dynamic events was catastrophic failure and fragmentation of the shell into small shreds.Item A predictive model for sand production in poorly consolidated sands(2010-12) Kim, Sung Hyun, 1983-; Sharma, Mukul M.; Prodanovic, MasaThis thesis presents a model for the process of sand production that allows us to predict the stability of wellbores and perforation tunnels as well as mass of sand produced. Past analytical, numerical, and empirical models on material failure and erosion mechanisms were analyzed. The sand production model incorporates shear and tensile failure mechanisms. A criterion for sand erosion in failed sand was proposed based on a force balance calculation on the sand face. It is shown that failure, post failure sand mechanics and flow-dominated erosion mechanisms are important in the sand production process. The model has a small number of required input parameters that can be directly measured in the lab and does not require the use of empirical correlations for determining sand erosion. The model was implemented in a numerical simulator. Three different experiments using different materials were simulated and the results were compared to test the model. The model-generated results successfully matched the sand production profiles in experiments. When the post-failure behavior of materials was well-known, the match between the simulation and experiment was excellent. Sensitivity studies on the effect of mechanical stresses, flow rates, cohesion, and permeability show qualitative agreement with experimental observations. In addition, the effect of two-phase flow was presented to emphasize the importance of the water-weakening of the sand. These results show that catastrophic sand production can occur following water breakthrough. Finally the impact of increasing sand cohesion by the use of sand consolidation chemicals was shown to be an effective strategy for preventing sand production.Item Shear strengthening of reinforced concrete beams with carbon fiber reinforced polymer (CFRP) under fatigue and sustained loading applications(2011-08) Satrom, Christopher Neil; Ghannoum, Wassim M.; Jirsa, J. O. (James Otis)Four specimens were tested to evaluate the shear performance of beams with carbon fiber reinforced polymer (CFRP) laminates and CFRP anchors under fatigue and sustained loading applications. The specimens consisted of 24-in. deep T-beams that were constructed and tested at Phil M. Ferguson Structural Engineering Laboratory at the University of Texas at Austin. The specimens were strengthened in shear with CFRP laminates anchored with CFRP anchors. One end of each specimen was strengthened using bonded CFRP laminates while the other end was strengthened using unbonded CFRP laminates. Two specimens were used for fatigue testing and two were used for sustained load testing. For each set of tests, one specimen was strengthened using CFRP laminates prior to cracking and one specimen was strengthened using CFRP laminates following the initial cracking of the specimen. The CFRP laminates showed no signs of deteriorations in strength during fatigue testing, with only small increases in strain occurring in the CFRP laminates during testing. After fatigue loading was completed, the specimens were monotonically loaded to failure. The failure loads were 5 to 15% lower than beams that were not subjected to fatigue loading. Sustained load tests were subjected to a constant midpoint load based on service load requirements for a period of 217 days. CFRP laminates performed well during sustained loading. CFRP strains increased slightly throughout testing, but no signs of deterioration were observed. For both types of tests, specimens strengthened using bonded CFRP laminates demonstrated an increased stiffness resulting in smaller crack widths and lower strains in the internal steel. These benefits were not as great in specimens strengthened after the initial cracking of the specimen.Item The Walk : holding space in the face of crisis, failure, and fear(2015-05) Hutchinson, Jessica Rae; Rasmussen, Sarah; Carlson, Andrew; Dietz, Steven; Engelman, ElizabethThis thesis is about fear, failure, and faith. The tools I have developed during my graduate study have enabled me first to tolerate and then to welcome the energy of these forces into my artistic process. By examining and establishing Structure, creating and empowering Ensembles, and insisting upon an Inquiry-driven process, I can encounter fear and failure as I seek out the unpredictable, unrepeatable transcendence of the living play. By cultivating and inviting uncertainty, I hold space for the emergence of grace.