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2020

Mechanical Engineering

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Articles 31 - 35 of 35

Full-Text Articles in Engineering

Defect Modeling And Vibration-Based Bending Fatigue Of Additively Manufactured Inconel 718, Wesley Earl Eldt Jan 2020

Defect Modeling And Vibration-Based Bending Fatigue Of Additively Manufactured Inconel 718, Wesley Earl Eldt

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Additive manufacturing (AM) is convenient for building components with complex features. However, the long-term integrity of these components is uncertain, since AM parts have defects such as pores and rough surfaces. In this work, an analytical model was developed to determine the impact of defects, and a novel bending fatigue test was used to determine the fatigue life of channeled specimens. The analytical model, based off the theory of critical distances, investigates coupled pores and predicts their potential for fatigue failure. This resulted in a maximum allowable pore size and spacing recommendation for coupled defects. Additionally, specimens with through channels …


Primary Processing Parameters And Their Influence On Porosity And Fatigue Life Of Additively Manufactured Alloy 718, Luke C. Sheridan Jan 2020

Primary Processing Parameters And Their Influence On Porosity And Fatigue Life Of Additively Manufactured Alloy 718, Luke C. Sheridan

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In many structural applications void-like defects cause significant performance debits which call for component redesign or post-processing to account for or remove the defects. For laser powder bed fusion (LPBF) processes, it has been shown that many of these features and their size and shape characteristics are controllable through LPBF process parameter manipulation. For design efforts, however, it is necessary to understand the direct influences of processing on the formation of porosity and the role that individual pores and porosity distributions have on the properties and performance of AM components. Additionally, design criteria must be established to facilitate implementation of …


Computational Assessment Of Aortic Valve Function And Mechanics Under Hypertension, Saurav Kadel Jan 2020

Computational Assessment Of Aortic Valve Function And Mechanics Under Hypertension, Saurav Kadel

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Calcific aortic valve disease (CAVD), the most common valvular heart disorder, is associated with complications such as stroke, heart attack, aortic aneurysm, left ventricular hypertrophy, and ultimately death. While hypertension has been identified as a major risk factor for CAVD, the mechanisms by which it may promote calcification are still unknown. Given the sensitivity of valvular tissue to mechanical stress alterations, the hemodynamic abnormalities linked to hypertension may play a role in the development of CAVD. Further, the effects of hypertension on the left ventricular functionality and coronary flow resistance remain largely uninvestigated. Hence, the objectives of this thesis were …


Additive Manufacturing Techniques To Enhance The Performance Of Electronics Created On Flexible And Rigid Substrates, Aamir Hamed Hamad Jan 2020

Additive Manufacturing Techniques To Enhance The Performance Of Electronics Created On Flexible And Rigid Substrates, Aamir Hamed Hamad

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Different additive manufacturing (AM) methods including fused deposition modeling (FDM) and piezoelectrical drop on demand (DOD) inkjet printing have been used in printed electronics for easy production, easy integration, better performance, and low cost. These methods have been used in producing everyday smart printed electronics such as conformal antennas (planner and non-planar antennas), sensors, actuators, and solar cells created on flexible and rigid substrates. The performance of printed electronics strongly depends on printing techniques and printing resolution that enhance their electrical and mechanical properties. In this dissertation, 3D and surface printing techniques were used to enhance the performance of printed …


Designing New Generations Of Bcc Lattice Structures And Developing Scaling Laws To Predict Compressive Mechanical Characteristics And Geometrical Parameters, Hasanain Abdulhadi Jan 2020

Designing New Generations Of Bcc Lattice Structures And Developing Scaling Laws To Predict Compressive Mechanical Characteristics And Geometrical Parameters, Hasanain Abdulhadi

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Lattice structures (LSs) have been exploited for wide range applications including mechanical, thermal, and biomedical structures because of their unique attributes combining the light weight and relatively high mechanical properties. The first goal of this research is to investigate the effect of strut orientation and length on the compressive mechanical characteristics of body centered cubic (BCC) LS subjected to a quasi-static axial compressive loading using finite element analyses (FEA). In this study, two lattice generations were built and analyzed in commercial finite element (FE) software, ABAQUS/CAE 2016 using “smart procedure”, a meshing technique which was developed for this research to …