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- Additive friction stir deposition (AFSD) (1)
- Anisotropy (1)
- Atomic diffusion additive manufacturing (ADAM) (1)
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- Crystal Plasticity (1)
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- High-frequency bending-fatigue testing (1)
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Articles 1 - 6 of 6
Full-Text Articles in Engineering Science and Materials
A Study On High-Frequency Bending Fatigue, Microhardness, Tensile Strength, And Microstructure Of Parts Made Using Atomic Diffusion Additive Manufacturing (Adam) And Additive Friction Stir Deposition (Afsd), Hamed Ghadimi
LSU Doctoral Dissertations
This dissertation reports the findings of several studies on the mechanical and microstructural properties of parts made using atomic diffusion additive manufacturing (ADAM) and additive friction stir deposition (AFSD). The design of a small-sized bending-fatigue test specimen for an ultrasonic fatigue testing system is reported in Chapter 1. The design was optimized based on the finite element analysis and analytical solution. The stress–life (S–N) curve is obtained for Inconel alloy 718. Chapter 2 presents the findings of ultrasonic bending-fatigue and tensile tests carried out on the ADAM test specimens. The S-N curves were created in the very high-cycle fatigue regime. …
Physics-Based Crystal Plasticity Model For Predicting Microstructure Evolution And Dislocation Densities, Juyoung Jeong
Physics-Based Crystal Plasticity Model For Predicting Microstructure Evolution And Dislocation Densities, Juyoung Jeong
LSU Doctoral Dissertations
This work presents three different studies investigating plastic deformation mechanisms in metals and alloys using crystal plasticity finite element (CPFE) modeling. The first study presents a new nonlocal crystal plasticity model for face-centered cubic single crystals under heterogeneous inelastic deformation. The model incorporates generalized constitutive relations that incorporate the thermally activated and drag mechanisms to cover different kinetics of viscoplastic flow in metals and describes the plastic flow and yielding of single-crystals using dislocation densities. The model is compared to micropillar compression experiments for copper single crystals and clarifies the complex microstructural evolution of dislocation densities in metals. The second …
Machine Learning Assisted Discovery Of Shape Memory Polymers And Their Thermomechanical Modeling, Cheng Yan
Machine Learning Assisted Discovery Of Shape Memory Polymers And Their Thermomechanical Modeling, Cheng Yan
LSU Doctoral Dissertations
As a new class of smart materials, shape memory polymer (SMP) is gaining great attention in both academia and industry. One challenge is that the chemical space is huge, while the human intelligence is limited, so that discovery of new SMPs becomes more and more difficult. In this dissertation, by adopting a series of machine learning (ML) methods, two frameworks are established for discovering new thermoset shape memory polymers (TSMPs). Specifically, one of them is performed by a combination of four methods, i.e., the most recently proposed linear notation BigSMILES, supplementing existing dataset by reasonable approximation, a mixed dimension (1D …
Atomistic Thermo-Mechanical Description Of The Deformation Behavior, Scaling Laws, And Constitutive Modeling Of Nanoporous Gold, Mohammed Hassan Yousef Saffarini
Atomistic Thermo-Mechanical Description Of The Deformation Behavior, Scaling Laws, And Constitutive Modeling Of Nanoporous Gold, Mohammed Hassan Yousef Saffarini
LSU Doctoral Dissertations
Metallic foams, or nanoporous (NP) metals as it is widely referred to in literature, with ligament sizes up to a few tens of nm show exceptional mechanical properties such as high strength and stiffness per weight ratio under different loading scenarios due to their high surface area to solid volume ratio. Therefore, they can be utilized in a wide range of applications making them of great interest to researchers. While their elasticity and yield strength have been the subject of several studies, very limited attention was given to the effect of size, strain rate, and temperature on the material plastic …
Modeling Hydraulic Fracturing Initiation And Propagation In Porous Rock Formationsl, Chang Huang
Modeling Hydraulic Fracturing Initiation And Propagation In Porous Rock Formationsl, Chang Huang
LSU Doctoral Dissertations
Hydraulic fracturing has long been introduced to the oil and gas industry since the early nineteenth century for both reservoir characterization and reservoir stimulation. Despite the progress made in the last two decades, many challenges still have not been tackled regarding not only the propagation problem but also the initiation problem due to its complexity. The dissertation is divided into two stages, i.e., before and after fracture initiation. The first stage of the research aimed at improving the accuracy in solving the poro-mechanical response of wellbore during fluid injection before a tensile fracture occurs, which is crucial to determine the …
A Coupled Thermo-Mechanical Theory Of Strain Gradient Plasticity For Small And Finite Deformations, Yooseob Song
A Coupled Thermo-Mechanical Theory Of Strain Gradient Plasticity For Small And Finite Deformations, Yooseob Song
LSU Doctoral Dissertations
In this work, a thermodynamically consistent coupled thermo-mechanical gradient enhanced continuum plasticity theory is developed for small and finite deformations. The proposed model is conceptually based on the dislocations interaction mechanisms and thermal activation energy. The thermodynamic conjugate microstresses are decomposed into energetic and dissipative components. This work incorporates the thermal and mechanical responses of microsystems. It addresses phenomena such as size and boundary effects and in particular microscale heat transfer in fast-transient processes. Not only the partial heat dissipation caused by the fast transient time, but also the distribution of temperature caused by the transition from the plastic work …