Computer-Aided Engineering and Design Commons^™

Soft Hexapod Robot With Tendon-Driven Continuum Legs For Internal Infrastructure Inspection, Setayesh Yavari

LSU Master's Theses

The need for robotic systems capable of operating in confined, hazardous, or complex environments has driven interest in soft and legged platforms for industrial inspection and structural integrity assessment. This thesis presents the design and fabrication of a tentacle-like, soft-legged hexapod robot, which uses six cable-stiffened, pre-curved, tendon-driven continuum robot (TDCR) legs. These biologically inspired legs are designed to offer a balance between compliance and control, enabling the robot to navigate unstructured terrains and potentially grasp cylindrical structures such as pipes. The design phase involved the development and comparison of multiple leg geometries using CAD modeling and finite element analysis …

Passive Vibration Isolation Systems For Mitigating Rotational Forces In Football Helmet Impacts, Julian Lee

LSU Master's Theses

Helmets have been used for centuries to mitigate head injuries, evolving with advancements in materials and design. They are critical in athletics, construction, and military applications, where shock and vibration isolation play a key role in head protection. Helmet performance is currently rated using the Head Injury Criterion (HIC) and Helmet Performance Score (HPS) metrics. HIC is a metric used in sports and automotive industries which focuses on the probability of injury occurring due to the magnitude and duration of linear acceleration of the head [1]. The HPS metric was created by using a linear combination of HIC and a …

An In-Situ Method For Quantifying Entropy Generation In Fatigue Via A Novel Thermographic Approach, Peyton J. Wilson

LSU Master's Theses

This work features a new approach that is used to measure the rate of plastic work during a cyclic fatigue test, based on the first and second laws of thermodynamics. Using the one-dimensional Fourier heat equation coupled with the concept of fracture fatigue entropy, the rate of plastic work during fatigue can be measured without the need to interrupt a fatigue test, and the accumulated entropy to failure can be quantified. Experimental fatigue tests are conducted on Aluminum 6061-T6 specimens under cyclic axial loading and Carbon Steel 1018 specimens under fully reversed cyclic bending loading. The obtained results in addition …

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. …

Tunable Passive Shock And Vibration Isolators For Rotational Isolation, Chase B. Lemaire

LSU Master's Theses

Shock and vibration isolation are a critical need in helmets, which are widely used to protect athletes, workers, soldiers, and astronauts. Passive vibration isolation systems are a good option when mass and volume should be minimized and when the experienced loadings can be predicted. However, it is frequently challenging to find materials and structures which exhibit the optimal vibration and impact isolation properties for an application. As a case study illustrating a novel design paradigm for rotational shock absorption, a family of optimal solutions for the physical properties of American football helmets is presented. Lumped parameter Simulink models simulate a …

A Case Study Of Protecting Bridges Against Overheight Vehicles, Aly Mousaad Aly, Marc Hoffmann

Faculty Publications

Most transportation departments have recognized and developed procedures to address the ever-increasing weights of trucks traveling on bridges in service today. Transportation agencies also recognize the issues with overheight vehicles’ collisions with bridges, but few stakeholders have definitive countermeasures. Bridges are becoming more vulnerable to collisions from overheight vehicles. The exact response under lateral impact force is difficult to predict. In this paper, nonlinear impact analysis shows that the degree of deformation recorded through the modeling of the unprotected vehicle-girder model provides realistic results compared to the observation from the US-61 bridge overheight vehicle impact. The predicted displacements are 0.229 …

Laser Surface Treatment And Laser Powder Bed Fusion Additive Manufacturing Study Using Custom Designed 3d Printer And The Application Of Machine Learning In Materials Science, Hao Wen

LSU Doctoral Dissertations

Selective Laser Melting (SLM) is a laser powder bed fusion (L-PBF) based additive manufacturing (AM) method, which uses a laser beam to melt the selected areas of the metal powder bed. A customized SLM 3D printer that can handle a small quantity of metal powders was built in the lab to achieve versatile research purposes. The hardware design, electrical diagrams, and software functions are introduced in Chapter 2. Several laser surface engineering and SLM experiments were conducted using this customized machine which showed the functionality of the machine and some prospective fields that this machine can be utilized. Chapter 3 …

Large Eddy Simulations Of Vertical Jets In Crossflow, Pranaya Pokharel

LSU Doctoral Dissertations

Jets in crossflow (JICF) have applications ranging from oil spill to film cooling of turbine blades. Hence, an understanding of the flow physics is important. The majority of the research has been conducted for low velocity ratios between jet and crossflow with round jets. JICF is demonstrated to behave differently for high velocity ratios and different jet shapes. Circular and rectangular jets are commonly used in aircraft applications. Current study focuses on high velocity ratio JICF issuing from both circular and rectangular exit.

For simulating JICF, an in house code “Chem3D” is used with Large Eddy Simulation (LES) to model …

Numerical Study Of Liquid Atomization And Breakup Using The Volume Of Fluid Method In Ansys Fluent, Sai Saran Kandati

LSU Master's Theses

The spherical metal particles produced from the centrifugal atomization process have been the topic of numerous theoretical, experimental and numerical studies from the past few years. This atomization process uses centrifugal force to break-up molten material into spherical droplets, which are quenched into solidified granules by the flow of cold air on the spherical droplets. In the present work, a transient three-dimensional multiphase CFD model is applied to three different materials: Molten slag, aqueous glycerol solution, and molten Ni-Nb to study the influence of the dimensionless parameters on the centrifugal atomization outcome.

Results from numerical experiments indicated that the droplet …

Modeling Of The Veterinary Anesthetic Circuit, Corinne Viloria Duplantis

LSU Master's Theses

Anesthesia is used to sedate both humans and animals for surgery. In veterinary practice, breathing systems are often used to supply anesthetic gas to the patient. Occasionally, a large amount of pressure can build up in the breathing circuit. This high pressure, if unnoticed, can lead to fatal injury to the lungs of the veterinary patient. The maximum allowable pressure in the anesthetic circuit for small animals is 25 cmH₂O or 2450 Pa. As such, it is necessary to monitor oxygen flow rate (ranging from 0.1-4 LPM), pressure, oxygen rate, anesthetic composition, among other variables during an operation. …

Numerical Simulation Of Uncoiling And Roller Leveling Processes From Steel Coils, Yufei Xiong

LSU Master's Theses

Uncoiling and roller leveling play an important role in pipe forming because it is prerequisite to make products with good quality. Uncoiling and roller leveling are used to reduce undesired characteristics such as imperfections in sheet flatness and residual stress. Considering residual stress in steel coil which has been ignored to date, a simplified coiling process is combined with uncoiling and leveling processes to investigate their effects on residual stress and curvature. The objective of this thesis research focuses particularly on studying the influence of coil diameter, uncoiling direction and leveling settings on residual stress and residual strip curvature after …

A 2-D Finite Element Modeling And Simulation Of 3-Roll Forming, Wenbo Zhao

LSU Master's Theses

Medium to large diameter carbon steel pipes are widely used in various applications such as gas and fluid transportation, tunnels construction and building construction. Based on manufacturing techniques and characteristics, they are mainly categorized into three categories: Seamless pipe, Butt-welded pipe and Spiral pipe. The forming of butt-welded and spiral pipe is often performed by a technique called 3-roller bending. While traditional trial-and-error method is costly, the geometry complexity, along with material nonlinearity makes exact theoretical analysis difficult unless heavy simplified assumptions are made. While the forming parameters in the 3-roller forming process of butt-welded pipe has been studied in …

Multiphase Flow Modeling For Design And Optimization Of A Novel Down-Flow Bubble Column, Mutharasu Lalitha Chockalingam

LSU Doctoral Dissertations

The application of the Euler-Euler framework based Computational Fluid Dynamics (CFD) models for simulating the two-phase gas-liquid bubbly flow in down-flow bubble columns is discussed in detail. Emphasis is given towards the modelling and design optimization of a novel down-flow bubble column. The design features of this novel down-flow bubble column and its advantages over a conventional Plunging Jet down-flow bubble column are discussed briefly. Then, some of the present challenges in simulating a conventional Plunging Jet down-flow bubble column in the Euler-Euler framework is highlighted, and a sigmoid function based drag modification function is implemented to overcome those challenges. …