CE Theses and Dissertations

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    Fastener size metrology with machine vision
    (Wichita State University, 2023-12) Sekar, Nirmal Kumar; Boldsaikhan, Enkhsaikhan
    This study aims to establish a new manufacturing systems integration method that enhances the fastener size metrology using a machine vision sensor that is mounted on the wrist of an industrial robot. This metrology method is applicable to inspection of any parts with varying sizes in advanced manufacturing applications, particularly in automotive and aircraft manufacturing. The proposed method offers a new way of integrating algorithmic principles into existing manufacturing systems. It consists of data processing and analysis steps that involve image acquisition via machine vision followed by image processing for feature extraction and metrology. Firstly, a machine vision camera is mounted on the end of a robotic arm and then calibrated. The robot arm is used to automatically move the camera to different perspective view poses for capturing images. Images from two different perspective views are used for disparity mapping that produces a depth map generated from two stereo images. Secondly, the disparity map edges are identified by using edge detection and metrology tools for fastener size metrology. The experimentation used ideal simulation images instead of actual camera images for analysis and validation. The results with simulation images indicate that the proposed methodology can detect ±0.005 cm variations in the fastener length. The accuracy of fastener size metrology depends on the accuracy of edge detection as the edge detection tool may make mistakes due to sporadic variations in the image quality. The hit/miss data of edge detection with the intensity difference threshold of 64 is statistically evaluated by the Probability of detection (POD) analysis. According to the POD analysis, an intensity difference greater than 192 can guarantee the 1.0 (100%) mean probability of detection with the 95% lower confidence interval curve that is greater than 0.8 (80%). Keywords: Stereo Images, Disparity Map, Probability of Detection, Machine Vision, Metrology.
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    Energy storage optimization using modified cuckoo search
    (Wichita State University, 2023-12) Wiebe, Kyle Garrett; Aravinthan, Visvakumar
    Renewable generation is a topical area of research due to its low environmental impact compared with conventional generation and the current push to reduce fossil fuel emissions. However, inconsistencies in renewable power generation can cause a variety of power system problems. Energy storage technologies, such as batteries, are able to be used to help smooth out the inconsistent generation patterns of renewable resources. This ability to, partially or completely, remedy the unpredictability inherent to renewable generation makes battery storage an important topic for academic progress and optimization to increase industry utilization. There are numerous parameters pertaining to batteries and the power grid that can be optimized, one of which being economic optimization, which is the subject of this thesis. This optimization goal enhances battery systems’ feasibility of installation in the industry. This thesis presents a modified version of Cuckoo Search Optimization [1] and validates it with a more conventional optimization technique, Dynamic Programming [2]. It is then shown how this optimization technique can be applied to optimize a battery’s charge and discharge schedule and to implement economic battery sizing for various battery capital cost estimates.
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    Numerical methods for modeling compression corners at hypersonic velocities
    (Wichita State University, 2023-12) Sen, Shreya; Hoffmann, Klaus A.
    This study explores hypersonic flow separation, vital for hypersonic space vehicle designs. It is challenging to model shock wave boundary layer interaction (SWBLI) in high-speed gas flow through compression corners. Comparative experiments on various flow models reveal insights into hypersonic chemical non-equilibrium flow. Divergence in shockwave behaviour is influenced by re-circulation zone variations, emphasizing the flow dynamics complexity. Compression corner tests, using the k-omega SST model, elucidate this turbulent boundary layer flow. The successful flow separation which occurs due to the effects of SWBLI interaction is captured. The use of RANS techniques requires advanced models for non-equilibrium turbulent processes, crucial for understanding shock wave boundary layer interactions' effects on pressure and heating loads. This study provides a comprehensive understanding of hypersonic chemical non-equilibrium flow, emphasizing the importance of suitable models, meticulous mesh refinement, and accurate boundary conditions for robust simulations and meaningful comparisons with experimental data.
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    Exploring the synthesis of boron nitride at low temperature
    (Wichita State University, 2023-12) Yara, Nikhil Kumar; Wei, Wei
    Boron nitride (BN) is one of the most advanced ceramic materials that have appealing properties such as electrical insulation, mechanical strength, and high thermal conductivity. There are a lot of methods to synthesize BNs. In this work, the chemical vapor deposition (CVD) which requires temperatures around 1000°C was used. This thesis work aimed to design and develop a lower- temperature CVD method for the production of BN to improve efficiency and reduce costs. B, MgO and Fe2O3 were used as the precursors in the ratio of 2:1:1 respectively. Along with this, He and NH3 gases were used to carry out the reaction to produce the BN as the end product which has nanotubes, flakes, hair-like structures, and bubbles. Various temperatures in the range of 800 to 1000ºC with varying reactions, flow rates of gases, and pressure were investigated. There was an effect on BN production by varying the flow rate and reaction time. XRD and SEM were employed to characterize the obtained BN. It showed that BNNTs were obtained at 800ºC, 850ºC and 900ºC with a shorter reaction time between 30 to 45 mins and an NH3 flow rate of 1.00 - 1.25 L/min. At various higher temperatures, BN with flakes, hair-like structures and bubbles were obtained. Under less optimal parameters, amorphous boron nitride nanostructures were formed. This thesis demonstrates a promising energy-efficient CVD route for BN and also synthesized BN with some structures like nanotubes, flakes and bubbles. Usually, these BNNTs are synthesized at very high temperatures but this work was able to produce BNs at about 200°C below the conventional temperatures. The results provide new insight into the relationships between temperature, flow rates, duration, and BN yield. Further work will be needed to improve nanotube purity and density. Nonetheless, the technique developed represents progress toward greener, more cost-effective BNNT production.
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    A study of stress and temperature distribution on tool face while cutting materials prone to shear banding
    (Wichita State University, 2023-12) Pandey, Aditya; Moscoso-Kingsley, Wilfredo
    Shear banded chip formation typically occurs with a shear banding frequency between 1 kHz and 100 kHz. Large cyclic changes in cutting force, contact length and stress distribution along the tool tip are predicted by finite element analysis. However, these output variables are sensitive to the mechanical behavior of the material under the large strain, strain rate and temperature conditions that exist in and around these shear bands. This study is aimed at experimental measurement of the stress distribution within cutting tools at very high speeds in order to measure the cyclic variation in cutting forces and contact stresses along the tool rake face. Orthogonal machining of Al-7075-T6 and Ti6Al4V tubular specimens is carried out with a transparent sapphire plate as the cutting tool. Machining is done at high feed and relatively low cutting speed to result in shear banded chips exhibiting a shear banding frequency of 3 to 5 kHz, as inferred from measured cutting forces and chip morphology. A Photron Crysta high-speed polarization measuring camera system is used to measure the principal stresses as well as the principal stress direction at 60,000 Hz. This high frame rate has helped resolve cyclic variations in stresses within individual shear band cycles. Quantitative analysis of the stress images using the shear difference method is carried out to yield the distribution of shear stress and normal stress over the rake face contact. The thermography study has been carried out to obtain the thermal behavior of Ti6Al4V when machined at high velocities and in order to compliment previously reported data on effect of high-speed machining of Ti6Al4V on the tool wear. A controlled effort was made to anneal and bevel the cutting edges of the tools and towards removal of radial and lateral runout from the workpiece material in an attempt to reduce tool chipping.
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