Mechanical Engineering Commons^™

Linear And Nonlinear Topology Optimization With Morphing Beam Networks, Andrew S. Montalbano

All Dissertations

Topology optimization (TO) is an engineering design discipline dedicated to optimizing material distribution within a given domain. In traditional gradient-based topology optimization, the solid domain is discretized into small volumetric elements. Using finite element analysis (FEA) of the structure, the gradient of the objective function with respect to the design variables (the pseudo densities) is computed, and these design variables are updated iteratively until convergence is achieved. Although gradient-based TO methods are well-established, sensitivity analyses of objective functions and constraints can be both mathematically complex and computationally intensive. The nonconvex nature of most TO problems often complicates efficient convergence. Furthermore, …

Hybrid Physics-Infused Machine Learning Framework For Fault Diagnostics And Prognostics In Cyber-Physical System Of Diesel Engine, Shubhendu Kumar Singh

All Dissertations

Fault diagnosis is required to ensure the safe operation of various equipment and enables real-time monitoring of associated components. As a result, the demand for new cognitive fault diagnosis algorithms is the need of the hour. Existing deep learning algorithms can detect, classify, and isolate faults. Still, most depend solely on data availability and do not incorporate the system's underlying physics into their prediction. Therefore, the results generated by these fault-detecting algorithms sometimes need to make more sense and deliver when tested in actual operating conditions.

Similar to diagnosis, the fault prognosis of diesel engines is paramount in numerous industries. …

Reactive Processing Of Hf-Nb-Ti-Ta Melts Into A B4c/C Packed Bed, Laura Leticia Sandoval

Open Access Theses & Dissertations

The reactivity of liquid Hf-Nb-Ti-Ta alloy in B4C/C packed bed to form boride-carbide precipitates for ultra-high temperature ceramics was investigated at 2800 K. The objectives were to predict the thermodynamic phases formed and verify them with microstructural characterization. A pseudo-isopiestic technique was used to significantly lower the oxygen potential as the liquid Hf alloy infused and reacted into a B4C packed bed within a graphite enclosure. The technique had a low temperature region (at 1300 K) to control the oxygen potential with a Y-Al/Y2O3-Al2O3/carbide mixture as a liquid Hf alloy at 2800 K and reacted with B4C/C. In addition, any …

On The Structure, Energy, And Segregation Behavior Of Grain Boundaries In Metallic Systems, Yasir Mahmood

All Dissertations

Nearly all structural metallic systems are multi-component polycrystalline aggregates; their microstructures are composed of crystalline grains that are internally joined at grain boundaries (GBs). This thesis focuses on GB structure, energy, and chemistry, as these greatly influence many material properties and processes, including boundary dynamics during processing treatments or under operating conditions.

Using atomistic simulations, we examine the impact of metastable GB structures on solute segregation. A wide range of GB geometries and metastable structures are used in our study. The Al-Mg alloy is used because it is of interest for light weighting. The atomistic simulation results are used to …

Convex Approach To Data-Driven Optimal Control With Safety Constraints Using Linear Transfer Operator, Joseph Raphel Moyalan

All Dissertations

This thesis is concerned with the data-driven solution to the optimal control problem with safety constraints for a class of control-affine nonlinear systems. Designing optimal control satisfying safety constraints is a problem of interest in various applications, including robotics, power systems, transportation networks, and manufacturing. This problem is known to be non-convex. One of this thesis's main contributions is providing a convex formulation to this non-convex problem. The second main contribution is providing a data-driven framework for solving the control problem with safety constraints. The linear operator theoretic framework involving Perron-Frobenius and Koopman operators provides the convex formulation and associated …

Development Of A Passive Drag Reduction Modification For The 25° Ahmed Body Using Large Eddy Simulation, Skylar Polek

UNLV Theses, Dissertations, Professional Papers, and Capstones

In the field of automotive aerodynamics, the Ahmed body is a generic vehicle-shaped bluff body which is meant to generalize the rear end of fastback and hatchback vehicles. Specifically, an Ahmed body with a rear slant angle of 25° has seen common use due to its resemblance of common rear windshield shapes as well as its notoriously complex wake structure. This research focuses on simulating the flow over a 25° in various situations with an ultimate goal of drag reduction. First, a simple benchmark of the k-ω shear stress transport (SST), large eddy simulation (LES) with the Smagorinsky-Lilly subgrid scale …

Dynamic Model Of An Overhead Crane, Leonard Ruesga

UNLV Theses, Dissertations, Professional Papers, and Capstones

In this thesis a novel spatial model of an overhead crane was developed. The model includes: bridge, trolley, driving and follower wheels for the bridge and trolley, drum, cable, and the payload. The model accounts for the winding/unwinding of the cable around the drum as the payload is raised/lowered. The cable and the payload were considered as rigid bodies with uniformly distributed mass. First, the kinematic equations of the model were developed by using constraint equations. Second, the dynamic equations were derived through use of Newton’s Laws. Developing the rotational dynamic equations required the determination of the angular momentum vectors …

Moving Towards The Electrification Of Medium- And Heavy-Duty Vehicles In The Inland Empire, Kimberly Collins, Raffi Der Wartanian, Francisca Beer, Yunfei Hou

Mineta Transportation Institute

This report investigates the transition to zero-emission medium- and heavy-duty vehicles (MDHD) within California’s Inland Empire (IE), emphasizing the significance of electric vehicle charging infrastructure and opportunity charging strategies in facilitating sustainable transportation. Utilizing a mixed-methods approach that combines a systematic literature review, geospatial and big data analytics, and thematic analysis of expert interviews, the study explores the multifaceted challenges and opportunities of electrification. The literature review assesses policies at various governance levels, while geospatial analysis identifies regional traffic patterns and infrastructure needs. Big data analytics examine vehicle movements, complemented by insights from interviews with 16 regional experts, offering a …

Investigating Near-Field Radiative Heat Transfer With Titanium Carbide Mxenes And Slanted Columnar Thin Films, Sean Luke Murray

Department of Mechanical and Materials Engineering: Dissertations, Theses, and Student Research

This work investigates the mechanisms to manipulate and control the magnitudes of Near-Field Radiative Heat Transfer (NFRHT) using two-dimensional materials and nanostructured surfaces. NFRHT occurs when the geometrical features of the radiating objects or the separation distance between interacting bodies are comparable to or lower than the characteristic thermal radiation wavelength. NFRHT magnitudes surpass the blackbody limit by several orders of magnitude due to phenomena such as photon tunneling and new modes of energy transfer, like surface polaritons. Therefore, it is crucial to understand how material properties and surface nanostructures affect NFRHT.

The first part of this work examines the …

Synergistic Strategies In Hybrid Mxed Matrix 3d Printing Of Thermoplastics & Thermosets: Design, Manufacturing, And Materials Development., Saleh Akram Khanjar

Electronic Theses and Dissertations

Composite manufacturing and mixed matrix structures have been produced using traditional manufacturing processes for various industrial applications due to their high mechanical properties to material weight and cost ratio. However implementation of composite and mixed matrix manufacturing with advanced manufacturing such as additive manufacturing is limited due to the hardware limitations of current 3d printing technologies and materials available for 3D printing applications. This work has developed and investigated a new hybrid 3D printing manufacturing process utilizing a variety of material systems (thermoplastic – thermoset, thermoplastic – thermoplastic, thermoset – thermoset, thermoplastic – thermoplastic – thermoset). This study developed thermoplastic …

Development And Processing Of Shape Memory Polymer Composites (Smpcs) For Application In Structural Robotics And Robotic Sensors., Kavish Sudan

Electronic Theses and Dissertations

Shape Memory Polymers (SMPs) have attracted significant attention since their introduction in the 1980s due to their remarkable ability to regain their original shape from a temporarily deformed state when exposed to an external stimulus, typically heat. This shape memory effect, driven by thermal transitions such as the glass transition temperature (T_g) or melting temperature (T_m), has made SMPs highly attractive for applications in soft robotics, aerospace, and biomedical devices. However, SMPs face challenges such as limited mechanical strength, thermal stability, and electrical conductivity, which hinder their broader adoption in advanced applications. To address these challenges, …

Development And 3d Printing Of Glass Fiber And Carbon Fiber Reinforced Shape Memory Polymer Composites For Structural Applications., Krishna Sai Aparna Munjuluri

Electronic Theses and Dissertations

This study aims at the development of shape memory polymer composites with two types of reinforcements, milled glass fibers, and chopped carbon fibers, for potential structural applications in aircraft and automotive industries. Glass fiber-SMP composites were made at fiber loading wt.% of 0%, 5%, 10%, and 20%. In contrast, carbon fiber-SMP composites were made at fiber loading wt.% of 0%, 5%, 10% and 15%. The feedstocks were extruded into filaments and characterized by their physical, rheological, chemical properties and morphologies. Fused Filament Fabrication 3D printing was used to manufacture specimens for mechanical testing of hardness and flexural properties. The findings …

Ultrashort Pulsed Laser Treatment Is Effective At Sterilizing Metal Surfaces For Planetary Protection, Kaleb Mcquillan

Department of Electrical and Computer Engineering: Dissertations, Theses, and Student Research

To prevent forward contamination from microbes aboard spacecraft intended for exploration of solar system bodies there is a need for effective sterilization methods. However, current techniques are both time-consuming and expensive. For example, dry heat sterilization requires removal from the assembly site and several days of treatment. Furthermore, some components such as optics and electronics are not compatible with current sterilization techniques. In this thesis, a novel femtosecond laser surface processing technique for the rapid sterilization of spacecraft hardware is reported. Femtosecond lasers produce extremely high photon fluxes (10²⁹ photons/s*cm², ~0.03 J/cm²) in extremely short …

Multimodal Boiling Dataset With Synchronized Acoustic, Optical, And Thermal Measurements Under Steady-State And Transient Heat Loads, Hari Pandey, Changgen Li, Han Hu

Mechanical Engineering Faculty Publications and Presentations

Boiling is a high-performance heat dissipation process that is central to electronics cooling and power generation. However, there exists a practical limit of boiling heat transfer known as the critical heat flux (CHF), beyond which significant performance degradation is observed. Understanding the physical mechanism that triggers CHF is essential to meet the increasing cooling demands driven by power densification and device miniaturization. However, the high dimensionality, stochasticity, and dynamicity of the boiling process have led to strong challenges in the experimental characterization and modeling of boiling CHF. As such, high-frame rate, high-resolution, multi-physics boiling datasets are critical to advancing the …

Synthesis Of Silica-Encapsulated Myristic Acid Phase-Change-Assisted Nanocapsules For Thermal Management Applications, Muhammad Ghufran, David Huitink

Mechanical Engineering Faculty Publications and Presentations

Myristic acid-based silica (MA/SiO₂) nano-encapsulated phase change materials (NePCMs) were synthesized by the sol–gel process. Five different samples of the MA/SiO₂ nanocapsules were prepared by varying the mass of the myristic acid. The nanocapsules were characterized by Fourier transform infrared spectrophotometer (FTIR), X-Ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscope (TEM), energy dispersive X-ray (EDX), and dynamic light scattering (DLS). These characterization techniques confirmed the successful encapsulation of the myristic acid inside the silica shell. The maximum latent heat was found to be 114.46 J/g for the sample which was prepared with 25 g myristic …

Review Of Fourth-Order Predictive Modeling And Illustrative Application To A Nuclear Reactor Benchmark. I. Typical High-Order Sensitivity And Uncertainty Analysis, Dan Gabriel Cacuci, Ruixian Fang

Faculty Publications

This work (in two parts) will review the recently developed predictive modeling methodology called “4th-BERRU-PM” and its applicability to nuclear energy systems as exemplified by an illustrative application to the Polyethylene-Reflected Plutonium (acronym: PERP) OECD/NEA reactor physics benchmark. The acronym 4th-BERRU-PM designates the “Fourth-Order Best-Estimate Results with Reduced Uncertainties Predictive Modeling” methodology, which uses the Maximum Entropy (MaxEnt) principle to incorporate fourth-order experimental and computational information, including fourth (and higher) order sensitivities of computed model responses to model parameters, while yielding best-estimate results with reduced uncertainties for the first fourth-order moments (mean values, covariance, skewness, and kurtosis) of the optimally …

Metal Casting Furnace Design Development Using Computer Simulation, Ramadhan Wahyu Irianto, Yanuar R.A. Pradana, Suprayitno Suprayitno

Journal of Mechanical Engineering Science and Technology (JMEST)

Metal foundries still rely heavily on crucible furnaces. The current furnace design, which is currently being used by the partner industry, has been found to be not properly designed and will result in a reduction in efficiency. CFD simulation will be used to find the optimal melting furnace design. This research simulation consists of 3 stages: pre-processing, solving, and post-processing. There are two furnace geometries, cylindrical and hexagonal, while the burner location will be divided into 3 positions, namely P1, P2, and P3. The most optimal furnace design will be used as a basis for the verification testing process. The …

Evolution Of Residual Stress, Crystal Orientation, And Texture On Preheating Weld Treatment Of Low Carbon Steel Astm A572 Grade 42, Suratno Adi Saputro, Andoko Andoko, Poppy Puspitasari

Journal of Mechanical Engineering Science and Technology (JMEST)

Preheating is one type of heat treatment on the material prior to starting the welding process by increasing the temperature of the material. It is used to reduce the cooling rate during the welding processes to minimize the risk of residual stress and cracking during welding. Besides the benefits of welding, it also has a negative impact, especially on the integrity of the material, because the heating process at high temperatures will cause residual stress, which will affect the mechanical properties, chemical composition, and microstructure of the material, especially on Heat Affected Zone (HAZ). This study aims to analyze the …

Static And Modal Analysis Of A Box Structured Satellite Deployment Mechanism With Self-Actuated Torsion Joint, Dongping Sheng, Renzhe Ma, Chun Su

Journal of Mechanical Engineering Science and Technology (JMEST)

A brand-new satellite deployment mechanism with boxed structure and self-actuated torsion joints is proposed and an effective method to verify the feasibility of this mechanism is established in this paper. This mechanism has the characteristics of high base frequency, high ratio of deployed and folded space occupation ratio. In order to meet the design requirements, the related analysis and optimization need to be conducted, and several conclusions are obtained. Firstly, the modal analysis of deployment mechanism at folded and fully deployed state is analyzed, and the result showed that the proper wall thickness is the key parameter to satisfy the …

A Review Of Fault Detecting Devices For Belt Conveyor Idlers, Fahad Alharbi, Suhuai Luo

Journal of Mechanical Engineering Science and Technology (JMEST)

The shift towards automated inspection methods represents considerable progress in conveyor system maintenance, enhancing safety and efficiency while posing challenges in data analysis and implementation costs. This study critically analyses sensor technologies and inspection methods for detecting faults in conveyor belt idlers, highlighting their essential role in preserving the operational integrity of industrial conveyor systems. By synthesizing various research findings, the study assesses the effectiveness of different sensor devices in identifying defects, including built-in sensors, fixed sensor options like acoustic, ultrasonic sensors, cameras, accelerometers, and Distributed Optical Fibre Sensors (DOFS), as well as mobile sensor systems. Our findings emphasize the …

Analysis Of Avgas Fuel Spraying Schemes Using The Ansys Application Approach, Dimas Endrawan Putra, Nasrul Ilminnafik, M Fahrur Rozy Hentihu, Muh. Nurkoyim Kustanto, Danang Yudistiro, Skriptyan N.H. Syuhri

Journal of Mechanical Engineering Science and Technology (JMEST)

Avgas fuel consumption on Cessna trainer aircraft is very high. However, there has been little research regarding spray impacts in Cessna aircraft engines. The phenomenon of avgas spray colliding with the cylinder wall may occur during fuel injection, resulting in a changed spray radius and height, which will affect the mixing of fuel and air. In several aspects, this affects engine performance and exhaust emissions on Cessna aircraft. This research aims to determine and study the phenomenon of spray impact on avgasfueled aircraft engines. The fuel spray in the study occurred in the combustion chamber using pressure from a fuel …

Effect Of Addition Titanium Dioxide Nanoparticle On Properties Of Pineapple Leaf Fiber Mediated Tempo Oxidation, Rahmad Ikrom Ramadhan, Heru Suryanto, Ahmad Atif Fikri, Aminnudin Aminnudin, Jibril Maulana, Faqih Fadillah, Mohamed T. Mito, Kemal Masera

Journal of Mechanical Engineering Science and Technology (JMEST)

Indonesia is an agricultural country with the potential to grow many plants as natural fiber sources. In order to improve its properties, natural fiber needs to be treated by applying nanomaterial so that it can compete with the characteristics of synthetic fibers. The study aims to determine the influence of adding titanium dioxide (TiO2) nanoparticles on pineapple leaf fiber (PALF) characteristics. The PALF was collected from the Subang plantation (Indonesia). The chemical treatment was carried out with pre-treatment using an alkalization process for 3 hours, and the oxidation process was carried out with TEMPO. TiO2 nanoparticle grafting was carried out …

Analysis Of Ballistic Capability In Making Bulletproof Multilayers Using Woven Ramie Fiber, Hardfacing Metal With Epoxy Matrix For Bulletproof Vests, Rizal Wahyu Permana, Syamsul Hadi, Bima Cahya Maula Dana

Journal of Mechanical Engineering Science and Technology (JMEST)

Bulletproof material in level III bulletproof vests must be created using hard and soft materials to prevent bullet penetration. Kevlar and SiC + PE are imported materials used as armor in bulletproof vests. The use of Kevlar and SiC is very dependent on foreign sources with high prices. An innovation was carried out by making bulletproof material using cheaper multilayer methods involving metal from hardfacing welding as a hard layer and ramie fiber as a soft layer with an epoxy matrix. To see the level of penetration and surface morphology structure in the specimens, 9 variations were made: 3 layers …

Computational Fluid Dynamics Analysis Of Temperature Distribution In Solar Distillation Panel With Various Flat Plate Materials, Trismawati Trismawati, Hendry Y. Nanlohy, Helen Riupassa, Susi Marianingsih

Journal of Mechanical Engineering Science and Technology (JMEST)

As the world population continues to grow, the demand for clean water is increasing daily, making it a crucial resource to access. However, there are ways to harness abundant resources like solar energy and seawater to produce clean water. The present studies have conducted experimental investigations to convert seawater into freshwater using solar stills, where solar energy is utilized as the primary heat source for evaporation. The temperature distribution inside the solar stills was analyzed using a flat plate made of three different materials: copper, stainless steel, and aluminum. To examine the temperature distribution and performance of the solar stills, …

Comparative Analysis Of The Effect Dual Spark Ignition And Single Spark Ignition On Performance And Exhaust Emissions In Bioethanol-Fueled Engines, Avita Ayu Permanasari, Ahmad Faizal Wahidin, Hasan Ismail, Erwin Komara, Poppy Puspitasari, Gina A. Lorenzo

Journal of Mechanical Engineering Science and Technology (JMEST)

Bioethanol is an alternative fuel that has a high octane value of around 100 to 110, making it difficult to be applied to spark ignition engines directly. So, it is necessary to make adjustments, including increasing combustion efficiency and thermal efficiency of the combustion chamber by increasing the compression ratio and adjusting the ignition system, both in single spark ignition (SSI) and dual spark ignition (DSI) types. The study aims to determine the effect of SSI and DSI applications on engine performance, specific fuel consumption (SFC), and exhaust emissions using 96% and 99% levels of bioethanol fuel. The results showed …

Performance Enhancement Of Dye Sensitized Solar Cell (Dssc) Through Tio2/Rgo Hybrid: Comprehensive Study On Synthesis And Characterization, Rustan Hatib, Khairil Anwar, Ramang Magga, Muh Anjas Astak, Denny Widhiyanuriyawan, Wardoyo Wardoyo

Journal of Mechanical Engineering Science and Technology (JMEST)

The TiO2 film is immersed in a graphite oxide solution, preparing it for thermal reduction, which converts the graphite oxide to reduced graphene oxide (rGO). This process produces rGO hybrid TiO2 photoanodes for dye-sensitized solar cells (DSSC). rGO in the TiO2 structure prevents electron recombination and improves overall efficiency. The main advantage of this method is its ability to prevent loss of rGO during the sintering process, which is a common problem with other methods. The study investigated heating temperatures ranging between 300˚C, 350˚C, 400˚C, 450˚C, and 500˚C to determine optimal conditions. The presence of rGO in the photoanode structure …

Crashworthiness And Deformation Pattern Analysis Of Single And Double Wall With Addition Infill Structure, Redyarsa Dharma Bintara, Moch. Agus Choiron, Yahya Zakariya, M. Hasbi Ash Shiddieqy, Fajar Adi Pratama

Journal of Mechanical Engineering Science and Technology (JMEST)

Ship collisions are a phenomenon that often occurs in maritime transportation. One part of the ship that often experiences damage is the ship's wall (hull). This research aims to analyze and compare deformation patterns, stress distribution, and energy absorption in three wall models, single wall, double wall, and double wall, with the addition of infill structures. The infill structure used Polylactic Acid (PLA) polymer material because it provided convenience in the manufacturing process, while the walls of the test model used Aluminum 6063 material. The test model was developed by carrying out the design process using CAD software. Furthermore, a …

Durability Of Thermoplastic Polyurethane Round Belt Joint With Variations In Heating Methods And Cutting Shapes, Achmad Sabilarrosyad Prawiro Kusumo, Anggit Murdani

Journal of Mechanical Engineering Science and Technology (JMEST)

Thermoplastic polyurethane round belts are widely used for conveyors in various industries, particularly in the food and beverage industry, due to their flexible and abrasion-resistant characteristics. These belts are also popular in manufacturing industries because of their ease of joint. However, a common issue arises when the conveyor belt breaks during the production process. This problem can be attributed to the lack of parameters in the belt joining process at companies. Operators do not have a standard parameter for the joining process. When there is an improper joining operation of an operator, the conveyor belt could fail earlier than the …

Heuristic Approach To Comparing The Environmental Impacts Of Carbon Nanotube Production Methods, Ahmad Atif Fikri, Irham Fadlika, Albarrobi Nabila Saeful, Krisna Dwipa Muhdi, Daniel Febrian Pratama, Nasir Garba Bello

Journal of Mechanical Engineering Science and Technology (JMEST)

Carbon Nanotubes (CNTs) production so far has its own advantages and disadvantages. Some methods that can be used in producing CNTs are chemical vapor deposition (CVD), laser ablation, and arc discharge. The three methods have their own requirements, this causes different environmental impacts on each method. Studies into the environmental impact of the CNTs production process found that during thermal pretreatment of the reactant gas, more than 45 by-products were formed, including methane, volatile organic compounds, and polycyclic aromatic hydrocarbons. Calculating the environmental impact of CNTs production method often has challenges in implementation, because each production process has different systems …

Mechanical Properties Of Corner Lap-45 Types Joined Using Friction Stir Welding, Widia Setiawan, Nugroho Santoso, Felixianus Eko Wismo Winarto, Radhian Krisnaputra, Wirawan Widya Mandala, Jibril Maulana

Journal of Mechanical Engineering Science and Technology (JMEST)

Solid welding has always been concerned with probe design, pins, and joint strength. Many researchers have conducted studies on joints, such as butt joints, lap joints, and T joints, but the results show low strength. This study analyzes the mechanical properties of a new design of a 90o angle joint joined by friction stir welding. This study connected aluminum 6061 using the friction stir welding method using a rectifying jig and a probe with EMS 45 material. The corner joint designs used corner-lap 45 with feed rate as independent variables in 6, 8, 10, 15, and 30 mm/min and dependent …