Mechanical Engineering

Permanent URI for this collection

https://hdl.handle.net/10315/34419

Browse

Now showing 1 - 20 of 109

Open Access
3D Printed Smart Materials of Continuous Wire Polymer Composites for Sensing Applications
(2023-03-28) Elsayed, Mennatullah Mohamed Adel Saleh; Melenka, Garrett; Kempers, Roger
Smart material with sensing capability is an exciting new technology that will impact many applications, including structural health monitoring, biomedical implants, wearable sensors, and actuators. Internal damage in polymer composites is usually hard to predict, and they need to be continuously monitored for any sign of internal damage for safety issues and to increase the life cycle. In this study, continuous wire polymer composites (CWPCs) were 3D-printed using the fused filament fabrication (FFF) technique to produce functional smart materials with different sensing capabilities like strain and thermal sensing. Here, the integrated wire within the conductive polymer composite structure acts as a sensing element. For strain sensing characterization, different design parameters such as matrix type, wire type, and loading condition were investigated to study the effect of these parameters on the efficacy of the CWPC sensor. The different matrices used have different mechanical properties representing rigid (polylactic acid) and flexible (thermoplastic polyurethane) structures to widen the range of applications of CWPCs as strain sensors. The change of the electrical resistance of the integrated wire within the CWPCs was measured under tensile loading and plotted against the applied strain. The results of this electromechanical testing demonstrate the ability of CWPCs to be used as strain sensor for either rigid or flexible structures. To check the reliability and reversibility of CWPCs structure as strain sensor, the electromechanical behaviour was investigated under fatigue/cyclic loading. The results of this work demonstrate the reverse piezoresistance behaviour of the CWPC sensor. From thermal sensing standpoint, different design parameters like wire type, matrix type, and sensor thickness were studied to investigate the application of CWPCs as temperature and heat flux sensors which can be readily designed and adapted to suit unique and bespoke thermal applications. The change of the electrical resistance of the integrated wires was correlated to the applied temperature to measure the heat conducted through a surface. A prototype of a real-world application was designed for the heat flux measurements using CWPC sensor. Generally, this study demonstrates the applicability of FFF technique to print sensors with continuous integrated wire with tuneable properties for different sensing applications.
Open Access
3D Printing of Continuous Wire Polymer Composite for Mechanical and Thermal Applications
(2019-07-02) Ibrahim, Yehia Elsayed Mahmoud; Kempers, Roger
Recently, continuous fiber reinforcement has been combined with 3D printing techniques such as fused filament fabrication to create stronger and stiffer printed composite components. The continuous nature of the reinforcing material can improve both mechanical and thermal properties of the polymeric material significantly. However, several parameters can affect the printed composite properties such as filler volume fraction, type of polymer matrix and filler treatment. The work presented in this study addresses the effect of reinforcing polymers with continuous metal wire on the composites properties and the potential applications for these composites. In the first part of this study we presented a novel 3D printing technique in which metal wires were combined with polymer matrixes in order to improve both mechanical and thermal properties of the printed components. In the second part, we investigated the tensile and bending properties of the continuous wire polymer composites which was superior compared to the base polymer. In addition, we studied the effect of introducing continuous wires to the polymer matrix on the effective thermal conductivity which was found to increase significantly. In addition, we investigated the use of the fabricated composites as a novel fabrication technique for low-temperature heating elements and explored this technology for de-icing and anti-icing applications.
Open Access
A Numerical Modelling Approach to Study the Impact of Ventilation Configurations on Airborne Transmission in Indoor Environments
(2024-03-16) Khan, Arma Mantissa; Freire-Gormaly, Marina
The airborne transmission of COVID-19 has been a topic of significant controversy since the pandemic began. Research was needed to demonstrate the importance of airborne transmission and develop tools to recommend appropriate control measures. This study aimed to analyze the factors that impact airborne transmission, find techniques for infection risk minimization, and develop methods to compare different control measures on infection risk. Computational Fluid Dynamics (CFD) studies were conducted to analyze the impact of ventilation layout and infection source location in indoor spaces. A novel spatio-temporal risk model was further developed to quantify the risk in indoor spaces based on different control measures. Conclusions have been made that the ventilation layout and infection source locations can significantly impact the risk of airborne transmitted infection. Further research into building design and airborne transmission minimization techniques is urgently needed to prepare for airborne infectious diseases that may emerge in the future.
Open Access
Active Thermography Using Cellphone Attachment Infrared Camera
(2020-08-11) Samadi, Nakisa; Tabatabaei, Nima Nima
Active thermography (AT) is a widely studied non-destructive testing method for the characterization and evaluation of biological and industrial materials. Despite promising applications of AT in industry and medicine, commercialization and wide-spread adaption of AT has long been impeded by the high cost (usually $10k-$100k) and large size of infrared cameras. In order to overcome these limitations, in this thesis, we aim to demonstrate feasibility of performing AT with cell-phone attachment infrared cameras with cost of -$250 and size significantly less than the research-grade infrared cameras. This involves developing a hardware-level code/software for controlling camera attributes in order to achieve stable acquisition of frames at high frame rates. Given the importance of portability, we also demonstrate possibility of developing a setting that is both portable and easy to set up The nominal frame rate of camera through its standard applet is less than 9fps. In order to achieve higher frame rate, we utilized USB 2.0 documentation and Microsoft Windows native application programming interfaces to set up packets of information. These packets of information were then sent to the cameras default endpoint address and, subsequently, acquire frame data from camera through a corresponding pipe. As such, the developed platform has not only the ability to control camera attributes (e.g., calibrate camera, acquire frame, etc) through a simple USB interface but also can achieve a stable high frame rate of 33fps through a circular buffer hierarchy and multi-threading. To demonstrate performance of developed low-cost and portable system, two series of AT experiments were conducted: (i) in response to the recent legalizations of marijuana in Canada, we interrogated the photothermal responses of commercially available oral fluid lateral flow immunoassays (LFIAs) with the developed system. The results of our low-cost setup represent that it can reliably detect THC concentrations as low as 2ng/ml in oral fluid with 95% accuracy. (ii) To demonstrate ability of the system in early detection of dental caries, artificially-induced caries were imaged using the low cost and portable system. Our results suggested the ability of the developed AT low cost system for detecting early dental carries.
Open Access
Active Turbulence Generation in a 3/4 Open-Jet Wind Tunnel
(2023-08-04) Marques, Joshua Zachary; Hanson, Ronald
The focus of this thesis is on the replication of on-road turbulent flow conditions within a 1/10th scale model of a 3/4 open-jet closed-loop return wind tunnel. This type of wind tunnel is commonly used in the automotive industry for testing aerodynamic performance of vehicles. Often, these types of wind tunnels are used to produce a clean laminar flow and testing results are limited to these idealized conditions. A novel system is designed to produce a wide range of turbulence scales in the scale model automotive wind tunnel using activated grid elements. It is shown that the turbulence produced by the novel turbulence generation system can generate turbulent flows having Taylor Reynolds numbers between 70 and 890, and turbulence intensities between 3.3 % and 33.1 %, depending on proximity to the grid.
Open Access
Additive Manufacturing of Novel Cemented Carbides with Self-Lubricating Properties
(2020-05-11) Agyapong, Joseph; Boakye-Yiadom, Solomon
In this research, WC-17Co and WC-Co-hBN cemented carbides were processed using Selective Laser Sintering (SLS) and heat treated at 400 C, 600 C, 800 C and 1000 C for 3 hours to understand the effect of processing and post-processing heat treatment on the structure and properties of the cemented carbide. Electron microscopy and X-ray diffraction (XRD) analysis revealed that the microstructure of the as-printed WC-17Co specimen was characterized by relatively large poly-angular WC/W2C chips, WC-Co dendritic structures, W-C-Co phase and Co-rich regions. WC-Co-hBN also revealed from the microstructure polyangular WC chips which were smaller in size with no W2C phases present in the sample. During heat treatment between 0 C to 600 C, the large poly-angular chips in both WC-17Co and WC-Co-hBN disintegrated to smaller poly-angular chips as a result of the conversion of the unstable W2C phase to the more stable WC phase and the generation of W-Co-N and Co-W-B phases respectively. Heat treatment above 600 C resulted in the coalescence and growth of relatively large WC phase chips. There was significant increase in hardness of the WC-17Co samples during heat treatment when compared with the as-printed WC-17Co sample, with the sample heat-treated at 600 C being 36% harder than the as-printed sample due to the breakdown of poly-angular WC chips and the increase in volume fraction and spatial distribution of the observed W-C-Co phase regions. The increase in hardness at 600 C was coupled with the highest fracture toughness, representing a 34% increase in fracture toughness, when compared with the as-printed sample. The high fracture toughness is attributed to the evolution of the ductile W6Co6C phase in the sample after heat treatment. Nevertheless, the as-printed sample had approximately 15% higher wear resistance than the sample heat-treated at 600 C. In the WC-Co-hBN, the heat-treated samples had lower hardness values compared to the as-printed WC-Co-hBN sample. However, the hardness values were 3 times higher than the hardness value of the WC-17Co sample. This was attributed to the lower grain sizes in the WC-Co-hBN as compared to the WC-17Co samples. The wear resistance of the WC-Co-hBN samples were much higher than the WC-17Co samples with the highest being on the WC-Co-hBN sample heat treated at 1000 C. It is concluded that post-processing heat treatment of SLS printed WC-17Co alloy at 600 C can be used to improve the structure and mechanical properties of the alloy. And a further improvement of the wear properties and hardness of the material can be done by adding a volume of hBN to the alloy.
Open Access
Advanced Photothermal Optical Coherence Tomography (PT-OCT) for Quantification of Tissue Composition
(2022-12-14) Salimi, Mohammadhossein; Tabatabaei, Nima; Villiger, Martin
Optical coherence tomography (OCT) is an imaging technique that forms 2D or 3D images of tissue structures with micron-level resolution. Today, OCT systems are widely used in medicine, especially in the fields of ophthalmology, interventional cardiology, oncology, and dermatology. Although OCT images provide insightful structural information of tissues, these images are not specific to the chemical composition of the tissue. Yet, chemical tissue composition is frequently relevant to the stage of a disease (e.g., atherosclerosis), leading to poor diagnostic performance of structural OCT images. Photo-thermal optical coherence tomography (PT-OCT) is a functional extension of OCT with the potential to overcome this shortcoming by overlaying the 3D structural images of OCT with depth-resolved light absorption information. Potentially, signal analysis of the light absorption maps can be used to obtain refined insight into the chemical composition of tissue. Such analysis, however, is complex because the underlying physics of PT-OCT is multifactorial. Aside from tissue chemical composition, the optical, thermal, and mechanical properties of tissue affect PT-OCT signals; system/instrumentation parameters also influence PT-OCT signals. As such, obtaining refined insight into tissue chemical composition requires in-depth research aimed at answering several key unknowns and questions about this technique. The goal of this dissertation is to generate in-depth knowledge on sample and system parameters affecting PT-OCT signals, to develop strategies for optimal detection of a molecule of interest (MOI) and potentially for its quantification, and to improve the imaging rate of the system. The following items are major outcomes of this dissertation: 1- Generated comprehensive theory that discovers relations between sample/tissue properties and experimental conditions and their multifactorial effects on PT-OCT signals. 2- Developed system and experimentation strategies for detection of multiple molecules of interest with high specificity. 3- Generated optimized machine learning-powered model, in light of the above two outcomes, for automated depth-resolved interpretation of tissue composition from PT-OCT images. 4- Increased the imaging rate of PT-OCT by orders of magnitude by introducing a new variant of PT-OCT based on pulsed photothermal excitation. 5- Developed algorithms for signal denoising and improving the quality of received signals and the contrast in images which in return enables faster PT-OCT imaging.
Open Access
Aerosol Transmission of COVID-19 and other Airborne Diseases in office environments using Computational Fluid Dynamic Modeling and Machine Learning
(2023-12-08) Webb, Kishon Winston; Freire-Gormaly, Marina
The COVID-19 pandemic has shown the world how quickly airborne diseases can spread and the lasting impact they can have. Computational fluid dynamic (CFD) models and simulations and machine learning (ML) are powerful tools that allow engineers to create models to predict and advance tools to fight these airborne diseases. The research in this thesis studied the effects of heating, air conditioning and ventilation (HVAC) strategies in small office spaces. A novel methodology was developed to utilize ML, CFD and parallel computing by utilizing the user defined function (UDF) tool of ANSYS Fluent. It was shown that the resulting risk models were quick and effective at predicting high risk areas using spatial data or predicting regions of high risk over time. Future research will refine this method by creating higher fidelity ML models and investigating a wider range of input and output parameters.
Open Access
Analysis of the Interface Properties of Multi-material 3D Printed Structures
(2024-11-07) Pahari, Shauvik; Melenka, Garrett
Multi-material 3D printed (MM3DP) samples offer enhanced mechanical performance with the added benefit of being customizable for specific applications. However, MM3DP structures have weak adhesion at the boundary interface. So, the interface characteristics in those structures are a critical factor in determining the strength of the structures and predicting failure. Digital image correlation (DIC) is a full-field strain measurement technique ideal for evaluating the non-uniform load response in anisotropic materials due to their heterogeneous composition. This thesis demonstrates the fabrication of MM3DP samples using two distinctly different printing methods. The multi-material samples were extensively compared with the homogenous samples of the same base material with a shear test to assess their mechanical performance. Strain variations on the samples were analyzed and post-processed with DIC software as different material combinations were explored. Additionally, statistical analysis was performed to validate the results and assess the feasibility of the methodology.
Open Access
Applications of Luminescent Solar Concentrators
(2020-11-13) Daigle, Quinn Joseph; O'Brien, Paul
Luminescent solar concentrators (LSCs) are a promising technology because they are inexpensive, lightweight, aesthetically versatile, and offer wavelength-selective transparency. This thesis investigates the use of LSCs for building energy applications, with emphasis on thermal energy utilization. A spectral modeling method is developed to analyze the benefits of integrating LSCs into greenhouse rooftops, solar thermal collectors, and solar air heaters. Results show red LSCs can increase greenhouse profits by up to 40%. Furthermore, a novel experimental method wherein Newtons law of cooling is used to determine the thermal energy generated by LSCs is demonstrated. The thermal energy generated by LSCs can be used to substantially reduce building energy consumption. By integrating LSCs into solar thermal collectors the temperature of the collector fluid can be increased from ~140C to over 200C. Despite these advances, the efficiency of LSCs must be improved to realize their full potential and make widespread commercialization viable.
Open Access
Asymmetric Behavior of a Drop Upon Impact onto a Surface
(2017-07-27) Almohammadi, Hamed; Amirfazli, Alidad
In this thesis, a systematic study was performed to understand drop impact onto hydrophilic and hydrophobic moving surfaces. Different systems (combination of liquids, surfaces, and drop impact conditions) were examined. Wide range of normal drop and surface velocities were studied; such normal and tangential velocity ranges are not available in systems where a drop impacts at an angle relative to a surface. The asymmetric nature of drop spreading on moving surfaces was elucidated. A model that for the first time is able to mathematically predict the time evolution of such asymmetric spreading was provided. Furthermore, a new model was developed to determine the splashing threshold of the drop impact onto a moving surface. The model is capable of describing the azimuthally different behavior of splashing. The effect of liquid viscosity on drop splashing was clarified. A comprehensive regime maps of drop impact outcome on a moving surface was provided.
Open Access
Attitude Determination using Asynchronous MultiSensor Fusion
(2022-08-08) Prabhudesai, Aniket Amol; Zhu, George Z.H.
CubeSat failures are a growing concern for amateur missions. Many of these failures stem from the chosen attitude determination algorithm. Hence, this thesis seeks to produce an attitude determination system standard for nanosatellites. The ESSENCE CubeSat is the primary focus of this study, as it is an amateur student led mission. The attitude sensors used in this thesis are low cost and affordable for most CubeSat missions. The thesis proves its functionality by examining various attitude determination techniques, orbit propagation and determination methods. Numerous tests and analysis for this thesis were done in a simulated environment along with a hardware in the loop experiment, to meet the objectives defined for this thesis. This thesis provides a thorough analysis under nominal and failure conditions. The outcome of the thesis produces an attitude algorithm is chosen as the standard for attitude determination for nanosatellites and is recommended for the ESSENCE mission.
Open Access
Behavior of Liquid Bridges between Nonparallel Surfaces
(2017-07-27) Ataei, Mohammadmehdi; Amirfazli, Alidad
Formation of liquid bridges between two solid surfaces is frequently observed in industry and nature, e.g. printing. When the two solid surfaces are not parallel (with dihedral angle between them), two significant phenomena emerge in the bridge behavior: First, if exceed a critical angle (_c), the bridge is no longer stable and propel itself horizontally towards the cusp of the surfaces. Second, if a stable bridge is squeezed and stretched, a horizontal bulk motion of the bridge along the surfaces can be observed. Through both experimental and numerical studies, we demonstrated that _c can be increased by increasing advancing contact angle (_a), and Contact Angle Hysteresis (CAH) of the surfaces. We also demonstrated that the magnitude of the bulk motion can be increased by increasing , the amount of compressing and stretching, and/or by decreasing _a and CAH of the surfaces.
Open Access
Biofabrication of a Heart Wall Section using the FRESH Bioprinting Method
(2024-10-28) Horvath, Victoria Bianca; Czekanski, Aleksander
This dissertation addresses the challenge of bioprinting cardiac wall tissues. It focuses on three different aspects. The first is around materials that mimic the different cardiac wall tissue layers by testing the different materials pre- and post-crosslinked for their characteristics and behaviour. Secondly, it explores the adaptation of a 3D printer for bioprinting using the FRESH bioprinting method, which utilizes a single extrusion point for multi-material printing. This printer came with a unique printhead design, allowing multiple materials to enter the chamber to print continuously. Lastly, it explores the 3D printing of hybrid tissue and the optimization of the printing process. The hybrid tissue creation started with two materials before moving to three materials for the cardiac wall. The outcomes of this study The outcomes of the study such as the bioprinter that can print multiple material without leaving the print site and the materials which work as the anatomical heart wall layers, represent a significant step forward in the field of tissue and organ engineering, offering promising new directions for personalized medical treatments and advances for organ transplants by bridging the research gap between hybrid tissue bioprinting with specialized materials and a unique bioprinter that specializes in multi-material printing with better precision and material structure. This research lays the foundation for future advancements in the field of regenerative medicine.
Open Access
Body force of plasma actuator with different operating conditions using phase-resolved approach
(2021-07-06) Alva, Venur Tejas; Hanson, Ronald E.
Plasma actuators are electric devices that can generate a flow of air without any moving parts. The salient feature of a plasma actuator is its ability to impart a body force in the region of the ionized air. The force produced is unsteady. A phase-resolved determination of force distribution is important to develop models that better approximate physical conditions for use in numerical simulations and design. Phase resolved study of the body force generated by the plasma actuator is performed experimentally using Particle Image Velocimetry. The primary objective of the present work is to study the ability of plasma actuators to transfer momentum to the air and the contribution of terms in the momentum equations used to compute the body force from the planar flow field measurements. The spatial and temporal evolution of the effect of the forcing by the actuator has been discussed with emphasis on the acceleration term.
Open Access
Characteristics of Air Flow Over a Sessile Droplet at the Verge of Shedding
(2020-08-11) Emami, Reza Yaghoubi; Amirfazli, Alidad
A Particle Image Velocimetry (PIV) study on the air flow over a sessile water droplet exposed to a boundary layer flow was done in a wind tunnel. Reynolds number based on free stream velocity and the height of the droplet was 600
Open Access
Characterization and Impact of Thermal Conductivity of Stainless Steel 316L Employed in Additive Manufacturing
(2021-03-08) Rojas Dorantes, Carlos Abel; Czekanski, Alex
The main objective of this research was to develop new methods to improve the mechanical properties of 3D printed metal parts by controlling the heat transfer mechanisms involved in the melting and solidification of powder particles. A number of experiments were carried out to study the parameters involved in the process. The first part of the work was dedicated to the measurement of effective thermal conductivity in 316L stainless-steel powder. The results showed that controlled samples had important increments in thermal conductivity. The experimental setup was based on a steady-state analysis, designed to safely expose the sample up to 1000 C. The best result was obtained from the 10% compacted sample, whose thermal conductivity was double that of the reference sample. In the second part of this work, simulations were performed of a laser track over a powder bed. The results obtained from the thermal conductivity experiments were compared with those from analytical models. The thermal behaviour of the powder displayed an important decrement in temperature gradients. Moreover, analysis of subsequent laser tracks showed important improvements under low energy density. In summary, the theorical findings of this work can help to reduce and control defects formed in the melting and solidification stages of the manufacturing process by limiting temperature gradients and improving thermal distribution.
Open Access
Characterization of Heat Exchange for Additively Manufactured Components
(2022-08-08) Elkholy, Ahmed Moustafa Sayed; Kempers, Roger
The current work aims to develop a fundamental understanding of thermal transport mechanisms within and on AM components and structures, which is addressed through three specific objectives. The first objective is to characterize the effect of the process parameters, of FFF and SLM, on the effective thermal conductivity of AM components. Secondly, to improve the pool boiling heat transfer coefficient (HTC) using AM-based structures. Finally, to investigate the application of SLM 3D-printed evaporators in a two-phase loop thermosyphon. To achieve the first objective, a high-accuracy steady-state guarded method was developed to measure the effective conductivity of AM components. First, this apparatus was employed to measure the thermal conductivity of several PLA polymer composites, either metal or carbon fiber. The experimental results showed that all samples featured high anisotropy in thermal conductivity, reaching up to 2 in the carbon fiber composite. Thereafter, the apparatus was modified to quantify the effect of the SLM process parameters, such as the laser power, hatch spacing, etc., on the effective thermal conductivity of AlSi10Mg, which were found to significantly decrease the resulting thermal conductivity up to 22%. With respect to the second objective, an FFF-based polymer fixture was proposed to enhance the pool boiling characteristics from copper surfaces. Due to the low conductivity of the fixture, it could create a spatial temperature distribution at the boiling surface, initiating the bubbles earlier and enhancing the HTC. A high-precision pool boiling apparatus was then built, addressing most of the experimentation issues found in the literature, such as repeatability, surface aging, and the heater's small size. This device was subsequently used to examine novel 3D re-entrant cavities fabricated using SLM on the pool boiling performance. It was observed that the surface with re-entrant cavities increased the nucleation site density and the bubble departure frequency, enhancing the HTC 2.8 times compared to the plain 3D-printed surface. The last objective was achieved by investigating the difference in the thermal performance of closed-loop thermosyphon between two surfaces: machined and additively manufactured via SLM. It was shown that the 3D-evaporator slightly increased the loop thermal resistance; however, it mitigated the temperature instabilities.
Open Access
Combined Tension-Torsion Loading of Braided Composite Structures
(2020-11-13) Armanfard, Abbas; Melenka, Garrett
Braided composites are a class of composite materials. They feature an inter-woven structure that improves structural stability and damage tolerance. Presently, braided composites under tension and torsion loading have been studied individually. Mechanical behaviour of braided composites under combined tension-torsion loading is common, yet no studies have explored this effect. In this study, mechanical properties of carbon fibre, fibreglass and Aramid 2D tubular braided composites (TBCs) were assessed and compared under coupled tension-torsion loading. Failure mechanism of braids was investigated by the plane stress theory. A contact-free three-dimensional digital image correlation (3D DIC) technique was used to derive detailed and continuous strain maps and understand buckling behaviour of TBCs. Benefitting from this research experiment, combined loading as a common and critical loading condition can be analyzed more realistically and accurately in designing elements out of braided composites to prevent structural failures.
Open Access
Deformation Behavior and Microstructural Evolution of Armox 500T with Varying Strain Rates and Temperatures
(2024-11-07) Tak, Gurnek Singh; Boakye-Yiadom, Solomon
Armour steels have long been used for ballistic performance application purposes as they provide high hardness, toughness, and strength to resist penetration. However, literature lacks a complete understanding of failure mode analysis under various stress-loading conditions. This thesis explores the microstructure and evolution of Armox 500T as well as the correlated stress-strain data to characterize and gain a deeper understanding of its behaviour under compression, tension, and torsion with temperatures ranging from 0°C - 400°C. Results indicate that performance was increased in high strain rate compression at elevated temperatures up to 200°C, withstanding 2.0% more impact momentum and 3.7% higher toughness than room temperature samples. Temperatures above 200°C showed compromised microstructural properties and decreased performance. At 400°C high strain rate compression, the samples fractured at lower impact momentum and displayed increased brittleness and microhardness. In a reduced temperature of 0°C, low strain rate tensile test conditions decreased toughness by 11.8%.