Browsing by Author "Park, Simon"
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- ItemEmbargoA Novel Scalable Approach to Solid Metal Microneedle Fabrication via an Automated Modified Wire Bonding Process(2024-01-15) Haider, Syed Kazim; Dalton, Colin; Kim, Seonghwan (Sam); Jones, Steven; Park, SimonHypodermic needles have played a pivotal role in medical treatments; however, their use often incites fear due to pain and tissue trauma. Microneedle arrays present a promising alternative, with their smaller size resulting in reduced pain and trauma, however they have faced manufacturing scale-up challenges due to the complex microfabrication processes involved, precluding their widespread adoption into clinical practice. This research introduces a novel microneedle fabrication method utilizing a modified wire bonding process, enabling rapid iteration of designs on a single automated system. Key fabrication parameters, such as loop settings and wire bonding capillary shape, were explored to understand their impact on microneedle geometry. This study finds how specific wire bonding parameters can influence microneedle tip sharpness, crucial for efficient skin penetration. Additionally, the research delves into how these parameters affect microneedle length, a crucial factor for delivering drugs to a sufficient depth below skin. A significant aspect of this work involved investigating three different bonding wire diameters (25, 33, and 50 µm). The findings revealed that the largest diameter, 50 µm, exhibited optimal performance in terms of robustness, and had the least tendency to bend upon insertion into porcine skin tissue, and the lowest failure rate during microneedle fabrication. Initial tests on porcine skin validated the effective penetration ability of the wire bonded microneedles. A computational simulation was also developed to illustrate how the unique tip shapes, achievable through wire bonding, can enhance skin penetration. This iterative process, encompassing simulation, fabrication, and testing, underscores the potential of this novel fabrication method as a versatile platform technology. This research lays a solid foundation for broad applications, paving the way for future optimizations and adaptations tailored to specific microneedle requirements for different applications.
- ItemOpen AccessBlending of Alberta Oilsands Asphaltene (AOA) with Polymers for Manufacturing of Carbon Fibres(2024-01-24) Ge, Lin; Park, Simon; Cheng, Frank; Hu, JinguangCarbon fibres (CFs), characterized by a carbon content of 90 wt.% or above, derived from polymeric precursors, have garnered considerable interest since their discovery by Shindo in 1961. Their unique properties have led to widespread applications in sectors such as energy, aerospace, medical, and sports, where lightweight structures with excellent mechanical attributes are essential. Anticipated growth in demand for CFs over the next five years underscores the need for a substantial reduction in manufacturing costs. Currently, the main precursors for carbon fibre (CF) production are poly(acrylonitrile) (PAN), pitch, and cellulose. However, the substantial costs associated with these raw materials and production methods present significant challenges. Alberta oilsands asphaltene (AOA), the heaviest fraction of Alberta Oilsands Bitumen, stands out as a promising alternative precursor. It is estimated to be one to two orders of magnitude less expensive than PAN, and it possesses favorable attributes such as high carbon content, high aromaticity, and abundant reserves. Despite these economic advantages, the brittleness of AOA limits its processing capabilities, impeding the widespread utilization of CFs derived from AOA. Polymer blending proves to be an effective method for enhancing the physical and chemical properties of polymer materials. This process enhances the melt spinnability of polymers, resulting in improved manufacturing efficiency and enhanced mechanical performance. The effects of polymer blending on the spinnability of AOA, subsequent post-treatment processes, and the ultimate properties of carbon fibres remain poorly. Investigating the behaviors of AOA with and without polymer additives is crucial, as it can provide meaningful insights for the manufacturing of carbon fibres derived from AOA. The manufacturing process for CFs involves melting precursors and processing them into spun fibres, followed by post-treatment processes like stabilization, carbonization, and graphitization. Stabilization process accounts for the most cost and determine the properties of the final carbon fibre products. Better and more efficient stabilization processes account for better performance of carbon fibres. The conditions to stabilize and carbonize AOA fibres, behaviors, and mechanism of the post-treatment remain unclear. This research focuses on the potential of AOA as a CF precursor, emphasizing (1) preprocessing AOA feedstocks, (2) modifying AOA using polymer additives, (3) designing a melt spinning process for AOA fibres, and (4) employing conventional thermal treatment for post-treatment including stabilization and carbonization processes. Solvent preprocessing and strategic additive use aim to enhance the viscosity and spinnability of AOA. Polystyrene and poly(styrene-butadiene-styrene) are employed and compared as polymer additives for blending with asphaltene, with the anticipation of enhancing the performance of AOA. Melt spinning is proposed for preparing fibres tailored for various applications. Melt spinning system, including extruder, melt pump, and godets, are designed for processing asphaltene sample. Thermal post-treatment, including stabilization and carbonization processes, were performed for stabilizing and carbonizing AOA fibres with or without polymer additives.
- ItemOpen AccessCarbon Nanotube Reinforced Polymeric Nanocomposites for Sensing and Monitoring(2015-07-07) Parmar, Kaushik kumar; Park, SimonCarbon nanotube (CNT) reinforced polymeric nanocomposites (PNCs) show significant potentials for various sensing applications. In recent years, a large number of laboratory-level sensor systems based on electrical conductivity have been reported; however, only a few commercial sensors based on CNT-PNCs have been produced. For commercialization, a sensor system should be highly reliable, reproducible, low-cost, stable and easy to install. To develop these characteristics in CNT-PNC based sensor systems, elucidation of various properties of CNT nanocomposites is vital to determine the behaviour and nature of sensor systems. In this study, the modelling and characterization of electromechanical properties of CNT-PNCs and the investigation of influencing factors, such as the base polymer matrix and the CNT network inside the polymer matrix, have been addressed. Most of the models in recent studies assume CNTs as straight fibres with a fixed size, and only few of them account for features such as waviness and size variations of CNTs. However, experiments show that during the manufacturing process of CNT-PNCs, nanotubes become wavy. They either get entangled or broken, and the CNT alignment in the polymer matrix can be impacted. In this thesis, a model has been developed that considers the behaviour of wavy nanotubes with varying nanotube lengths. The model also incorporates varying degrees of CNT alignment in the polymer matrix and determines its effect on the physical properties of CNT-PNCs. Nanocomposite specimens were fabricated using three different techniques, i.e. compression moulding, injection moulding and spray painting. The effects of various fabrication methods on the alignment and dispersion of multi-walled CNTs were experimentally characterized through microscopy and electrochemical impedance spectroscopy (EIS) techniques and compared with modelling results. A process has been developed that uses EIS analysis as a reliable, albeit indirect, tool to accurately predict the CNT alignments without any of the disadvantages of expensive imaging techniques. This study also presents an analytical model for determining the piezoresistive and piezoelectric properties exhibited by CNT-reinforced piezoelectric polymer matrix nanocomposites. It has been well established that CNT nanocomposites exhibit a piezoresistive property. Force, pressure or strain applied to the nanocomposites contributes to changes in the network between CNTs and alters the inter-CNT distances, thereby modifying electron conduction and varying the resistivity of the nanocomposites. By using piezoelectric polymers, such as polyvinylidene difluoride (PVDF), which can be converted in to piezoelectric beta phase through electrical polarization, a piezoelectric property can be imparted to CNT-PNCs. This unique behaviour of CNT/PVDF nanocomposites has been thoroughly examined through analytical modelling and experimental analysis. The results of this study show a new class of nanocomposite materials fabricated using piezoelectric polymers admixed with CNTs that exhibit enhanced electromechanical properties and both piezoresistive and piezoelectric behaviour. These nanocomposites were highly sensitive and could be effectively utilized as in situ sensors to monitor applied force/stress or pressure. We have focused on the design and development of various sensor systems, such as a flexible strain sensor, tactile sensor and multi-axis machining dynamometer, fabricated in this study using these nanocomposites. The present research work provides a fundamental understanding of novel CNT-PNCs that can be used as sensing material in broad applications in the civil, mechanical, aerospace, biomedical, electronics, microelectromechanical (MEMS) systems and petroleum engineering fields.
- ItemOpen AccessCatalytic Bitumen Upgrading under Methane Environment(2016) Zhao, Lulu; Song, Hua; Chen, Nancy; Dong, Mingzhe; Park, SimonIn industrial field, hydrocracking is conventionally used to upgrade crude oil and improve the quality of oil products. However, the high investment cost and strict experimental conditions limit the development of this technology. The utilization of methane, which is naturally available as the principal component of natural gas, to play the role of H donor, attracts the attentions from both the oil companies and the academic research. In this thesis, three catalytic formula are identified through the catalysts screening. All these catalysts show a significant viscosity reduction companied by acceptable coke yield, better stability and compatibility and the high liquid yield. With series of experiment results, it can be concluded that the catalysts promote the activation of methane and the incorporation into the product oil efficiently. The current achievement of this research can also further improves the commercial application feasibility of this technology.
- ItemEmbargoCellulose Nanocrystal-Reinforced Nanocomposite Hydrogel Electrolyte for Supercapacitor(2023-06) Chen, Ningxin; Lu, Qingye; Sundararaj, Uttandaraman; Park, SimonThe development of hydrogel electrolytes for electronic devices has garnered significant attention due to their remarkable flexibility, operation safety, and electrochemical stability, making them a highly competitive material for wearable and flexible electronic devices, such as flexible supercapacitors. However, hydrogel electrolytes also have certain drawbacks that limit their utility in flexible supercapacitors. Specifically, hydrogel electrolytes face two primary challenges: 1) insufficient cross-linking leading to unfavourable mechanical properties, and 2) delamination between electrode and electrolyte under deformation due to weak adhesion at the interface. Consequently, it is crucial to develop mechanically robust hydrogel electrolytes with promising adhesion to the electrodes for their widespread application in future flexible electronic devices. This thesis provides a design and synthesis of a self-repairable, adhesive, strong, and stretchable hydrogel electrolyte for supercapacitors. A highly stretchable and tough hydrogel was firstly synthesized by incorporating green nanomaterial, cellulose nanocrystal (CNC) as nano-reinforcement, and physical (hydrophobic, electrostatic, and hydrogen bonding) interactions to reinforce the hydrogel matrix. The synthesized hydrogel demonstrated outstanding mechanical performance with the best tensile stress of 1085 ± 14 kPa and elongation of 4106 ± 311%. Then the prepared hydrogels were loaded with 1 M KOH by soaking to make hydrogel electrolytes. The results of this work demonstrate that CNC-incorporated hydrogel electrolytes are promising and competitive materials for flexible supercapacitors. The best capacitance was obtained as 67.31 F/g at 0.05 A/g by using the hydrophobized CNC hydrogel with 6-hr soak-loading of KOH. And almost 100% capacitance retention was obtained at 0.1A/g after 2200 cycles. This thesis also provides a fundamental understanding of how the CNC and different interactions will affect the mechanical and electrochemical performances of the hydrogel as a supercapacitor with thoughtful evaluations in various aspects.
- ItemOpen AccessChatter Suppression in Boring Operations through Altering Tool Dynamics(2016) Alammari, Youssef; Park, Simon; Freiheit, Theodor; Dalton, Colin; Tu, Paul; Xue, DeyiIn machining, a phenomenon known as chatter, which is a self-excited excessive vibration, is considered one of the most limiting factors for productivity. Particularly in boring process, the long cantilevered structure of boring bar makes it the most flexible part of machine tool system. As a result, there is a high possibility for chatter to occur compared with other machine tool components. In this research, two methods were investigated to attenuate chatter and increase stability in boring operations by manipulating the boring bar structure dynamics. First, the effect of altering the boring bar’s natural frequency on chatter is investigated through varying the boring bar’s overall mass. Second, a tuned liquid column damper (TLCD) is developed to improve the dynamic stiffness for boring bars application for improving the overall stability. Several models and experiments are carried out for evaluating the performance of the proposed methods.
- ItemOpen AccessContrast Mechanisms on Nanoscale Subsurface Imaging in Ultrasonic AFM: Scattering of Ultrasonic Wave and Contact Stiffness of Tip-Sample(Royal Society of Chemistry, 2017-01-13) Sharahi, Hossein J; Shekhawat, Gajendra; Dravid, Vinayak; Park, Simon; Egberts, Philip; Kim, SeonghwanUltrasonic atomic force microscopy (AFM) and its associated derivatives are nondestructive techniques that can elucidate subsurface nanoscale structures and properties. Despite the usefulness of these techniques, the physical contrast mechanisms responsible for the reported subsurface features observed in ultrasonic AFM are not well defined. In this study, we present a comprehensive model combining ultrasonic wave scattering and tip–sample contact stiffness to better reproduce the experimentally measured phase variations over subsurface features in two model systems. These model systems represent the two extreme sample types typically imaged by ultrasonic AFM, one being a hard material and the other a soft polymeric material. The theoretical analysis presented and associated comparisons with experimental results suggest that the image contrast depends on the combination of two contrast mechanisms: the perturbation of the scattered ultrasonic waves and the local variation of the contact stiffness at the tip–sample contact. The results of this study open up a new door for the depth estimation of buried nanoscale features into hard (engineering structures) and soft (polymers and biological structures) materials, and eventually lead to non-invasive, high-resolution 3D nano-tomography by ultrasonic AFM.
- ItemOpen AccessDevelopment and Investigation of Micro Mechanical Machine Tools and Processes(2013-09-06) Park, Chaneel; Park, SimonMicro-mechanical machining using diamond tools is advantageous to other micro-manufacturing techniques as it can create complicated geometric features with high precision, and it is applicable to a wide range of materials including polymers and metals. The effectiveness of manufacturing micro-scale features can be enhanced by understanding the process and interactions between the tools and materials. Investigation of material properties with respect to the machining process is especially important when the material has unique mechanical properties such as polymeric carbon nanotube (CNT) nanocomposites with aligned CNTs and when the process itself is a unique such as an elliptical vibration machining (EVM) process. This study has sought to develop a micro indenter-scriber system for investigation of mechanical machining characteristics of the injection molded polymeric CNT nanocomposites, identifying parameters to model the micro scribing process. The study also aimed to develop a versatile EVM system with motion amplification without limiting the operation frequency to the natural frequencies of the system. The developed system was used to investigate its range of motion and effects of vibration frequency to reduce machining forces. A custom micro indenter-scriber system was developed, capable of 3-axis nanometric displacements and 3-axis force sensing, along with a Berkovich diamond tool with known geometry. Polystyrene based multi-walled CNT – polystyrene (MWCNT-PS) composite samples at varying CNT concentrations (0, 0.5, 2.0 and 5.0 wt.%) were prepared through micro injection molding procedures to align CNTs in the composite. Using the custom indenter-scriber system, indentation and scribing experiments were performed to identify the indentation hardness, modulus of elasticity and scribing forces in varying concentrations and orientations of CNTs. Indentation experiments have found that CNT composite samples have increased hardness with small addition of CNTs (i.e. 0.5 wt.%); however, adding more CNTs (i.e. 5.0 wt.%) would result in decreased hardness. Scribing forces were revealed to have similar trends, showing the highest scribing forces at 0.5 wt.% of CNT concentrations but less at 5.0 wt.%. The orientation of CNTs also affected the forces, as higher forces were observed when scribing perpendicular to the CNT flow direction than scribing parallel to them. A micro scribing force model was proposed to predict forces from given material properties, then three unknown parameters, namely the shearing coefficient, the plowing coefficient and the adhesion friction coefficient were identified from experimental scribing tests. A relationship was established between three parameters with respect to the material properties, which would enable prediction of scribing forces from material properties. To minimize forces in micro machining, a versatile EVM system was developed which consist of a diamond tool, two piezoelectric actuators, flexure joints and levers capable of amplifying vibrational motions. A mathematical toolpath generation algorithm was developed and compensated through experiments. Using the EVM system, experiments were performed at varying frequencies (i.e. 0, 1, 10 and 50 Hz) to measure the vertical and horizontal forces. It was found that increasing the vibration frequencies reduced the forces. Its surface pattern generation ability was also tested at a relatively high feed rate (300 µm/s) to examine whether the system can accurately fabricate dimples of 5 and 20 µm depths. Understanding micro scribing force model of polymeric CNT nanocomposites provides fundamental understanding in the relationship of cutting forces and material properties, while the development of new EVM system and understanding of its mechanism provides a basis for optimization of machining parameters of more accurate, precise and efficient micro mechanical machining. This knowledge will be applicable not only to conventional materials but to hard-to-cut materials such as glass, ceramics and polymeric CNT nanocomposites, providing accurate and economic methods to fabricate micro channels for biomedical applications, micro thermal exchanger, micro electromagnetic interference shield, micro optical lens and various functional surfaces with geometrically complex features.
- ItemOpen AccessDevelopment of a Drilling Simulator to Achieve Drilling Optimization(2023-08) Etaje, Darlington Christian; Roman, Shor; Gates, Ian; Chen, Nancy; Park, Simon; Azadbakht, SamanIn summary, drilling simulation, a set of physic-based models run through time or depth steps to mirror events in the drilling rig, is the backbone of all field testing of technologies or procedures. If a model has been validated using drilling simulation, the risk of wasted field trial is lowered significantly. This is why the formulation of models that make up drilling simulation is key and this is what this thesis has focused on. 20 functions were used to simulate the processes described in this research. Finite element formulation of space models linked with time-based models have been developed for the 2-node system in X (axial loading and axial torsion), Y (transverse bending of Z), and Z (transverse bending of Y) directions. Laplace transform was used to solve the time based partial differential equation paving way for the development of velocity, acceleration, force, and torque equations. Drill ahead modeling using build and walk relation to resultant forces was validated. Stick slip mitigation using the optimized RPM objective function was used to optimize the mechanical efficiency of drilling. Particle swarm optimization was the process used for optimization where each solution is considered a particle in search of the global minimum. An expression of the optimized RPM was developed and simulated with field data. Confined compressive strength of the field data was compared with the CCS obtained from the simulation but there was no perfect match yet. Further runs of the simulation would show more lessons as to how to improve the results. It can be concluded that the MSE minimization process should rather be called MSE optimization process as the decision to raise or lower MSE should be based on the data supplied to the particle swarm optimizer since the objective function is built with constraints to lower drill string vibrations. When tested with field data, the objective function and optimizer built in this research was found to increase MSE but lower the downhole stick slip index by 28 percent. The downhole stick slip index was below 0.5.
- ItemOpen AccessDevelopment of a High-pressure Rotational Rheometer for Investigation of Effects of Dissolved CO2(2018-01-08) Lee, Keonje; Park, Simon; Kim, Seonghwan; Wong, Joanna; Natale, GiovanniantonioRheological information is often used to determine viscoelastic fluid properties, and to model and predict fluid behavior under influence of external stress or deformation. Many industrial processes involve the dissolution of gas under high pressure, so it is important to evaluate the rheological properties of viscoelastic materials under high pressure. In this research, a high pressure rotational rheometer was developed to measure the rheological parameters of viscoelastic fluids and investigate the influence of the dissolution of gases on rheology. The rheometer utilized a piezoelectric torque transducer, which enabled transient and dynamic rheological measurements under high pressure. First, the rheometer was designed, fabricated, and calibrated using a calibration fluid. Second, the capability of the rheometer was verified using polydimethylsiloxane (PDMS), which is a typical viscoelastic fluid. Viscosity and viscoelastic properties, such as storage/loss modulus, and complex viscosity, were evaluated. Thirdly, the effects of the dissolved CO2 on the rheological properties of PDMS were investigated. The effects of temperature and dissolved CO2 were investigated individually at the temperature of 25, 50, 80°C and CO2 saturation pressures of 1, 2, 3 MPa. Then, the combined effect was correlated using a generalized Arrhenius model. The proposed model expressed viscosity as a function of temperature and pressure without the need for thermodynamic and volumetric information of the fluid. The achievement of this research provides an alternative method to measure rheological properties of viscoelastic materials under high pressure and enables the prediction of the viscosity of a fluid with dissolved gas through modelling.
- ItemOpen AccessDevelopment of an Improved Repeater-free Acoustic Telemetry System Through Experimental Investigation and Modelling(2021-11-23) Pagtalunan, Jediael R.; Park, Simon; Kim, Seonghwan; Xue, Deyi; Wang, XinMeasurement while drilling (MWD) enables real-time measurement of downhole conditions for directional drilling, but most commercial MWD telemetry techniques such as mud pulse or electromagnetic methods suffer from limited transmission speeds. Acoustic telemetry has the potential for significantly faster transmission speeds, albeit with limited range due to drill string attenuation and noise. A common solution to this is to use acoustic repeaters, which incur high costs and require complex implementation. Instead of using repeaters, we utilized two carrier frequencies at the modes to transmit redundant data in combination with a lock-in amplifier (LIA) to extract the signals from the carriers. The extracted signals were then fused at the receiver to increase signal fidelity. An experimental setup was developed to transmit acoustic signals through a simulated drill string. The signals were first attenuated by the rubber section of the simulated drill string. The results show that the proposed system was able to achieve error-free transmission of packets at 64 bps up to 1.95 km without the use of a repeater which is an order of magnitude faster than current commercial MWD methods.Moreover, the acoustic telemetry system requires the identification of the carrier frequencies near the natural frequencies of drill string with specified boundary conditions. This work proposes a finite element (FE) model based on the Timoshenko beam theory that predicts the dynamics of an actual drill-string over a wide frequency range. The frequency response of the model is compared to models in literature with similar components. Then, three configurations that follow a specified trajectory are defined with increasing lengths and curvature to represent the drill string assembly as it approaches the target reservoir. The frequency responses of the of the three configurations are determined and a carrier frequency was selected at the center of the third passband. Like the lab-scale experiments, packets of bits are first generated as telemetry data and then convolutionally encoded to reduce errors at the receiver. The signal is modulated using differential binary phase shift keying (DBPSK) and upconverted to the carrier frequency which is used as the force input to the model. Finally, the receiver at the surface demodulates and decodes the received acceleration to recover the transmitted bits using a digitally implemented LIA. The transmitted and received bits are again compared to calculate the bit-error rate (BER) for each signal-to-noise ratio (SNR) condition and used as the measure of performance. To simulate transmission, the time impulse responses are first recorded for the three different drill string configurations. These are then used to develop a finite impulse response filter (FIR) for simulation of the acoustic transmissions. The results show that the passband locations stay at the same frequencies and that transmission speed is limited by the passband widths.
- ItemOpen AccessDevelopment of an Optical System for High Precision Multi-Axis Force Measurements(2015-10-19) Sandwell, Allen; Park, SimonAccurate and precise force measurements are critical in machining operations for maximizing production, detecting tool failure, and monitoring. Currently, the most accurate force sensors are piezoelectric sensors. The accuracy of these sensors is very high, yet they are expensive, are limited in their measurement bandwidth and are only suited for dynamic measurements. To overcome the challenges of existing sensors an alternative incorporates optical components to measure very small displacements. The sensor uses photo detector technologies which can measure positional changes from a laser on the order of nanometres. To improve sensitivity a mechanical amplification system based on levers is introduced, along with algorithms to extract the effects of multiple sources and a single detector. To extract more accurate information, an analysis of the photodiode and laser beam characteristics is performed. For implementation, a prototype sensor is fabricated. The sensor is benchmarked against a commercial dynamometer to characterize performance.
- ItemOpen AccessDevelopment of cable-assisted robotic system for machining(2023-01-10) Wang, Zhanhao; Lee, Jihyun; Park, Simon; Lee, Jihyun; Park, Simon; Goldsmith, Peter B; Carriere, JayNowadays, industrial robots are the synonym for automation and efficiency, and have developed a strong presence in the manufacturing industry. The main application of industrial robots is widely known as handling, assembly, and welding, while the interest in employing industrial ro-bots as machine tools is rising in many manufacturing sectors. Compared with conventional CNC machine tools, industrial robots are advantageous in terms of easy integration, ample workspace, and cost saving. These unique advantages motivate the industry to replace CNC machine tools with industrial robots. However, among various sources of errors, their low structural rigidity is the most significant challenge, hindering the application of the robot in machining tasks and de-grading the machining quality.Herein, this study seeks to propose an innovative robotic configuration named cable-assisted ro-botic system (CARS) to solve the structural stiffness problem of industrial robots. The concept of CARS is explained in this study, and its prototype is built up with customized cable-winches based on servo motors and a serial industrial robot. The design of the mechanical structure, elec-trical circuit, and multi-platform control program are detailed to provide guidelines for duplica-tion. The performance of the implemented PID controller is examined under different conditions.The theoretical foundation is also provided, and the feasibility of CARS is evaluated in this study. The kinematic model of CARS is derived from the closed-loop kinematic chains. CARS's dynamic model is derived based on the rigid-link-flexible-joint multibody dynamic model of ro-bot and cable's elongation dynamic equations to account for elastic effects. Dynamic analyses are performed to compare the dynamics of the CARS prototype and the serial industrial robot. Along the most flexible direction, the static stiffness is improved by approximately 92% in the CARS prototype, and its dynamic stiffness is almost doubled. In order to construct the numeri-cal dynamic model of CARS, the inertia parameters of the KR6 industrial robot are identified via the least-square method, followed by fitting elastic parameters to modal measurements from ex-perimental modal analysis and measuring cable elongation stiffness. The constructed model is then transformed into the form of frequency-response function and validated with the experi-mental modal measurements. A novel configuration optimization framework is proposed in this study, targeting providing design guidelines and evolving dynamics towards desired perfor-mance. A case study of the optimization framework is presented based on the acquired dynamic model of CARS, where the effectiveness of the optimization framework is verified, and the dy-namic stiffness with the optimal configuration improves by 42% compared with the original con-figuration’s dynamic stiffness. Lastly, a series of machining tests are conducted to evaluate the CARS prototype's improvement in chatter resistance. The proposed CARS system will be appli-cable to robotic machining applications and intends to improve the accuracy and finish quality of applications such as milling, drilling, grinding, etc.
- ItemOpen AccessDevelopment of Nanocomposite Sensors for Smart Work holding System(2022-01) Sandwell, Allen; Park, Simon; Hugo, Ron; Li, Simon; Xue, DeyiThe advent of Industry 4.0 necessitates developments of new sensor technologies. One of the emerging techniques of fabricating these new types of electronics and sensors is by depositing conductive inks and additional electrically active materials to serve as sensor layers onto flexible polymeric substrates. This study presents copper nanoparticle-based inks. The new formulation is developed that provides both oxidation resistance as well as improved flexibility with suitable rheological properties for deposition using traditional screen-printing practices. To create a conductive matrix from the deposited ink, a sintering step is needed. Intense pulsed light (IPL) using a xenon flash lamp is used to sinter the ink. As the IPL sintering process is applied to the surface of the ink, the sintering process and resulting materials are analysed. The addition of polymeric nanocomposite-based films has significant benefits when used as the sensing layer. In this study we developed a sensing material comprised of (poly)vinylidene fluoride as a piezoelectric polymer matrix, along with carbon nanotubes to create an electrically conductive network. Exhibiting both piezoelectric and piezoresistive properties, the developed sensors are capable of measurement in a wide frequency band. The performance of these nanocomposite sensors was assessed as they are subject to an applied strain under both static and dynamic conditions. As an application for the printed sensors, we investigate their suitability as imbedded sensor systems for smart workholding. We present the design of a smart chuck (the SmartJaw) that can measure the gripping forces on a workpiece during machining operations on a lathe. Continuous monitoring of the jaw clamping forces provides the required feedback to minimize the likelihood of adverse events occurring. Analytical models are developed and presented that reconstruct the cutting forces based on the input jaw gripping forces and other parameters such as spindle speed, workpiece geometry and tool location. The accuracy of the models is examined. The SmartJaw is fabricated using the developed nanocomposite sensors and conductive inks, and the performance is compared with the commercial strain gauge system. Both accurate and precise measurements of forces are critical in machining operations for maximizing production, detecting tool failure and process monitoring.
- ItemOpen AccessEffect of Surface Treatment on the Rate of Convective Heat Transfer for a Cylinder in Crossflow(2018-01-08) Elliott, Mark; Johansen, Craig; Park, Simon; Gates, Ian; Hugo, Ron; Mohamad, AbdulmajeedA method of roughening the surface of cylinders by media-blasting with micron scale particles was tested for heat transfer enhancement and pressure drop characteristics with an air flow over a range of Reynolds numbers from 200 to 7000. It was found that the surface treatment had an adverse effect on the rate of convective heat transfer over a range of Reynolds numbers. However, over the same range, the surface pressure drop was unaffected by the surface treatment. The pressure data likely indicates that the stream turbulence of the oncoming air flow was high enough to cause the critical Reynolds number to drop to the lower end of the Reynolds number range and nullify any positive effects that a roughened surface might have. Lower Nusselt numbers for the blasted wires suggest that for flows with high free-stream turbulence intensity a roughened surface decreases heat transfer. This decrease is possibly caused by earlier turbulent boundary layer separation on the rough surface due to the fact that the flows are all in the trans-critical flow regime at every Reynolds number tested.
- ItemOpen AccessElectrical, Thermal, and Machining Behaviour of Injection Moulded Polymeric CNT Nanocomposites(2013-10-02) Mahmoodi, Mehdi; Park, SimonCarbon nanotubes (CNTs) are promising additives for thermoplastics, resulting from their superior electrical, thermal and mechanical properties. Due to the desirable properties of CNT/polymer composites and their wide application in technological devices, these materials have attracted a great deal of attention from both academia and industry. A considerable amount of research has been devoted to the processing of CNT-filled nanocomposites, but only a few investigations have focussed on the injection moulding of these nanocomposites. This research was aimed at the study of the flow-induced alignment of CNT/polymer nanocomposites through the injection moulding process. We focussed on the understanding of the alignment of multi-walled carbon nanotubes (MWCNTs) in a thermoplastic matrix and the investigation of the alignment’s effect on the electrical, thermal and machining characteristics of the injection moulded nanocomposites. The nanocomposites were first prepared with a melt mixing technique (i.e. twin screw extrusion), and they were then injection moulded under various processing conditions and mould geometries. High aspect ratio nanotubes could be partially aligned in the parallel-to-flow direction, resulting from the in-plane shear flow exerted on the polymeric melt in the injection cavity. It can be concluded that the volume resistivity of the moulded samples could be varied up to 7 orders of magnitude by changing the processing conditions and gate type in the injection moulding process. The electromagnetic interference shielding effectiveness (EMI SE) of the moulded composites was studied by considering the alignment of the MWCNTs. The EMI SE decreased with an increase in the alignment of the injection moulded MWCNTs in the polymer matrix. Anisotropic thermal conductivity was observed for the injection moulded nanocomposites. It was shown that thermal conductivity can be enhanced by aligning the nanotubes in the parallel-to-flow direction. The post-processing of injection moulded CNT nanocomposites, such as their machinability, plays an important role in their economic viability. The addition of CNTs to polymers can improve the machinability of the polymers, mostly due to the high thermal conductivity of these nano particulates. However, there are some challenges in the machining of CNT-filled nanocomposites, such as the absence of comprehensive knowledge of the material properties, especially at the high strain rates encountered in machining. In this study, the micro mechanical machining of injection moulded MWCNT-filled nanocomposites was examined, and some of their machining characteristics were compared with those of pristine polymers. In addition, the effect of the nanotube alignment on the cutting forces was experimentally investigated, and a mechanistic micro-milling force model was used to predict the cutting forces. It was found that the CNT alignment and concentrations influence the micro cutting forces, and the force model was verified with the experimental milling forces. The machinability of the CNT nanocomposites was improved over that of pure polymer, due to the enhanced thermal conductivity and mechanical characteristics. In addition, better surface quality and dimensional stability of the machined slots was observed for CNT-based nanocomposites. From the results obtained in this study, one can determine the optimal processing conditions for the injection moulding of CNT-filled thermoplastics. It can be concluded that the electrical and thermal conductivities of these nanocomposites strongly depend on the alignment of the nanotubes within a polymer matrix, which can be controlled by selecting proper processing conditions and mould geometry. These parameters can be selected based on the desired application of the product. In addition, this research work provides a fundamental understanding of the material removal behaviour of CNT-filled composites, which is very important in the design of these novel materials for specific engineering applications.
- ItemOpen AccessFundamental Understanding of Warm Lime Softening Process to Improve Steam Assisted Gravity Drainage Produced Water Treatment Performance(2021-01-15) Zhang, Lu; Lu, Qingye; Husein, Maen; Park, SimonSince the commercialization of the first steam assisted gravity drainage (SAGD) enhanced oil recovery facility in 2001, the warm lime softening (WLS) process has been commonly deployed as part of a SAGD central processing facility (CPF) water treatment plant. The principal process goal of the WLS process is to remove dissolved hardness (e.g. calcium and magnesium ions) and silica by the addition of lime (Ca(OH)2), magnesium oxide (MgO), soda ash (Na2CO3), coagulant, and flocculant. Although the WLS process has been operated for almost 30 years in the oil sands industry, the fundamental electrokinetic properties of the particles generated are not thoroughly investigated. The high temperature, high silica and dissolved organic concentrations also make the WLS unique compared to the traditional cold lime softening process used in municipal water treatment and other industrial water treatment. The understanding of the electrokinetic properties of particle suspensions is of paramount importance as it directly relates to the performance of sedimentation and clarification, as well as the selection of chemicals and doses. Furthermore, the understanding of the impact of feed water chemistry deviations on the charge behaviors of the particle suspensions and on the coagulant dose is of significant practical implications for the WLS operations. This research was undertaken to investigate the surface charges of the two most common softening particles, calcium carbonate (CaCO3) and magnesium hydroxide (Mg(OH)2), under SAGD WLS conditions from zeta potential perspective. A number of experimental conditions (pH, temperature, presence of other ions, additions of other chemicals) were varied to exam the impact on the zeta potential of two softening particles. Visual MINTEQ modelling was utilized to predict chemical speciation under various conditions and was used to assist with data interpretation. High temperature (65°C) jar tests were also performed using synthetic SAGD produced water (PW) samples to simulate the WLS process and assess the impact of feed water deviations (silica, clay, humic acid, Ca(OH)2, MgO, Na2CO3, NaHCO3, CaCl2, and MgCl2) on the dose of a polyamine-based cationic coagulant. The electrokinetic study revealed that pH, and the type of ions and functional groups present in solution are the main impacting factors on the zeta potential of softening particles. The coagulation study revealed that the coagulant dose was significantly influenced by humic acid and silica. The findings of this research can provide insightful knowledge to SAGD operators regarding process monitoring, approaches to onsite chemical optimization, possible controls during an influent water off-specification event.
- ItemOpen AccessHybrid Machining using Direct Laser Assistance and Micro Texturing(2018-09-25) Wei, Yuan; Park, Simon; Kim, Seonghwan; Xue, DeyiHard-to-cut materials, such as structural ceramics, metallic glasses, and fibre reinforced polymers, are widely used in aerospace engineering, medical appliances, and other fields. However, due to the materials’ high strength and hardness, the machining costs for these materials are high. Consequently, improving the machining process of hard-to-cut materials is necessary. Laser assisted machining is often used to improve the machining process of hard-to-cut materials. However, the current laser assisted machining method normally uses high power lasers due to low heating efficiency; overheating and surface phase changes cannot be avoided, especially for metallic glasses and resin-based composites. In this study, a novel laser assisted machining method, direct laser assisted machining (DLAM), is proposed and developed to improve the machining of hard-to-cut materials. In the conventional laser assisted machining process, a workpiece is pre-heated by a laser prior to the removal of the material to soften the workpiece material and improve the machinability. Whereas DLAM passes the laser beam through a cutting tool, and then directly heats the location (at the tool tip) where the material is to be removed. Energy consumption is reduced and overheating the workpiece can be avoided. In the DLAM process, the cutting tool is made from sapphire because sapphire is very hard and has perfect optical transparency so that laser can pass through. The sapphire tool not only works as a cutting tool but also delivers the laser beam to its rake face. Effects of micro tool surface texture on the rake face in DLAM are also investigated. Tool surface texturing can reduce the cutting forces and tool wear by minimizing friction and reducing the contact area. A new tool texturing, micro-abrasive blasting method is used to fabricate the micro texture on a sapphire tool rake face. The texture effects in the tribological test and the cutting process are investigated. The numerical modeling of the DLAM cutting process was performed using a commercial finite-element analysis software. Cutting model coupling with laser heating effect and tool surface texture were built and carried out. The simulation results were used as a reference for the cutting test design, and they were compared with the cutting tests data. A series of cutting tests were performed on metallic glass, CFRP, and aluminum alloy under different cutting conditions. The cutting forces were measured and analyzed. The machined surface and chips were examined and compared to the simulations. For all materials, the cutting forces were reduced when optimal laser power is applied. For the bulk metallic glass, DLAM significantly reduced the cutting forces at a low output power of 2.8 W. However, a high laser output power (7.9 W) did not decrease the cutting forces; in certain cases, it led to higher cutting forces due to a phase change of material. The surface roughness was improved when the laser power was 2.8 W. When the laser output power was 7.9 W, the surface roughness changed slightly compared to 2.8 W. The shear band formation was affected using the laser. Less chip segmentation was identified when the laser was applied, implying an enhanced ductility of the bulk metallic glass (BMG) material. In addition, the combined application of DLAM and a tool surface micro texture reduced the cutting forces even further. DLAM combined with tool surface texture provides a possible laser assisted solution for machining temperature-sensitive materials without unwanted material phase change. This study also provides an understanding of chip formation on BMGs when additional heat is applied during the cutting process. Finite-element model of the process provides a fundamental understanding of the DLAM working mechanism, and it can be used to predict cutting forces and cutting temperature.
- ItemOpen AccessInvestigation of durability and design of direct methanol fuel cells(2012-08-27) Kianimanesh, Amir; Park, Simon; Freiheit, TheodorDirect Methanol Fuel Cells (DMFCs) have become a potential alternative for rechargeable batteries in portable electronic devices since they can operate at the higher power density (generated power over the volume of the system) of conventional rechargeable batteries; and have advantages such as a simpler system design (with the potential for low-volume lightweight stacking), eliminating the requirement for fuel reforming, and classification as a zero-emission power system. There are several challenges in DMFCs which need to be overcome before they can become commercially viable energy sources. These challenges are system durability and the design optimization of system components. The durability of the DMFCs has been investigated by considering the effects of operating factors on the degradation of a single-cell DMFC with serpentine flow channels. Degradation in the performance of the DMFC system was observed and modeled over time by a linear regression model considering the cumulative exposure of the operating factors to the fuel cell and the moving average concept in the degradation analysis. In addition, the influence of the flow fields design in the DMFC system with a focus on performance was investigated. Three bipolar/end plates with a single-channel serpentine configuration were fabricated with three different channel widths and experimentally tested the performance. To understand the details of the phenomenon and the fluidic behaviours, a computational fluid dynamics (CFD) model was developed, which showed that the diffusion of fuel to the diffusion layer was higher and the fuel distribution more uniform in the narrower channel. Their performance showed that the cell equipped with the narrowest channel width had an overall higher performance compared to the widest channel width. The results of this study could enhance the performance of DMFC by modeling the polarization and degradation behaviour of the tested DMFC and provide a better understanding of the degradation phenomenon. Furthermore, the design of the DMFCs can be improved and optimized by studying the geometry of bipolar/end plates and their effect on the performance of cells. This can result in DMFCs with higher overall efficiency that approaches the targets for commercial viability.
- ItemOpen AccessInvestigation of Polymeric Composites with High Aspect Ratio Nanoparticulates for Coatings(2016) TabkhPaz Sarabi, Majid; Park, Simon; Park, Dong-Yeob; Roberts, Edward; Sundararaj, Uttandaraman; Li, Simon; Chang, Gap-SooTo overcome some of the challenges associated with existing pipeline coatings, the use of polymeric nanocomposites as coating materials are proposed in this research. By employing novel inclusions such as hexagonal boron nitride (hBN) nanoplatelets, carbon nanotubes (CNTs), graphene nanoplatelets (GNPs), and zinc particulates within a conventional polymer coating, high-performance polymeric nanocomposites can be created for the purposes of pipeline protection. The excellent performances of the proposed polymer-based composites are due to unique mechanical, electrical, thermal, and anti-corrosive properties of the additives. The addition of 2D nanoplatelets such as hBN and GNP to the pure polymers may result in the fabrication of nanocomposites with lower coefficient of thermal expansion (CTE), high gas barrier, high mechanical stability, and anti-corrosive performances. Application of CNTs and zinc particles as hybrid compositions can also improve corrosion protection of the composite coatings due to the synergistic effects of zinc particles as sacrificial material and CNTs as connectors of an electrically conductive network. This research is aimed at investigating the feasibility of using these nanocomposites as coating materials. Initially, the effects of dispersion and geometry of CNTs on the final properties of nanocomposites were examined. Then, two random walk models were developed to study the effects of the addition of inclusions on the electrical and thermal conductivities of nanocomposites. Finally, the selected nanoparticulates were added to polymers, and the coating capabilities of composites were evaluated. From the tests and investigations conducted on the developed composite coatings, it was observed that thermal expansion, gas barrier, mechanical strength, adhesion, and corrosion protection performances were improved compared to the pure polymeric coatings. The corroded area on the cathodic disbondment test specimens reduced down up to 90% for the composite with zinc (20 wt.%), MWCNTs (2 wt.%), and GNPs (2 wt.%), compared to a specimen coated with a pure polymer. It is seen that the presence of nanoparticulates decreased gas penetration and thermal expansion of the matrix by 75% and 65%, respectively.
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