bluuebunny/crossref_metadata_2025 huggingface dataset:
Change of the Effective Strength of Grain Boundaries in Alloy 617 Under Creep-Fatigue Loadings at 800°C
Authors: Suzuki Wataru , Ishihara Kenta , Kikuchi Ryo , Suzuki Ken , Miura Hideo
Published: January 2020

In this study, both EBSD (Electron Back-Scatter Diffraction) analysis and a micro tensile test system with FIB (Focused Ion Beam) equipment were applied to bicrystal specimens of Alloy 617 in order to establish a quantitative theory of the lifetime evaluation method under creep-fatigue loadings. The IQ (Image Quality) value which is obtained from the diffraction pattern (Kikuchi pattern) indicates the total density of defects such as vacancies, dislocations, and local strain was used for quantitatively evaluating the crystallinity of the alloy. KAM (Kernel Average Misorientation) value was also used for density analysis of GN (Generally Necessary) dislocations. Continuous changes of microtexture of grains and grain boundaries were observed by applying an intermittent creep fatigue test. As a result, it was confirmed that the IQ value around specific grain boundaries in damaged specimen was drastically degraded compared to that of the initial specimen. Intergranular cracks always occurred when the IQ value decreased to a certain value. Therefore, there is a correlation between the IQ value and the strength of a grain boundary in this alloy. The decrease of the IQ value was attributed to the accumulation of both dislocations and vacancies around the specific grain boundaries under creep loading. The accumulation rate under the creep-fatigue loading was clearly higher than that under simple fatigue and creep loadings. Finally, it was clarified that the degradation of the crystallinity in the vicinity of a grain boundary was a criterion of an intergranular crack under creep-fatigue loadings.
Edge States in Nonlinear Model of Valve Spring
Authors: Gzal Majdi , Gendelman Oleg V.
Published: January 2020

We address the dynamics of helical compression valve springs of an internal combustion engine. To this end, the spring is mathematically modeled as a finite non-homogenous one-dimensional mass-spring-damper discrete chain. Regarding the boundary conditions, the upper end of the chain is forced with periodic displacement, which mimics the actual camshaft profile, while the other end is fixed. In order to model the interaction between the valve and valve seat, the displacement of the upper mass is constrained to be nonnegative by adding an obstacle such that when it approaches the obstacle, it experiences an impact that satisfies the Newton impact law with restitution coefficient less than unity. Another source of damping in this model arising from the internal damping of the spring material. The nonlinearity of the model originates from the periodic impact interactions.

This interplay between nonlinearity and discreteness supports time-periodic and spatially localized solutions characterized by a strong localization at the edge of the chain (i.e. edge states) such that the periodicity of the impact allows derivation of exact analytical solutions for the forced-damped edge state. Then, the governing equations are solved numerically in order to illustrate the exact solution. The results are compared to experimental findings from analysis of actual automotive valve spring.
Experimental Investigation of a Backing Sheet Stiffener in Incremental Forming of Polycarbonate
Authors: Grimm Tyler J. , Kulkarni Shubhamkar , Mears Laine , Mocko Gregory
Published: January 2020

Single point incremental forming (SPIF) is a dieless forming process for sheet materials. This process forms materials with a hemispherical forming tool which locally deforms the sheet at incremental depths. The freeform nature of this process promises significant efficiency improvements within small and medium volume industries where stamping is traditionally used. However, several drawbacks currently inhibit its widespread use. One of these drawbacks is springback or elastic recovery resulting in reduced geometrical accuracy. An existing approach to counter this involves using a dedicated backing die, increasing the cost of the forming apparatus and the overall energy input per part. Other springback reduction methods involve the direct addition of energy to the workpiece through electrical or heat input.

This study investigates the use of sacrificial steel blanks as backing dies for incremental forming of polycarbonate sheets, to overcome the loss in geometrical accuracy affiliated with forming geometries with a relatively large distance between the geometry periphery and the clamped edge. The blanks were not bound to each other, but rather clamped along their edges. In this study, polycarbonate blanks were tested using a three-factorial design of experiments, with relative plate thicknesses of 0.4, 0.5, and 0.6, and wall angles of 15°, 30°, 45°, and 60° as independent factors. The test geometry used was a straight walled pyramid with a square base. Using the backing sheet, a reduction in the springback was observed, demonstrating the effectiveness of sacrificial backing blanks. Particularly, the ‘pillow effect’ at the base of the geometry was reduced. This is attributed to the higher stiffness of the steel plates, increasing the plastic strain on the polycarbonate. However, the formability is found to decrease for higher values of the backing plate thickness due to premature steel failure. In future studies, this work will be expanded to include additional thickness ratios, geometries, toolpath types, step sizes and materials to form a more complete trend.
Computationally Efficient Thermo-Mechanical Analysis for Predicting Process-Induced Deformations of Composite Structures
Authors: Zappino Enrico , Zobeiry Navid , Petrolo Marco , Vaziri Reza , Carrera Erasmo , Poursartip Anoush
Published: January 2020

This paper presents an innovative numerical model for the calculation of process-induced deformations of composite structures. The capabilities of a refined one-dimensional model, based on the Carrera Unified Formulation, have been exploited to describe the complex displacement field that originates during the curing process of a composite component. The refined kinematic models adopted are able to describe a three-dimensional solution and make it possible to predict the through-thickness deformation that is one of the causes of the origins of the process-induced deformations. The evolution of the material properties during the curing process is evaluated using the software RAVEN and the manufacturing process is simulated using an ‘incrementally elastic’ constitutive model. The results demonstrate the capabilities of the present approach to predict the process-induced deformations including the complex stress field due to thermal and mechanical loads.
Influence of Lateral Restraint on Thermocapillary Migration of Wetting Droplets
Authors: Srinivasa Sagar Kalichetty , Dwaraknath K. G. , Pattamatta Arvind , Sundararajan T.
Published: January 2020

The present study aims at studying the characteristics of thermocapillary migration with varying levels of lateral restraints. A temperature gradient is created by heating and cooling either side of the substrate. When a droplet is placed near hot side it spreads as thin film and migrates towards the cold side. The advancing end assumes the shape of a parabolic rim while the receding end stays as a thin film. It is observed that the droplet decelerates to attain a steady state velocity and undergoes slight acceleration near the cold end of the substrate. The observed velocity trend follows the temperature gradient on the substrate. The velocity increases with the droplet volume and substrate temperature gradient. The liquid viscosity is observed to have a diminishing effect on migration velocity. The effect of lateral spread confinement is studied by performing experimental trails on substrates with different widths. It is found that reducing the substrate width increases the migration velocity due to increased footprint resulting in larger thermocapillary force. The results observed in the present study highlights the importance of thermocapillary flows in many academic and industrial applications.
Design and Development of a Cost-Effective LIDAR System for Transportation
Authors: Wiklund Theodore , Heim Mark , Halberstadt Jaret , Duncan Michael , Mittman Deven , DeAgostino Thomas , Depcik Christopher
Published: January 2020

Light Imaging Detection and Ranging (LIDAR) cameras and Light Detecting and Ranging (LiDAR) rangefinders were initially implemented in the 1960s as a higher-resolution and increased capability alternative to radar. Since then, LIDAR and LiDAR (hereto called lidar) have expanded into applications in aerial geographical surveying and collision-detection systems for autonomous vehicles. Current commercial systems are relatively expensive and potentially oversized for noncommercial applications. Consequently, this deters their use on consumer products like bicycles, where lidar systems can enable safety advancements that are necessary to counter the rising numbers of hazards affecting riders. In addition, widespread usage of inexpensive lidar systems can facilitate a more complete picture of our transportation infrastructure by delivering information (e.g., pavement quality) suited for U.S. Department of Transportation Highway Performance Monitoring System (HPMS) reports. This will aid in the creation of a safer infrastructure by highlighting critical areas in need of improvement and repair.

As a result, this effort outlines the development of a compact and cost-effective lidar system. The constructed system includes the ability to generate a static image by collecting several hundred thousand distance signals measured by a lidar rangefinder. Since the rangefinder has no self-contained rotation or translation systems, an Arduino Mega 2560 v3 microcontroller operates a pair of stepper motors that adjusts its azimuthal angle and pitch. Coalescing these signals into an ASCII text file for viewing in MATLAB results in a reasonably accurate picture of the surroundings. While the current system takes 1–2 hours to complete a full sweep, it has the potential to provide sufficient accuracy for HPMS reports at a moderate expenditure: the entire system costs less than $300. Finally, upgrading to a more powerful microprocessor, implementing slip rings for enhanced electrical connectivity, and refining the code by including interpolation between points will enable faster point cloud generation while still maintaining an inexpensive device.
Parametric Data-Driven Reduced Order Models With State Consistence for Aeroelastic Analysis
Authors: Krolick William C. , Wang Yi , Pant Kapil
Published: January 2020

This paper presents a framework to develop data-driven parametric reduced order models (PROMs) for aeroelastic (AE) analysis of flexible vehicles within a broad flight envelop. It is based on the separate domain and mode shape perturbation method. The flight envelop is first partitioned by multiple grid points, on each of which an aerodynamic ROM (AeroROM) is constructed using system identification (SYSID) techniques to capture dependence of the generalized aerodynamic force on the generalized displacement using data generated by high-fidelity CFD simulation. Then AeroROMs not on the grid point are obtained by interpolating those at neighboring grid points. Two interpolation schemes, i.e., the output-based interpolation and coefficient interpolation are developed. The parametric AeroROM is then coupled with the mode-based structural ROMs to enable integrated AE analysis under various flight conditions. The state consistence enabled by different SYSID techniques and performance of both ROM interpolation methods are also investigated. For the first time, it is found that the autoregressive exogenous ROM allows state consistence and direct model coefficient interpolation. The ROMs exhibit excellent agreement with CFD simulations (< 3% relative error) and orders of magnitudes speedup. The effort opens up new opportunities for parametric AE analysis and flight control design.
Nonlinearity of Enhanced Cell Structures Having Auxetic Material Properties
Authors: Yang Chulho , Chang Young Bae , Lee Dongchan
Published: January 2020

This research is aimed at proposing an enhanced re-entrant hexagonal structure and examining its auxetic behavior in compressive or tensile load conditions. An integrated experimental and finite element analysis (FEA) approach was used to investigate the behavior of the proposed structures in combination with polymeric materials (thermoplastic polyurethane (TPU) materials such as Ninjaflex® and Semiflex®). We focused on the effect of nonlinearity of the structure on the overall stiffness and shock-absorption performance of the body protection pads. FEA models were used to examine how the stiffness and Poisson’s ratio are affected by static load conditions and also how the dynamic loads are transmitted through the auxetic structure. The static FEA models were verified through experimental testing. Advanced additive manufacturing (3D printing) techniques such as Fused Deposition Modeling (FDM) were used to build fixtures and prototypes of the auxetic polymeric structures. Structural stiffness and Poisson’s ratio were examined not only in tensile loading condition but also in compression. Axial and lateral deformations were measured for given axial forces on the experimental model, and the measured values of Poisson’s ratio were compared with the computational results. It was shown that the enhanced re-entrant hexagonal structures had nonlinear behavior, which could be a useful property for developing body protection pads and stiffness-varying structures.
Study of Peripheral Milling of Magnesium Matrix Composite
Authors: Anandan Nishita , Ramulu M.
Published: January 2020

An experimental investigation on peripheral milling of magnesium composite AZ91 magnesium matrix with 15 vol.% SiC particles of a nominal 3–4 μm was performed to study the cutting forces generated, surface finish of the machined surface and the tool wear as a function of cutting conditions. The feed force was found to increase with feed and spindle speed, while the thrust forces were found to increase with feed and no significant trend was observed with the increase in spindle speed. The feed and spindle speed were varied from 0.2 to 1 mm/rev and 1000 to 4000 rpm respectively. The length of cut was kept constant at 32 mm.

The tool wear was measured along the helical cutting edge and the wear mechanism was studied through SEM images of the cutting edge. A tapered wear geometry was observed which can be attributed to the varying chip load along the helix. Abrasive wear was identified as the main wear mechanism. Micro-ploughing and micro-pitting were also observed. The extent of micro-ploughing and micro-pitting depended on the cutting condition. When the impact on the cutting edge was high during aggressive machining condition of 0.5 mm/rev and 4000 rpm, extensive micro-pitting and micro-ploughing were observed on the flute. The cutting edges appeared to be smooth due to repeated rubbing against SiC particles and wear debris.
Innovative Hole Making Process in Woven Composite Laminates
Authors: Jadhav Vishwas S. , Kelkar Ajit D.
Published: January 2020

This paper proposes an innovative hole making manufacturing method for the composite laminates. The laminates were fabricated using heated vacuum assisted resin transfer molding (HVARTM) technique using plain weave carbon fibers and epoxy resin. Plain weave carbon fabric laminae were stacked together, and five metal pins were inserted in dry fabric at specific distances without causing any damage to the carbon fiber strands. The stacked plies were then infused with epoxy resin to fabricate laminates, which were about 2.6 mm (0.1″) thick. The laminates were cured as per the manufacturer specifications and after curing metal pins were popped out from the laminate. This resulted in holes in the panels without any damage to the continuous carbon fiber strands. The fabricated laminates then were cut into open hole compression coupons using a water jet machine to obtain holes precisely at the center of the coupon. From the remaining panel, ten coupons were machined and half of them were drilled using traditional drilling machine and the remaining half were drilled by nontraditional water jet machining process. The coupons were then tested using ASTM D6484 method to study the mechanical properties of the laminates. The present method shows promising fabrication technique to create holes in the composite laminates without sacrificing the integrity of the continuous fibers.
An Analysis of the Aerodynamic Response of an Electroactive Membrane
Authors: Pulok Mohammad Khairul Habib , Sarker Pratik , Chakravarty Uttam K.
Published: January 2020

Dielectric elastomer membranes are a category of electroactive polymers composed of a thin elastomer film sandwiched between two compliant electrodes. An electrostatic pressure is created when there is an externally applied voltage on the electrodes which creates compression in the thickness direction and extension in the in-plane direction. This outlines a variation of the tension in the membrane that can be used to change its dynamic behavior. In this study, a specimen of an electroactive membrane, VHB 4910 is considered to observe the aerodynamic characteristics under external flow of air. Both experimental and numerical analyses are performed to predict the fluid-structure interaction behavior of the specimen for different angles of attack. A vibration testing arrangement is used to estimate the resonance frequencies and the mode shapes which are validated by the finite element results. From the study, the coefficient of lift is found to increase with the angle of attack up to a critical value. Similarly, the coefficient of drag increases with the angle of attack. Both lift and drag coefficients decrease with the Reynolds number. The magnitudes of the natural frequencies decrease as the applied voltages rise. The natural frequencies and mode shapes of the membrane can be tuned by changing the pretension, the pressure, and/or the voltage.
Fiber Creation and Deposition on Arbitrary Surfaces With Gas-Modified Electrospinning
Authors: Kooistra-Manning Emily A. , Huston Lane G. , Skinner Jack L. , Andriolo Jessica M.
Published: January 2020

Electrospinning (ES) is a manufacturing technique used for the fabrication of polymer-based nano to microscale fibers with a high surface-area-to-volume ratio. Traditional ES involves a large floor or tabletop apparatus and must include a collection substrate that is electrically charged relative to the spinneret. Here, we report a miniaturized electrospinner designed for efficiency and portability, which eliminates dependency on an electrically connected deposition surface through addition of gas flow. Using the portable system, polyethylene oxide (200k MW) fiber mats were deposited. During ES, air flow rate, separation distance, and applied voltage were varied, and resultant fiber mats were analyzed and compared for quality and dimension. Finite element analysis was used to predict fiber deposition coverage in conjunction with experimental parameters.
Mechanical Behavior of Collagen Mimetic Peptides Under Fraying Deformation via Molecular Dynamics
Authors: Rawal Atul , Rhinehardt Kristen L. , Mohan Ram V.
Published: January 2020

Collagen is a pervasive, triple helical, extracellular matrix (ECM) protein, found in human body from skin and bones to blood vessels and lungs, making it biocompatible, biodegradable, capable of cell attachment, and relevant for applications in bio-polymers, tissue engineering and a plethora of other bio-medical fields. Natural collagen’s extraction from natural sources is time consuming, sometimes costly, and it is difficult to render, and could present undesired biological and pathogenic changes. Nanoscale collagen mimetic peptides (Synthetic Collagen), without the unwanted biological entities present in the medium, has shown to mimic the unique properties that are present in natural collagen. Synthetic collagen, thus provides a superior alternative compared to natural collagen for its utilization in several applications. Their properties are affected by surrounding environments, including various solvents, and can be tailored toward specific applications. The focus of this paper is to investigate the mechanical properties of these nanoscale collagen mimetic peptides with lengths of about 10nm, leading to understanding of their feasibility in bio-printing of a composite polymeric collagen biomaterial with a blend of multiple synthetic collagen molecules. Molecular dynamics modeling is used to simulate, model and analyze mechanical properties of synthetic collagen peptides. In particular, mechanical behavior of these peptides are studied. An in-depth insight into the deformation and structural properties of the collagen peptides are of innovative significance for a multitude of bio medical engineering applications. Present paper employed steered molecular dynamics as the principal method of investigating the mechanical properties of nanoscale collagen mimetic peptide 1BKV, which closely resembles natural collagen with a shorter sequence length of 30 amino acids. A detailed comprehension of the protein’s mechanical properties is investigated through fraying deformation behavior studied. A calculated Gibbs free energy value of 40 Kcal/mol corresponds with a complete unfolding of a single alpha-helix peptide chain from a triple helical protein in case of fraying. Force needed for complete separation of the alpha-helix from the triple-helical protein is analyzed, and discussed in this paper.
Replicas Fabrication by Laser Scanner and Additive Manufacturing: A Preliminary Investigation
Authors: Rossoni Marco , Colombo Giorgio
Published: January 2020

This paper presents a preliminary investigation on the workflow that allows to replicate object by using 3D laser scanner and a desktop fused filament fabrication 3D printer. Pitfalls and limitations of those technologies will be pointed out in order to find the bottleneck of the workflow, paying specific attention to what concerns the digital workflow from the acquisition to the generation of the g-code. The findings and conclusions are drawn from a case study that has been carried out using the minimum amount of human intervention, especially during the digital postprocessing of the data. The objects under investigation is a broken car door handle. Firstly, it has been digitalized using a 3D laser scanner properly calibrated and set. The accuracy, precision and resolution of the measurement tool have been recorded and the as-is acquired data has been checked against topological errors. The as-is acquired model has been compared with the original geometry. The 3d polygonal mesh has been prepared for being printed: the material, machine and process parameters have been chosen. A simulation of the deposition process to estimate warps and deviation from the nominal geometry was carried out. Finally, the object has been additively manufactured using a desktop Fused Filament Fabrication machine: the printed object has been again compared with the original geometry.
Current Trends of Mechanical Engineering Undergraduate Curricula in California
Authors: Ngo Chean Chin , Oh Sang June
Published: January 2020

This paper reviews and compares 29 ABET accredited mechanical engineering undergraduate curricula in California which include 13 programs from the California State University (Cal State or CSU) System, 8 programs from the University of California (UC) System and 8 programs from private universities. The programs examined in the present paper include both Ph.D.-granting and non-Ph.D.-granting institutions in public and private universities. Some CSU mechanical engineering programs have been taking steps to implement changes recently in their curricula to reduce the total required degree requirement to 120 units and yet satisfy the minimum requirement of general education units. This paper presents a summary of the current curricula structure of these programs in Cal State universities by delving into the study of their degree requirements and compare with that of UC and private universities. For example, the number of units of college level mathematics and basic science required by the program is examined closely and determine if it is beyond the one-year requirement by ABET General Criterion 5 Curriculum. In addition, one of the ABET program criteria requires the mechanical engineering program to prepare students to work professionally in either thermal or mechanical systems. As such, this present paper also examines how each program is proportionately distributing courses in each of these two areas. Attention is also given to how each program integrates first year experience, senior capstone design experience, hands-on laboratory experience and internship experience (if any) in the curriculum. In January 2016, CSU launched the Graduation Initiative (GI) 2025 to increase graduation rates of CSU students while eliminating opportunity gap for underrepresented minorities and Pell-eligible students. One of the main goals of GI 2025 is to increase the freshman 4-year graduation rate of CSU students to 40% by 2025. Part of the strategies for GI 2025 from some CSU campuses is to review the curriculum and identify potential barriers to timely graduation and find strategies to eliminate them. The goal of this paper is to provide educators a timely summary of reference while examining their own curricula. Although different institutions carry curricular revisions that stem from different motivation, the ultimate goal will be the same — provide students optimally the best curriculum to better prepare them for the industry workforce and have positive impact for the society.
Dynamic Behaviour of a Dacron Aortic Graft
Authors: Tubaldi Eleonora , Ferrari Giovanni , Balasubramanian Prabakaran , Amabili Marco
Published: January 2020

Woven Dacron grafts are still considered the clinical standard practice in thoracic vascular reconstruction in the case of aortic aneurysm and acute dissection. Despite its characteristics of biocompatibility and durability, very little is known about the dynamic response of Dacron grafts and about their side effects on the heart workload and cardiovascular system. In this study, physiological blood flow conditions are imposed in a Dacron graft via a specifically-developed mock circulatory loop. The effects of different physiological pulsation-per-minute rates are investigated. Since the Dacron prosthesis is extremely stiffer circumferentially and compliant axially with respect to an aortic segment of the same length, bending oscillations are preferred by the graft. This leads to a very significant different dynamic behavior with respect to the replaced human aortic portion altering cardiovascular pressure and blood flow dynamics and eventually causing long-term implant complications.
Numerical Study of the Percussive Riveting Process: Initial Results
Authors: Krovvidi Sai C. , Ramulu M. , Reinhall Per G.
Published: January 2020

Percussive riveting is a dependable assembly method that produces high-quality joints in the aerospace industry. Its successful application is derived from its ease to implement in an assembly floor environment. The rivets are formed on the shank end of the rivet using a forming tool like a bucking bar and the head is constrained and impacted with a rapid succession of hits using a pneumatic gun with a special purpose die head. The rivet forms an interference fit joint because of the residual compressive stresses that are set up in the circumferential direction due to plastic flow of rivet material. These compressive stresses are balanced by tensile stresses in the skin and stiffener bulk material. Compressive stresses in the longitudinal direction help keep the skins pressed together. Research studies focused on the dynamics modeling of the percussive riveting process for robotic automation have not delivered an understanding of the temporal evolution of stress and strain fields in the vicinity of the rivet and the rivet hole. These studies aimed to produce joints of equal strength using automated assembly process compared with the manual assembly process. No modeling efforts have been published up to this point in time. This understanding is important in order to produce joints of predictable strength. A simulation effort for an unstiffened percussive riveting stackup assembly will be undertaken to study the trends of beneficial compressive residual stresses and strains within the bucked rivet. It is our goal to eventually estimate joint strength for prescribed sets of joint assembly parameters. The domain of interest will be restricted to few inches from the rivet axis.
Printability of Hydrogels for Hydrogel Molding Based Microfluidic Device Fabrication
Authors: Vicente Adam , McCreery Zachary , Yan Karen Chang
Published: January 2020

Microfabrication-free methods have been developed in recent years for fabricating microfluidic devices to enable the applications of microfluidic devices to a broader range. Our group has been working on developing a process for fabricating electrospun fiber embedded microfluidic devices by integrating hydrogel molding (HGM) and electrospinning (ES), and the feasibility of this integrated method has been demonstrated through our initial study. Recently, we have modified an extrusion based 3D printer kit to deposit hydrogels and form microchannels. Agarose has been used for our previous studies owning to its temperature dependent gelation.

In this study, we examined the feasibility of using gelatin gel as an alternative material for hydrogel molding. Gel materials with various concentrations were examined via printability assessments; and optimal gel materials were identified. Upon completion of pattern printing, the samples were then encapsulated in polydimethylsiloxane (PDMS) and cured; formed microchannels were then characterized via micrographic image analysis. The results show that three gels, 2% w/v agarose gel, 7.5% w/v gelatin gel, and a mixture of 2% w/v agarose gel and 7.5% w/v gelatin gel (1:1 ratio), yield consistent printed patterns and form consistent microchannels subsequently.
Numerical Investigation of the Euler Turbomachinery Equation and Analysis of the Impact of the Impeller Design on the Fan Performance by an Optimization Study
Authors: Fritsche Manuel , Epple Philipp , Gast Stefan , Delgado Antonio
Published: January 2020

The working machines such as fans, blowers and pumps are often used for transporting fluids in technical systems. The rotating impeller is used for energy conversion of mechanical work into hydraulic work. Leonhard Euler published this relation of energy conversion in 1752–1756 and is still used today for the basic design of turbomachinery.

In the present work, the Euler-Equation is described and presented in detail. Furthermore, a simplified parameterized blade channel of a centrifugal impeller is investigated with numerical simulation methods. The theoretical Euler-Equation is compared and validated with the numerical CFD-results. Based on an extensive CFD-optimization study, the impact of the impeller design parameters on the fan performance has been investigated. For this purpose, the blade shape and the operating conditions (speed and volume flow rate) were systematically varied.

After an extensive grid study, the influence of the blade channel contour on the fan performance was investigated. The results of the study are presented in detail.
Development of Vision-Based Control System for Mobile 3D Printer
Authors: Duan Pengji , Liu Yutong , Ding Junjun , Zhang Mingshao
Published: January 2020

The 3D printing technologies can produce objects with a very complex shape or geometry nowadays thanks to the advanced researches in their precision, repeatability, material ranges, etc. The size of 3D printed objects also varies. The Oak Ridge National Lab printed a 17.5 feet long, 5.5 feet wide and 1.5 feet tall tool for Boeing that weights 1,650 lbs. On the other hand, using Two Photon Polymerization, sub-μm structures can be produced. The majority of current 3D printers design resembles the traditional FDM 3D printer. The printer is stationary during the printing period, limiting the print zone by the size of the robots, regardless as to the printer designs (Cartesian, polar, delta or articulated robots). In addition, all current 3D printers work as stand-alone equipment, which prevents the possibility of further speeding up the fabrication by using multiple collaborating 3D printers.

Using mobile robots as a 3D printer could eliminate the size limit of the print zone and enable collaboration among different mobile robots to speed up the printing process. However, major problems are remaining unsolved in the current mobile 3D printer research, such as the precise localization of the robot, material slipping, accumulative printing error, etc. In this paper, a vision-based feedback control system is presented as a solution to these problems in mobile 3D printers. The system is equipped a single camera as sensory input. Using Simultaneous Localization and Mapping (SLAM) methods, the mobile 3D printer could potentially achieve sub-millimeter accuracy for localization. The slipping and accumulative error could also be mediated using image processing and object recognition. The system also enables the possibility for multiple 3D printers to work simultaneously. It is believed that mobile 3D printers equipped with vision-based feedback control system could have a great potential in the future.
Applying Static Fault Detection and Diagnosis Methods to Transient Air Conditioning Data Using an Equilibrium Prediction
Authors: Rogers Austin , Guo Fangzhou , Rasmussen Bryan
Published: January 2020

Fault detection and diagnosis methods for air conditioning systems typically apply static models after filtering out transient data using a steady state filter. However, air conditioning systems operating in the field often do not achieve a meaningful steady state and therefore the models cannot be applied because only transient data is available. This paper proposes a solution to this problem by predicting the equilibrium point using an exponential regression. The transient response of many system parameters such as cooling capacity, airflow, and refrigerant mass flow may be approximated as a first order dynamic response because the thermal mass in the system dominates other higher order dynamics. The best-fit for a decaying exponential will therefore yield a prediction for the equilibrium point, and static models may then be applied, thus enabling the use of static models with transient data. The method’s performance is quantified using both randomly generated data (Monte Carlo simulations) and the measured response of a field-operating system during both fault-free and faulty operation.
Effect of Photoactivated Cross-Linking Compound on Mechanical Properties of Porcine Carotid Arteries Post-Angioplasty
Authors: Mogharrabi Farshad , Kuhlenhoelter Jonathan , Anderson Blake , Kauser Katalin , Monson Kenneth
Published: January 2020

Percutaneous transluminal angioplasty (PTA) is a medical procedure performed on patients with severe atherosclerosis to open up stenosed blood vessels by inflating a balloon at the narrowing location. In many cases of PTA, restenosis occurs post-surgery due either to elastic behavior of the artery, also known as elastic recoil in medical literature, or to plaque reformation within the lumen. For that reason, stents are commonly deployed to keep the arterial lumen open. Stent deployment causes problems in some cases; for example, the presence of stents in arteries with frequent movements and large deformations can cause ruptures in the arterial wall.

Recent studies on 1,8-Naphthalimide organic compounds have shown that when these compounds are activated using a certain wavelength of light, it causes cross-linking between the components of the extracellular matrix. This observation has led to studies with the goal of developing a method to utilize this process to replace stents for cases with limiting conditions for stent deployment.

In this study we focused on measuring and quantifying the effects of this compound on the mechanical properties of treated arteries undergoing PTA under a variety of loading conditions.
Fused Deposition Modeling With Added Vibrations: A Parametric Study on the Accuracy of Printed Parts
Authors: Dei Rossi Joseph , Keles Ozgur , Viswanathan Vimal
Published: January 2020

Additive manufacturing is a potentially disruptive technology with a rapidly growing market. The recent development of RepRap style 3D printers has made this technology available to the public at a low cost. While these 3D printers are being used for a variety of purposes, many mechanical engineering students use them for prototyping in their projects. The quality of the 3D printed parts has been a concern in such cases. There are many variables within the operation of these printers that can be varied to obtain optimum print quality. This study explores the use of externally induced mechanical vibrations to the nozzle tip as a potential method to improve the quality of 3D printed parts. Induced vibration is expected to decrease the porosity of printed parts and improve the cohesion between print beads, ultimately improving their mechanical properties. The objective is to understand the positional accuracy of the prints with the added vibration and then to determine the optimum level of vibration to achieve best quality prints. For the study, the extruder filament is replaced with a pointed-tip pen that can mark the exact location where the printer delivers the material. A comparison between the locations marked by the pen with and without vibrations shows that the errors induced by the added vibration are not significantly different from those caused by the uncertainties of the printer itself. Further, this study also explores the optimum motor speeds to achieve a uniform distribution of material and determines medium motor speeds that provide maximum amplitude of vibration which are more desirable for a uniform infill.
Thermal Properties of Thin Film Uranium Oxides and Thorium Oxides
Authors: Thorum Aaron , Page Logan , Munro Troy , Allred David , Hua Zilong , Hurley David
Published: January 2020

Uranium and thorium oxides have critical roles as fuels in existing nuclear power plants, as well as in proposed reactor concepts. The thermal conductivity of these materials determines their ability to transfer heat from the reactor core to the surrounding coolant. Additionally, these actinide compounds are of interest in condensed matter physics because of the 5f orbitals and unique electron interaction, coupling, and scattering events that can occur. Because of the radioactivity of thorium and uranium, thin film measurements of actinide materials are used to limit the amount of operator exposure, but standard thermal characterization methods are not well suited for thin films. This paper presents the process of depositing thin film UOx and ThOx samples of nm-μm thicknesses and the results of thermal property measurements. Thin films were deposited on silicon and glass substrates via dc-magnetron sputtering using an argon/oxygen mixture as the working gas. The thermal properties of the films were measured by the Thermal Conductivity Microscope (TCM). This uses one laser to generate thermal waves and a second laser to measure the magnitude and phases of the thermal waves to obtain the conductivity of materials. The results of the research show that the UOx film properties are lower than bulk values and that the role of the substrate has a considerable effect on determining the measured properties. Future work aims at improving the deposition process. Epitaxial film growth is planned. Additional understanding of thermal property measurements is targeted.
Effect of Ion-Exchange Chemistry on the Fracture of Chemically Strengthened Sodium Aluminosilicate Glass
Authors: Egboiyi Benedict O. , Sain Trisha
Published: January 2020

The widespread use of sodium aluminosilicate glass in many critical applications due to its hardness, weight, density and optical properties (transparency, dielectric etc.), instead of metals or plastics has become common in recent years.

However, glass which is known to be a brittle material has its own vulnerability to fracture. Processes such as heat treatment (heat tempering) or chemical strengthening, through ion-exchange have been deployed to create residual stress profile on the glass, in a bid to improve its strength for applications such as in the automobile windshield design, consumer electronics mobile communication devices e.g. smartphones and tablet etc. However, failure still occurs which is mostly catastrophic and expensive to repair. Therefore, understanding, predicting and eventually improving the resistance to damage or fracture of chemically strengthened glass is significant to designing new glasses that would be tougher, while retaining their transparency. The relationship between the glass residual stress parameters, compressive stress (CS), depth of layer (DOL), center tension (CT) and fracture strength was investigated in this study using a grit particle blast plus ring on ring test method, based on IEC standard for retained biaxial flexural strength measurements. This technique can be used to measure both the surface and edge fracture strength of the glass. Preliminary results showed that for a reasonable level of CS, and CT, high DOL are beneficial to resisting fracture due to severe surface damage, while a high CS and low CT are beneficial to resisting fractures due to shallower flaws. The correlation of critical stress intensity factor versus DOL and CT for various level of CS were also determined and discussed. These results provide a valuable piece of information in the design of a more robust glass in engineering applications.
Innovative Product/Service for Personalized Health Management
Authors: Marques Maria , Lopes Fabio , Costa Ruben , Agostinho Carlos , Oliveira Pedro , Jardim-Goncalves Ricardo
Published: January 2020

Smart4Health project is a European project aiming to empower citizens with electronic health(care) record exchange, personal connected health services, and the ability of data donorship to the scientific community. The Smart4Health platform will enable citizens to manage, collect, store, access and share own health and healthcare data, at international level, through an easy-to-use, secure, constantly accessible and portable health data and services prototype within the EU and beyond. This shall also comprise self-quantified and citizen-generated data through IoT and wearables (e.g. smart watches, smart devices/textiles/shoes). Therefore, the citizen will not only be able to access data produced in the context of health systems, but become important contributor of health data more generally speaking. The information to be collected will feed the Smart4Health platform (4HealthPlatform – 4HP), enabling the Smart4Health user portal (4HealthNavigator – 4HN) services and applications to provide advanced personalised health services accessible whenever and wherever. In this paper we explore the work being developed for data integration coming from different smart devices aiming at enriching the citizen health and personal data as well as providing insight about citizen behaviour and support on how to modify/adapt postures and habits that may contribute for better health and wellbeing.
Impact Analysis of a Composite Armor System
Authors: Alam Shah , Saquib Mohammad Nazmus
Published: January 2020

Present day demands composite material with even lighter weight and higher strength for using in aerospace, automobile and defense industries. Due to posing significantly weight saving and higher stiffness attribute, use of sandwich composite structure is the demand of the time. Impact analysis of sandwich composite armor system is necessary to design and develop new armor for defense sectors.

The goal of this study is to design, model and analyze the dynamic response of the composite armor system in terms of residual velocity and energy absorption capacity.

The design parameters are investigated for different fiber reinforced polymers (High tensile strength Carbon/epoxy, Carbon Fiber/Carbon Nanotube reinforced polymers) as top and bottom skin, with an Aluminum Alloy 7039 corrugated core structure and square prismoid assembled Ceramic (SiC) core centerpieces at different velocities (50 m/s, 100 m/s, 200 m/s, 400 m/s).

This non-linear explicit dynamic study is performed using commercial software ABAQUS CAE 2017. Best combination for the composite armor system is suggested based on the results.
Development of a Cleaning Robot for Trench Drains
Authors: Kaushik Adithya , Dong Janet , Gao Ce , Elzarka Hazem
Published: January 2020

This paper discusses the design and conceptualization of a novel robotic mechanism to clean the trench drains. It describes a different approach for drain cleaning with lesser human intervention and more safety to personnel involved. The robot is designed and built to be 4 inches in width and operate entirely within the limited space inside the drain. To achieve a wholesome cleaning process, the entire robot is modular in design and consists of a drive system, a suction tube and a cutting arm assembly with metal brushes installed onto it. The bidirectional drive system enables the robot to move through drain segments repeatedly for optimal performance. The purpose of the cutting arm assembly is to aid the removal of dirt from the drain. In order to improve the robot performance, two prototypes were designed and built. The overall design and modularity of both robot prototypes will be discussed in detail in the paper.
Temperature Change of Spindle Using Non-Contact Controllable Excitation and Response Measurement
Authors: Su Wenjun , Wan Shaoke , Hong Jun
Published: January 2020

The main error source effecting the mechanical precision of the machine spindle is the structural thermal deformation under temperature variation. So, we focused on temperature variation investigate of spindle in experiment approach. A magnetic loading device has been used for the measurement, which have a more compact stator and shorter axis length. Meanwhile, the FEM 3D analysis of the compact magnetic loader has been presented. By using this contactless loader, the temperature variation when spindles are rotating under different loads have been monitored and recorded. Experiment results show that the radial load has increased the temperature of spindle, but the higher speed directly weakened this influence. Furthermore, this experiment approach is verified and proved to be suitable for spindle tests.
Experimental Study of Surrogate Particle Transport and Deposition in a Square Channel Using Particle Tracking Technique
Authors: Orea Daniel , Nguyen Thien , Vaghetto Rodolfo , Anand N. K. , Hassan Yassin A. , Sabharwall Piyush
Published: January 2020

This paper presents an experimental study of hydrodynamics flow characteristics and particle transport in a test facility. Experimental measurements of fluid flow and particle deposition are studied under isothermal conditions using particle image velocimetry (PIV) and particle tracking velocimetry (PTV) techniques. These non-intrusive optical measurement techniques have been applied in experiment conditions of Reynolds number Re = 5,077 in a 3-inch square channel and 72-inches in total length. The fluid within the channel is air seeded with aerosol droplets while the measurements of particle transport is facilitated using surrogate particles dispersed in the channel flow. Results obtained from the PIV and PTV measurements included the hydrodynamics fluid flow characteristics, and characteristics of particle transports, such as particle velocity, particle diameter distributions and particle concentration profiles. Results from the preliminary test have shown 11.08% deposition of particles. To supplement this experimental work, upstream fluid flow characteristics were provided as boundary conditions for a comparable numerical study.