bluuebunny/crossref_metadata_2025 huggingface dataset:
Control of a Head Stabilization System for Use in Robotic Disaster Response
Authors: Sebastian Bijo , Williams Adam , Ben-Tzvi Pinhas
Published: January 2018

This paper systematically describes the design and validation of a feasible control scheme for a robotic head stabilization system. Over the past few decades there has been a growing need for robotic systems to perform human rescue operations in the event of natural or manmade disasters. Before autonomous or remotely controlled robotic victim extraction can be realized, support systems with the capability to secure the head of a trauma victim in a manner that does not exacerbate existing spinal injuries needs to be developed. The paper starts with a brief description of one such previously developed robotic head stabilization system and examines the various functional requirements from a design and control standpoint. Detailed dynamic analysis of the system is done based on which a force control scheme involving Series Elastic Actuators (SEA) is proposed. The proposed control scheme is then tested on an ADAMS-MATLAB co-simulation where the dynamic head support system is modelled in ADAMS and the force controller in Simulink. Based on the results of the simulation, a physical prototype is integrated and the proposed control scheme is validated through experiments. The results of the simulation and experiment are analyzed, and improvements to the system are proposed for future experimentation. Based on the results of the simulation and experiments, the proposed control was found to successfully meet the desired control metrics in providing accurate force control for the head support device. The paper ends with a discussion on possible modifications to the overall system for it to be used in field robotic rescue.
Effect of the Spatial Inhomogeneity of Fracture Strength on Fracture Pattern for Quasi-Brittle Materials
Authors: Clarke Philip L. , Abedi Reza , Bahmani Bahador , Acton Katherine A. , Baxter Sarah C.
Published: January 2018

The response of quasi-brittle materials is greatly influenced by their microstructural architecture and variations. To model such statistical variability, Statistical Volume Elements (SVEs) are used to derive a scalar fracture strength for domains populated with microcracks. By employing the moving window approach the probability density function and covariance function of the scalar fracture strength field are obtained. The Karhunen-Loève method is used to generate realizations of fracture strength that are consistent with the SVE-derived statistics. The effect of homogenization scheme, through the size of SVE, on fracture pattern is studied by using an asynchronous spacetime discontinuous Galerkin (aSDG) finite element method, where cracks are exactly tracked by the method’s adaptive operations.
Computational-Experimental Investigation of Progressive Damage Using Johnson-Cook and Cohesive Zone Models in Fiberglass Composites
Authors: Tenorio Max C. , Pelegri Assimina A.
Published: January 2018

Fiber-matrix debonding is a common type of failure in composite materials. A computational model that illustrates this damage-induced separation between glass fiber and epoxy matrix in a fiberglass composite model is created from the ground-up. Material properties for the simulations are determined via in-house performed experiments. The tensile modulus of the epoxy matrix is determined to be 8.21 GPa measured using resin-only specimens according to ASTM D638-14. The glass fiber is a bundle of glass fibers extracted from a lattice-woven tape with the original purpose of fiberglass crack patching. These bundles contain approximately 1000 individual fibers per roving. A field-emissive scanning electron microscope study of the glass fiber reveals that the individual fiber diameters vary from 11.04μm to 13.52μm with an average of 11.97μm and a standard deviation of 0.604μm. Tensile tests are performed to the glass fiber bundles using custom grips designed in accordance to ASTM D7269. From these tests, it is found that the fiber Young’s Modulus ranged from 42 GPa to 61.7 GPa. Furthermore, in order to simulate a physical analogue to our computational simulations cylindrical composite specimens of a single bundle of fibers running through the central axis of the cylinder with 6.35mm diameter and 100mm length were prepared and tested. It is found that all of the test specimens exhibit some amount of debonding post-failure. The computational simulation is created in ABAQUS 6.14 to replicate the effects of the experimental composite and elucidate the debonding behavior on smaller time scales. The lower outer face is given a static pinned boundary condition while the upper outer face is given a displacement boundary condition to simulate the fixed lower grips and moving upper grips during the tensile test. The material properties obtained by the experimental tests are applied to the materials in the simulation. Two separate damage models are used in order to simulate breakage; the fiber and matrix utilize the Johnson-Cook failure model as plastic strain-to-failure and the fiber-matrix interface is governed by cohesive-zone elements. The computational model exhibits realistic stress distribution as well as calculates element deletion to simulate interfacial debonding. The simulations are able to show the matrix cracking at the notch and subsequently a separation between the fiber-matrix interface similar to the physical composite analogue.
Experimental Investigation of Peripheral Milling of Functionally Gradient Al-SiC Metal Matrix Composite
Authors: Anandan Nishita , Ramulu Mamidala
Published: January 2018

Metal matrix composites (MMCs) offer superior mechanical and thermal properties, but the poor machinability of these composites hinders their wide application [1,2]. The machinability of the MMCs are found to be largely dependent on the particle size and volume fraction of the reinforcements used. Experimental investigation on process modeling of MMCs by milling is undertaken. In this study, peripheral milling of functionally gradient concentration of SiC in aluminum matrix using carbide tools is discussed. The process conditions were varied namely, the feed was varied from 0.1 mm/rev to 0.3 mm/rev and the speed from 1000 to 5000 rpm with a constant depth of cut of 1.27mm. The variation of cutting force, surface roughness and cut surface morphology with varying SiC particle distribution, feed and speed are reported. The interaction of the cutting edge with hard SiC particles in Al matrix was also studied using the scanning electron microscopy (SEM). The cutting force and surface roughness were found to increase with increasing volume fraction of SiC particles. Preliminary observation showed that the SiC particles were either removed from the matrix by debonding due to mismatch of thermal coefficients or were fractured by the action of the cutting edge or were pushed into the aluminum matrix.
Facilitating Fluid Flow Through Carbon Nanotube Arrays Using 3D Printing
Authors: Emery Travis S. , Jensen Anna , Kubrin Koby , Schrlau Michael G.
Published: January 2018

Three-dimensional (3D) printing is a novel technology whose versatility allows it to be implemented in a multitude of applications. Common fabrication techniques implemented to create microfluidic devices, such as photolithography, wet etching, etc., can often times be time consuming, costly, and make it difficult to integrate external components. 3D printing provides a quick and low-cost technique that can be used to fabricate microfluidic devices in a range of intricate geometries. External components, such as nanoporous membranes, can additionally be easily integrated with minimal impact to the component. Here in, low-cost 3D printing has been implemented to create a microfluidic device to enhance understanding of flow through carbon nanotube (CNT) arrays manufactured for gene transfection applications. CNTs are an essential component of nanofluidic research due to their unique mechanical and physical properties. CNT arrays allow for parallel processing however, they are difficult to construct and highly prone to fracture. As a means of aiding in the nanotube arrays’ resilience to fracture and facilitating its integration into fluidic systems, a 3D printed microfluidic device has been constructed around these arrays. Doing so greatly enhances the robustness of the system and additionally allows for the nanotube array to be implemented for a variety of purposes. To broaden their range of application, the devices were designed to allow for multiple isolated inlet flows to the arrays. Utilizing this multiple inlet design permits distinct fluids to enter the array disjointedly. These 3D printed devices were in turn implemented to visualize flow through nanotube arrays. The focus of this report though, is on the design and fabrication of the 3D printed devices. SEM imaging of the completed device shows that the nanotube array remains intact after the printing process and the nanotubes, even those within close proximity to the printing material, remain unobstructed. Printing on top of the nanotube arrays displayed effective adhesion to the surface thus preventing leakage at these interfaces.
Damage Initiation and Evolution of Panicum Miliaceum Seeds Under Compression
Authors: Hasseldine Benjamin P. J. , Gao Chao , Li Yaning
Published: January 2018

Panicum Miliaceum (common millet) is an ancient crop and spread widely across the world. The high survivability and adaptability of this species is attributed to the unique structure of the seedcoat. Recently, it was found the seedcoat has a fascinating complex microstructure with star-shaped epidermis cells, articulated together via wavy suture interfaces, to form a compact jigsaw puzzle-like layer. To explore the damage initiation and evolution during quasi-static uniaxial compression, finite element simulations were performed for full seeds, and single seedcoat and kernels. A parametric study was conducted for the seedcoat and kernel to explore the relationship between material properties and damage. The material properties of the seedcoat and kernel were obtained by nanoindentation testing. A Hashin progressive damage material model was used to capture damage evolution of the seedcoat, combined with a damage plasticity model for the kernel. The simulation results show the capabilities in modeling the damage of seeds.
Data and Knowledge in IIoT-Based Maintenance Application
Authors: Bergonzi Luca , Colombo Giorgio , Rossoni Marco , Furini Francesco
Published: January 2018

Along with increased digitalization, virtualization of processes and automation in industry, Industrial Internet of Things opens for new possible scenarios and business models. The opportunities of this technology rely, among the others, on new way for data and knowledge management. Knowledge Based Engineering (KBE) is greatly considered to support design activities related to digital technologies. The paper aims at analyzing the role of Industrial Internet of Things for supporting maintenance operations and evaluating whether the adoption of data structure and the integration with the KBE system can face the actual gaps and needs. After a brief overview of different technologies for knowledge management, a possible scenario has been identified. It represents the framework within IIoT technologies can be applied. This conceptual environment considers a multilevel structure: local facilities, the whole company, suppliers, retailers and global network have been involved into the analysis. Upon that scenario, how data and knowledge can be mapped and managed for each level have been investigated. Moreover, these data can be used to improve the predictive maintenance model as well as to enhance the design of new products through the acquisition and monitoring of an effective set of parameters. Finally, in order to demonstrate the feasibility of the proposed approach with the use of simulation as well as physical devices, a prototypical application related to the maintenance of refrigerated display cabinets has been developed.
Steady-State Pressure Drop for Two-Phase Flow in Pipelines: An Integrated Genetic Algorithm-Artificial Neural Network Approach
Authors: Chaari Majdi , Ben Hmida Jalel , Seibi Abdennour C. , Fekih Afef
Published: January 2018

This paper develops an artificial neural network (ANN) model for steady-state two-phase flow pressure drop estimation in pipelines. Mechanistic models are traditionally considered in pipeline flow modeling. However, their reliance on fundamental laws of physics can negatively impact their accuracy when dealing with large experimental data sets and various pipeline inclinations. Hence, ANN models prove to be highly accurate compared to mechanistic models. Dimensional analysis is used to derive a broad reservoir of dimensionless groups and form candidate inputs to the ANN model. Identifying the groups leading to the best correlation of the output variable requires a laborious and nonsystematic trial-and-error procedure. To circumvent this problem, genetic algorithms (GA) were considered to identify the best ANN input combination, thereby allowing a good prediction of steady-state two-phase flow pressure drop in pipelines with all inclinations. The sensitivity of the model accuracy to some GA parameters such as the population size and the parent selection scheme was investigated. The proof of concept of the proposed approach was illustrated using the Stanford multiphase flow database. Based on the obtained results, the proposed model was shown to outperform existing mechanistic models when cross-examined using the same database. In addition, the proposed model allowed good prediction accuracy for all pipe inclinations and all flow patterns.
Design, Implementation, and Evaluation of Thermal Performance of a Thermosiphon Flat-Plate Solar Collector for Water Heating in Ecuadorian Coastal Region
Authors: Sánchez Carola , Macías José , León Jonathan , Zamora Geancarlos , Soriano Guillermo
Published: January 2018

Passive solar water heating (SWH) is a convenient method to meet domestic hot water requirements in rural areas, where electricity may not be available or fuel supply might be limited due to difficult access. In this work, a low-cost thermosiphon flat-plate solar collector alternative is presented. The design was purposely limited to materials and recyclable products widely available in the local market, such as Tetra Pak, plastic bottles, and polypropylene (PP) fittings and pipes. Since PP is a thermoplastic polymer, a poor heat conductor, it was necessary to ensure a suitable system isolation to obtain an optimum thermal performance, comparable to commercial solar collectors. The design was built and tested in Guayaquil, Ecuadorian coastal city. Six inexpensive temperature sensors were placed at the entrance and exit of the collector, on the flat-plate and inside the hot water storage tank. Data was recorded using an Arduino single-board computer and later analyzed with the data gathered via weather station. The implementation costs of the system are approximately US$300, the overall performance during January 2017 fluctuated between 54% and 23%, and the storage tank temperature range varied from to 46°C to 33°C. Due to its reliability and affordable cost, the SWH system is an attractive alternative to an Ecuadorian commercial solar flat plate collector, which price is set between US$600 and US$700, it has an efficiency around 60%, and the average annual storage tank temperature is 62°C.
Demonstration of a Solid-State Inflation Balloon Deorbiter
Authors: Roddy Morgan , Hodges Haden , Roe Larry , Huang Po-Hao Adam
Published: January 2018

This paper updates on the recent development of the novel Solid State Inflation Balloon (SSIB), a simple, reliable, low-cost, non-propulsive deorbit mechanism for the full range of small satellites, defined by NASA as less than 180 kg. It aims to focus on the recent demonstration, for the first time, inflation of a ∼10 cm sized balloon in a vacuum chamber. Small satellites typically rely on aerodynamic drag to deorbit within the FAA’s 25 year requirements. The SSIB will enhance aerodynamic drag by inflating a balloon at the end-of-life of a satellite mission. This technology will provide a scalable and non-existing capability, low-cost deorbit, for applications in the full-range of smallsats, from CubeSats to MicroSats. The SSIB system is composed of three major components: a Micro-Electro-Mechanical Systems (MEMS) Solid-State Gas Generator (SSGG) chip, a balloon structure made of thin film compatible with space environment (i.e. Mylar, Kapton, or Teflon), and a sub-system package suitable for spacecraft integration. The SSGG is composed of a 2D addressable array of sodium azide (NaN3) crystals, confined by Su-8 wells, on a glass substrate. Current versions include 2×2 and 8×8 arrays designed for a full range of small satellites. Under each well is a resistive heater and when heated to above 350 °C, the NaN3 spontaneously decomposes to generate N2 gas in time scales on the order of 10 milliseconds. Each well is designed with a typical volume of 10–15 m3 to 10−6 m3 of NaN3 (i.e. 1,500 μm × 1,500 μm × 150 μm on the larger end of the spectrum). The SSIB system is low power (∼1 W per well for less than 10 seconds) and have low mass (∼100 grams, where mass is dominated by the size of the required balloon). Initial simulations have shown that the SSIB with balloons of 1 m2 cross-section can deorbit small satellites from above 1000 km well within 25 years.
Design, Implementation, and Incorporation of a Control System Platform in an Undergraduate-Level Control Systems Course
Authors: Hassanpour Pezhman A.
Published: January 2018

This paper presents the design, implementation, and incorporation of an educational control system platform in an introductory course on control systems, with the goal of relating abstract concepts involved in this course to a real-world engineering system. This study builds upon the previously published attempt by the author involving design of a general control system platform for position-controlling of a shaft. In the present work, the need for incorporating a hardware-based hands-on project for teaching control systems is discussed first. Then, the contents of the undergraduate senior-level course MECH 412-Control Systems and the way the course is organized around a master example are explained. In addition, this paper elaborates on the challenges involved with introducing the concept of microprocessors to the mechanical engineering students taking MECH 412. The term project, which is founded on the master example in question, is discussed in details with emphasis on the objectives and learning outcomes, and evaluation. In the results section, the outcomes of the implementation of the proposed platform during the Fall 2016 semester are presented. These outcomes include the various types of controllers students selected to design, the observations they made for each type of controller, samples of submitted codes, and evaluation of the students’ learning outcomes. The evaluation includes the statistical analysis of pre- and post-test questionnaire completed by the students at the beginning and end of the semester, respectively. The reason why a control group could not be secured is explained in detail. The statistical analysis shows a significant improvement in the mechanical engineering students’ degree of the confidence in using tools that are traditionally perceived to be for electrical engineers.
A Mixed Reality Based Hybrid Swarm Control Architecture for Manned-Unmanned Teaming (MUM-T)
Authors: Das Aditya N. , Doelling Kris , Lundberg Cody , Sevil Hakki Erhan , Lewis Frank
Published: January 2018

Recent advancements in robotics have established standard control and planning algorithms for robot localization, navigation, and manipulation, which extend the automation from skill-based to rule-based. Such automation approaches, however, are susceptible to environmental dynamics and the burden of corresponding event handling falls on the human operator. In multi-agent systems, any deviation from the otherwise inefficient one operator to one robot mapping can result in an exponential growth of system complexity, and, in the absence of some form of artificial intelligence supervisory control, the overall framework can quickly become unmanageable, counterproductive, and even hazardous. Therefore, for future manned-unmanned teaming, a knowledge-based cooperative control architecture is warranted that can process cognitive reasoning at the meta-level to autonomously carry out some or all tactical parts of the mission while maintaining constant connection with the human operator. Furthermore, in such a scenario, the human operator needs to be able to communicate with multiple robotic agents via natural language and gesture interface so that he/she can efficiently manage not just one robot but the entire swarm or at least a segment. This paper will discuss a hybrid swarm autonomy architecture to coordinate a diverse team of robots using an immersive and intuitive interface technology for cooperative control of unmanned platforms. This novel interactive interface will offer situational awareness and decision presentation capabilities. Implemented through a real time, networked, mixed reality environment, it will be designed to support rapid exploration and evaluation with the swarm as well as dynamic interaction among different human operators. One of the major objectives of this research is to reduce cognitive load on operators and enable trust among robots and humans. This paper will discuss the approach to design and evaluate a distributed trust control algorithm for high-throughput hybrid swarm autonomy, and implement it through a curated, controlled-access portal to integrate swarm algorithms and collective behavior. Major discussion points will include: customization of unmanned platforms for distributed control and sensor fusion, development and implementation of a mixed reality human robot interface portal, and incorporation of a neuro-cognitive dynamic trust controller for swarm autonomy. It is envisioned that through such interconnection between humans and robots the effectiveness of the swarm can be boosted to carry out the missions with unprecedented speed and accuracy at a fraction of the cost for complex systems. This paper presents experimental validation to the analytical models involving real and virtual platforms.
Numerical Analysis and Simulation (FEM) of a Double Deep Drawing Sink Height
Authors: García Zugasti Pedro de Jesús , Medellín Castillo Hugo Iván , Limon Leyva Pablo Alberto , Govea Valladares Eder Hazael , Hernández Rivera José Luis
Published: January 2018

This paper presents the results of a research project obtained using theoretical, numerical and experimental methods, in order to solve the problems encountered when increasing the height of a double deep drawing sink, and the proposed solution. The analysis considers: Manufacturer limitations (eg. tool modifications, steel material changes etc.), the process parameters observed and measured during the deep drawing operation of the failure part, the theoretical fundamentals of sheet metal forming and the analysis and simulation with a computer program based in the finite element method (FEM). The analysis and simulation results using a FEM program showed that, it is possible the height increment of the sink, utilizing a variable blankholder force, to an 11% above from the fabricated parts before the application of the proposed solution but 5% less than the required final product height.
Lecturers’ Perceptions of a Semester-Wide Interdisciplinary PBL in a Master’s Degree Program in Industrial Engineering and Management
Authors: Moreira Francisco , Rodrigues Cristina , Alves Anabela C. , Malheiro M. Teresa , Brito Irene , Carvalho M. Alice
Published: January 2018

The present study, conducted at the end of a PBL edition at the University of Minho, reports on the results of a questionnaire issued to the lecturers of the Project Supporting Courses of a semester-wide interdisciplinary PBL approach. The questionnaire was intended to gather the perceptions on a number of relevant aspects, such as on the validity and acceptance of the PBL methodology, dynamics of team-based learning and its impact on development of transversal competences, the assessment methodology in place, the learning process and development of technical competences, the impact of choosing a project theme and leave it open, and, additionally, to acquire other relevant perspectives on the running of the project. This study aims to close the loop regarding a continuous and ongoing improvement process of the PBL approach. The results show that the lecturers acknowledge PBL as a valid learning methodology on the IEM field; that the chosen theme was contemporary and stimulating; provided an excelling experience on the development of communication competences, among others. They also point out the excessive size of the teams and call the attention to the specialization problem inside the teams. The assessment mechanism in place seems to require further attention.
Electrokinetic Driven Micro-Mixing of Fluids in a Circular Electrode Pattern
Authors: Guduru Rakesh , Islam Nazmul
Published: January 2018

Manipulation of fluids in a small volume is often a challenge in the field of Microfluidics. While many research groups have addressed this issue with robust methodologies, manipulation of fluids remains a scope of study due to the ever-changing technology (Processing Tools) and increase in the demand for “Lab-On-a-Chip” devices. This research peruses the flow pattern and fluid mixing behavior in a metallic circular electrode, charged with AC voltage.

In this study, micromixing in a circular electrode pattern device is demonstrated with numerical and experimental values. Experiments were performed using two buffer solutions with conductivities 1.62 S/m and 0.0732 S/m. The efficiency of mixing was found to be three to five times faster than the normal diffusion process. It was found that the increase in the conductivity of fluid increases the efficiency of mixing in the proposed device.
Thermal Modeling of 304L Stainless Steel for Selective Laser Melting: Laser Power Input Evaluation
Authors: de Moraes Diego Augusto , Czekanski Aleksander
Published: January 2018

Selective Laser Melting (SLM) process is a Powder Bed Fusion (PBF) technique, which has shown significantly growth in the recent years. The demand for this process is justified by the versatility and ease in manufacturing the parts from 3D models as well for the increased complexity of engineered parts generated from topology or shape optimization. Automotive, aerospace, medical and aviation industries are taking great advantage of this process due the unique geometry characteristics found in the components. To enhance the benefits of SLM, a vital task is to analyze the laser power input impact on the temperature distribution through the powder bed, important for posterior residual stresses analysis. The Finite Element Method proposed in this study is a transient thermal model, able to predict temperature distribution through different sections of the powder bed when performing a single track of the laser scanning. Furthermore, the impact of the laser power input is carried out utilizing SS 304L, a low cost Stainless Steel alloy that can be employed in the SLM process, in order to determine the influence on the temperature distribution along the different cross sections.
Characterization of Black Powder Found in Sales Gas Pipelines
Authors: Khan Tariq S. , Alshehhi Mohamed S. , Khezzar Lyes
Published: January 2018

Black powder (BP) is a typical contaminant usually found in sales gas pipelines. Its presence may cause major operational and maintenance issues including blockage of sensors and filters, erosion of pipeline bends and compromise the sales gas quality. There has been little known about its composition and sources of formation in the gas pipelines. Understanding its characteristics is considered crucial for appropriate mitigation planning and execution of smooth pipelines operations. Black powder samples collected from sales gas pipelines network of a Middle Eastern gas company are analyzed using scanning electron microscopy with energy dispersive x-ray spectroscopy (SEM-EDX) and x-ray diffraction (XRD) methods for surface analysis and phase identification of the crystalline material. These analyses revealed variation in size distribution and shape of the BP samples. Likewise, most of the BP particles were found agglomerated. EDX analysis of the sample has shown presence of iron as the most abundant element after sulfur. XRD patterns can be indexed with both iron oxides and sulfides suggesting presence of moisture and hydrogen sulfide in the gas.
Direct Measurement of the Particle-Induced Flow Structure in a Confined Microchannel
Authors: Zhang Runlin , Pan Zhenhai , Wu Huiying
Published: January 2018

Understanding the transport details around a microparticle in confined microchannel geometry is of importance in many microfluidics-based applications such as cell/ particle manipulation and separation. Despite of numerous studies contributed in the past decade, the micro flow structure induced by the moving particle is still not quantitatively measured in experiments. In this paper, we demonstrate direct measurement of the fluid flow around a single particle traveling in a confined microchannel based on the micro particle image velocimetry technique (μPIV). In the experiments, the straight polydimethylsiloxane (PDMS) microchannel was fabricated by the standard soft-lithography technique with 100 μm height, 60 μm width and 60 mm length. The polystyrene microparticles with 20 μm diameter were employed to travel in the microchannel and induce micro flows, while smaller fluorescent particles with 1μm diameter were used as seeding particles to indicate the local velocity. After being injected in the microchnnel with water, the microparticle with 20 μm diameter quickly reached its hydrodynamic equilibrium positions, which located on the horizontal symmetry plane of the microchannel, and got captured by the μPIV system together with seeding particles. By analyzing the motion of seeding particles, the time-averaged local flow vectors, velocity fields, vortex structures and fluid streamlines were quantitatively measured under different Reynolds numbers. The proposed experimental setup can serve as a basic platform to investigate the transport phenomenon of microparticles traveling in confined flow. The quantitatively measured flow structure can also be used for model validation by other researchers.
Study of Micro Ultrasonic Machining of CFRP/Ti Stacks
Authors: Sonate Abhishek , Vepuri Dheeraj , James Sagil
Published: January 2018

Carbon fiber reinforced plastic (CFRP) composite is one of the most sought after material owing to its superior physical and mechanical properties such as high-durability and high strength-to-weight ratio. CFRP composites are often used by stacking up with titanium (Ti) to form multi-layered material stacks for applications involving extreme mechanical loads. However, machining of CFRP/Ti multi-stacks is quite complex and challenging task since both materials are difficult-to-machine materials and show completely different machinability properties. The challenge is further escalated when there is a need to machine CFRP/Ti stacks at micron level. Several problems arise during the machining process due to the non-homogeneous structure, anisotropic and abrasive properties of composite. Traditional methods of micromachining the CFRP/Ti stacks results in several issues including high cutting force and torque and high tool wear, composite delamination, large groove depth in composite, and poor surface quality. Ultrasonic machining (USM) process has been successfully used to machine titanium, CFRP and CFRP/Ti stack at macro scale. Micro Ultrasonic machining is a downsized version of macro ultrasonic machining process that is developed to machine hard and brittle materials. This research explores the possibility of using Micro USM process to conduct micromachining of CFRP/Ti multi stacks. The effect of various process parameters including abrasive grit size, tool material and type on the material removal process is studied. The study found that micro ultrasonic machining process is capable of successfully micromachining CFRP/Ti stacks with zero CFRP delamination, minimal variation in CFRP and Ti hole sizes and longer tool life. Further, a three-dimensional finite element simulation study is performed on micro ultrasonic machining of CFRP/Ti stacks. The simulation results revealed that the workpiece is not subject to any significant normal stresses during the machining process, while variations in shear stresses is seen on the inside surfaces of the machined cavities.
Hybrid Nanocomposite Membrane for Wearable Bioelectronics
Authors: Fomo Fondjo Fabrice , Kim Jong-Hoon
Published: January 2018

There are strong needs for flexible and stretchable devices for the seamless integration with soft and curvilinear human skin or irregular textured cloths. However, the mechanical mismatch between the conventional rigid electronics and the soft human body results in many issues including contact breakage, or skin irritation. Due to the mechanical and electrical versatility of nanoscale forms, various nanomaterials have rapidly established themselves as promising electronic materials, replacing rigid wafer-based electronics in next-generation wearable devices. Here, we introduce a flexible, wearable bioelectronic system using an elastomeric hybrid nanocomposite, composed of zero-dimensional Carbon Black (CB) and one-dimensional Carbon Nanotubes (CNTs) and silver nanowires (AgNWs) in a polydimethylsiloxane (PDMS) matrix. Those materials were chosen due to their good electrical properties and their different length scale providing a continuous connection in the flexible PDMS matrix. To achieve a homogeneous dispersion, these nanomaterials were mechanically mixed in PDMS under shear flow using an overhead mixer. A hybrid nanocomposite membrane with dimensions of 15 mm diameter was then prepared by replica molding process. The electrical properties of the nanocomposite were measured over 5, 10 and 15hrs mixing time to investigate the point of electrical stability of the electrode and the electrical performance during EMG signal measurement. This soft nanocomposite, laminated on the skin, enables highly sensitive recording of electromyograms.
The Plant Kingdom in Engineering Design: Learning to Design From Trees
Authors: Jawaharlal Mariappan , Vargas Gustavo , Gutierrez Lorenzo
Published: January 2018

A tree may be the earliest multifunctional structure, and wood is the oldest known engineering material. Yet, trees have no place in engineering education. If we view a tree from merely a mechanical or civil engineering perspective, engineering mechanics can be learned from the tree’s example.

Trees have survived by adapting to the most difficult circumstances: heavy winds, rains, floods, droughts, earthquakes, mammal damage, human intervention, etc. The root system must be strong and flexible enough to support the tree’s entire structure from varying load conditions and to provide food storage and nutrient transfer. The stem system provides structural support for the tree’s above-the-ground parts and transfers water and nutrients from the roots through the network of thick-walled cells to other parts of the tree. Leaves produce food and form the surface area surrounding the tree. Leaves come in a variety of shapes and sizes. The tree’s crown, comprising branches, leaves, and reproductive elements, help the tree to catch more sunlight. It moves upward and outward to expose more of its leaves to direct sunlight for photosynthesis while maintaining physical balance on the earth.

A tree’s lifecycle can span hundreds of years, despite its vulnerability to constantly changing loads throughout the day and throughout its life. In monsoon and windy seasons, trees endure extremely difficult fatigue-loading. Various parts of the tree and its stem are subjected to combined loading conditions: tension, compression, shear, bending, and torsion. Trees develop and adapt stress management strategies by adjusting their shapes to the type or level of stress they endure: they add more mass where more strength is needed, allows material to easily break off (or physiologically inactive) from locations where it is not necessary, design optimum shapes, and create variable notch radii for reducing stress concentration. But a tree is much more than a structural member. It provides food and shelter for wildlife. It absorbs atmospheric carbon dioxide and produces oxygen. It lowers air temperature and facilitates the water cycle.

Structural analysis of a tree can benefit engineering students and practicing engineers alike. Furthermore, a deeper understanding of trees can help us to create multifunctional designs that are in a symbiotic relationship with other members in the system. In short, studying tree mechanics can help us to become better engineers.

This paper presents our efforts to integrate trees into engineering curricula to teach mechanics ranging from equilibrium study to stress analysis. Students of statics, dynamics, the strength of materials, stress analysis, material science, design, etc., can benefit from learning about trees. This approach enables students to understand the complexities of real-world living systems, appreciate the genius of nature’s design, and develop methods for creating sustainable designs.
Rheometric Studies of New Class Ionic Liquid Nanolubricants
Authors: Bakhtiyarov Sayavur I. , Siginer Dennis A.
Published: January 2018

The traditional lubricating materials used in space, such as mineral oils, polyol ester, PFPE, Pennzane, etc. have limited lifetimes in vacuum due to the catalytic degradation on metal surfaces, high vaporization at high temperatures, dewetting, and other disadvantages. The lubricants for the space applications must have vacuum stability (i.e. low vapor pressure), high viscosity index (wide liquid range), low creep tendency, good elastohydrodynamic and boundary lubrication properties, radiation atomic oxygen resistance, optical or infrared transparency. Thermophysical and chemical analyses are another important required set of tests for the newly developed space lubricants. Some of these properties for liquid lubricants are base oil and additive volatility, creep, surface tension, viscosity, chemical composition, weight loss, density, vapor pressure, etc. Unfortunately, the properties such as non-linearity in the rheological behavior of the lubricants were not studied well for newly developed systems. The rheological properties are crucial to analyzing thermodynamic and energy dissipative aspects of the lubrication process. The rheological measurements for the newly developed ionic liquid nanolubricant were conducted using rotational rheometer AES G-2 of “parallel-plates” mode.
Effect of Artificial Aging on Mechanical Properties and Corrosion Behaviour of A356 Alloy
Authors: Velukkudi Santhanam Senthil Kumar , Manickam Dhanashekar
Published: January 2018

Aluminium alloys used in automobile applications are generally heat treated to obtain a desired combination of strength and ductility. The knowledge in treatment temperature as well as the time of this process is essential for optimum results. In this paper A356 alloy is subjected to different heat treatment conditions and examined its effects on the mechanical properties and corrosion behaviour. The solutionizing temperature and time were 540°C and 1 hour respectively, followed by 24 hours of natural aging and the artificial aging temperature and time were 180°C and 0.5, 1, 1.5, 2, 2.5, 3, 3.5, 4, 4.5, 5, 5.5, 6 hours respectively. The standard T6 heat treatment process performed were used as reference in-order to compare the effect of artificial ageing. The solutionizing temperature for 1 hour and artificial ageing time of 4.5 hours produced peak compressive strength when compared to other aging times.
A Detailed Methodology for FEM Analysis of Long Bones From CT Using Mimics
Authors: Yassine Reem A. , Elham Mohammad Karim , Mustapha Samir , Hamade Ramsey F.
Published: January 2018

A detailed and experimentally verified methodology is outlined on how to properly process a long tibia bone starting from computed tomography (CT) scans to finite element modeling (FEM). For pre-processing of the bone, CT scan in the form of Digital Imaging and Communications in Medicine (DICOM) files are segmented using Mimics. Next comes assigning gray value Hounsfield Units (HU) of the bone constituents into their cortical and cancellous regions. To have the FEM model arrives at the same mass of that measured experimentally, it was found that cut-off density, cut-off HU, and the utilized number of sub-materials must be considered as varying parameters. The values of these parameters had to be adjusted to properly demarcate cancellous regions from those of the cortical resulting in heterogeneous medium. Next, prior to generating the FEM mesh from the generated 3D model, volume and surface meshes had to be produced. In order to validate the methodology, the modal frequencies of a long tibia bone were experimentally measured. The FEM values of the properly processed CT scans compared favorably with those found experimentally.
In Vitro Biocompatibility Study on Stainless Steel 316L After Nano Finishing
Authors: Sundararaj Kathiresan , Bangaru Mohan
Published: January 2018

In this present study, the nano finishing of stainless steel 316L (SS316L) was obtained by means of magneto rheological abrasive flow finishing (MRAFF) process by varying the amount of current to the electromagnet. The MRAFF process is an advanced machining process in which the metal removal process is effectively controlled by means of the rheological property of the magneto rheological abrasive (MRA) fluid. After the finishing process, the surface roughness profiles and parameter were obtained with the help of Talysurf coherence correlation interferometer (CCI). Stainless steel 316L sample surfaces obtained by means of MRAFF process with different nano roughness values are utilized to study its biocompatibility by an in vitro study to examine the cell viability, proliferation of a fibroblast cell line (NIH-3T3) by means of MTT assay. The optical density (OD) values were utilized to determine the amount of viable cells. The cell proliferations studies were conducted and observed for 1, 3 and 7 days of incubation period with respect to the absorbance value of the samples. The protein adsorption studies are also made by using bicinchoninic acid assay (BCA) kit. The characters of biocompatibility are correlated with the nano scale surface roughness parameters of the SS316L samples.
Production-Like Robotics and Automation Laboratory Resources for a Manufacturing Engineering Program
Authors: Cox Daniel J.
Published: January 2018

Instructional resources pose significant challenges when attempting to meet the goal of hands-on experiences in a manufacturing engineering curriculum with realistic plant floor production-like operations. The strategy to accomplish the goal of providing a production-like flexible manufacturing system laboratory resource associated with the courses in a manufacturing engineering curriculum is described in this paper. A hands-on approach to instruction using state-of-the art manufacturing equipment is accomplished with physical resources that can be used in a variety of laboratory sections that augment courses in manufacturing engineering. Many experiments and laboratory exercises in practical aspects of manufacturing can make use of common sets of state-of-the-art, industrial-grade, manufacturing equipment. The equipment for a flexible manufacturing system includes a material handling system integrated with industrial robotics and automation equipment. These hardware resources must also be compatible and integrated with software and computing resources including computer-aided design tools, programmable logic controllers, automation software, manufacturing execution systems software, and additional software resources.
Multi-Axial Fatigue of Sheet Metal Joints Under Clamp Load and Cyclic Bending
Authors: Piccatto Andrea , Belingardi Giovanni , Wu Zhijun , Nassar Sayed A.
Published: January 2018

A validated Von-Mises stress-based model is presented for multi-axial fatigue evaluation of clamped sheet metal joints that are subjected to a cyclic bending stress additional to the compressive bearing stress in the bolted joint. Joint material, bolt preload level, and the amplitude level of the cyclic bending moment are studied for their effect on the fatigue life of the clamped sheet metal plate. Bolt tightening to a precise preload level is accomplished by using an ultrasonic instrument that has been mechanically pre-calibrated to convert the time delay of longitudinal ultrasonic wave reflection to a bolt elongation and corresponding preload value. Fatigue data is generated using an MTS fatigue testing system. Experimental and FEA results are fitted into a multi-axial model for predicting the fatigue behavior of the bolted joint. Discussion and data analysis are provided.
Technology and parameters of thin membrane-anode for MEMS transmission electron microscope
Authors: Krysztof Michał , Grzebyk Tomasz , Szyszka Piotr , Laszczyk Karolina , Górecka Drzazga Anna , Dziuban Jan
Published: January 2018

A concept of a miniaturized microelectromechanical system based transmission electron microscope is presented. This device consists of two parts: part 1—electron optics column with a high vacuum micropump and part 2—sample chamber with a detector. These two parts are separated with a common electrode, called the anode. The anode consists of a very thin membrane (membrane-anode) that encloses the electron optics microsystem. It is used to let the electron beam pass to the sample and it must endure the pressure difference between its both parts. In this paper, the authors describe the fabrication process of the membrane-anode. It is made of Si3N4 layer deposited on an oxidized silicon substrate and is fabricated in five steps: photolithography, plasma etching, wet anisotropic etching, oxide stripping, and removing the Si3N4 and SiO2 layers. The membranes were characterized, and their preliminary performance parameters are presented, i.e., the endurance and the electron transmission.
Plasmacytoid dendritic cells promote systemic sclerosis with a key role for TLR8
Authors: Ah Kioon Marie Dominique , Tripodo Claudio , Fernandez David , Kirou Kyriakos A. , Spiera Robert F. , Crow Mary K. , Gordon Jessica K. , Barrat Franck J.
Published: January 2018

The production of CXCL4 and IFN-α by plasmacytoid DCs in response to TLR8 signaling contributes to skin fibrosis and systemic sclerosis.