bluuebunny/crossref_metadata_2025 huggingface dataset:
Study on Vibration Characteristics of Tires Related to Tire-Road Noise of Automobiles
Authors: Kawakami Akihiro , Saito Takashi
Published: January 2018

The occupants on board are being exposed to an environment in noise and vibration. Among them, the tire-road noise has come to relatively conspicuous because of improvement of silence. To improve comfort for occupants, reduction about the environmental noise and vibration is strongly expected. In this paper, we aim at knowing the vibration characteristics of tires related to tire-road noise of automobiles. Taking two kinds of tires, we carried out the impact tests. One has standard specification and the other has comfort specification absorbing vibration. Setting non-contact and contact to the ground, accelerances are obtained for single fixed input and multi output by impacting tests about tire treads and side-walls. To identify natural angular frequencies, modal damping ratios and modal amplitudes, the real and imaginary parts of accelerance are used in the error function of the optimized problem, which is solved by the down-hill simplex method. Both the natural angular frequencies and modes are identical for two kinds of tires each other. However, it is found that the modal damping ratio of the tire considered to be superior is not much different from the other. It is also found that when the tires contact with the ground, some natural frequencies could increase and other could decrease. Concerning about mode shapes, some axial mode shapes of tread might contradict with those of side-wall.
Transportation Work of Gel Object Done by a Paramecium in the Vertical Plane Pool
Authors: Hayasaka Nozomi , Kikuchi Takumi , Itoh Akitoshi
Published: January 2018

We have been investigating how to use microorganisms for bio-micromachines. In this paper, we investigated the motion control property of Paramecium in the vertical plane to prepare the real 3-dimensional motion control. First, we developed a motion control pool for the vertical set up. Basically, the controllability of Paramecium in the vertical plane is not so different to the controllability in the horizontal plane. We can control paramecium very stably for over 100 laps along the star-shaped target route by using this newly made experimental pool. The controllability was improved with the progression of making a circuit. It may relate to the dropping of the swimming speed. The swimming trace, however, showed the peculiarity that related to the vertical movements. The swimming speed of the downward direction is higher than that of the upward direction. The overrun on the downward route was larger than that on the upward route in the vertical plane. It was caused by the difference of the swimming speed on each of routes. Therefore, we developed a new motion control algorithm to decrease this overrun. In our former algorithm, the change timing of the target point was decided by the previous change timing and the previous turning point. In the new algorithm, we change this adjusting method to refer the same target point of the past laps using smoothing value calculated by the integral of the equal ratio attenuation. By using this adjustment method, we succeeded to decrease the overrun. We also investigated the transportability of the object by using motion controlled paramecium in the vertical pool. We found that paramecia often cause their avoiding reaction when they hit object made of hard material. In the case of the object made of soft material, paramecia can push more often and more easily. Therefore, we decided to change the target object from hard plastic to soft gel. We succeeded to transport and drop a gel oval sphere to the target place by manually controlled paramecium in the vertical plane pool.
Fabrication of Friction Stir Processed 6082-T6 Aluminum Alloy With Reinforced Powder
Authors: Sanusi Kazeem O. , Akinlabi Esther T.
Published: January 2018

In this study, Friction Stir Processing (FSP) technique was applied for the development of surface composites of 6082-T6 aluminum alloy reinforced with Titanium Carbide with the aim of investigating the possibility of enhancing the surface property of aluminium alloy by reinforcing it with Titanium Carbide to form metal matrix composites using one pass and three passes respectively. The groove with depth of 1.5 mm and width range from 0.5mm to 1.9mm were machined and filled with reinforcement powder using axial load of 20 kN. The rotational speed of the tools employed is 1000 rpm and the feed rate of 60 mm/min was used. The hardness properties to provide a sense of mechanical response and the surface morphology of the eroded samples were studied and characterised to reveal the microstructural features by using Scanning Electron Microscopy (SEM). Energy dispersive x-ray spectroscopy (EDS) was used to analyse the specimens. This study would motivate future studies to further explore the viability of composites produced using FSP technique.
Flow Across a Butterfly Valve in a Dam Penstock
Authors: Lattouf Dominic , Huynh B. P.
Published: January 2018

Butterfly valves are typically used as emergency closure devices in dam penstocks; these valves must be capable of closing if a penstock bursts. This paper summarizes a 3D CFD (Computational Fluid Dynamics) study that was conducted on the water flow across a sizable butterfly valve (1.6m in diameter) in a dam penstock with 57m of water head. The main aim is to determine the maximum torque required to close the valve. Thus semi steady flow conditions across the valve at various degrees of closure were investigated and the corresponding torque calculated. A maximum torque of about 87 700 N-m has been obtained, occurring at valve angle 40° (with valve totally closed at 0°, and fully open at 90°). Visual results were analyzed at each valve angle to understand the nature of the flow through the butterfly valve using various 2D contours and streamline images. The CFD software ANSYS Fluent has been used employing a Finite Volume Method. The RANS (Reynolds-Averaged Navier-Stokes) approach with Realizable K-epsilon turbulence model was employed. A grid independence study with up to 10 million cells has also been carried out, resulting in the adoption of 7.5 million cells in all models. Comparison with other available data was also completed, adding to the reliability of the computational results. Distribution of pressure, flow velocity, and turbulence parameters are also presented.
Node-Dependent Kinematic One-Dimensional Models for the Analysis of Rotating Structures
Authors: Carrera Erasmo , Filippi Matteo , Zappino Enrico
Published: January 2018

In this paper, the dynamics of rotating structures has been studied using a refined one-dimensional finite element model with a node-dependent kinematics. The present approach has been used to derive models where refined theories are used only in the region in which they are required and classical models elsewhere. This produces a reduction in the computational cost without a reduction in the accuracy of the analysis. The equations of motion have been derived in a three-dimensional fashion and they include all contributions due to the rotational speed, namely the gyroscopic, the spin softening, and the centrifugal stiffening terms. Classical and higher-order refined models have been established with the Carrera Unified Formulation. The numerical model has been assessed and then a number of applications to thin-walled structures have been proposed. The current methodology appears very effective when rotors are constituted of components with different deformability such as compact shafts and disks. The results have been compared with those obtained from uniform kinematic models and convergence analyses have been performed. The results show the efficiency of the proposed model.
A Comparison of the Capacity for Precise Motion Control Between Hinged Joints and Flexure Joints
Authors: Lusty Chris , Bailey Nicola Y. , Keogh Patrick S.
Published: January 2018

Hinged joints are ubiquitous in machine and mechanism design where components must rotate relative to one another. Their simplicity and reliability, coupled with limited alternatives, make them an obvious choice. However, the propensity of such joints to exhibit unpredictable discontinuities in their operation can limit the precision with which a mechanism incorporating such a joint can be controlled. In particular, almost all hinged joints experience some degree of both backlash and stiction. An alternative to hinged joints in many applications may be the use of large-displacement flexure-link joints. The use of flexure joints in micro-mechanisms is already an established practice, but their use in joints with large angular displacements (e.g. 30 degrees) is far less common. Such joints are inherently non-linear, and introduce more complex motion than simple hinges, but they offer the considerable advantage of highly predictable behaviour, without the exhibition of discontinuities. These characteristics open the way to increased mechanism precision and repeatability, and consequent new possibilities in machine design. This work makes a comparison of the precision which can be achieved when controlling similar mechanisms employing each of i) a realistic hinged joint, and ii) a large-displacement flexure-link joint. The modeling techniques used to represent each mechanism are discussed, and a series of results are presented illustrating the performance and prospects for precision motion of each system.
Data Flow and Communication Framework Supporting Digital Twin for Geometry Assurance
Authors: Bohlin Robert , Hagmar Jonas , Bengtsson Kristofer , Lindkvist Lars , Carlson Johan S. , Söderberg Rikard
Published: January 2018

Faster optimization algorithms, increased computer power and amount of available data, can leverage the area of simulation towards real-time control and optimization of products and production systems. This concept — often referred to as Digital Twin — enables real-time geometry assurance and allows moving from mass production to more individualized production.

To master the challenges of a Digital Twin for Geometry Assurance the project Smart Assembly 4.0 gathers Swedish researchers within product development, automation, virtual manufacturing, control theory, data analysis and machine learning. The vision of Smart Assembly 4.0 is the autonomous, self-optimizing robotized assembly factory, which maximizes quality and throughput, while keeping flexibility and reducing cost, by a sensing, thinking and acting strategy. The concept is based on active part matching and self-adjusting equipment which improves geometric quality without tightening the tolerances of incoming parts. The goal is to assemble products with higher quality than the incoming parts. The concept utilizes information about individual parts to be joined (sensing), selects the best combination of parts (thinking) and adjust locator positions, clamps, weld/rivet positions and sequences (acting).

The project is ongoing, and this paper specifies and highlights the infrastructure, components and data flows necessary in the Digital Twin in order to realize Smart Assembly 4.0. The framework is generic, but the paper focuses on a spot weld station where two robots join two sheet metal parts in an adjustable fixture.
The Effects of Spraying Parameters on Spray Cooling Heat Transfer Performance in the Non-Boiling Regime
Authors: Salman Azzam S. , Khan Jamil A.
Published: January 2018

Experiments were conducted in a closed loop spray cooling system working with deionized water as a working fluid. This study was performed to investigate the effect of the spraying parameters, such as Sauter mean diameter (SMD), the droplet velocity, and the residual velocity on the spray cooling heat transfer in the non-boiling region. Thermal effects on plain and modified surfaces with circular grooves were examined under different operating conditions. The inlet pressure of the working fluid was varied from 78.6 kPa to 183.515kPa, and the inlet temperature was kept between 21–22 °C. The distance between the nozzle and the target surface 10 mm. The results showed that increasing the coolant inlet pressure increases the droplet velocity and the number of droplets produced while decreasing the droplet size. As a consequence of these changes, increasing inlet pressure improved the heat transfer characteristics of both surfaces.
Non-Rigid Variation Simulation Using the Sherman-Morrison-Woodbury Formulas
Authors: Lorin Samuel , Lindau Björn , Lindkvist Lars , Söderberg Rikard
Published: January 2018

Variation simulation is one important activity during early product development. It is used to simulate the statistical distribution of assemblies or sub assemblies in intended manufacturing process to assure that assembly, function and aesthetical properties comply with the requirements set. In non-rigid variation simulation, components or sub assemblies can deform during assembly. To simulate non-rigid variation the Method of Influence Coefficient (MIC) is typically used. Solving the necessary sensitivity matrices used by MIC is time consuming. In this article we will apply the Sherman-Morrison and Woodbury formula (SMW) for updating the sensitivity response in the different assembly steps. It is shown that SMW can lead to substantial saving in computation time, when compared to the standard MIC.
MicroSurface Texturing for a Minimum Coefficient of Friction
Authors: Rashwan Ola H. , Stoilov Vesselin
Published: January 2018

In recent years, micro surface texturing for friction and adhesion control has gained momentum in a wide range of applications, such as MEMS devices, punches, and tools used metal forming processes, and injection molding machines.

In this study, air hardened tool steel, A2, with micro hexagonal dimples of different sizes and densities but constant depth, have been modeled and tested under dry sliding contact. Three-dimensional finite element models depict sliding dry contact between a rigid indenter and elastic-plastic textured surfaces are simulated. Coefficients of friction have been determined and compared for different texturing sizes and densities. In addition, these hexagonal patterns were fabricated on tool steel (A2) samples using photolithography. Coefficients of friction were experimentally measured using micro scratch tribometer. Both simulation and experimental results show there is a strong correlation between micro-texturing parameters and coefficient of friction. The results demonstrate that under dry sliding contact, coefficient of friction can be controlled through optimization of micro texturing parameters, specifically the spatial texture density (D/L) which is equal to the ratio of the size of the dimple (D) to the distance between the centers of two consecutive dimples (L). A minimum coefficient of friction exits at values of spatial texture densities (D/L) that range between 0.25 and 0.5 for this specific material.
Individualization of Thermophysiological Models for Thermal Sensation Assessment in Complex Environments: A Preliminary Study
Authors: Abou Jaoude Rachelle , El Khoury Roch , Psikuta Agnes , Nemer Maroun
Published: January 2018

Thermal comfort of drivers and passengers inside cars compartments is a subject bouncing back to the spotlight with the electrification of vehicles. In fact, air conditioning and heating systems can reduce the battery autonomy of electric vehicles by up to 50% under certain conditions. On the other hand, although some researchers attempted to consider the individualization of thermal sensation and comfort models, the most used thermal sensation and comfort models nowadays are still those that consider a standard average person. Many studies showed the limitations of these models in predicting thermal comfort for different populations in complex environments. Therefore, if a personal thermal comfort at minimum vehicle energy consumption is required, a deep consideration should be given to the understanding of the individualization of the thermophysiological model and to identifying key parameters that have the most influence on thermal comfort. In order to evaluate the impact of different parameters on thermal sensation and comfort, a literature review was undertaken followed by a sensitivity analysis of some potentially influential parameters such as the basal metabolic rate, body weight, cardiac output, body fat content and clothing by considering the influence of their variations on thermal neutrality status and thermal sensation and comfort.
Design and Additive Manufacturing of Lower Limb Prosthetic Socket
Authors: Vitali Andrea , Regazzoni Daniele , Rizzi Caterina , Colombo Giorgio
Published: January 2018

Additive Manufacturing (AM) is not only an innovative approach of fabrication but it fosters a new paradigm to design products. The possibility to confer inhomogeneous properties to the product provides an important design key. This paper concerns the design and manufacture of medical devices that require a high level of customization. We focus the attention on lower limb prosthesis and in particular on the prosthetic socket. The proposed method is centered on the virtual modeling of patient’s residual limb and the virtual process is highly integrated and the data flow is as fluid as possible. Three main phases can be identified: design, validation and manufacture of the socket. Firstly, the technician uses the Socket Modeling Assistant (SMA) tool to design the socket shape. Then, a numerical simulation is run to check pressure distribution and validate the socket shape. Finally, a multi-material 3D printer is used to build the socket. Preliminary results are presented and conclusions are drawn concerning the challenge of multi-material 3D printing of the socket.
Global-Local Characterization and Numerical Modeling of TWB Laser Welded Joints
Authors: Nalli F. , Russo Spena P. , Cortese L. , Reiterer D.
Published: January 2018

Sheet forming of tailor welded blanks (TWBs) of advanced high strength steels is complex because of the notable differences in mechanical properties, and hence in formability, of base metals, heat affected zones and weld seam. In this work, an accurate characterization of the mechanical behavior of these regions in TWBs made of a DP and TRIP steel was carried out. Micro-samples, machined from base metals and fusion zone were employed to retrieve the local constitutive laws up to fracture. At the same time, macro-samples, extracted throughout the welded joint were tested to assess the weldment overall behavior. Along with global load-displacement data, strain and displacement fields of the joint were evaluated, using a Digital Image Correlation technique. An FE simulation of the entire joint was setup, using the previously identified material properties. In a comparison between the FE model and experiments, good results were obtained both at a global and local level, up to fracture.
Material Model for Helmet Pads
Authors: Zhang Timothy G. , Satapathy Sikhanda S.
Published: January 2018

Quasi-static compression and dynamic impact experiments were conducted on comfort and stiff foam material used in the helmet pads. The time histories of displacement and total force applied to the foam were measured, from which the engineering stress-strain curves were calculated. At high rate, the material did not reach equilibrium and the calculated stress-strain curves may not represent the actual stress-strain response. Numerical models were developed in LS-DYNA to calibrate a material model for the comfort and stiff foams. The rate-dependent foam material response was captured reasonably well in the model.
3D Printed Passive Compliant and Articulating Prosthetic Ankle Foot
Authors: Schlafly Millicent , Ramakrishnan Tyagi , Reed Kyle
Published: January 2018

The human ankle is crucial to mobility as it counteracts the forces and moments created during walking. Around 85% of the 1.7 million people in the United States living with limb loss are transtibial (below knee) and transfemoral (above knee) amputees who are missing their ankle and require a prosthetic. This paper presents the Compliant and Articulating Prosthetic Ankle (CAPA) foot, a solution that uses torsional springs to store and release energy at three different locations on the mechanism, assisting in forward motion. The CAPA foot utilizes 3D printing and allows for the full ankle range of motion in the sagittal plane. Testing was performed with the CAPA foot on the Computer Assisted Rehabilitation Environment on an able-bodied person wearing a prosthetic simulator. Compared to the conventional non-articulating Solid Ankle Cushioned Heel foot, the CAPA foot is shown to better mimic the ground reaction forces and ankle angles of a healthy gait.
Formation and Breakup of Liquid Jets Curved by Gravity
Authors: Borthakur Manash Pratim , Nath Binita , Biswas Gautam , Bandyopadhyay Dipankar
Published: January 2018

The formation and breakup of a liquid jet in air with gravity acting perpendicular to the direction of the jet is studied computationally. The liquid jet follows a parabolic path due to the influence of gravity which curves the jet trajectory. Both symmetric and asymmetric perturbations develop on the liquid surface which lead to jet breakup with varying droplet size distribution. The limiting length of the jet at breakup increases with increase in the Weber number and Ohnesorge number. At higher value of Weber number, the liquid jet traverses a longer horizontal distance when released from the same vertical height. Increasing the Bond number leads to a significant increase in the curvature of the jet trajectory. The volume of drops produced varies temporally for a given Weber number and decreases with the increasing value of Weber number. The detached drops undergo rolling motion as well as shape oscillations as they continue to fall on their trajectories.
Characterization of 3D Surface Texture Directionality Using Multi-Scale Curvature Tensor Analysis
Authors: Bartkowiak Tomasz
Published: January 2018

Anisotropy of surface texture can in many practical cases significantly affect the interaction between the surface and phenomena that influence or are influenced by the topography. Tribological contacts in sheet forming, wetting behavior or dental wear are good examples. This article introduces and exemplifies a method for quantification and visualization of anisotropy using the newly developed 3D multi-scale curvature tensor analysis. Examples of a milled steel surface, which exhibited an evident anisotropy, and a ruby contact probe surface, which was the example of isotropic surface, were measured by the confocal microscope. They were presented in the paper to support the proposed approach. In the method, the curvature tensor T is calculated using three proximate unit vectors normal to the surface. The multi-scale effect is achieved by changing the size of the sampling interval for the estimation of the normals. Normals are estimated from regular meshes by applying a covariance matrix method. Estimation of curvature tensor allows determination of two directions around which surface bends the most and the least (principal directions) and the bending radii (principal curvatures). The direction of the normal plane, where the curvature took its maximum, could be plotted for each analyzed region and scale. In addition, 2D and 3D distribution graphs could be provided to visualize anisotropic or isotropic characteristics. This helps to determine the dominant texture direction or directions for each scale. In contrast to commonly used surface isotropy/anisotropy determination techniques such as Fourier transform or autocorrelation, the presented method provides the analysis in 3D and for every region at each scale. Thus, different aspects of the studied surfaces could clearly be seen at different scales.
The Effects of Hybrid Sandblasting Patterns on the Heat Transfer Performance in a Single-Phase Microchannel Heat Sink
Authors: Oudah Saad K. , Fang Ruixian , Tikadar Amitav , Egab Karim , Li Chen , Khan Jamil A.
Published: January 2018

An experimental investigation was conducted on a single phase microchannel heat sink, in which the bottom surface of the microchannel was modified with hybrid micro-sandblasting of elliptical patterns (HSEP) and fully sandblasting (FS) to passively enhance the microchannel heat transfer performance. The dimension of the microchannel is measured as 26 mm (L) × 5mm (W) × 0.35 mm (H), which results in a hydraulic diameter of 654 μm. Deionized water was used as the coolant, and the Reynolds number range between 85 to 650 was tested. The experimental results show that fully sandblasting (FS) bottom surface of the microchannel only slightly improved the heat transfer performance. However, the modified surface with HSEP enhanced the heat transfer performance substantially, compared to the benchmark results obtained with the bare surface (BS) microchannel. The pressure drops of the HSEP increased slightly compared to the BS and FS, due to the flow resistance of the microstructures. The proposed surface for enhancement of heat transfer will be useful in many high heat flux engineering applications. In the future, this study will be further extended to two-phase microchannel heat transfer.
Experimental Investigation of Transverse Mechanical Properties of High-Performance Kevlar KM2 Single Fiber
Authors: Raju Hermise , Pelegri Assimina A.
Published: January 2018

Transverse nanoindentation modulus of high performance Kevlar KM2 single fibers are experimentally studied using a nanoindenter. Researchers have investigated the transverse compression behavior of these fibers using flat punch indentation heads, in which the curved circular transverse shape of the fiber is not included, and consecutively fit the data into the analytical models to calculate their mechanical properties. During this process, the force is normalized to a point on the transverse fiber surface and the analytical model assumes a flat semi-infinite plate for substrate. Other studies consider embedding the fibers on a substrate and indenting on the transverse surface. This method bounds the fibers resulting in inaccurate measurements of their mechanical responses. There has not been an appropriate study on the transverse material properties of the Kevlar fibers determined via nanoindentation without embedding them because it is challenging to rigidly secure the fibers. Here, we have developed a methodology to secure the Kevlar fiber on an SEM puck under pretension. The tension at the fiber is calculated and accounted for in the final determination of the mechanical properties. Fibers are glued at the ends and are not embedded. The employed Vantage nanoimpactor indents the fiber radially at three different loads, namely, 2, 3, and 5 mN and calculates the mechanical properties. A Berkovich indenter is used for indentation. The Kevlar fibers are assumed transversely isotropic and have 12μm diameter measured via the Vantage optical microscope. For Kevlar KM2 fiber the experimental transverse modulus using impact nanoindenter instrument is ∼3.46 GPa. The presented experiments aim to improve our understanding of the mechanical properties of these high performance fibers on the transverse direction.
A CPFEM Investigation of the Effect of Grain Orientation on the Surface Profile During Tensile Plastic Deformation of FCC Polycrystals
Authors: Balusu Kranthi , Huang Haiying
Published: January 2018

A Crystal Plasticity Finite Element Method (CPFEM) investigation was performed to study the effect of the grain orientation on the surface profile changes in FCC polycrystals undergoing plastic tensile deformation. A grain embedded in an isotropic sample was used to ensure that grain profile is influenced only by the grain orientation. Simulation with multiple sets of grain orientations has determined that strain compatibility is the key criterion dictating the relative sinking and rising of grains. As a consequence, the grains with axial orientations close to [001] and [111] orientations, i.e. the most compatible orientations, sink irrespective of the normal orientation. However, grains with other axial orientations may relatively rise or sink depending on the orientation normal to the surface.
Characterization of Wrapped Coil Tank Water Heater During Charging/Discharging
Authors: Elatar Ahmed , Nawaz Kashif , Shen Bo , Baxter Van , Abdelaziz Omar
Published: January 2018

Heat pump water heaters (HPWH) are an energy efficient method for water heating compared to conventional electric water heaters. A wrapped coil around the water tank is often used as the condenser for the heat pump for such applications. Thermal stratification, caused by varying heat transfer rate from the condenser to the water depending on the phase of the refrigerant and the wrap configuration, is often observed inside the tank, especially for HPWHs using CO2 as the refrigerant. The current study investigates the impact of the charging/discharging process on thermal stratification. A series of simulations were conducted based on the draw patterns recommended by the DOE method of test for rating water heater performance. We also analyzed the water circulation patterns during charging/discharging process. The thermal stratification was adversely affected because of the circulation even when the Heat Pump (HP) was operational. It was observed that a relatively higher charge/discharge flow rate disrupts the thermal stratification quickly and thus lowers the supply water temperature. Furthermore, the duration of charging/discharging also plays an important role. It was noticed that the back flow has insignificant effect on the supply water temperature if charging/discharging time is relatively small. However, the effect was obvious for larger water draw flow rates that last for longer time.
Erosion Optimized Radial Fan Impellers and Volutes for Particle Flows
Authors: Fritsche Manuel , Epple Philipp , Steber Michael , Rußwurm Hans J.
Published: January 2018

Fans in industrial plants can be exposed to a strong erosion load due to particle flows. In the present work, the erosion behavior for large radial fans with spiral casings is investigated using the Finnie erosion model, see [1] [2]. Theoretical approaches concerning particle velocity and particle impact angle are validated by numerical methods. For this purpose, a baseline impeller and a parameterized baseline spiral casing have been designed and simulated using computational fluid dynamics. Than different geometrical variations of the spiral casing shape and the blade shapes of the impellers have been designed and simulated in order to determine their respective influence on the erosion behavior as well as on the performance characteristics. Finally, recommendations for an optimal design are presented and explained in detail.
Design Optimisation of Composite Overwrapped Pressure Vessel Through Finite Element Analysis
Authors: Alam Shah , Divekar Abhijeet
Published: January 2018

COPVs are currently used at NASA to contain high-pressure fluids in propulsion, science experiments and life support applications. These COPVs have a significant weight advantage over all-metal vessels; but, as compared to all-metal vessels, COPVs require unique design, manufacturing, and test requirements. The most significant difference from metal pressure vessel designs is that COPVs involve a much more complex mechanical understanding due to the interplay between the composite overwrap and the inner liner.

Often only limited analysis is performed to obtain an initial design, and then the design is refined through number of “build and burst” iterations. However, the cost in material and resources to fabricate multiple test specimens is extremely prohibitive. To avoid these high cost and time for build and burst iterations, FEA is often employed in an attempt to reduce the number of iterations required. FEA process becomes more of a design confirmation effort rather than a design iteration effort. In this research, we aimed to establish a detailed design optimization of a complete COPV through Finite Element simulation.
A Numerical Analysis on Cavitation Effects in Microchannels
Authors: Uyanna Obinna , Najafi Hamidreza
Published: January 2018

Cavitation process in microchannels has been widely studied from variety of perspectives. In diesel engines, smaller droplets provide a larger surface area and this leads to more efficient combustion. It has been observed that the atomization process is influenced by turbulence and cavitation in the nozzle. These factors therefore contribute to the size of the droplets, the spray angle, penetration of the fuel and other characteristics. In the present study, a numerical simulation of cavitation process in microchannels similar to nozzles is conducted using ANSYS Fluent. Cavitation phenomenon has been analyzed numerically for a variety of downstream pressures and L/D ratios. The effect of the geometry of the nozzle (length to diameter ratio) and downstream flow pressure conditions on the cavitation are also studied. The results can be used for optimal design of diesel injectors.
High Performance Buildings: The Impact of Building Orientation on HVAC System Loads
Authors: Shah Rushang B. , Goudarzi Navid
Published: January 2018

Energy demand growth and depletion of conventional energy resources in recent years have led to exploring alternative energy resources and further concentration on improving energy efficiency of segments with higher energy consumption. Building energy demand is among the main areas of concern with a 40% average of total energy consumption in the US energy market. Within building energy demand approximately, the Heating, Ventilation and Air Conditioning (HVAC) system, lighting system, has the largest energy consumption share compared to other systems such as electronics systems, water-heating-cooking, and other systems. This implies that small improvements in HVAC system loads will result in significant energy savings. Novel cost-effective solutions should be developed to integrate and optimize all the essential high-performance building attributes, especially energy efficiency and occupant productivity. Employing comprehensive building energy analysis (BEA) simulation tools are among the cheapest, yet are the cost-effective approaches in improving building energy performance. This paper follows the energy saving practice using existing BEA simulation tools with a focus on two major aspects that can contribute to building thermal loads: building orientation and integrating renewable energy. The results show the significant impact of building orientation for developing energy efficiency solutions with focus on integrating renewable energy technologies within high performance buildings.

This work provides a basis for the follow on phases of this research to develop smart energy saving solutions using current BEA simulation platforms. Such adds-on features enable users to improve building energy saving by determining building design features and integrating renewable energy solutions based on identified optimal building orientations.
System Identification of Force of a Silver Coated Twisted and Coiled Polymer Muscle
Authors: Jafarzadeh Mohsen , Wu Lianjun , Tadesse Yonas
Published: January 2018

The demand of using artificial muscle similar to the human muscle is significantly increased during past decades. Recently, silver-plated Twisted and Coiled Polymer (TCP) muscle was employed in many research projects. A first order differential equations (1st ODE) was used to predict the force of this muscle, assuming that the TCP muscle acts similar to a mechanical spring that has variable stiffness depending on the electrical power supplied. Thus, extensive study should be performed on different types of TCP muscles to reach a conclusion. In this paper, a black box system identification method is used to examine the behavior of TCP muscles under different input conditions. Different order differential equations are compared with experimental results. Prediction error method (PEM) is used for estimation of the force of silver-plated TCP muscle with several linear time invariant (LTI) discrete time state space system. In addition, we suggest a fast method (rule of thumb) to model a TCP muscle. Moreover, two key parameters have been introduced to compare the quality of the TCP muscle from force perspective.
A Framework to Bridge Teachers, Student’s Affective State, and Improve Academic Performance
Authors: Calado Jorge , Luís-Ferreira Fernando , Sarraipa Joao , Jardim-Goncalves Ricardo
Published: January 2018

Some of the biggest problems tackling Higher Education Institutions (HEI) are student’s drop-out and academic disengagement. Physical or psychological disabilities, social-economic or academic marginalization, and emotional and affective problems, are some of the factors that can lead to it.

This problematic is worsened by the shortage of educational resources that can bridge the communication gap between the faculty staff and the affective needs of these students.

In this paper, we present a framework capable of collecting analytic data, from an array of emotions, affects and behaviours, acquired either by human observations, like a teacher in a classroom or a psychologist, or by electronic sensors and automatic analysis software, such as eye tracking devices, emotion detection through automatic facial expression recognition software, among others.

This framework compiles the gathered data in an ontology, and will be able to extract patterns outliers via machine learning, enabling the profiling of the students in critical situations, such as disengagement, attention deficit, drop-out, and other sociological issues, setting real time alerts when these profiles are detected.

The goal is that, by providing insightful real time cognitive data and allowing the profiling of the student’s problems, a faster personalized response to help the student is enabled, allowing academic performance improvements.
Additive Manufacturing Techniques for Soft Electroactive Polymer Hydrogels Using a Customized 3D Printer
Authors: Thien Austen , Pochiraju Kishore
Published: January 2018

Electroactive polymers (EAP) have shown promise in producing significant and controllable linear displacement in slim and lightweight packages. EAPs allow for seamless integration and multi-functionality since they are actuated by a driving voltage that could be controlled by a microprocessor. Polyacrylamide (PAAM)/Polyacrylic acid (PAA) hydrogel EAPs are commonly chosen due to their low driving voltage, significant amount of displacement, and rapid manufacturing capabilities, as these gels can be 3D printed. To effectively extrude these gels in 3D printers, their viscosity, gelation time, shear thinning, and self-wettability must be characterized. In this research, ungelled solutions of PAAM are prepared and then strain-tested at temperatures from 60C to 80C and with 1–2 drops of TEMED catalyst to determine the gelation time that is optimal for 3D printing. Strain testing of ungelled PAAM solutions is also used to determine the shear thinning propertie of the gel. All strain testing is conducted using a rheometer with 25 mm diameter plates and an oven enclosure. A prototype extrusion system is designed and fabricated to be used for self-wettability testing of the gel. The process data will then be used in the design of a modified 3D printer to manufacture and test different configurations of these hydrogel actuators.
Evaluation Method for Mechanical Stress Dependence of the Electrical Characteristics of SiC MOSFET for Electro-Thermal-Structural Coupled Analysis
Authors: Goryu Akihiro , Kato Mitsuaki , Kano Akira , Izumi Satoshi , Hirohata Kenji
Published: January 2018

Power semiconductor devices such as MOSFET/IGBT and PiN diodes are widely used as basic components for supporting infrastructure in the field of electronics, including in power conversion, industrial equipment, railways, and automobiles. Recently, increasing attention has been paid to silicon carbide (SiC) as a wide-band-gap semiconductor suitable for use in power devices with low loss and high breakdown voltage. However, basic knowledge of the material properties and reliability of SiC devices, and particularly the influence of mechanical stress on device characteristics, is still incomplete. In this paper, we evaluated the effect of mechanical stress on the electrical characteristics of SiC devices. In order to investigate the effect of stress on the SiC device characteristic, we propose a simple evaluation method using four-point bending, which is a classical method capable of applying uniaxial stress to a device. With this method, we evaluated the stress in a SiC device using residual stress measurement by Raman spectroscopy and stress simulation based on the finite element method. Our proposed experimental method is as follows. First, the SiC device was bonded with AuGe solder to a metal plate [phosphor bronze; Young’s modulus: 105 GPa; Poisson’s ratio: 0.33; dimensions: 100 mm (W) × 12 mm (L) × 2 mm (T)], and aluminum wire (wire radius: 200 μm) was also bonded to the device. Second, the prepared device was placed on the specially designed four-point bending apparatus for mechanical stress experiments. Finally, the sample was bent in compression or tension in the in-plane direction by the four-point system. The SiC device was subjected to compression or tensile stress via the metal plate. The electrical characteristics of the SiC-MOSFET were measured with a curve tracer in our proposed system. Id−Vds characteristics changed linearly as stress was applied to the device. As a result, the on-resistance was increased by 7.6% by applying a tensile stress of 300 MPa and was decreased by 1.0% by applying a compressive stress of 100 MPa at room temperature, respectively. A power device circuit with multiple chips was also simulated by SPICE based on the experimental results to confirm the effects of stress on SiC devices in a power module. Simulated MOSFET model contains stress factors obtained from experimental results. The circuit was simulated by electro-thermal coupled analysis using a one-dimensional model of the electric circuit and thermal circuit constructed in SPICE. The results show that the proposed method is powerful simulation method for power device design.
Gradient Optimization of Inverse Dynamics for Robotic Manipulator Motion Planning Using Combined Optimal Control
Authors: Gong Shangdong , Alqasemi Redwan , Dubey Rajiv
Published: January 2018

Motion planning of redundant manipulators is an active and widely studied area of research. The inverse kinematics problem can be solved using various optimization methods within the null space to avoid joint limits, obstacle constraints, as well as minimize the velocity or maximize the manipulability measure. However, the relation between the torques of the joints and their respective positions can complicate inverse dynamics of redundant systems. It also makes it challenging to optimize cost functions, such as total torque or kinematic energy. In addition, the functional gradient optimization techniques do not achieve an optimal solution for the goal configuration. We present a study on motion planning using optimal control as a pre-process to find optimal pose at the goal position based on the external forces and gravity compensation, and generate a trajectory with optimized torques using the gradient information of the torque function. As a result, we reach an optimal trajectory that can minimize the torque and takes dynamics into consideration. We demonstrate the motion planning for a planar 3-DOF redundant robotic arm and show the results of the optimized trajectory motion. In the simulation, the torque generated by an external force on the end-effector as well as by the motion of every link is made into an integral over the squared torque norm. This technique is expected to take the torque of every joint into consideration and generate better motion that maintains the torques or kinematic energy of the arm in the safe zone. In future work, the trajectories of the redundant manipulators will be optimized to generate more natural motion as in humanoid arm motion. Similar to the human motion strategy, the robot arm is expected to be able to lift weights held by hands, the configuration of the arm is changed along from the initial configuration to a goal configuration. Furthermore, along with weighted least norm (WLN) solutions, the optimization framework will be more adaptive to the dynamic environment. In this paper, we present the development of our methodology, a simulated test and discussion of the results.
Experimental Visualization and Numerical Simulation of Liquid-Gas Two-Phase Flows in a Horizontal Pipe
Authors: Darzi Milad , Park Chanwoo
Published: January 2018

This paper presents the results of both visualization experiment and numerical simulation for two-phase (water-air mixture) flows in a horizontal tube. A visualization experimental setup was used to observe various two-phase flow patterns for different flow rates of water/air mixture flow in a glass tube of 12 mm in diameter. Total of 303 experimental data points were compared with Mandhane’s flow map. Most of the data for stratified, plug and slug flows were found to be in good agreement. However, annular flow was observed for relatively lower gas flow rates and also wavy flow occurred at relatively higher liquid flow rates in this experiment. A three-dimensional Computational Fluid Dynamics (CFD) simulation was performed using OpenFOAM employing “interFoam” as the solver to simulate the two-phase flows in horizontal pipe based on Volume-Of-Fluid (VOF) method. The simulated and experimentally observed flow patterns for the same set of superficial velocities shows acceptable similarities for stratified, wavy, plug, slug and annular flows. Also, the computed values of the void fraction and pressure drop for the numerical simulations shows reasonable agreement with well-known correlations in literature.
Characterizing Surface Quality Through 3D Parameters: Why 2D Average Roughness Alone Is No Good
Authors: Ghosh Suhash , Sahay Chittaranjan
Published: January 2018

Typically, the design of machine parts is based on the dimensional and form tolerances and fragmentally on the surface roughness parameters (predominantly roughness average Ra). Despite the range of available 3D surface quality parameters, and the modern equipment to accurately measure them, design and quality professionals continue to specify surface finish based solely on the value of Ra. There are many reasons that contribute to this tendency: average roughness remains so easy to calculate, it is well understood, and vast amount of published literature explains it, and historical part data is based upon it. The same outlook trails in undergraduate education and their textbooks. It has been seen that Ra, typically, proves too general to describe surface’s true functional nature. Additionally, the push for complex geometry, coupled with tight tolerances, has reinforced the need to maintain increased process control along with improved surface finish. In turn, the surface finish over the entire area, not just the 2D parameters, tends to dictate the performance and reliability of the component. This article explores how these multitudes of 2D and 3D surface quality parameters are to be understood in the design and development of high performance surfaces, and the strong need for them to be incorporated into undergraduate engineering curriculum, and be taught as an improved toolkit to the aspiring engineers, process engineers and quality control professionals.