bluuebunny/crossref_metadata_2025 huggingface dataset:
Constitutive Modeling for Flow Behavior of As-Cast 1026 Carbon Steel Under Hot Compression Experiments
Authors: Ju Li , Li Yongtang , Fu Jianhua , Lei Bufang , Qi Huiping
Published: March 2016

Nowadays, modern casting theories and technologies have got marked progress in reducing steel casting’s defects, such as shrinkages, cracks, porosities, and segregations, which make it possible to manufacture industrial parts with casting instead of forging billet. Compared with the traditional technology, the new method will have many obvious advantages in reducing heating times and discharge, saving materials and energy, and improving productivity. In order to produce parts with sound mechanical properties by employing the new technology, it is important to probe the flow behavior of as-cast carbon steel under hot deformation for premium controlling processing parameters, reasonable planning procedures and a reliable constitutive equation for precise simulation. In this paper, high temperature flow behavior of as-cast 1026 carbon steel is investigated by conducting hot compression experiments on Gleeble-3500 simulator in the temperature range from 1 173 K to 1 473 K at an interval of 100 K and the stain rate range from 0.1 s−1 to 2.0 s−1. The relationships of deformation parameters (temperature, strain rate) with material’s flow behavior are found. The deformation activation energy and the stress index are worked out and the mathematical model of the flow stress under hot deformation is established by means of the liner regression analysis of true stress-strain data. Meanwhile, the effect of initial grain sizes on flow behavior of as-cast 1026 steel is also studied by compressing samples cooled to 1 173 K from 1 273 K, 1 373 K and 1 473 K respectively. The experimental results reveal that strain hardening and flow softening mainly characterize the flow behavior. It is also found that with the increase of deformation, the flow stress first increases rapidly, then reaches the peak slowly, after that it begins to decrease and finally comes to a steady value. At the temperature of 1 173 K, material’s softening is not apparent even if the strain rate is increased, while at the strain rate of 2 s−1, it is also not apparent even when the deformation temperature is raised to 1 473 K, so the final forging temperature is supposed to be about 1 173 K and the maximum stain rates should be below 2 s−1. In addition, at the same deformation temperature and strain rate, the more refined initial grain, the easier material dynamically recrystallizes and the lower the steady stress is. Therefore, the heating process of material is expected to be tightly controlled. The maximum error of flow stress between the model predictions and actual results is only 5.90%. The good agreement signifies the applicability of this method as a general constitutive equation in hot deformation studies.
Melting/Solidification Analysis of the Pb Free-Solder in Sleeve Soldering
Authors: Imanishi Ken , Nomura Hajime , Ebisawa Mitsuo , Tsuji Katsuyuki , Enoki Shinichi
Published: March 2016

Automatic soldering technic called Sleeve soldering has been developed recently. In the technic, a ceramic tube has been used instead of a soldering iron. It is called Sleeve. Fixed amount of solder is loaded into this Sleeve. The melted solder is poured from tip of the Sleeve to glue electronic parts into electronic boards. At present Sleeve soldering has been produced and introduced. However condition of soldering failure and concept of process design are not clear due to a few data of melting behavior and solidification. In this research we intended to express these standards by comparing numerical analysis and experiment. Moreover we explain about the establishment of numerical analysis method in this paper.

Result in the behavior using the solder model has been similar to actual phenomenon in this simulation. Besides, we have confirmed that the fillet and back fillet was arisen on both sides of the electronic board.
ROM of Voltage Response of Parametric Resonance of Electrostatically Actuated MEMS Plates
Authors: Caruntu Dumitru I. , Oyervides Reynaldo , Garcia Valeria
Published: March 2016

This paper deals with electrostatically actuated Micro-Electro-Mechanical Systems (MEMS) circular plates. The system consists of a flexible circular plate with the edge fixed above a parallel ground plate. The forces acting on the MEMS plate are the electrostatic, damping, and elastic restoring force. In this work Casimir and/or van der Waals forces are neglected, since they are significant for gaps less than one micron and/or 50 nanometers, respectively. The electrostatic force is given by a soft Alternate Current (AC) harmonic voltage between the two plates. The electrostatic force leads the flexible plate into vibration. The assumption of axisymmetrical vibrations is valid in this work. The AC frequency is near natural frequency of the flexible circular plate. Since the electrostatic force is proportional to the square of the voltage, this results in an electrostatic force of frequency twice the natural frequency. Therefore the system experiences a parametric resonance. The partial differential equation of motion is non-dimensionalized. Next the resulting lumped parameters are found from a typical MEMS circular plate resonator. Reduced Order Model (ROM) is the method of investigation used in this work, specifically two terms ROM. Numerical simulations are conducted to predict the voltage response of the system. The effects of frequency and damping on the response are predicted as well. MEMS circular plate systems are excellent candidates for resonator sensors, i.e. sensors functioning at resonance. They are capable of detecting cells, viruses, as well as any microparticles provided the plates are coated for such recognition.
Eye Movement Influence of Stacking Worker in Autoclave Molding
Authors: Uchida Toshikazu , Kuroda Koji , Endo Atsushi , Migaki Masakazu , Ochiai Junpei , Uozumi Tadashi , Goto Akihiko , Zhao Defang , Yang Yuqiu
Published: March 2016

Three-dimensional components which incorporate CFRP are molded by skilled workers manually. This makes quality control difficult. In this study, we aim to establish standardization of work and set a standard of quality examination. We focus on the eye movement to examine that the differences of worker’s proficiency level influence on the hand lay-up process. Carbon cloth prepreg was stacked in three layers in the mold. The fiber orientation of the carbon cloth was set using one edge of the mold as the plane of reference. The first layer was 0°, the second was 45°, and the third was 0°. The hand lay-up process was applied and subjects chose their own process and tools. Subject A had 13 years of experience, subject B had 1 year of experience, and subject C had no experience. The process was recorded with a video camera and results compared in an interview format, inspecting footage of the process together with the subject. Subject A’s movements were very smooth, his body and face close to the mold, whilst subject B’s movements were very awkward. Subjects’ use of tools and hands were analyzed. In the mold used for this study, there are roughly three elements. In order to obtain flat smoothness in corner R and the four deep corners of the edge, a high degree of skill was required. A significant gap in mechanical dexterity was clearly observed between an expert and beginners. We will repeat this study on a constant basis with more subjects, and further clarify the elements.
Performance Evaluation of Dry EDMed Aluminium Alloy
Authors: Kumar M. Pradeep , Pragadish N.
Published: March 2016

In this research work, experiments were conducted using Electrical Discharge Machining (EDM) in dry and conventional mode, and the results were compared and analyzed. LM13 Aluminium alloy is used as the workpiece and pure cylindrical copper rod is used as the tool electrode. Since the machining was difficult in dry EDM, some modifications were made in the existing tool design to conduct the experiments in dry EDM. The experiments were designed using Taguchi’s L27 orthogonal array. Discharge current (I), gap voltage (V), pulse on time (TON), pressure (P) and speed (N) were chosen as the various input parameters. Three levels of values were chosen for each input parameter, whereas speed was chosen as the fixed parameter. The variation in the material removal rate (MRR), surface roughness (SR), surface morphology and elemental composition of the machined surface due to variation in the input parameters were analyzed in both dry and conventional mode. Better MRR, and surface roughness were observed in the work piece machined under conventional EDM process. The MRR is observed to be 84% more in the conventional mode when compared with dry EDM. Also, when compared to the dry EDM, about 15.33% better SR values is observed in the conventional EDM process.
Stresses of an AMB-Supported Rotor Arising From the Sudden Contact With Backup Bearings
Authors: Sikanen Eerik , Halminen Oskari , Heikkinen Janne , Sopanen Jussi , Mikkola Aki , Matikainen Marko
Published: March 2016

High speed technology has a fundamental advantage when compared to conventional motors. Active magnetic bearings (AMBs) are often needed in the high speed motors, as they can provide almost frictionless support and allowing control for the dynamics of the system. AMBs require backup bearings to avoid damage resulting from a failure in the component itself, in the power system, or in the control system. During a rotor-bearing contact event, substantial impact forces may occur between the backup bearing and the rotor.

In this study the rotor model is implemented using a finite element approach including backup bearings which are modelled as simplified cageless ball bearings. Based on results of this study, the increase in backup bearing misalignment can have proportional impact on the rotor bending and shear stresses in touchdown situation.
Fast Bayesian Inference on Optimal Wavelet Parameters for Bearing Fault Diagnosis
Authors: Miao Qiang , Wang Dong
Published: March 2016

Rolling element bearings are widely used in various machinery to support rotation shaft and they are prone to failures. Once a bearing fails, it accelerates failures of other adjacent components and results in unexpected machine breakdown. To prevent machine breakdown and reduce unnecessary economic loss, bearing fault must be detected as early as possible. Besides spectral kurtosis, empirical mode decomposition, cyclostationarity, etc., wavelet transform has proven to be an effective method for identification of different bearing faults because it aims to highlight the inner product between an artificial wavelet function and a signal to be analyzed. In the application of wavelet transform, optimization of wavelet parameters attracts much attention because proper selection of wavelet parameters can maximize performance of wavelet transform and extract impulses caused by bearing faults in the case of interruption from other strong low-frequency vibration components and heavy noises. Compared with other optimization methods, such as genetic algorithm, particle swarm optimization, etc., an analytic and fast Bayesian inference on optimal wavelet parameters for an optimal wavelet filtering for bearing fault diagnosis is proposed in this paper. Prior to Bayesian inference, a state space model of wavelet parameters should be constructed to reflect the relationship between wavelet parameters and measurements. Here, measurements are monotonically increasing kurtosis values, which are able to quantify bearing fault signals. The first kurtosis value and initial wavelet parameters are provided by the fast kurtogram, which is a fast algorithm that can be used to locate one of resonant frequency bands for further demodulation with envelope analysis. For other measurements, they are generated by artificial extrapolations of the first kurtosis value. To iteratively infer posterior probability density functions of wavelet parameters and track the artificial measurements, an unscented transform based Bayesian method is introduced. As the iteration number increases, posterior probability density functions of wavelet parameters converge. Then, the optimal wavelet parameters can be found to conduct an optimal wavelet filtering so as to isolate bearing fault signals from other strong low-frequency vibration components. At last, squared envelope analysis and Fourier transform are utilized to demodulate bearing fault signals enhanced by the proposed method and to identify bearing fault characteristic frequencies, respectively. One real case study is used to illustrate how the proposed method works and to demonstrate that the proposed method can be effectively and efficiently used to extract bearing fault signatures. Additionally, a comparison with the fast kurtogram is conducted to show the proposed method is better than the fast kurtogram for bearing fault diagnosis.
Identification of Location and Magnitude of Impact Force on a Composite Sandwich Structure With Lattice Truss Core
Authors: Kalhori Hamed , Ye Lin , Li Zheng , Li Bing
Published: March 2016

In this study, a new method was developed to estimate both the location and magnitude of an impact force applied to a composite sandwich panel with lattice truss core using an inverse algorithm based on dynamic characteristics of the structure. A method utilizing deconvolution with a transfer function in the time domain was employed to tackle the problem. The dynamics signals were captured using a Scanning Laser Doppler Vibrometer (SLDV) and the force is applied using a shaker. It is assumed that a set of impact forces be applied at a set of locations of the structure at the same time, but the magnitude of all impact forces except one is set to zero, implying that an impact event has occurred at only one of the possible locations. The aim is then to find the unknown impact location among the other possible ones as well as the magnitude of the impact force. The least-square approach is adopted, and the truncated singular value decomposition is then used to regularize and solve the problem.
System Uncertainty Propagation Using Automatic Differentiation
Authors: Bani Younes Ahmad , Turner James
Published: March 2016

In general, the behavior of science and engineering is predicted based on nonlinear math models. Imprecise knowledge of the model parameters alters the system response from the assumed nominal model data. We propose an algorithm for generating insights into the range of variability that can be the expected due to model uncertainty. An Automatic differentiation tool builds exact partial derivative models to develop State Transition Tensor Series-based (STTS) solution for mapping initial uncertainty models into instantaneous uncertainty models. Development of nonlinear transformations for mapping an initial probability distribution function into a current probability distribution function for computing fully nonlinear statistical system properties. This also demands the inverse mapping of the series. The resulting nonlinear probability distribution function (pdf) represents a Liouiville approximation for the stochastic Fokker Planck equation. Numerical examples are presented that demonstrate the effectiveness of the proposed methodology.
Feedback Control Sensitivity Calculations Using Computational Differentiation
Authors: Bani Younes Ahmad , Turner James
Published: March 2016

Feedback control is a powerful methodology for handling model and parameter uncertainty in real-world applications. Given a useful nominal plant model for developing the control approach, it is well-known that optimal solutions only perform well for a limited range of model and parameter uncertainty. A higher-order optimal nonlinear feedback control strategy is presented where the feedback control is augmented with feedback gain sensitivity partial derivatives for handling model uncertainties. The computational differentiation (CD) toolbox is used for automatically generating higher-order partial derivatives for the feedback gain differential equations. An estimator is assumed to be available for predicting the model parameter changes. The optimal gain is computed as a Taylor series expansion in the gains, where the feedback gains are expanded as a function of the system model parameters. Derivative enhanced optimal feedback control is shown to be robust to large changes in the model parameters. Numerical examples are presented that demonstrate the effectiveness of the proposed methodology.
To Understand Myopic Alleviation by Conducting Finite Element Structural Analysis of a Cornea With an Intrastromal Corneal Ring Implant
Authors: Khan Salman N. , Shiakolas Panos S.
Published: March 2016

Myopia or shortsightedness is a visual impairment condition that is affecting more than 32 million Americans according to the American Academy of Ophthalmology, and this number is expected to increase even further with the increasing life expectancy in the United States. Myopia occurs when light rays entering the cornea are focused in front of the retina due to: high corneal curvature, short axial length of the eye, or high optical power of the natural lens. These reasons suggest that light refracting elements play a pivotal role in determining visual acuity. The cornea is the principal refractive element in the eye contributing almost 75 percent of ocular refractive power and if the shape of the cornea can be changed to increase or decrease the focal length of the converging light rays it could present a possible solution to improving myopia. The presented research focuses on the effects of intrastromal corneal ring (ICR) implantation on the shape of the cornea by developing a computationally efficient 3D axisymmetric finite element (FE) model of the cornea utilizing hyperelastic material properties. The results of the developed corneal FE model with a 360° ICR implant are analyzed and discussed. The FE model results provide confidence in the ability of the ICR implants to reduce myopia. The attained FE model results not only agree qualitatively with published clinical data but also provide a valuable insight into the surgery.
Effect of Fuel Injection Angle on Combustion and Emissions Characteristics in Taper Can Gas Turbine Combustion Chamber
Authors: Srinivasan D. R. , Vootukuri Pandurangadu , Gupta A. V. S. S. K. S.
Published: March 2016

The rate of volatility of liquid fuel droplets sprayed in a stream of turbulent swirling air flow inside the taper can gas turbine combustion chamber had greatly affected the combustion and emission performance of the combustor. There had been extensive investigation that was carried out earlier which are both experimental and numerical in nature to improve the fuel volatility. In this paper, a novel method was proposed to predict the influence of fuel injection angle on combustion and emission characteristics in the taper can type combustion chamber. A detailed numerical investigation was carried out by modelling a sector of combustion chamber with an angle of 51.42° and simulated using commercial CFD code by varying the fuel injection angle of liquid fuel droplets sprayed in the gas turbine combustion chamber starting from a minimum angle to the maximum angle where fuel droplets strike the combustor wall. The turbulence model adopted was k–ε model with high Reynolds number and also with standard wall treatment. The combustion in the combustion chamber occurs by non-premixed type of combustion and correspondingly Magnussen’s eddy break-up (EBU) model was selected. The fuel droplets were tracked by using Lagrangian multiphase model due to presence of two phases i.e. air and liquid fuel droplets that were injected in combustion chamber. The droplet breakup model selected was Reitz Diwakar model and for the interactions of fuel droplets with the wall Bai’s model was used. The droplet diameters and probability density functions were defined by using Rosin-Rammler method. All peripheral boundaries were considered as adiabatic in nature. Symmetry boundary conditions were imposed on the sector walls that were separated by 51.42°. The combustion reaction involving liquid fuel and oxidiser with products of combustion as carbon dioxide and water vapour had been defined as a three step reaction. The model was meshed for different cell sizes from 3mm to 8mm with step size of 1mm and checked for grid independency. It was found that results obtained for 3mm and 4mm cell sizes were almost identical. Hence 4mm cell size was considered for investigation due to less computational time. The cases were run for different fuel injection angles. The results obtained were presented in the form of contour plots taken at mid-section in axial direction along the length of the combustor. The graphical values were obtained as the average values at the outlet of combustor. Some of the contour plots that were discussed are plots of carbon dioxide, nitric oxide and soot. It was concluded from the above analysis that variation of fuel injection angle had played a pivotal role which had resulted in better combustion with lower emissions on Nitric Oxide and Soot thereby producing maximum power for minimum amount of fuel burnt.
Experimental Investigation Into Droplet Impingement Upon Moving Films Using High Speed Video and Thermal Imaging
Authors: Mitchell Antony J. , Simmons Kathy , Hann David
Published: March 2016

Aeroengine bearing chambers are geometrically complex, typically containing shafts, bearings, seals and stationary components. Oil is supplied for lubrication and cooling and so the chamber contains a highly rotating two-phase (oil/air) flow where the oil is typically present as droplets, ligaments, mist and films. These films may be thick or thin and film speed varies with chamber location. It is desirable to know a priori the outcome of a droplet-film impact event in terms of mass, momentum and energy transfer.

There is a significant body of research on the interaction between droplets and static films. The experimental parameter space has been characterised on the basis of film thickness and impact parameter to predict the outcome of an impingement. The impingement of droplets on moving films has only begun to be investigated over the last decade and consequently models have not yet been developed and the parameter space has barely begun to be characterised.

Within this paper results are presented from an experimental study in which water droplets of 3 mm and 3.8 mm at 20°C falling under the influence of gravity impinged onto water films flowing down an inclined plane. Film temperature was 30°C and film thicknesses were between 2.3 mm and 4.2 mm. High speed imaging was used to determine the impingement outcomes and cavity morphology. A high speed infrared camera was used to determine the extent of the thermally affected region and its temperature behaviour.

We find that by using the resultant droplet velocity (combining droplet and film velocities) the film impingement outcomes can be characterised into regions very similar to those for static films. The data is presented as a function of splashing parameter and non-dimensional film thickness. It was observed that for these impacts on supercritical films (Fr > 1) there is less propensity for secondary droplet formation through jet breakup than on static and subcritical films (Fr < 1).

Data was obtained for extent of the thermally affected region. It was found that the cooler droplet liquid spreads over the inside of the crater before heating up to film temperature. Development of crater shape and size was also studied and data compared to established models for droplet impact on deep static films. During the initial stages of an impact crater area increases similarly to that for static films although the crater shape itself is less similar and is asymmetrical due to the film motion.
Enhancing Engineering Learning Experience at UTB by Freshmen iHOP
Authors: Islam Nazmul
Published: March 2016

Most of the engineering courses focus more on theory and very little on hands-on, project-based learning in the classroom. Integration of real-world engineering problems and applications in lower division engineering courses will produce engineering students, who will be technically sound and be able to execute and manage real-world projects, when they will do senior design projects in their final year of engineering study. To overcome the engineering design challenges we have developed iHOP (Ingenieŕia Hands on Project) and integrate it with our lower division engineering courses. iHOP has been developed to emphasis the design component at the University of Texas at Brownsville (UTB) Engineering Physics curriculum and the project is now an integral part of Introduction to Engineering class. The iHOP project is one that is challenging, fun, requires teamwork, associated with the engineering material being studied, low cost, and doable in a limited amount of time. The experience from iHOP project motivates our freshman students to choose a better senior design project in senior year of their college career.

The objectives of the iHOP projects are — to have students develop teamwork skills, and to teach students basic engineering design concepts in a complementary format to the traditional lecture. Various techniques related to team selection, encouraging teamwork, incorporation of engineering topics, keeping costs down, project results presentations, and gathering feedback from students will also be presented in this paper. Integrating iHOP Project with Introduction to Engineering class helped us to improve our retention effort in the engineering department.
Distribution of Porosity in Cortical (Bovine) Bone
Authors: Hage Ilige S. , Hamade Ramsey F.
Published: March 2016

Pores (namely lacunae, clusters of canaliculi, Haversian canals, and resorption cavities) are present throughout cortical bone. This paper characterizes the area fraction (AF, %)) of each type of these pores as function of distance from the bone’s geometric center while noting the region in which such pores are located: midcortical or periosteal.

Optical slides (at 20X) are taken from 2 cortical bone biopsies named bone 1 and bone 2 and cut at mid-diaphysis femur from 2 different (about 2 year-old) bovine cows. The slides are collected from posterior (pericortical) and anterior (intracortical) locations. The area of each of these biopsies is about 2.5mm × 3mm located near the outer cortex of the bone. In polar coordinates from the bone’s center, the areas cover radial distance of about 3.3 mm (of radius, R) and encompass an arc of 10°.

Automated segmentation is used to locate and identify all pores in the optical slides the shapes of which are best fitted into ellipses. Values of area fraction, AF (%) of said fitted ellipses are then automatically calculated in secondary osteons for both regions. Variations in values of area fraction AF (%) are related to actual areas of pores (based on their defining equations).

Observations suggest that area fractions (%) of all pores (but to lesser degree for Haversian canals), to significantly decrease linearly and in a steep fashion with R (statistically significant, p < 0.01) in the anterior region where osteonal growth is expected to have continued to develop. However, in the posterior region where osteonal growth appears to have matured, area fraction (%) values seem to have reached a steady state resulting in fairly flat behavior versus R. All observations are equally applicable for biopsies collected from bone 1 and bone 2.
CAD Information Handling for Obtaining Dependable Manufacturing Systems
Authors: Miron E. , Mendonca J. P. , Machado J. , Olaru D. , Prisacaru G.
Published: March 2016

The design of mechatronic systems is a multidisciplinary task that involves skills from mechanic, electronic and informatics areas. Recently, the expertise from such different fields is able to communicate and exchange the necessary contribution to successful design solutions, through a myriad of internet tools available. The introduction of internet of services on the design of mechatronic systems, mainly when teams, with different skills, operate in different geographic places, has contributed to flawlessly integrate better and interoperable final solutions. The design of mechatronic systems without errors — that operate without failures — is an important contribution to such goal. Safe behavior of mechatronic systems is crucial, mainly, in what concerns human safety. The correct behavior of those systems can be improved by the development of safe software for their controllers using some analysis techniques. Among them, Formal Verification (FV) is able to guarantee the best results. One of the main gaps using this technique is the difficulty of obtaining adequate plant models, in a systematic way, because this task is, usually, related with high level of expertise of designers and, in industry, this fact causes some difficulties for using those methods and tools. The work presented in this paper is a part of a larger project developed in the context of Software as a Service (SaaS) platform. It is intended to develop a systematized approach in order to obtain meaningful plant models out of existing CAD data, from Autodesk Inventor (or CATIA), and translate those models to formatted files according to input data of the UPPAAL model-checker (because it allows dealing with time variable).

The main idea is to obtain, systematically, plant models for Formal Verification purposes, considering that nowadays companies with different CAD systems are using increasingly often STEP-File format. A solution for this specific problem is explored and presented in this paper.
Intracranial Pressure Response to Controlled Cortical Impact: An Experimental Study on a Surrogate Head
Authors: Hua Yi , Kelso Matthew , Gu Linxia
Published: March 2016

The controlled cortical impact (CCI) model is commonly used for replicating the trauma events. However, the impact parameters vary considerably among different laboratories, making the comparison of research findings difficult. The goal of this work is to quantify the intracranial pressure responses to the input parameters of the CCI device using a surrogate head, i.e., a gel-filled ping pong ball. Findings from this work could be used to better design CCI tests.
Application of Scaling to Multibody Dynamics Simulations
Authors: Prescott William
Published: March 2016

This paper will examine the importance of applying scaling to the equations of motion for multibody dynamic systems when applied to industrial applications. If a Cartesian formulation is used to formulate the equations of motion of a multibody dynamic system the resulting equations are a set of differential algebraic equations (DAEs). The algebraic components of the DAEs arise from appending the joint equations used to model revolute, cylindrical, translational and other joints to the Newton-Euler dynamic equations of motion. Stability issues can arise in an ill-conditioned Jacobian matrix of the integration method this will result in poor convergence of the implicit integrator’s Newton method. The repeated failures of the Newton’s method will require a small step size and therefore simulations that require long run times to complete. Recent advances in rescaling the equations of motion have been proposed to address this problem. This paper will see if these methods or a variant addresses not only stability concerns, but also efficiency. The scaling techniques are applied to the Gear-Gupta-Leimkuhler (GGL) formulation for multibody problems by embedding them into the commercial multibody code (MBS) Virtual. Lab Motion and then use them to solve an industrial sized automotive example to see if performance is improved.
Study on High Efficiency Energy Harvesting Using Piezoelectric Coupled Beam With Self-Tuning Process
Authors: Cheng Yukun , Wu Nan , Zhao Shengjie
Published: March 2016

Studies on renewable energy harvesting have experienced significant growth due to the increasing demand of portable electronic devices and wireless sensor networks. We introduce the first time a beam energy harvester coupled with piezoelectric layers and stack actuators subjected to harmonic base excitation for achieving efficiency energy harvesting with a new developed self-frequency-tuning process. The self-frequency-tuning process of the harvester is realized by an adjustable axial force, which is generated by a piezoelectric stack actuator, through a feedback filtering electrical circuit. By the feedback filtering circuit, the value of axial force is determined by the amplitude of the output voltage generated on piezoelectric layers to tune the first natural frequency of the beam harvester close to the excitation frequency leading to a resonance of the harvester system. To describe and simulate the energy harvesting and the self-tuning process, a mathematical model is presented to calculate the dynamic response of the harvester as well as the output electric charge and voltage from piezoelectric layers for adjusting the axial force. It is noted that an iteration process is indispensable for the tuning process because of the transient nature of the vibrating system. A novel iteration numerical model is hence developed, and the whole energy harvesting process is divided into many short periods to represent the iteration steps and the self-tuning process. From numerical simulations, it shows that the self-tuning process helps increase the efficiency of the harvester, especially when the harvester is tuned close to its resonant state.
Environmentally Sustainable Design: A Case Study of LILYPAD Project
Authors: Shah Simran , Parveen Mallika
Published: March 2016

Environmentally Sustainable Design is in accordance with the concept of sustainability to design objects and built environment achieving a balance that causes no overall net environmental burden. At a time when global warming is proceeding at a rate, unprecedented in the past 1,300 years, we not only need to switch to greener energy sources and reduce consumption on the whole, but also make provision for the victims of future calamities that are inevitable due to irreversible environmental damage. This paper talks about creating an ecological balance in natural and manmade ecosystems. The need for Environmentally Sustainable Energy as well as the concept and its principles has been explained. A case study was taken up on the LILYPAD Project by architect Vincent Callebaut to showcase an excellent example of an environmentally sustainable design concept for future climatic refugees. The prototype is termed as an “auto sufficient amphibious city” and takes up the challenges launched by the OECD namely climate, biodiversity, water and health. The research also states how we can incorporate the idea of living symbiotically with nature in the construction of future homes with the implementation of one such concept i.e. Passivhaus standards. This paper aims to create awareness about environmental responsibility and how the use of environmentally sustainable design can help us realize this practically. All structures must be constructed with the aim of making them as energy efficient as possible by implementing the Passivhaus Principles and many such standards that can reduce our energy consumption and emission.
Dispersive Mixing Consideration of Twin-Screw Compounding Scale-Up Methodologies
Authors: Dryer Benjamin , Fukuda Graeme , Webb Jake , Bigio David I. , Wetzel Mark , Andersen Paul
Published: March 2016

Twin-screw polymer extrusion has shown increased utility for creating composite materials. However, in order to achieve the desired product properties, sufficient mixing is essential. Dispersive mixing, or the breaking-up of particle agglomerates, is critical to create filled compounds with the required material properties. In a twin-screw compounding process, the Residence Stress Distribution (RSD) has been used to quantify the dispersive mixing induced by the stresses in the polymer melt. These stresses are quantified by the percent break-up of stress-sensitive polymeric beads. It was found that the amount of material that experiences the critical stress is a function of the operating conditions of screw speed and specific throughput [1]. The quantification of dispersive mixing allows for better control of a compounding process and can be used to design new processes.

During the development of a new compounding process, screw geometries and operating conditions are often refined on a laboratory-scale extruder and then scaled up to a manufacturing level. Scale-up rules are used to translate the operating conditions of a process to different sizes of extruders. In a compounding process, the goal when scaling-up is to maintain the same material properties on both scales by achieving equivalent mixing. The RSD methodology can be used to evaluate the effectiveness of scale-up rules by comparison between two or more scales.

This paper will demonstrate the utility of the RSD in evaluation of two unique scale-up rules. Conventional industry practice is based on the volumetric flow comparison between extruders. The proposed approach demonstrates that in order to maintain equivalent dispersive mixing between different sizes of extruders, the degree of fill, or the percent drag flow (%DF), must be kept equivalent in the primary mixing region. The effectiveness of both rules has been evaluated by experimental application of the RSD methodology. A design of experiment approach was used to generate predictive equations for each scale-up rule that were compared to the behavior of the original small-scale extruder.

Statistical comparison of the two scale-up rules showed that the %DF rule predicted operating conditions on the large-scale extruder that produced percent break-up behavior more similar to the small-scale behavior. From these results, it can be concluded that the %DF scale-up rule can be used to accurately scale operating conditions between different-sized extruders to ensure similar dispersive mixing between two processes. This will allow for greater accuracy when recreating the material properties of a small-scale twin-screw compounding process on a larger, mass production machine.
Fatigue Analysis of Dental Prostheses by Finite Element Method (FEM)
Authors: Agostinho Hernandez Bruno , Paterno Alexander , Capello Sousa Edson Antonio , de Oliveira Freitas João Paulo , Foschini Cesar Renato
Published: March 2016

Introduction and Objectives: The dental prostheses are typical biomechanical structures because they have the objective to restore the mastication functions and are responsible for replacing the original tooth that was damaged. In the last few years, many studies have been done and big achievements have been noticed in this area. However, clinical studies and experimental procedures for these conditions are sometimes impractical, due to the biological nature of these components and the difficult to reproduce and to analyze such conditions. Moreover, it involves complex geometries, loads and mechanical behaviors, which analytical solution is very difficult to achieve. For these reasons, many researchers have applied the Finite Element Method (FEM). This method allows the evaluation of non-linear situations (e.g. biomechanical interactions) with complex geometries where experimental tests are usually difficult to be conducted. Furthermore, the uses of this method allow failure evaluation and it forecast occurrence. Like any mechanical structure, prostheses are sensible to failures. The cyclic nature of the loading that components are exposed means that fatigue failures are the type of failure which needs more attention in these kinds of structures. Therefore, this project aims to develop a tridimensional finite element model of dental prosthesis in order to evaluate the fatigue problem. Methods: A geometric model from a single dental prosthesis compounded by an implant, an abutment screw, an abutment, a fixation’s screw and a crown will be generated from Micro CT and scanning data. Then, the geometry will be exported to finite element software where a finite element model will be created. After these steps, boundaries conditions will be applied and simulations will be done. Finally, the simulation results will be analyzed. Results: The results from fatigue simulations and analysis demonstrated that abutment screw will have a finite life in most of the analyzed cases, and the fixation screw will be an infinite life. Conclusion: The results obtained illustrate the efficiency of Finite Element Method on simulating the biomechanical conditions, mainly in dental prostheses. In this study, the fatigue conditions were explored and analyzed. Finally, the knowledge about this problem could be improved.
Design of a Personalized Skin Grafting Methodology Using an Additive Biomanufacturing System Guided by 3D Photogrammetry
Authors: Ding Houzhu , Tourlomousis Filippos , Babakhanov Azizbek , Chang Robert C.
Published: March 2016

In this paper, the authors propose a novel method whereby a prescribed simulated skin graft is 3D printed, followed by the realization of a 3D model representation using an open-source software AutoDesk 123D Catch to reconstruct the entire simulated skin area. The methodology is photogrammetry, which measures the 3D model of a real-word object. Specifically, the principal algorithm of the photogrammetry is structure from motion (SfM) which provides a technique to reconstruct a 3D scene from a set of images collected using a digital camera. This is an efficient approach to reconstruct the burn depth compared to other non-intrusive 3D optical imaging modalities (laser scanning, optical coherence tomography). Initially, an artificial human hand with representative dimensions is designed using a CAD design program. Grooves with a step-like depth pattern are then incorporated into the design in order to simulate a skin burn wound depth map. Then, the *.stl format file of the virtually wounded artificial hand is extruded as a thermoplastic material, acrylonitrile butadiene styrene (ABS), using a commercial 3D printer. Next, images of the grooves representing different extents of burned injury are acquired by a digital camera from different directions with respect to the artificial hand. The images stored in a computer are then imported into AutoDesk 123D Catch to process the images, thereby yielding the 3D surface model of the simulated hand with a burn wound depth map. The output of the image processing is a 3D model file that represents the groove on the plastic object and thus the burned tissue area. One dimensional sliced sections of the designed model and reconstructed model are compared to evaluate the accuracy of the reconstruction methodology. Finally, the 3D CAD model is designed with a prescribed internal tissue scaffold structure and sent to the dedicated software of the 3D printing system to print the design of the virtual skin graft with biocompatible material poly-ε-caprolactone (PCL).
Multi-Layer Construction Process for Fabricating Electrospun Fiber Embedded Microfluidic Devices
Authors: Yan Karen Chang , Sperduto John , Rossini Michael , Sebok Michael
Published: March 2016

Microfluidic devices are widely used in biomedical applications owing to their inherent advantages. Microfabrication techniques are common methods for fabricating microfluidic devices, which require specialized equipment. This paper presents a multi-layer construction process for producing microfluidic devices via integrating two accessible fabrication techniques — hydrogel molding, a microfabrication-free method, and electrospinning (ES). The formed microchannels were examined via analyzing micrographs. Preliminary results demonstrate the feasibility of the method and potential for incorporating complex channels and device optimization.
Effect of Gravity on Human Lung Deformation
Authors: Seyfi Noferest Behnaz , Santhanam Anand P. , Ilegbusi Olusegun J.
Published: March 2016

The effect of gravity is considered on biomechanical modeling of human lung deformation for radiotherapy application. The lung is assumed to behave as a poro-elastic medium with spatially dependent property. Finite element simulation is performed on a three-dimensional (3D) lung geometry reconstructed from four-dimensional computed tomography (4DCT) scan dataset of real human patient. The spatially-dependent Young’s modulus (YM) values are estimated using inverse analysis from a linear elastic deformation model. First, the gravity-generated deformation in the lung is calculated. Next, inlet pressure loading is applied at the hilium from an initial stress-free resting volume. Then, the lung model is preloaded by its weight, followed by prescription of the inlet pressure. In each case the maximum and minimum deformation of selected landmarks are monitored with and without gravity. The results show that gravity indeed significantly affects the magnitude and distribution of lung deformation. The maximum displacement increases by 54% in the direction of gravity when it is considered in the model.
On the Capabilities of a Multi-Modality 3D Bioprinter for Customized Biomedical Devices
Authors: Ravi Prashanth , Shiakolas Panos S. , Welch Tre , Saini Tushar , Guleserian Kristine , Batra Ankit K.
Published: March 2016

Currently, there is a major shift in medical device fabrication research towards layer-by-layer additive manufacturing technologies; mainly owing to the relatively quick transition from a solid model (.STL file) to an actual prototype. The current manuscript introduces a Custom Multi-Modality 3D Bioprinter (CMMB) developed in-house, combining the Fused Filament Fabrication (FFF), Photo Polymerization (PP), Viscous Extrusion (VE), and Inkjet (IJ) printing technologies onto a single additive manufacturing platform. Methodologies to address limitation in the ability to customize construct properties layer-by-layer and to incorporate multiple materials in a single construct have been evaluated using open source 3D printing softwares Slic3r and Repetier-Host. Such customization empowers the user to fabricate constructs with tailorable anisotropic properties by combining different print technologies and materials. To this end, procedures which allow the integration of more than one distinct modality of the CMMB during a single print session were developed and evaluated, and are discussed. The current setup of the CMMB provides the capability to fabricate personalized medical devices using patient data from an MRI or a CT scan. Initial experiments and fabricated constructs demonstrate the potential of the CMMB for research in diverse application areas within biomedical engineering.
Additive Manufacturing of Carbides Using Renewable Resources
Authors: Islam Monsur , Martinez-Duarte Rodrigo
Published: March 2016

Here we report initial results towards additive manufacturing of carbides. We shaped and heat treated biopolymers-metal oxide gel composites in order to obtain 3-D carbide structures. Renewable biopolymers such as iota-carrageenan, chitin and cellulose were used to form the gels. Heat treatment of the gel composites resulted in amorphous porous carbonaceous material with high surface area. The carbonaceous materials preserved the original 3D shape. The ongoing work is on optimization of the conditions for carbide synthesis. We are also studying the rheology of the gel composites to aid to the additive manufacturing.