bluuebunny/crossref_metadata_2025 huggingface dataset:
The NSF REU/RET Research on Energy Absorbing 3D Printed Polymer Structures
Authors: Lewis Benjamin , Leary Jonah , Dickman Cynthia , Petroski Walter , Bellows Victoria , Morneault Abbie , Bucher Amanda , Copeland Diondra , Mian Ahsan , Srinivasan Raghavan
Published: January 2018

Energy absorption capability of structures with embedded pores depends upon the amount of voids present and their configurations/distributions. In this study, the energy absorption of acrylonitrile butadiene styrene (ABS) and polylactic acid (PLA) structures with varying pore shapes and sizes are investigated. The research was performed by two teams comprised of High School/Middle School teachers and undergraduate students as part of National Science Foundation (NSF) sponsored Research Experience for Teacher (RET)/Research Experience for Undergraduates (REU) teams. ABS samples were fabricated by Team 1 and utilized cubic unit cells with octahedral pores while Team 2 fabricated PLA samples that utilized unit cells with spherical pores. Eight sets of samples with dimensions 25mm × 25mm × 20mm were fabricated using a Makerbot Replicator 2X for ABS samples and a Lulzbot TAZ 5 for PLA samples. Each sample incorporated a 5 × 5 × 4 array of pores. All the samples were tested in compression and energy absorption per unit material volume of all the samples up to a particular maximum load was calculated from load-deflection curves. It is observed that the specific energy absorption of PLA and ABS porous structures greatly increases with increased porosity.
Dynamic Tensile Behavior of Fiber Bundles Freshly Isolated From Nerve Roots
Authors: Tamura Atsutaka , Hongu Jun-ichi , Yamamoto Tomomi , Koide Takao
Published: January 2018

Viscoelasticity of the nerve root may play a significant role in biomechanical stability of the spine. To date, however, relatively few studies have been conducted to characterize and elucidate this complex mechanical behavior. Thus, a series of tensile stress relaxation tests with a ramp-hold phase was performed using fiber bundles isolated from the nerve roots. In addition, the current study presents the application of a curve fitting technique, i.e., a stress relaxation response of the fiber bundles was theoretically predicted based on the measured data obtained at moderate to sub-traumatic loading conditions. To do that, a least squares optimization method was employed, and we revealed that this technique is applicable to reasonably predict even an instantaneous “elastic” response as well as subsequent slow stress decay of the neural fiber bundles. The resultant fitted coefficients also suggested that the viscoelastic tensile behavior of the nerve root is mainly dominated by the long-term time constants (100–1000 s) rather than the short-term time constants (0.1–1 s). Since a mathematical human body model is a powerful tool to investigate injury mechanisms involving high-contact sports and traffic accidents, our results will be useful in predicting potential spinal injuries and alleviating mechanical damage of the nerve roots, while preventing neck/low back pain due to such traumatic events.
Nonlinear Vibrations of Piezoelectric Carbon Nanotube-Reinforced Composite Trapezoidal Actuator Under Strong Electric Field
Authors: Bakhtiari-Nejad F. , Noroozi M.
Published: January 2018

In recent years, piezoelectric actuators have been extensively utilized in novel technologies such as insect-sized micro air vehicles. Utilization of common piezoceramics and high performance nanocomposite materials coupled with special geometry like trapezoidal plates which are driven at high electric field yields suitable actuators for use in such applications. First, in this paper the nonlinear vibrations of the carbon nanotube reinforced composites cantilever trapezoidal plate with two surface-bonded piezoelectric layers is modeled in accordance to classical laminate plate theory and large deflection Von Karman type equations for the geometric nonlinearity by using the Hamilton’s principle. The geometry of trapezoidal plate is mapped into rectangular computational domain. Second, the Galerkin discretization method is used for changing the partial differential equations into ordinary differential equations. Finally, the governing equations of the motion of piezoelectric laminated carbon nano-tube reinforced composite trapezoidal actuator with cubic nonlinearities under the external excitation and strong electric field with considering electroelastic and electrostrictive effects, is modeled and the linear natural frequency of transversal deflection is obtained.
Modular Prosthetic Design for Transtibial Child Amputees
Authors: Hickey Brendan M. , Woo Samuel T. , Shady Sally F.
Published: January 2018

Lower limb deficiencies and below knee amputations are the most common form of deficiency that may arise from disease or trauma, and returning a patient close to a normal quality-of-life requires prosthetics, which can be quite challenging. Children present even further difficulty to prosthetists and physicians than adults. Although the underlying prosthetic principles for adults are the same for children, additional considerations must be made for practicality, such as downsizing while maintaining its degree of complexity, and frequent appointments to account for the rapid growth of an adolescent. This review article will evaluate the current state-of-the-art in the field of transtibial-amputee prosthetics, review the insurance coverage a typical family would face, and suggest potential improvements to children’s biomimetic prostheses that aid in reducing the frequency of health care provider intervention.
Effect of Curing Time on the Mechanical Properties of a High Viscous PMMA Cement
Authors: Motalab Mohammad Abdul , Parvej M. S. , Kallol K. M. Zaman , Khandaker M.
Published: January 2018

It has been found from our previous studies that the time of curing of high viscous polymethylmethacrylate (HV-PMMA) cement influences the shear strength of titanium (Ti) implant/ HV-PMMA cement samples during pull out static tests, although the reason for the influence is not understood yet. This study hypothesizes that time of curing of cement influences the strength and hardness of the cement adjacent to the implant, which resulted in the variability of the shear strength between Ti and cement. To test this hypothesis, this study conducted ASTM standard three point bend (3PB) test on a HV-PMMA cement to measure the flexural strength of HV-PMMA cement that was cured for 10 and 60 minutes. In addition, this study conducted pull out tension tests on Ti/ HV-PMMA cement to measure the shear strength between Ti and HV-PMMA cement that was cured for 10 and 60 minutes. The hardness of the HV-PMMA cement at the adjacent to Ti was measured using a Rockwell R hardness test scale. Two groups of samples were produced for each type of experiments by varying the curing times: 10 and 60 minutes. The cement during the liquid phase poured into a custom made mold to create the 3PB cylindrical samples. For the pull out tension tests on Ti/cement samples, the Ti implant was fastened at the top gripper and a custom made holder that has a hole was fastened at the bottom gripper of universal mechanical test system. Cement was poured in to the gap between implant and holder. The cement was cured for an hour. This study found that the curing time significantly increases the values of bending, shear and hardness properties (p<0.05). The study concludes that the variability of the shear strength between Ti and cement depends on the strength and hardness of the cement adjacent to the implant.
Evaluation of Biomechanical Performances of Electrospun Fiber Anchored Silicone Disc As an Intervertebral Disc Implant
Authors: Tummala Subhakar , Dogan Oguz , Karpat Fatih , Riahinezhad Shahram , Khandaker M.
Published: January 2018

A tissue engineered intervertebral disc (IVD) anchor the circumference and top/bottom sides of nucleus pulposus (NP) implants with annulus fibrosus and endplates. The proper anchorage of a NP implant to annulus fibrosus and endplates is possible by enclosing the NP by electrospun fiber mesh that mimics the surrounding structures. The biomechanical performance of silicone based NP can be improved if electrospun fiber mesh can secure all sides of silicone NP. However, it is unknown whether silicone surrounded by an electrospun nanofiber matrix can better restore the biomechanical functions of the disc in compare to intact, IVD made with silicone only, and, IVD made with silicone anchored all sides by nanofiber. This study compared the compressive and viscoelastic properties of a silicone and electrospun nanofiber anchored silicone discs (ENAS) under compression and shear with the same properties of human NP. This study developed a nonlinear finite element model (FEM) for the intact and ENAS implanted human lumbar vertebra segments. The compression test results show that ENAS disc compressive modulus (87.47 ± 7.56 kPa, n = 3) is significantly higher in compare to silicone gel (38.75 ± 2.15 kPa, n = 3) and the value is within the range of the compressive modulus of human NP (64.9 ± 44.1 kPa). The rheological test results show that ENAS disc compressive modulus (16 ∼ 40 kPa) is significantly higher in compare to silicone gel (0.10 ∼ 0.16 kPa) and the value is within the range of the compressive modulus of human NP (7 ∼ 20 kPa). These results confirm the suitability of ENAS disc over silicone as NP implant. A finite element model has been developed based on the ENAS properties. The FEA results showed that ENAS can restore better the biomechanical motions of a lumbar vertebra segments in compare to silicone NP.
Numerical Optimization of a Gravity Dust-Catcher for Improving Operation Efficiency
Authors: Wang Yifan , Silaen Armin K. , Tang Guangwu , Barker David , Zhou Chenn Q.
Published: January 2018

Gravity dust-catchers are widely utilized in steelmaking plants to separate particles from the gas flow produced by the blast furnace (BF). The BF recycle system often experiences high total suspended solid (TSS) levels with a significant increase in sludge generation. This increased sludge generation results in higher costs in operation, chemical treatment and sludge removal. Due to the environmental limitations inside an operating dust-catcher, direct measurement of operating conditions can be extremely difficult. Computational fluid dynamics (CFD) models provide a method of gaining an understanding of the operating conditions and phenomena that occur inside a blast furnace dust-catcher on both full process and detailed levels. In this paper, a numerical geometry of the dust-catcher is designed and simulated under typical operating conditions. The Discrete Phase Model (DPM) is employed to track the flow patterns and paths of dust particles. The collection efficiency performance is evaluated at different conditions (quarter full, half full, and three quarter full). From these results, an alternative design to enhance process efficiency is proposed and investigated.
Product Lifecycle Management Tools to Support Next Generation of Mechatronic Systems at Aerospace Industry
Authors: Guerra-Zubiaga David A. , Briceno Simon
Published: January 2018

Product Lifecycle Management (PLM) Tools have been used extensively in different companies in recent years. These tools enable the development of components, products or assemblies in a digital way through their lifecycle. The entire lifecycle presents different challenges implementing digital tools and this paper explores relevant features between part design and manufacturing at mechatronics systems in the aerospace industry. New Product Introduction (NPI) process is a challenging task. In some cases, it is required not only the use of sophisticated robotics applications, but also in the integration of different instruments and controls in order to meet the accuracy and repeatability requirements. Complex scenarios need to be validated at early NPI stages at aerospace industry at not only part design, but also exploring the manufacturability of complex mechatronics processes demonstrating low cost production. Digital manufacturing tools in PLM are able to evaluate these complex scenarios through virtual prototyping to support the next generation of mechatronics systems in the aerospace industry. This paper argues that the understanding of virtual prototyping using digital PLM tools is an important issue for NExt GenerAtion MechAtronics SYstems (NEGAMASY) to support Aerospace Industry.
Experimental Specimen Selection for Stress-Displacement Behavior and Crack Initiation in Fiber Reinforced Composites
Authors: Daniels Mitchell A. , Rawlings Taylor J. , Parmigiani John P.
Published: January 2018

With the increasing use of composite materials in multiple industries, especially aerospace, better understanding of damage mechanisms is needed. Damage in composites can be categorized into four types: fiber tension, fiber compression, matrix tension, and matrix compression. Experimental methods for classifying damage and propagation have been thoroughly studied for the first three categories but matrix compression has received little attention. A previous study showed that compact compression (CC) specimens, modified from standard ASTM compact tension specimens, can be used to determine the behavior of matrix compression damage in carbon fiber reinforced polymers (CFRP), however CC specimens are not as effective as needed at identifying initiation conditions [1]. This paper presents a specimen to determine the strain energy dissipation rate at crack initiation and the primary failure mechanism of a selected CFRP that is small, has simple geometry, and requires a simple loading fixture. The simple geometry of the UC specimens allows for the stress-displacement behavior to be measured in a more direct manner than the CC specimens providing an opportunity for examination and classification of the material response. Small 15 mm × 15 mm × 3 mm rectangular cuboid uniform compression (UC) specimens were manufactured and tested to compare experimental results with previously tested CC specimen results. UC specimens were loaded in compression until fracture using two flat plates on the thickness face with fibers oriented at 90° from the loading face. The results indicate CC and UC specimen agreement between the strain energy dissipation rate at crack initiation for comparable crack angles, with a range of values between 33.6 kJ/m2 and 45.7 kJ/m2. The primary failure mechanism for both specimens was observed to be shear cracks through the thickness of the laminate with an angle between 47° and 73° measured from the plane normal to the loading direction. UC specimen results also indicate an inverse relationship between the strain energy dissipation and the fracture angle. The stress-displacement results suggest behavior can be split into three distinct response regions: elastic, plastic, and visible damage progression. These results indicate that small, simple UC specimens can be used to directly measure the stress-displacement behavior, determine the strain energy dissipation rate at crack initiation, and determine the primary failure mechanism under compressive loads. Further studies need to be conducted to fully understand the relationship between crack angle and strain energy dissipation at crack initiation.
Design and Control of an Assistive Bionic Joint for Leg Muscle Rehabilitation
Authors: Nagel Vincent , Chu Sarah , Forney Jack , Kosinski Lyle , Viswanathan Vimal
Published: January 2018

This project aims to create an electronically powered and controlled knee brace to aid stroke victims with partial paralysis with their leg muscle rehabilitation process. The newly designed assistive bionic joint takes the functionality of the existing assistive knee braces to the next level by incorporating a control algorithm that uses sensor signals gathered from the patient’s leg muscles. Electromyography (EMG) is used for gathering impulse signals from electrodes placed on key muscles as inputs for the device. The action of each major leg muscle is replicated using a set of fluidic muscles that mimic the functionality of the actual leg muscles. A microcontroller is used to interpret sensor data and adjust the contraction length of the muscles, thereby providing the wearer with augmented strength and mobility. Initial testing of a proof-of-concept prototype has led to finite control over muscle contraction length based on sensor data and has a response time of 280ms from full extension to contraction. Further testing of the brace assembly, fluidic muscles and control system is conducted and the results indicate a 600ms response time due to a step input. This personalized, powered brace has many implications for the enrichment of muscle rehabilitation such as higher patient morale, more muscle activity, and shortened recovery times.
An Ultra-Low Frequency Active Vertical Vibration Isolator With Geometric Anti-Spring Structure
Authors: Yao Jiamin , Wu Kang , Qian Jin , Wang Guan , Guo Meiying , Wang Lijun
Published: January 2018

Vibration isolators have been widely used to keep the target object from the ground vibration in order to improve the measurement accuracy. Nowadays, the ultra-low frequency vibration isolator based on a two-stage structure shows the best performance. Traditionally, vertically suspended springs are usually applied as the second-stage. As the requirement of the low stiffness, the springs need to be long, which brings the disadvantages of relatively large size and small allowable load. A novel ultra-low frequency active vertical vibration isolator is proposed in this paper, which applies geometric anti-spring (GAS) instead of the second-stage suspended springs. The isolated object (the second stage) is supported by GAS fixed on an inner frame (the first stage), and the inner frame is hung with supporting springs from the base of the vibration isolator. The inner frame is driven by a voice coil to track the motion of the isolated object according to the relative motion signal detected by a photoelectric detector. Ideally, GAS provides zero restoring force for the object, thus realizing a long natural resonance period. Experimental results show that the isolator can achieve a resonance period of 14.7 s, compared with a simulated result of 20.7 s. Therefore, it is accessible to reduce the isolator’s volume and increase the allowable load by replacing the traditional second-stage suspended springs with GAS, without harming the vibration isolation effect. Promisingly it will be applied in free-falling and atomic-interference absolute gravimeters, and other precise measurements.
Residual Stress Characterization From Numerical Analysis of the Multi-Particle Impact Behavior in Cold Spray
Authors: Moonga Kando Hamiyanze , Jen Tien-Chien
Published: January 2018

In cold spray, bonding forms between a substrate and the particles and between particles through impact deformation at high strain rates. A prominent feature of the cold spray process is the compressive residual stress that arises during the deposition process. Compressive residual stress on the surface can be beneficial for fatigue resistance. As a post processing technique several applications require surface treatment processes that produce this state of stress on component surfaces such as shot peening, laser shock peening, ultrasonic impact treatment, low plasticity burnishing, etc. In all of these methods, the compressive stress is produced through plastic deformation of the surface region. In a similar manner, the cold spray process induces compressive stress by high speed impact of the sprayed particles on the surface, causing a peening effect. The effects of these variations in the properties of the coatings are rarely reported. Moreover, there are some applications which require minimal residual stresses in the components such as in optics. In this study, we have investigated the residual stress using numerical analysis of the multi-particle impact behavior in cold spray.
Application of a Multi-Scale Hysteresis Friction Model to Aircraft Tires During Landing
Authors: Bothe Johan Steffen , Wangenheim Matthias
Published: January 2018

The friction characteristics of tires on rough surfaces depend on several variables. In this publication, the multi-scale model for tire-road-contact by Lind [1] is expanded in order to account for temperature influence. Implementing the temperature dependence of rubber material behavior allows a wider range of application. Simulations using aircraft tire conditions with experimentally obtained temperatures show that this multi-scale model is robust against high velocities and high contact pressures and yields coefficients of friction close to experimental results.
Directional Noise Reduction via Asymmetric Downstream Fluidic Injection
Authors: Rajput Pankaj , Kumar Sunil
Published: January 2018

The main aim of this investigation is to analyze directional noise reduction resulting from asymmetric high momentum fluidic injection downstream of a Mach 0.9 nozzle. Jet noise has been identified as one of the primary obstacles to increasing commercial aviation capacity. Microjets in cross flow are known to enhance turbulent mixing in the shear layer due to the induced stream-wise vortices. This enhanced mixing can be used for reorganizing the spatial distribution of acoustic energy. Targeted reduction in the downward-emitted turbulent mixing noise can be achieved by strategically injecting high momentum fluid downstream of the jet exhaust. Detailed Large Eddy Simulations were performed on a hybrid block structured-unstructured mesh to generate the flow field which was then used for near field and far field noise computation. Aeroacoustic analogy based formulation was used for computing far-field noise estimation. Benchmark cases were validated with preexisting experimental data sets. Mean flow measurements suggest shorter jet core lengths due to the enhanced mixing resulting from fluidic injection. The induced asymmetry due to the fluidic injection gives rise to an asymmetric acoustic field leading to targeted directional noise reduction in the far field as measured by pressure probes.
Thermal Foundation Benefits and Efficiency
Authors: Aoun Youssef , Kadi Maya , Bou-Mosleh Charbel
Published: January 2018

In this paper, a novel type of ground heat exchanger for geothermal applications is introduced. This heat exchanger is installed in the foundations of a commercial and residential building that has piles and diaphragm walls. This dramatically reduces the cost of the ground heat exchanger and makes the application more cost efficient with a payback period of 1–2 years compared to 10 years with the conventional vertical loops. The system will be detailed and its basic operation will be explained. In addition, test results of an in-situ thermal test response of a loop that is already installed in a foundation of a building in Beirut, Lebanon will also be presented. This test allows the approximation of the thermal conductivity of the ground and the amount of heat that is absorbed and extracted from and to the ground. The preliminary tests have given very promising results, since the ground is water dense and has a high thermal conductivity which increases the heat transfer between our heat exchanger installed in the foundation and the ground. In addition, in the current application, and around the foundation, there exists a lot of circulating water. This renders the application more and more efficient since the ground temperature will not fluctuate in the next 10 years.
Robustness Analysis of Various Approaches to Modeling of the Phase Change Front Propagation
Authors: Mauder Tomas , Klimes Lubomir , Charvat Pavel , Stetina Josef
Published: January 2018

Latent heat thermal energy storage (LHTES) has recently evolved into a promising approach for energy savings and pollution reduction. Phase change materials (PCMs) and the latent heat accompanying the phase change can be utilized to accumulate, store, are release the thermal energy when needed. The latent heat of the phase change allows for a storage of a relatively large amount of heat in a narrow temperature interval. The solid-liquid phase transition is widely utilized in such LHTES applications. Computer simulation tools are usually applied in the optimal design and real-time control of LHTES devices as the simulations are fast, relatively easy to perform and not expensive. Different numerical methods exist for modeling of heat transfer problems with phase changes. The methods can be assessed in several ways — accuracy, mathematical and programming complexity, demands for computational time and hardware, robustness etc. The well-known enthalpy method, the effective heat capacity method and the temperature recovery method are widely utilized as they are simple and easy to implement. These so-called domain or front capturing methods suffer from a low accuracy in the vicinity of the phase interface and they are quite sensitive to the size of the time step. On the other hand, front tracking methods allow for very precise results near the phase interface, but they are more complex and computationally quite demanding. An important point is also the sensitivity and robustness of a method in relation to the thermal conditions and properties. In particular, the large heat flux at the boundary and the high thermal conductivity often cause numerical difficulties and instabilities. In practice, computer models have to be precise enough and sufficiently fast, especially in real-time applications. However, these two objectives are related in an opposite direction. The paper presents a robustness and sensitivity analysis of the above mentioned methods. The responses and numerical behavior of the methods are investigated and analyzed. The test problems with distinct grid spacing, sizes of time steps and thermophysical properties of phase change materials. The results show that the front tracking method can achieve higher accuracy for coarse mesh sizes than other tested methods. This characteristic compensates for higher computational demands of the front tracking method.
Low Speed Orthogonal Machining of Pre-Heated FCC:BCC Alloys
Authors: Payton Lewis N.
Published: January 2018

Cocquilhat’s first documented (1851) how heat in a tool shortens the life of the tool. Research since his time has generally concluded that the tool gives up a relatively higher percentage of it’s “cold hardness and toughness” as compared to the work stock. This paper looks at the previously unstudied advantages/disadvantages which may be gained by pre-heating the work stock to a relatively modest temperature, thereby preferentially shifting the ratio/percentages back toward the tool. A widely-used body centered cubic (BCC) steel and a widely-used face centered cubic (FCC) aluminum were chosen to test common commercially machined crystalline structures. The materials were heat treated and/or aged to provide various levels of hardness within the crystalline structures. The selection of two cutting speeds, two levels of cut and three tool rake angles completed the factor level combinations chosen for the study. Parts were preheated immediately prior to the machining operations with an additional resistance heater mounted in the work holder to maintain the temperatures during the trial run. Tensile specimens of all the samples were undertaken to establish the cold working flow stress values of the materials tested. Machining was conducted in a specially modified Cincinnati Horizontal Milling machine using an improved Videographic Quick Stop Device (VQSD) to capture the geometry of the cutting formation simultaneously with the forces in the X, Y and Z-axes using a standard Kistler force plate dynamometer. Utilizing the VQSD greatly increases the number of replicates available for statistical analysis by the metal cutting researcher. This allows for comprehensive multivariate analysis of the data with high confidence (> 95%) in the obtained results. Forces and geometry were collected and analyzed. Wear was measured on the face of each tool using surface profilometers and white light microscopy. The specific horsepower (HPs), also known as the specific cutting energy, normal force (N), and wear rate data indicated there is a definite advantage to be had in pre-heating the workpiece by even a modest amount. In fact, the temperature was a significant prime factor (p-value <= 0.0001, Fstat > 5 with 95% certainty) in all factor level combinations. It was often ranked as the primary number one factor or the number two ranked factor. Many interactions with the temperature were also significant. This, combined with improved tool cooling methods, should result in all tools living a longer time while undergoing less chatter and/or deflection.
Evaluating Rosenbrock Methods for Usage in Real-Time Simulation of Multibody Models
Authors: Prescott William
Published: January 2018

The upward trend in the usage of sensors and intelligent systems in mechanical systems is requiring the continuing growth in hardware-in-the-loop (HIL) testing in theautomotive industry. This trend in turn is requiring that more sophisticated multibody system models (MBS) be incorporated into hardware-in-the-loop design and testing phases. Running sophisticated multibody models consisting of a large number of bodies and a variety of compliant elements is a challenging on a HIL system. The models must be detailed enough to give realistic results yet run fast enough to meet strict turnaround times of the HIL system. This paper will explore the use of a Rosenbrock method in a real-time environment and compare its performance and accuracy to other integrators in particular to a Backward Difference Formula (BDF) that is restricted in order and number of iterations.
An Effective Parameter Screening Strategy for High Dimensional Models
Authors: Chitale Janhavi , Khare Yogesh , Muñoz-Carpena Rafael , Dulikravich George S. , Martinez Christopher
Published: January 2018

The method of Elementary Effects (EE) is a parameter screening type sensitivity analysis technique that combines advantages of inexpensive one-at-a time methods and expensive variance decomposition based global Sensitivity Analysis (SA) techniques. Most of the sampling strategies for EE either use random sampling or maximize sample spread through oversampling. The Sampling for Uniformity (SU) is the only available strategy that combines the principle of sample spread with the principle of uniformity.

In this work, we proposed modifications to SU (eSU) to further improve sample uniformity. Performance of eSU was compared to that of SU based on uniformity, sample spread, sample generation time, and screening efficiency. Importance of the concept of uniformity was strengthened as eSU outperformed SU across all evaluation criteria. Further, it was found that eSU does not need oversampling and can result in better screening with relatively few trajectories indicating significantly reduced requirement on computational resources.
A Survey of Approaches for the Design of the Suspension of an Off-Road Vehicle
Authors: Maradey Lázaro Jessica Gissella , Roa Prada Sebastián , Rivera Cabezas Juan Sebastián , Castellanos Hernández Jonatan Fernando
Published: January 2018

The suspension is a very influential system in the performance of the vehicle, giving safety and maneuverability to the passengers in the usual movements (acceleration, braking, curves, irregular path, etc.). Since there are different types of suspension systems, a criterion must be stablished to determine which is the best or most suitable type for a given vehicle.

This article aims to review and analyze the different approaches, methodologies and design-performance criteria to be taken into account for the design of the off-road vehicle suspension; including the study of dynamics, geometric and dimensional factors, as well as the importance of the availability of components in the spare parts market, and some progress made in optimization, taking into account the feasibility of its implementation.

The results of this research provide guidelines for selecting some criteria and show the methodologies to achieve good suspension design and to help reduce the execution time and / or launch of an automotive project.
Mesoscale Models Characterizing Material Property Fields Used As a Basis for Predicting Fracture Patterns in Quasi-Brittle Materials
Authors: Acton Katherine A. , Baxter Sarah C. , Bahmani Bahador , Clarke Philip L. , Abedi Reza
Published: January 2018

To accurately predict fracture patterns in quasi-brittle materials, it is necessary to accurately characterize heterogeneity in the properties of a material microstructure. This heterogeneity influences crack propagation at weaker points. Also, inherent randomness in localized material properties creates variability in crack propagation in a population of nominally identical material samples. In order to account for heterogeneity in the strength properties of a material at a small scale (or “microscale”), a mesoscale model is developed at an intermediate scale, smaller than the size of the overall structure. A central challenge of characterizing material behavior at a scale below the representative volume element (RVE), is that the stress/strain relationship is dependent upon boundary conditions imposed. To mitigate error associated with boundary condition effects, statistical volume elements (SVE) are characterized using a Voronoi tessellation based partitioning method. A moving window approach is used in which partitioned Voronoi SVE are analysed using finite element analysis (FEA) to determine a limiting stress criterion for each window. Results are obtained for hydrostatic, pure and simple shear uniform strain conditions. A method is developed to use superposition of results obtained to approximate SVE behavior under other loading conditions. These results are used to determine a set of strength parameters for mesoscale material property fields. These random fields are then used as a basis for input in to a fracture model to predict fracture patterns in quasi-brittle materials.
Comparison of Multiscale Analytical Model of Friction and Wear of Viscoelastic Materials With Experiments
Authors: Emami Anahita , Khaleghian Seyedmeysam , Su Chuang , Taheri Saied
Published: January 2018

Friction and wear of viscoelastic materials like rubbers are topics of extreme practical importance such as the construction of tires, shoe heels and soles, rubber O-ring seals, and wiper blades. Friction of viscoelastic materials differs from the frictional properties of the elastic solids as friction is directly related to energy dissipation via the internal damping of such materials while purely elastic materials do not dissipate energy. Based on hysteresis properties of viscoelastic materials, physics based multiscale models were developed by Persson for fiction [1, 2] and powdery wear [3] of rubbers sliding on rough surfaces. In this research, these theories were studied and the theoretical results were compared with experimental results obtained from a dynamic friction/wear tester. The inputs to the theoretical models were the fractal properties of the rough surface, the dynamic modulus, and the fatigue behavior of the viscoelastic material. The fractal properties of the rough surface was obtained from the 3D profile of the surface measured using an optical profilometer. The dynamic modulus of the rubber samples was characterized via dynamic mechanical analysis at different frequencies and temperatures. The fatigue crack growth behavior of the samples were found from experimental results of crack propagation versus tearing energy obtained from the fatigue test. Then, the friction coefficient between different rubber samples and rough surfaces was calculated as a function of sliding velocity using both analytical model and experimental approach. In the dynamic friction/wear tester, normal force was adjusted and measured accurately, in addition, the frictional force was measured using a load cell in longitudinal direction along the sliding axis. The experimental sliding friction coefficient was calculated as the ratio of longitudinal force at a constant velocity to the normal force. The mass loss of rubber sample was measured by weighting the sample before and after each test to obtain the wear rate. The comparison between experimental and analytical results showed that the friction model could predict the friction coefficient accurately while the theory of powdery wear is unable to capture all the physics involved in rubber wear on rough surfaces.
CNT Bucky Paper Enhanced Sandwich Composites for In-Situ Load Sensing
Authors: Luo Wenyuan , Liu Yingtao , Saha Mrinal
Published: January 2018

The objective of this paper is to develop in-situ structural health monitoring in polymer matrix composites using embedded bucky paper. Bucky paper based sandwich composites has been used for damage and load sensing in aerospace and defense applications due to high electrical conductivity, low density, and outstanding load sensitivity. Recent research focuses on improving mechanical, electrical, thermal properties of certain composites with improved gauge factor for sensing applications. To better understand certainly quantity strain change effects, it is essential to design composite materials and sensors for in-situ and embedded strain monitoring in composites using piezoresistance feedback.

In this paper nanocomposite bucky papers are manufactured to monitor the load and damage condition in fiber reinforced polymer matrix composites. We first investigated the fabrication of bucky papers using different nanomaterials. Then the micro-scale morphology and structures are characterized using a scanning electron microscopy. The sensing function is achieved by correlating the piezoresistance variations to the stress or strain applied on the sensing area. Due to the conductive network formed and the tunneling resistance change in neighboring nanoparticles, the electrical resistance is able to show a good correlation with the load conditions. The prepared bucky papers are embedded in composites and the sensing capability is experimentally characterized under three-point bending experiments. The characterized membrane structures have the potential to be further applied to in-situ structural health monitoring and structural state awareness during their entire service lives.
Development of a Predictive Model for the Mass Transfer on the Paddy Rice (Oryza Sativa) Tower Drying Operation at Industrial Scale
Authors: Aldana Andrés , Guillen Diego , Bula Antonio , Sanjuan Marco
Published: January 2018

Paddy drying is one of the main operations on the rice milling industry and it has a wide impact in terms of kernel quality, infestation reduction and costs of operation. That is why process control is one of the main fields to ensure a successful operation. This paper presents the development of an industrial scale drying rate prediction model. The model includes on his structure mass balance equations, drying rate and bulk density equation and an experimental expression that estimates the rate of change in moisture as a function of the dry basis kernel water fraction, Sherwood number, mass transfer Biot number and a proposed non-dimensional temperature -Nt-. The importance of including -Nt- parameter is based on the thermal gradients between the drying air, internal kernel water and the installation environmental conditions. These factors create a distinctive characteristic from other drying rate prediction models because they associate the process with environmental conditions of the location where drying operation takes place.
Performance Evaluation of Empirical Mode Decomposition for EEG Artifact Removal
Authors: Alam MD Erfanul , Samanta Biswanath
Published: January 2018

Electroencephalography measures the sum of the post-synaptic potentials generated by many neurons having the same radial orientation with respect to the scalp. The electroen-cephalographic signals (EEG) are weak and often contaminated with different artifacts that have biological and external sources. Reliable pre-processing of the noisy, non-linear, and non-stationary brain activity signals is needed for successful extraction of characteristic features in motor imagery based brain-computer interface (MI-BCI). In this work, a signal processing technique, namely, empirical mode decomposition (EMD), has been proposed for processing EEG signals acquired from volunteer subjects for characterization and identification of motor imagery (MI) activities. EMD has been used for removal of artifacts like electrooculography (EOG) that strongly appears in frontal electrodes of EEG and the power line noise that is mainly produced by the fluorescent light. The performance of EMD has been compared with two extensions, ensemble empirical mode decomposition (EEMD) and multivariate empirical mode decomposition (MEMD)using signal to noise ratio (SNR). The maximum SNR values found for EMD, EEMD and MEMD are 4.30, 7.64 and 10.62 respectively for the EEG signals considered.
Experimental Analysis for Wire-Cylinder Electrostatic Precipitator
Authors: Li Chang , Alshehhi Mohamed S. , Khan Tariq S. , Salam Saqib
Published: January 2018

With the development of modern industry, the separation of suspended droplets from the gaseous flow has become increasingly important. In many industrial applications it is required to control the fine liquid droplets concentration in moving gaseous media. Refrigeration and Heating Ventilation Air Conditioning (HVAC) system is one major application. Electrostatic Precipitator (ESP) can be adopted for separation of fine droplets in gases, since corona discharge could charge these droplets, then use of electrostatic force to implement separation and collection. However, separation of droplets in gaseous flow is a complex process which is combination of electrostatic and flow field. The current study investigates effects of key parameters like applied voltage, flow temperature, flow velocity and particle’s size on particles separation efficiency using a wire-cylinder assembly. Monodisperse particles are used in this study where above mentioned parameters have shown significant effect on the separation efficiency.
Active Vibration Control for Robotic Machining
Authors: Wang Zheng , Keogh Patrick
Published: January 2018

Due to their flexibility, low cost and large working volume, 6-axis articulated industrial robots are being used increasingly for drilling, trimming and machining operations. However, producing high quality components has proven to be difficult, as a result of the inherent problems of robots, including low structural stiffness, hence excitation of structural modes, low positional accuracy, and bandwidth limitations associated with dynamics and control. These limit robotic machining to non-critical components and parts with low accuracy and surface finish requirements. As a part of the “Light Controlled Factory” project at the University of Bath, studies have been carried out to improve robotic machine capability, specifically positioning accuracy and vibration reduction. This paper describes experimental studies in reducing robot machining vibrations induced by cutting forces with active vibration control, using accelerometers to measure vibration and inertial actuators to mitigate vibration forces. With a relatively simple controller, a 25% reduction of RMS vibration amplitude is demonstrated.
The Significance of Hair Thermal Diffusivity on Melanoma Incidence
Authors: Huang Xiyong , Protheroe Michael D. , Al-Jumaily Ahmed M. , Paul Sharad P.
Published: January 2018

There is an increased risk of melanoma in adulthood when a child (pre-puberty) has been exposed to high levels of ultraviolet radiation (UVR). It has also been hypothesized that the childhood body air (vellus hair) plays a role in the increased incidence of melanoma later in life. This is attributed to the fact that the vellus hair has properties and physiology which encourage the transmission of harmful energy into the follicle of the hair and ultimately cause damage to the stem cells in residence there. Later in life these damaged stem cells become involved in the generation of melanomas in the epidermis.

It has been debated whether the UVR or the heat generated by it is the main contributor to melanoma occurrence. This research is the first step in investigating this phenomenon by focusing on the contribution of changes in thermal characteristics on the incidence of melanoma. To test the hypothesis that child hair can transmit energy more easily than adult hair the transient electro-thermal technique is used to determine the thermal diffusivity of the hair. This involved subjecting platinum coated hair samples to a current pulse and measuring the subsequent voltage response in the sample. Results show that the child hair has a thermal diffusivity around two times higher than adult hair, thus supporting the hypothesis. Further research will be needed, in particular, quantifying the optical transmission characteristics of child hair compared to adult hair.
Implementation and Evaluation of Mixed Model Representation of Virtual Objects in a Haptic Based Virtual Assembly Platform
Authors: González Badillo Germánico , Medellín-Castillo Hugo I. , Espinoza López Víctor E.
Published: January 2018

Virtual assembly systems have become popular in recent years due to its ability to simulate natural interaction between parts and ease of manipulation by the user. One of the most relevant technologies used in virtual assembly systems are haptic devices that provide force feedback and allow simulating real word conditions, such as weight, inertia, texture and collisions. Physics simulation engines (PSE) are another important tool used to simulate a realistic behavior in virtual assembly systems by enabling the effect of gravity and collision response of the virtual objects, resulting in a real world behavior. However, the use of haptic systems together with physics simulation engines is costly in terms of computing resources. This cost is mainly associated to collision detection between virtual objects, and increases when the shapes represented within the PSE are more complex, resulting in a poor performance of the virtual assembly system, making very difficult to simulate the assembly of complex parts or use several parts in the assembly. The present work shows a new algorithm to simulate complex objects, by using a different representation of the same object according with its dynamic state during the assembly process. The results show that the use of mixed model representation reduce the computing time when assembling objects, thus improving the performance of the virtual assembly system and finally allowing a better comfort and performance of the user during the assembly process. The system HAMS (Haptic Assembly and Manufacturing System) was used for the experimental validation, also the simulation of four assembly tasks that simulate real assembly objects, has been conducted.