bluuebunny/crossref_metadata_2025_split huggingface dataset:
A New Technique for Evaluating Disassembly and Maintenance Using an Example of Underground Escalator
Authors: Shetty Devdas , Poudel Naresh , Xu Jiajun 
Published: March 2016

Few products are designed for disassembly or easy dismantling. As manufacturers recognize their responsibility for products at the end of their operational lives, the dismantling of products has emerged as a serious consideration in manufacturing. Disassembly is generally achieved by taking apart individual components or subassemblies of a large product. In situations involving integrated design principles, certain assembly procedures or joining techniques can make the disassembly of a product and separation of components into useful and non-useful groups very difficult. Designers are becoming steadily aware of the problem, and are employing techniques that allow them to design with greater responsibility - Design for Disassembly (DFD) is such techniques. In the case of a durable good with a long life cycle or a product with parts subject to wear, maintainability/serviceability may be more important than initial product acquisition cost, and the product must be designed for easy maintenance. The DFD principles identify the ease with which products can be fabricated, maintained, serviced, and recycled.
This paper examines a special case of evaluation of escalator housing using DFD method. Escalator system plays an important role in transporting passengers safely between underground and station platforms. However, due to the complex working conditions such as uneven load, extreme weather etc. of the escalator system, maintenance is constantly needed and unexpected failure and repair also happens frequently. The escalators used in train subway/metro stations are exposed to some extreme operating conditions such as extreme weather/temperature, uneven loads and shock etc. that can greatly shorten their life span. The increase to labor and maintenance cost impedes the escalator’s ability to efficiently serve its riders and affects its overall stability. The failure and repair of the escalator systems take a significant amount of labor and cost, in addition to customer dissatisfactions. This paper examines and identifies different types of failure modes and defects that occur in the major components of escalator drive systems, such as the motor and its drive chain system, handrail and its drive system, bearings/lubrication systems that are in adjunct with the bearing shaft assembly. The normal maintenance and repair of these sub systems is time consuming. For evaluating the design of the in the escalator, a new approach involving Rating Chart is used. This paper examines various existing DFD techniques and compares them with the Rating Chart method to evaluate DFD efficiency. The paper concludes by showing the robustness of the new DFD methodology in an environment where the products are exposed to extreme working conditions.
Fracture Mode Analysis of Lithium-Ion Battery Under Mechanical Loading
Authors: Luo Hailing , Jiang Xuqian , Xia Yong , Zhou Qing 
Published: March 2016

Due to its extensive application, the safety issue of lithium-ion battery has received increasing attention. For crashworthiness design of battery in electric vehicles, it is of great importance to investigate the response of the battery under mechanical loading and understand the mechanism of internal short circuit.
Quasi-static and intermediate strain rate uniaxial tension tests were conducted on the electrodes and the separators. The high speed camera and DIC (digital image correlation) method were adopted to measure the strain while a self-design load cell was used to measure force in dynamic test. Either loading velocity or loading direction was varied in different tests. The upper limit of the test strain rate achieved 66 /sec. All the component materials showed strain rate dependency and separators demonstrated noticeable anisotropy.
Quasi-static penetration tests were conducted on two different types of pouch cell using steel and plastic punch heads. For both Type A pouch cell and Type B pouch cell, during penetration process using plastic punch head, no significant voltage drop or temperature rise was observed. During penetration process using steel punch head, only Type A pouch cell produced short circuit. When the punch head was removed, the voltage of the cells could recover to certain level. From post mortem examination, it was found that for a single pouch cell, all the electrodes presented the same fracture mode that the stacked anode and cathode formed several fragments in the penetration path, while the separators in between only formed a central crack when the punch head went through. Since the separators had a larger elongation ratio than the electrodes, the extended separators around the rupture location could block the direct and constant contact between anode and cathode, electrodes and steel punch, which explained why no massive internal short circuit was initiated.
The drop tower was used to conduct dynamic penetration test. The results indicated that under dynamic loading, internal short circuit was more likely to be triggered which can be explained by the strain rate effect of the separators.
This study highlighted the importance of the separator to the safety performance of pouch cells.
Numerical Investigation on Vertical Axis Wind Turbine in Search for an Efficient Design
Authors: Rahman Mosfequr , Bashar Mohammad , Molina Gustavo , Soloiu Valentin , Salyers Travis 
Published: March 2016

The continuous improvement of this world is based on technological advancement. And the technological advancement is directly related to the utilization of energy. The demand of energy is creeping up every day due to increase of population, industrial and agricultural advancement. But the conventional energy sources are becoming limited which is ultimately making them more expensive. In addition to this, everyone is concerned about global climate change. This whole scenario is pushing the world to find the alternative sources of energy. Alternative sources involve natural phenomena such as sunlight, wind, tides, plant growth, and geothermal heat. Solar and Wind power are the most popular among the various sources of renewable energy.
Wind alone can fulfill most of the energy requirement of the world by its efficient conversion in to energy. Though Horizontal Axis Wind Turbine (HAWT) is more popular but needs high wind speed to extract energy from the wind. On the Other hand Vertical Axis Wind Turbine (VAWT) can run at low wind speed, independent of wind direction and can be installed anywhere with cheapest cost. The main objective of this research is to improve the design and performance of VAWT to make it more attractive, efficient, durable and sustainable. For a VAWT, the blades perform the main role to extract energy from the wind. Airfoil is considered as the blade for this new design of VAWT. Airfoil has some good aerodynamic characteristics, matches with the characteristics of Savonious type VAWT, such as good stall characteristics and little roughness affect, relatively high drag and low lift coefficient. Three dimensional CAD models of various simple airfoils have been designed in Solidworks. Using these airfoils CFD simulation has been performed for five different VAWT designed models. Moving mesh and fluid flow simulation have been performed using CFD software FLUENT. The findings of these numerical simulations provided pressure contour, velocity contour, drag coefficient, lift coefficient, torque coefficient and power coefficient for all these models. From the results it can be concluded that NACA7510 airfoil VAWT model gives the better performance at higher Tip Speed Ratio (λ) than other models.
Influence of Ignition Timing and EGR on the NOx Emission and the Performance of an SI Engine Fueled With Hydrogen
Authors: Khairallah Hassan A. , Vaz Warren S. , Koylu Umit O. 
Published: March 2016

Exhaust gas recirculation (EGR) and ignition timing have strong effects on engine performance and exhaust emissions. In the present study, detailed chemical reactions with 29 steps of hydrogen oxidation with additional nitrogen oxidation reactions were coupled with an advanced CFD code to investigate the engine performance and emission characteristics of a SI engine fueled with hydrogen. The NOx formation within the engine was computed using the extended Zeldovich mechanism with parameters adjusted for a carbon-free fuel such as hydrogen. The computational results were validated against experimental results with equivalence ratio of 0.84 and fixed ignition timing at crank angle of 5° BTDC (before top dead center). The simulations were then employed to examine the effects of EGR and ignition timing on the engine performance and NOx formation and emission. The EGR ratio was varied between 5% and 15% while the ignition timings considered were 5°, 10°, 15°, and 20° BTDC. It was found that NOx emission increased with advancing the ignition timing away from TDC while the indicated engine power showed an increasing trend with further advancing the ignition timing. Higher indicated mean effective pressure (IMEP) and indicated thermal efficiency were obtained with an advanced ignition timing of 20° BTDC. The model was also run with three different EGR ratios of 5%, 10% and 15% with fixed ignition timing at 5° BTDC. The simulation results quantified the reduction in NOx and the indicated engine power with the increase in the EGR ratio. The computations were consistent with the hypothesis that the combustion duration increases with the EGR ratio. Finally, the maximization of engine power and minimization of NOx emissions were considered as conflicting objectives. The different data points were plotted in the objective space.
Using the concept of “knee”, (5° BTDC, 0% EGR) was selected as the optimal operating point representing the best trade-off between maximum engine power and minimum NOx emissions.
Numerical Analysis of Transient Temperature Distribution in a Partially Cooled Nuclear Fuel Rod
Authors: Patil Sandeep , Chintamani Siddarth , Kumar Rajeev , Kumar Ratan , Dennis Brian H. 
Published: March 2016

Critical safety studies of a nuclear power plants are often associated with inadequate and improper cooling of the reactor core or the spent fuel rods. Coolant flow over the hot nuclear fuel rods often gets stalled during major accidents resulting in high temperature levels. These elevated temperature levels can potentially melt the fuel rod material and cause the release of radioactive gases. Research activities, both numerical and experimental in nature to explore these rare but potentially catastrophic possibilities have resulted in sophisticated numerical codes capable of simulating the various post-accident scenarios. These codes, although reasonably accurate and reliable have steep learning curves and are not often very user-friendly. A fast and accurate prediction of the critical temperature conditions using popular commercially available software packages is the subject of current study.
Results from this parametric study of temperature distribution over a partially cooled fuel rod carried out using ANSYS as the numerical analysis tool is reported. Nuclear fuel rods being inadequately cooled inside a stagnant pool of coolant water in an accident scenario resulting in disrupted coolant flow has been simulated. This situation can arise within the reactor (design-basis accidents) or in the waste-fuel storage (as faced in Fukushima). In these situations, the fuel rod is often left partially immersed in the coolant water resulting in immersed portion of the rod cooled by water and the exposed portion cooled by air leading to non-uniform and improper cooling of the system.
Realistic dimensions and materials as in commercial nuclear fuel rod have been used in the study. Taking advantage of the symmetry, an axisymmetric radial plane sliced longitudinally has been analyzed. Variations in the tangential direction have been neglected. The heat transfer problem uses homogeneous convective boundary conditions and assumes temperature dependent thermal conductivity. The parameters varied are the coolant level and the heat generation rate inside the fuel rod. A macro to automatically capture the transients in the temperatures was written in ANSYS (a finite element package). The governing energy equations were implicitly solved using finite volume scheme in MATLAB. ANSYS results are in close agreement with those obtained using MATLAB. The centerline temperature of the fuel rod shows a sharp rise below a certain coolant level.
Design and Development of Virtual Reality Environments for Biomedical and Engineering Applications
Authors: Govea Eder , Medellín-Castillo Hugo I. 
Published: March 2016

Virtual Reality (VR) is one of the areas of knowledge that have taken advantage of the computer technological development and scientific visualization. It has been used in different applications such as engineering, medicine, education, entertainment, astronomy, archaeology and arts. A main issue of VR and computer assisted applications is the design and development of the virtual environment, which comprises the virtual objects. Thus, the process of designing virtual environment requires the modelling of the virtual scene and virtual objects, including their geometry and surface characteristics such as colours, textures, etc.
This research work presents a new methodology to develop low-cost and high quality virtual environments and scenarios for biomechanics, biomedical and engineering applications. The proposed methodology is based on open-source software. Four case studies corresponding to two applications in medicine and two applications in engineering are presented. The results show that the virtual environments developed for these applications are realistic and similar to the real environments. When comparing these virtual reality scenarios with pictures of the actual devices, it can be observed that the appearance of the virtual scenarios is very good. In particular the use of textures greatly helps in assessing specific features such as simulation of bone or metal. Thus, the usability of the proposed methodology for developing virtual reality applications in biomedical and engineering is proved. It is important to mention that the quality of the virtual environment will also depend on the 3D modelling skills of the VR designer.
‘Acoustic Fiber’ Aluminum-Clad Copper Cable for Communication and Power Transmission
Authors: Litman R. B. , Scarton H. A. , Wilt K. R. , Saulnier G. J. 
Published: March 2016

An ‘acoustic fiber’, analogous to optical fiber, is presented as a means of long-distance data and energy transfer. Low-loss axial guided waves are produced along a cable-like waveguide, which is composed of a solid core and a cladding layer, where the cladding’s acoustic speeds of sound, both longitudinal and transverse, exceed those of the core. A similar condition exists in glass fiber optic cables consisting of a core surrounded by a cladding of lower index of refraction. This results in total internal reflection of light at the core-cladding interface and effective confinement of light to the core. A specific acoustic waveguide construction is analyzed, composed of an aluminum cladding with longitudinal wave speed of 6.198 km/s and shear wave of 3.122 km/s and copper core with longitudinal speed of 4.505 km/s, and shear speed of 2.164 km/s. Finite element simulations show that a guided wave mode that is confined largely to the core exists and is capable of propagating long distances with very little loss to the surroundings.
A 6 mm diameter aluminum-cladded copper core (2 mm diameter) fiber was found to have a propagation loss of 0.023 dB/m when operating at 2 MHz predict (neglecting material attenuation). When including material attenuation, the same waveguide produced a propagation loss of 0.24 dB/m. Similarly, a 12 mm cladding with 4.8 mm core at 1 MHz had losses of 0.10 dB/m, and a 22 mm diameter cladding with 9 mm core at 500 kHz had losses of 0.062 dB/m.
Relationships were found between frequency, total diameter and core diameter yielding the highest efficiencies. The minimum total dimension of an aluminum-clad-copper acoustic fiber was found to have an inverse relationship with frequency. The optimum ratio of core to total diameter was about 0.45 but between values of 0.35 and 0.5, attenuation was relatively constant (insensitive to frequency). Outside of that range, attenuation climbed rapidly. Due to this property, attenuation in properly designed fibers should always be dominated by, and roughly equivalent to, the material attenuation rather than attenuation due to leakage.
Finite Element Analysis of Various Projectiles Modeled as Bullets
Authors: Rahman Mosfequr , Chrysosferidis Steven , Salekeen Sirajus , Chevalier Adam , Bell David , Jones Bowen , Barlow Adam 
Published: March 2016

The objective of this research work was to perform a flow simulation around a running bullet and then compare and analyze three types of widely used bullet models. These are 7.62mm × 39mm, 7.62mm × 51mm, and 5.56mm × 45mm caliber popular NATO rounds respectively. Due to limited processing and computational resources, these bullet are modeled as cylindrical projectiles of similar length and diameter. Finite element analysis (FEA) are performed on these models using ANSYS explicit dynamics analysis code to investigate the effect of high velocity impact of these projectiles on a concrete plate. Three different types of meshing (coarse, fine, and fine with curvature) for each of these three cases have been used. Each projectile was fired at a different velocity. These velocities are selected in consultation with Hornady Manufacturing, Inc which has done extensive research on these bullets. The selected firing velocities for 7.62mm × 39mm, 7.62mm × 51mm, and 5.56mm × 45mm caliber bullets are 2021ft/s, 2539.4ft/s 2706.7ft/s respectively.
Overall, the simulation result of explicit dynamics clearly demonstrated cavitation and mushrooming of projectiles when impacting a 0.25 inch concrete plate. The 5.56mm × 45mm projectile seemed to have the largest overall total deformation values of 2.0303, 1.0487, and 0.26079 feet as obtained from simulation of the three types of mashing. This can be attributed due to the higher velocity (2706.7ft/sec) as compared to the other two cases. Similarly, the 7.63mm × 39mm has the highest average change of velocity of 144.7, 92.3, and 99.6ft/sec respectively from the three types of meshing among the three bullets which can be attributed due to its lowest impact velocity (2021ft/s).
Stress Analysis of Bone Scaffold Designed for Segmental Bone Defects
Authors: Slaoui Idriss , Stephenson Makeda K. , Abdul Rauf Huma , Dow Douglas E. , Shady Sally S. 
Published: March 2016

Segmental bone defects result in isolated bone fragments. These defects may be caused by trauma or disease and are a leading cause for orthopedic surgery. Segmental defects pose a challenge as they contain gaps between the ends of bones, which are too large for the regenerating tissue to naturally bridge and repair. A widely used clinical approach to repair such defects is the use of autografts that provide the essential bone growth features. However, autografts generate a secondary deficit in the region from which the graft was harvested. This grafting procedure may result in other complications, such as infections, inflammation, scarring, and bleeding. Synthetic bone scaffolding has been explored as a viable method of helping the body repair segmental bone defects. While synthetic bone scaffolding is a promising approach in orthopedic treatments, limitations exist. Bone is a complex organ with many cell types, emergent, anisotropic, mechanical properties and molecular interactions. Studies have shown that the inner geometries, such as pore size, play an integral role in bone regeneration, cell proliferation, differentiation and recovery. An architecturally-based approach in the design and fabrication of the scaffold may support the differentiation of complex bone tissues.
This study developed and tested scaffold designs having different pore size and beam thickness. The designs were developed and simulated for compression and tension in SolidWorks. A hexagonal unit cell was the basis for scaffold design. In one experimental trial (Group 1), the offset of the layers was varied. In another experimental trial (Group 2), the ratio between pore size and beam thickness was varied while using the optimal offset from the former trial. The material for simulation was poly-L-lactic (PLA) acid.
In the analysis of the simulation results, the optimal layer offset configuration of 100%,50% in the positive x-y direction showed the lowest stress distribution for both compression and tensile simulations compared to the other offset configurations analyzed. In the second trial of Group 2 models, two models with pore size to beam thickness ratios (7:1 and 8:1) demonstrated low stress distribution under the simulated physiological environments. These results suggest that both models can potentially have different applications in the repair of segmental bone defects.
Fracture Toughness of Samarium Cobalt Magnets
Authors: Curtin Paul R. , Constantinides Steve , Iglesias Victoria Patricia 
Published: March 2016

Samarium Cobalt (SmCo) magnets have been the magnet of choice for a variety of industries for many years due to their favorable magnetic properties. Their high coercivity, combined with a low temperature coefficient, make them the ideal permanent magnet for demanding high temperature applications. One of the biggest concerns with rare earth magnets is their brittleness. Samarium Cobalt magnets in particular are prone to fracturing during machining and assembly. In manufacturing, great care must be taken to avoid chipping or fracturing these magnets due to their brittle nature.
There are two main grades of Samarium Cobalt magnets, 1:5 and 2:17. These ratios define the nominal ratio of rare earth to transition metal content.
In this paper, an investigation is performed on the fracture toughness of permanent magnets based on the Samarium Cobalt 2:17 composition. Various techniques are used to characterize the microstructure of the material, and quantify the material properties.
Optical microscopy is used to characterize the grain structure of the material and quantify the porosity of the material after sintering. By comparing the average grain size and fracture toughness of several samples, grain size was shown to not affect fracture toughness in standard material. Latent cracks in defective material showed no preference to follow grain boundaries, oxides inclusions or voids.
River marks in fracture surfaces are seen through scanning electron microscopy, confirming the transgranular cracking pattern seen by Li et al [1]This suggests that the toughness of the material is an inherent property of the main phase, not of grain boundaries or contaminants.
Samarium Cobalt magnets exhibit both mechanical and magnetic anisotropy due to the alignment of their crystal structure in the manufacturing process.
Using Palmqvist indentation crack techniques, the magnetic orientation of the grains was seen to greatly influence the direction of crack propagation from the tip of the indenter. Measurements of fracture toughness using this technique produce highly scattered data due to this anisotropic nature of the material. Specimens loaded with the indenter axis parallel to the direction of orientation show normal Palmqvist cracks, while specimens loaded perpendicular to the direction of magnetization exhibit crack propagation initiating from the faces of the indenter.
To better quantify the material’s brittleness, fracture testing is performed on specially prepared samples to obtain an absolute measure of fracture toughness (K1c). Results show that SmCo is measurably weaker than other magnetic materials such as neodymium iron boron magnets[2]. Furthermore, neither relative concentration of Samarium nor source of raw material show notable effect on the fracture toughness of the material.