bluuebunny/crossref_metadata_2025_split huggingface dataset:
Shape Optimization of Clutch Cushion Disc Using Differential Evolution Method
Authors: Kaya N. , Kartal S. , Çakmak T. , Karpat F. , Karaduman A. 
Published: March 2016

The clutch is an element which makes a temporary connection between gear box and vehicle engine. It transmits not only engine torque, but also ensures comfort and drivability during slippage. One of the main functions of clutch disc is to transmit the engine torque while absorbing vibrations. It allows a soft gradual reengagement of torque transmission. The cushion disc which is located between two clutch facings has wavy surface, thus it behaves like a spring during engagement and disengagement. The axial elastic stiffness of the clutch disc is obtained by a cushion disc. The load-deflection curve is obtained by compressing clutch disc between two plates, representing pressure plate and flywheel. The wavy shape of the cushion disc provides progressive stiffness curve of the clutch disc.
The cushion disc participates in drivers comfort during engagement of the clutch. The comfort depends on the limits of the progressive stiffness curve. Outside the limits of this cushion function, the clutch engagement would be harsh and uncomfortable for the driver. Besides, engine torque may not be transmitted during the later service lifetime and the life of the clutch might be decreased. In the case cushion disc has no cushioning function, then the engine might be stopped. Additionally, improper cushioning function causes heat and deform of the pressure plate and it also decreases the transmitted engine torque. Therefore, cushion disc has to have certain cushioning characteristics in order to overcome these problems.
In this study, the optimum shape design of cushion disc was performed using an evolutionary optimization algorithm. Differential evolution algorithm was selected as the optimization method because it guarantees the global optimum. Design of experiment method has been employed to construct the response surface that approximates the behavior of the objective function inside a certain design space. Three shape parameters of cushion disc have been selected. The objective of the shape optimization is to find the optimum shape parameters that provide the target stiffness curve. After solving the optimization problem with differential evolution method, optimum shape parameters of cushion disc have been found for two case studies. A Pascal code based differential evolution optimization code was developed for shape optimization and Ansys finite element software was used for calculating stiffness curve of cushion disc.
A Smart Method for Developing Game-Based Virtual Laboratories
Authors: Zhang Zhou , Zhang Mingshao , Chang Yizhe , Esche Sven K. , Chassapis Constantin 
Published: March 2016

Virtual laboratories are one popular form of implementation of virtual reality. They are now widely used at various levels of education. Game-based virtual laboratories created using game engines take advantage of the resources of these game engines. While providing convenience to developers of virtual laboratories, game engines also exhibit the following shortcomings: (1) They are not realistic enough. (2) They require long design and modification periods. (3) They lack customizability and flexibility. (4) They are endowed with limited artificial intelligence. These shortcomings render game-based virtual laboratories (and other virtual laboratories) inferior to traditional laboratories.
This paper proposes a smart method for developing game-based virtual laboratories that overcomes these shortcomings. In this method, 3D reconstruction and pattern recognition techniques are adopted. 3D reconstruction techniques are used to create a virtual environment, which includes virtual models of real objects and a virtual space. These techniques can render this virtual environment fairly realistic, can reduce the time and effort of creating the virtual environment and can increase the flexibility in the creation of the virtual environment. Furthermore, pattern recognition techniques are used to endow game-based virtual laboratories with general artificial intelligence. The scanned objects can be recognized, and certain attributes of real objects can be added automatically to their virtual models. In addition, the emphasis of the experiments can be adjusted according to the users’ abilities in order to get better training results. As a prototype, an undergraduate student laboratory was developed and implemented. Finally, additional improvements in the approach for creating game-based virtual laboratories are discussed.
A Thermodynamic Analysis of the Temperature Drop and Potential Cooling Effect of Cavitation
Authors: Alkotami Abdulmalik , Beck B. Terry , Sorensen Christopher M. , Hosni Mohammad H. , Eckels Steven J. , Tomasi Don 
Published: March 2016

The main objective of this paper is to evaluate the temperature drop and potential cooling effect due to cavitation of an arbitrary liquid. Cavitation results from a pressure decrease into the metastable liquid region, to the point where some of the liquid nucleates (boils). Under adiabatic conditions, the energy required to produce this phase change is pulled from the fluid itself, which results in a temperature drop.
The paper discusses the fundamental thermodynamics associated with the temperature drop in an effort to better understand the cooling process and to identify of the optimum fluid capable of developing significant cooling results.
The analysis presented here focuses on a general Equation of State (EOS), to represent an arbitrary fluid. At a given temperature, such an EOS yields a relationship between pressure and density (or specific volume). The van der Waals EOS was used initially to define the saturated liquid and saturated vapor lines, for water, R134a, R22 and R123. Work later focused on the Peng Robinson EOS, which better represents the properties of a wide variety of substances. The Peng Robinson EOS was used to investigate different fluids such as water, R134a, R22 and R123. The principle of corresponding states was introduced, to express the thermodynamic variables in terms of reduced (or relative) state variables. Coexistence curves and spinodal curves were determined numerically. This stems from the unique values of the acentric factor for each fluid.
A basic theory was then formulated using the Peng Robinson EOS to determine the maximum temperature reduction. ΔTmax, which will occur if the cavitation phase transition occurs adiabatically. Variables that affect this maximum temperature drop are identified are shown to include latent heat of vaporization, specific heat, and “equivalent quality” at the spinodal line limit.
Further analysis of the temperature drop as a function of reduced pressure was investigated for water, R134a, R123, and R22, and reveals that an apparent optimum (or maximum) temperature drop is achieved for a general fluid when the reduced pressure equals approximately 0.5.
The Boundary Integral Method Applied to Non-Spherical Cavitation Bubble Growth and Collapse Close to a Rigid Boundary
Authors: Alhelfi Ali , Sunden Bengt 
Published: March 2016

Recently much attention has been paid to studies concerning bubble dynamics in the cavitation phenomena and this topic has been the subject of many research works. In fact, the simulation of non-spherical bubble dynamics and its interaction with solid boundaries have received much less attention due to the complexity of the problem. One of the main reasons of the structural damages in the cavitation phenomenon is due to the formation of micro jets generated due to the bubble collapse and impinging on the solid surfaces or boundaries.
The boundary integral method (BIM) based on Green’s function is used to model the oscillation and collapse of a cavitation bubble close to a rigid boundary. The liquid is considered to be incompressible, inviscid, and irrational around the bubble. These assumptions satisfy the conditions for the Laplacian equation.
The theory permits one to predict correctly the interaction between the bubble and the rigid boundary, which is of great importance in the study of cavitation damage due to a bubble collapsing close to the boundaries. The results reveal that the amplitude of bubble oscillation depends on the bubble location away from a rigid surface. Also, the theory for the cavitation bubble dynamics presented in this study has many advantages in various situations and might be helpful to understand effects of the cavitation phenomenon such as generation of excessive vibration, surface erosion and undesirable acoustic emission.
Collapsible Wind Powered Energy Generation and Storage Device
Authors: Chambers Justin R. , Lowery Andrew D. , Smith James E. 
Published: March 2016

The described research is a light weight, inexpensive portable and collapsible wind turbine, small enough to be carried in a backpack, ruck sack or within the storage compartment of a vehicle, which can be used to recharge batteries and provide off-site, emergency, or campsite power. As a means to extend the battery life of electronic equipment while moving away from the power grid and extra battery storage, a power generating unit is needed. Current approaches are to carry the anticipated number of spare batteries, to use solar cells or any number of small generating thermionic devices. While each of these have a place in the market, they also have negative cost, size, and weight drawbacks.
The objective of this research is to create a power generating/storage wind turbine device for recreational, emergency, and military use that can easily be collapsed and transported as needed. The device is a lightweight, collapsible wind turbine constructed of rugged materials to be used on camp sites, remote locations etc. and carried within a pack for travel. It is of a size and weight to be part of an emergency or survival pack. The wind turbine, in its preferred embodiment, is a self-starting/sustaining device that starts at low wind speeds so no monitoring or priming of the device is necessary. In addition to the novelty of it being collapsible, the wind turbine device employs advanced features to increase its wind energy capture efficiency and its energy storage and delivery system, along with unique design features that make it rugged, lightweight and easily assembled.
Variable Stiffness Mechanisms Using Spherical Continuously Variable Transmissions
Authors: Capehart Twan , Moore Carl A. 
Published: March 2016

Some robot developers are considering elasticity to provide compliance for better adaption to a changing environment, shock resistance and safer human-robotic interactions (HRI). In this study we simulate a spherical continuously variable transmission (CVT) to validate its ability as the primary mechanism in a variable stiffness device for a 1D robotic hopper. The spherical CVT has been used in many robotic applications including cobots by Peshkin et al. [1] and as the driving unit in the load sensitive mechanism by Tadakuma et al. [2].
A CVT based variable stiffness/damping device intended for vibration mitigation was presented by Little [3]. That paper presented the kinematics and experiments of the CVT based variable stiffness/damping device for the specific application of vibration mitigation. This study considers the dynamics of the CVT based variable stiffness/damping device and modifies the device based on previous studies. We use ADAMS to simulate the modified system because it captures many of the real world dynamics arising from the CVT’s rolling friction dynamics. Finally we present a conceptual design of the variable stiffness CVT and briefly discuss its use in a 1D legged hopper application.
A Numerical Study of Multiphase Dielectric Fluid Immersion Cooling of Multichip Modules Including Effects of Nucleation Site Density and Bubble Departure Diameter Functions
Authors: Nguyen Jonathan , Knight Roy W. , Bhavnani Sushil H. , Harris Daniel K. , Fincher Seth , Gess Joshua , Sridhar Aravind 
Published: March 2016

In this study, the computational fluid dynamics programs ANSYS Icepak along with ANSYS Fluent were used to model and simulate the multiphase dielectric fluid immersion cooling of a multichip model on a printed circuit board using a variety of functions for nucleation site density and bubble departure diameter. Numerical results were validated against experimental data for the same geometry and working fluid. The numerical model in this study is a reduced form of an experimental setup, which consisted of four equally spaced, 24 mm by 24 mm die, arranged in a square pattern and centered on a printed circuit board. The numerical model consisted of the die and printed circuit board vertically suspended in a large, quiescent 15°C subcooled pool of Novec 649. Heat was uniformly dissipated from the die at fluxes ranging from 3 to 12 W/cm2. Pool boiling curves were generated from the numerical results and compared with experimental data.
This study involved the comparison of several functions for two boiling parameters: nucleation site density and bubble departure diameter. Four combinations of the standard functions available in Fluent were simulated. Numerical results for the worst combination over predicted the wall superheat by an average of 35°C for heat fluxes ranging from 3 to 12 W/cm2. In addition, the vapor fraction was under predicted by an order of magnitude and the increasing slope of heat flux versus wall temperature seen in the nucleate boiling regime of typical boiling curves was not consistently reproduced. Parametric studies were performed in which six bubble departure diameter functions and twelve nucleation site density functions were simulated with the remaining boiling parameters set to default Fluent functions. Next, combinations of nucleation site density and user-defined bubble departure diameter functions were simulated together. The worst of these over predicted the wall superheat by an average of 3.4°C for heat fluxes in the range of 3 to 12 W/cm2. The best agreement was seen when experimental data for bubble departure diameter were implemented as a user-defined function along with user-defined nucleation site density; these simulations matched experimentally measured wall superheat within 1.3°C in the same heat flux range.
Optimum Design of Tractor Clutch PTO Finger by Using Topology and Shape Optimization
Authors: Dogan O. , Karpat F. , Kaya N. , Yuce C. , Genc M. O. , Yavuz N. 
Published: March 2016

Tractors are one of the most important agricultural machinery in the world. They provide agricultural activities in challenging conditions by using various agricultural machineries which are added on them. Therefore, there has been a rising demand for tractor use for agricultural activities. During the power transmission, tractor clutches are exposed to high static and cyclic loading directly. Thus, most of clutch parts fail before completing their design life which is under 106 cycles. Especially, because of the high stress, there are a number of fractures and breakages are observed around the pin area of the finger mechanisms. Due to these reasons, it is necessary to re-design these fingers by using modern optimization techniques and finite element analysis.
This paper presents an approach for analysis and re-designs process of tractor clutch PTO finger. Firstly, the original designs of the PTO fingers are analyzed by using finite element analysis. Static structural analyses are applied on these fingers by using ANSYS static structural module. The boundary conditions are determined according to the data from the axial fatigue test bench. Afterwards, the stress-life based fatigue analyses are performed with respect to Goodman criterion. It is seem that the original design of the PTO finger, failed before the design life. Hence, the PTO finger is completely re-designed by using topology and shape optimization methods. Topology optimization is used to find the optimum material distribution of the PTO fingers. Topology optimization is performed in solidThinking Inspire software. The precise dimensions of the PTO fingers are determined by using shape optimization and response surface methodology. Two different design parameters, which are finger thickness and height, are selected for design of experiment and 15 various cases are analyzed. By using DOE method three different equations are obtained which are maximum stresses, mass, and displacement depending on the selected design parameters. These equations are used in the optimization as objective and constraint equations in MATLAB. The results indicate that the proposed models predict the responses adequately within the limits of the parameters being used. The final dimensions of the fingers are determined after shape optimization. The new designs of the PTO fingers are re-analyzed in terms of static and fatigue analysis. The new design of the PTO finger passed the analysis successfully. As a result of the study, the finger mass is increased 7% but it is quite small. Maximum Equivalent Von-Misses stress reduction of 25.3% is achieved. Fatigue durability of the PTO finger is improved 53.2%. The rigidity is improved up to 27.9% compared to the initial design. The optimal results show that the developed method can be used to design a durable, low manufacturing cost and lightweight clutch parts.
An Experimental Study of the Effect of SiO2 Nanoparticles on the Phase Change Characteristics of KNO3-NaNO3 Mixtures for Thermal Energy Storage
Authors: Gimenez-Gavarrell Pau , Fereres Sonia 
Published: March 2016

Combining latent and sensible heat storage within a single material has lead researchers to propose off-eutectic salt mixtures for solar thermal energy storage. A binary salt mixture with an off-eutectic composition presents a melting temperature range as opposed to a melting point, providing additional storage capacity through the sensible heat present during the melting/solidification. However, some drawbacks of off-eutectic mixtures include a higher propensity towards incongruous melting, phase segregation of the mixture upon solidification, and thermal cycling issues. Here the solid-liquid transitions of a series of eutectic and off-eutectic KNO3-NaNO3 mixtures are evaluated to determine if the addition of nanoparticles can limit phase segregation yet still present good thermal properties.
Measurements performed with a Differential Scanning Calorimeter show that the effect of nanoparticles is unimportant compared to the difference between eutectic and off-eutectic phase change behavior. Onset temperatures, latent heats, and the width of the phase transition temperature trace during melting/solidification are compared for the eutectic and off-eutectic salt mixtures with and without silica nanoparticles. A reduction in the latent heat is observed and explained through classical mixing theory. The modification of the phase change properties of eutectic and off-eutectic nanofluids are discussed.
Risk Evaluation and the NFPA 654 Layer Depth Criteria for Dust Explosion and Flash Fire Hazards
Authors: Ramirez Juan C. , Ogle Russell A. , Carpenter Andrew R. 
Published: March 2016

What is an acceptable thickness of accumulated combustible dust in an industrial facility?
Combustible dusts present both flash fire and explosion hazards. Companies which generate, handle, process, store, or distribute combustible dusts need to cost-effectively manage these hazards. In the United States, the Occupational Health and Safety Administration (OSHA) has stepped up its enforcement activity and is conducting inspections at these locations to verify that the facility is being operated in accordance with recognized and generally accepted good engineering practices (RAGAGEP). The combustible dust safety standard from the National Fire Protection Association, NFPA 654 (1) is often cited as the RAGAGEP for combustible dust risk management. One aspect of combustible dust risk management is the monitoring and control of fugitive dust accumulation on horizontal surfaces. NFPA 654 gives specific guidance on how to determine an acceptable level of combustible dust accumulation using different risk scenarios. These acceptable levels or thresholds were only recently added as requirements in the 2013 edition of NFPA 654 and there is debate as to whether they are accurate. An examination of this guidance reveals that it is very conservative because it omits consideration of several distinct events necessary for a dust deflagration or flash fire to occur.
NFPA 654, 2013 edition presents four techniques to determine if a flash fire or explosion hazard exists in a building or enclosure. These are: the layer depth criterion, Mass Method A, Mass method B, and Risk Evaluation. The standard gives explicit directions on how to calculate critical layer thickness using the first three methods. The standard does not give guidance on how to conduct a risk evaluation. In this paper we present a risk evaluation based on the NFPA 654 layer depth criteria. We formulate the dust accumulation scenario as a sequence of distinct events, estimate probabilities for each event, and illustrate how the NFPA 654 guidelines generally skew the layer depth criteria towards lower values. It is argued that the NFPA 654 guidance may result in layer depth criteria that are too conservatively low for facilities that manage marginally combustible dusts. In those facilities a more quantitative risk analysis will likely yield better, i.e., more practical criteria.
Safety-Informed Design: Using Cluster Analysis to Elicit Hazardous Emergent Failure Behavior in Complex Systems
Authors: McIntire Matthew G. , Hoyle Christopher , Tumer Irem Y. , Jensen David C. 
Published: March 2016

Identifying failure paths and potentially hazardous scenarios resulting from component faults and interactions is a challenge in the early design process. The inherent complexity present in large engineered systems leads to non-obvious emergent behavior, which may result in unforeseen hazards. Current hazard analysis techniques either focus on small slices of failure scenarios (fault trees and event trees), or lists of known hazards in the domain (hazard identification).
Early in the design of a complex system, engineers may represent their system as a functional model. A function failure reasoning tool can then exhaustively simulate qualitative failure scenarios. Some scenarios will be identified as hazardous by hazard rules specified by the engineer, but the goal is to identify scenarios representing unknown hazards.
A clustering method is applied repetitively to the large set of failure propagation results. Then, an algorithm identifies the scenario most likely to be hazardous, and presents it to the engineer. After viewing the scenario and judging its safety, the engineer may have insight to produce additional rules. The collaborative process of computer rating and human judgment will identify previously unknown hazards.
The feasibility of this methodology is being tested on a relatively simple functional model of an electrical power system. Related work applying function failure reasoning to a team of robotic rovers will provide data from a more complex system.
Retracted: “The Mechanical Performance of Subarachnoid Space Trabeculae” [ASME 2015 International Mechanical Engineering Congress and Exposition, Volume 3: Biomedical and Biotechnology Engineering, Houston, Texas, USA, November 13–19, 2015, Conference Sponsors: ASME, ISBN: 978-0-7918-5738-0, Copyright © 2015 by ASME. Paper No. IMECE2015-52463, pp. V003T03A092; 3 pages; doi:10.1115/IMECE2015-52463]
Authors: ASME  
Published: March 2016

The above referenced paper has been removed from publication. July 5, 2016.
Copyright © 2016 by ASME