bluuebunny/crossref_metadata_2025 huggingface dataset:
Numerical Research on Dual Fuel Combustor Combustion Performance
Authors: Pan Gang , Zheng Hongtao , Zhou Chunliang , Song Zhijia
Published: April 2014

In order to operate with reformed gas and oil, one gas turbine combustor which burned oil was modified and a dual fuel nozzle was developed. The CFD software FLUENT was applied to study the combustion flow field of the dual fuel combustor. The PDF (Probability Density Function) model, realizable k-ε turbulence model, DPM (Discrete Phase Model), NOX model and SIMPLE (Semi Implicit Method for Pressure Linked Equations) algorithm were adopted. In this study, the enthalpy of the two fuels which entered the combustor kept constant. The parameters of combustor temperature filed, gas temperature near wall and pollutant emissions with the two fuels were obtained and analyzed. Comparing to the oil combustor, the simulation of reformed gas combustor shows that the back flow velocity in main back flow region is higher, the high temperature zone in the combustor is closer to the combustor nozzle, the OTDF (Outlet Temperature Distribution Factor) is smaller, the average gas temperature near wall is about 60K lower, and the NOX emission at combustor outlet is lowered to 12.8ppm.
Multiscale-Based Simulations of Longitudinal Mechanical Behaviors of Single-Walled Carbon Nanotubes Reinforced Polymer Nanocomposites
Authors: Han James , Ko Yu-Fu , Yeh Hsien-Yang
Published: April 2014

Longitudinal elastic mechanical behavior of the armchair and zigzag single-walled carbon nanotubes (SWCNTs) and the SWCNTs reinforced polymer nanocomposites are investigated. Finite element analysis (FEA) models of the SWCNTs and the SWCNTs reinforced polymer nanocomposites are developed utilizing multiscale modeling technique along with molecular structural mechanics (MSM), which provides material properties at molecular scale and establishes relations between the steric potential energy and the classic structural mechanics. Material properties of C-C bond were obtained using multiscale-based modeling method with the consideration of shear deformation. In addition, for the interphase layer interaction between the carbon molecules of SWCNTs and the molecules of polymer matrix, multiscale-based modeling method was utilized to obtain the stiffness of nonlinear spring elements representing the van der Waals interaction. It is observed that the mechanical behavior of the SWCNTs reinforced polymer nanocomposites is dictated by the mechanical behavior of the SWCNTs embedded in the polymer matrix. Furthermore, varying radius and length of the SWCNTs would affect the longitudinal elastic mechanical properties of the SWCNTs reinforced polymer nanocomposites. Specifically, the simulation results had demonstrated that longitudinal elastic mechanical properties of the SWCNTs reinforced polymer nanocomposites would vary due to different loading conditions applied, i.e., discrete and continuous loading conditions.
Distributed Sensing in Actuator Array Manipulation
Authors: Bedillion Mark D. , Parajuli Deepak , Hoover Randy C.
Published: April 2014

Actuator arrays are planar distributed manipulation systems that use multiple two degree-of-freedom actuators to manipulate objects with three degrees of freedom (x, y, and θ). This paper describes methods of sensing the position and orientation of objects on an actuator array using only binary object sensors at each actuator. The object sensor information, when combined, forms a binary image of the object which may be processed to recover object pose. The methods’ effectiveness for rectangular objects is verified via simulation.
Evaluation of Aerodynamic and Seismic Coupling for Wind Turbines Using Finite Element Approach
Authors: Asareh Mohammad-Amin , Volz Jeffery S.
Published: April 2014

The behavior of a wind turbine consists of complex interactions between different components and subsystems. As more large scale wind turbines are constructed in seismically active regions, earthquake excitation makes an even more challenging problem when calculating extreme loads. Turbine specific simulation codes that directly include simulation of aerodynamics and seismic loading often include considerable simplifications to the turbine model that might cause unrealistic scenarios when designing such structures. Turbine related simulation codes are also often unfamiliar for civil engineers. For these reasons, it is desirable to come up with an approach that can handle a more realistic model that can simulate coupling between the influenced loads involved. In this work, the emphasis is put on the response of the tower of a large scale wind turbine subjected to aerodynamic and seismic loading. To capture the inclusive behavior of the structure, finite element analysis was used that consisted of shell elements for the tower, and beam elements for the blades. Various interactions were also used to model the rotation of the rotor during the operation of turbine under wind loading. Results of this approach were compared with previous findings using a selection of ground motions and turbulent wind fields. It is shown that for the turbine operational condition, the presented approach agrees well with the previously verified design codes. The outcome of this approach will provide a better understanding of more detailed structural aspects of wind turbines such as nonlinear behavior and failure criteria that might be considered necessary for a more comprehensive design.
A Thermoplastic Constitutive Modeling and Geotechnical Centrifuge Simulation of Partially Saturated Soil Under Buried Explosive Loading
Authors: Yarahmadi Asghar , Brannon Rebecca , Lista Carlos Bonifasi
Published: April 2014

In high-rate failure models for geological and rock-like materials, heating due to inelastic deformation is often neglected or accommodated incompletely through the use of an isentropic elastic response. However, for realistic prediction of geomaterials response to high-rate large deformations with significant released energy (such as buried explosive), dissipation caused by the initial mechanical work of the blast wave results in a non-negligible entropy generation that must be accounted for in constitutive modeling. In this study, thermal effects in the vicinity of a buried explosive in partially saturated soil are investigated using the Jones-Wilkins-Lee (JWL++) detonation model of High Explosive (HE) material, along with coupled multiphysics balance equations in an open-source massively parallel computational framework (Uintah) via Material Point Method (MPM) and Implicit, Continuous fluid, Eulerian (ICE) for compressible multi-material formulation of fluid-structure interactions (including highly pressurized explosive gaseous products). The temperature is allowed to evolve according to thermo-plasticity equations (derived from dissipation inequalities and basic conservation/thermodynamics laws) and thereafter, the state of internal variables (porosity, entropy, yield stress, etc) and stress in the partially saturated soil are determined for the obtained temperature. In order to account for material hardening from pore collapse, a yield surface based on Gurson’s upper bound theory evolves with stress, temperature, and internal state variables in plastic phase. Comparisons of soil response to blast loading are provided to quantify the importance of thermal effects.

Furthermore, geomaterials develop anisotropy in their response to deformation caused by prompt high-pressure shock waves. Thermodynamic admissibility implies that the fourth-order tangent stiffness tensor of geomaterials must develop a recoverable deformation-induced anisotropy (RDIA) even if the material is initially isotropic. This effect is significant for materials, like geomaterials, that have strongly pressure-sensitive strength. The degree of RDIA and the required additional terms in the form of deformation-induced anisotropy based on thermodynamics requirements in a high-temperature phenomenon are summarized for the region near the buried explosive source in partially saturated soil.
On Utilization of Material Failure Criterion in Modeling Pull-Out Failure of Spot-Welded Joints
Authors: Zeng Long , Xia Yong , Zhao He , Zhou Qing
Published: April 2014

Two distinct failure modes of spot welds, interfacial and pull-out failure, are observed in impact of spot-welded structures. Automotive industries prefer pull-out as the predominant failure mode since it makes more use of load-bearing capacity of a joint. For the time being, finite element models for predicting pull-out failure of spot weld have not been well developed. The dependence of failure on the stress state, i.e., a locus in the space of failure strain and stress triaxiality, needs to be known for base metal sheets when modeling spot weld pull-out. Existing failure criteria, with or without physical base, were formulated to provide an effective way to utilize a limited number of tests to reconstruct the failure locus.

This paper is aimed to evaluate influence of failure criterion form for identifying failure parameters on modeling spot weld pull-out. As for material tests, various specimen configurations of metal sheets were designed to obtain stress states around a number of typical stress triaxialities. These test results constructed a set of test data for calibrating failure criterion. The spot-welded joints were also tested two different coupon configurations. The force-displacement curves were obtained, and the deformation fields around the spot weld nugget were achieved with DIC. These test results of joints were utilized to validate the model of spot weld pull-out.

Two prevailing failure criteria, shear-modified Gurson model and Modified Mohr-Coulomb model, were selected to predict the complicated spot weld pull-out failure. Parameters in each of the two failure criteria were identified with material test data. Various simulation results were thereafter obtained based on different failure criteria. The two criteria were evaluated in terms of their predictive capabilities for spot weld pull-out failure.
Growth of Pre-Existing Micro-Void in Infinite Elastoplastic Body Under Remote Thermal and Mechanical Loads
Authors: Shi X. Y. , Shang X. C.
Published: April 2014

Growth of pre-existing micro-void in infinite elastoplastic body under remote thermal and mechanical loads is analyzed. A geometrical nonlinear mathematic model based on the Hooke elastic law and the ideally Mises yield criterion is constructed. The stress and the displacement distributions near the micro-void are presented by the elastoplastic analysis in this paper. The critical temperature and mechanical loads of cavitation can be calculated by the limiting case of a micro-void. The radius of the micro-void and the radius of the plastic zone increase rapidly when the remote temperature and mechanical load increase and close to the critical value from the numeric computation. It is shown that the unlimited micro-void growth under the critical thermal and mechanical load is referred to as an unstable cavitation.
New Curve Optimization Method and its Application to Shape Design for Die Casting Using a CFD Simulation
Authors: Kanazawa Ken’ichi , Yano Ken’ichi , Ogura Jun’ichi , Baba Shuhei
Published: April 2014

We propose a nonparametric curve optimization method based on a genetic algorithm. With conventional curve optimization methods, since the shape of a curve is defined by a finite number of design variables of real numbers and also has only finite flexibility, such methods may not provide the proper optimum curves. In contrast, the method we propose directly treats curves as solutions in the form of functions, without design variables, and can effectively optimize the curves by numerically synthesizing several functions. We demonstrate the effectiveness of the curve optimization method by applying it to an optimum design problem for die casting using a computational fluid dynamics (CFD) simulation.
Technical, Economical and Environmental Evaluation of Large Scale Commercial Coal Gasifiers
Authors: Ramirez Orlando M. , Corredor Lesme
Published: April 2014

Coal is the most interesting gasification resource in commercial application due to its wide reserves and low prices, therefore numerous commercial coal gasification technologies have been developed. The features of the most important have been studied in this paper. The gasifiers considered are the British Gas Lurgi, Siemens, General Electric, Conoco Phillips and Shell; principal parameters have been taken into account such as the cold gas efficiency, the production capacity, oxygen, electricity and steam consumption, effect of coal type, syngas produced for the desired final product, capital, operation costs, and environmental performance. From assessment of the latter features for each gasifier, one can conclude that although the BGL has the lowest production capacity with 1000 tons/day, it represents the best technology option due to its highest cold gas efficiency of 89%, the lowest oxygen and electricity consumption and the lowest capital costs with 50 million dollars per unit.
Accuracy Evaluation of the Coupled Eulerian-Lagrangian Method in Abaqus/Explicit Using a Passenger Airbag Model
Authors: Nandi Biswanath , Buettner Joerg
Published: April 2014

Computer simulations are widely used in modern automotive industry to design effective restraint systems, such as airbags. Until recently, the uniform pressure method (UPM), which assumes uniform pressure distributions inside the airbag, is mostly used in the design of airbags. The uniform pressure method is appropriate with fully inflated airbags interacting with in-position or belted occupants. However, with recent safety regulations for protecting occupants of various sizes and seating positions as well as the implementation of side airbags, Out-of-Positions (OOP) simulations are becoming more and more important for airbag suppliers and the OEMs. To simulate OOP cases, gas flow approaches are implemented in various commercial finite element codes in different forms.

This paper discusses the recent developments in the Coupled Eulerian-Lagrangian (CEL) method for airbag deployment simulations available in Abaqus/Explicit. A passenger airbag model was selected for the evaluation of accuracy of the CEL method. This paper also discusses some advanced Coupled Eulerian-Lagrangian method features available in Abaqus/Explicit in order to facilitate efficient occupant safety simulations.
Bending Stiffness and Dynamic Characteristics of a Rotor With Spline Joints
Authors: Wu Fayong , Liang Zhichao , Ma Yanhong , Zhang Dayi
Published: April 2014

Spline is a kind of typical joint structures widely used in the aero-engine rotor system. The stiffness distribution of the spool is affected by the spline joint’s stiffness directly. Therefore, it is significant to investigate the spline joint’s stiffness characteristics and its influences on the dynamic characteristics of the rotor system. To figure out the factors that affect the bending stiffness of the spline joint, a mechanical model which takes contact state into account was built based on the structure analysis and force state analysis. In addition, an actual rotor with a spline joint was established to measure the stiffness under different loads, and the results were compared with the analysis by three modeling methods. Furthermore, the natural frequencies of the rotor were tested.

Obtained results indicate that the structural discontinuity, the surface stiffness and the clearance fit cause the loss of local angular stiffness and linear stiffness. Meanwhile, the stiffness of the rotor with the spline joint is weaker along with the increase of the load/deformation, and become stable when undergoing the huge load/deformation. Besides, the local blending stiffness is presented as nonlinear and uncertainty subjected to an interval, which further affected the dynamic characteristics of rotor system.
Thermal Design of Alkaline Water Electrolysis Assisted by Combined Flash Binary Geothermal Power Plant
Authors: Kanoglu Mehmet , Yilmaz Ceyhun
Published: April 2014

The purpose of this study is thermoeconomic performance evaluation of alkaline water hydrogen production assisted by geothermal energy. In this study energy, exergy and cost balances of combined systems of each component for hydrogen production assisted by geothermal energy will be written. Exergy of each involved stream will be calculated and the exergetic balance of each subsystem will be assessed, as well as the global system, identifying and quantifying losses. This will allow thermodynamic performances of combined systems and each component. This information will be relevant to optimize the system performance from an economical point of view.

We consider a geothermal resource at 230°C available at a rate of 230 kg/s. Under realistic operating conditions, 21545 kW power can be produced in a power plant. The produced power is used for the electrolysis process. The electrolysis water can be preheated to 67.6°C by the geothermal water leaving the power plant and hydrogen can be produced at a rate of 0.1125 kg/s. Also, combine flash binary geothermal power plant energy and exergy efficiencies are calculated to be 12.1% and 57.4% at this condition. Electrolysis system energy and exergy efficiencies are calculated to be 71.4% and 60.7% of geothermal water temperature at 230°C and geothermal water flow rate at 230 kg/s. We evaluated at unit exergetic cost of electricity combined flash binary system is 10.1$/GJ (0.0364 $/kWh) and unit exergetic cost of hydrogen is 34.6$/GJ (4.16 $/kg H2).
Inertial Amplification Induced Phononic Band Gaps in SC and BCC Lattices
Authors: Taniker Semih , Yilmaz Cetin
Published: April 2014

This paper investigates effects of inertial amplification mechanisms on the phononic band structure of infinitely periodic simple cubic (SC) and body centered cubic (BCC) lattices. First, these three-dimensional lattices are formed using mass and spring elements. Then, dispersion curves of these lattices are obtained. Consequently, inertial amplification mechanisms are embedded around each spring in these lattices and their dispersion curves are calculated again. When compared to the cases in which inertial amplification was not used, phononic band gaps are obtained at much lower frequencies.
Performance of Lasered PCD- and CVD-Diamond Cutting Inserts for Machining Carbon Fiber Reinforced Plastics (CFRP)
Authors: Henerichs M. , Dold C. , Voß R. , Wegener K.
Published: April 2014

Carbon fiber reinforced plastics (CFRP) combine superior mechanical properties with a low weight. Consequently, this material is highly interesting for the aircraft as well as the automotive industry, leading to a massively increased application over the last years. However machining CFRP still faces different difficulties: The material is highly abrasive, most tool substrates and coatings face massive abrasive wear. Machining CFRP often results in many material defects like delamination, fiber pull-out, high surface roughness and burnt matrix material. Several technologies have been developed to combine ultra-hard tool surfaces and most adaptable cutting edge geometries. One of the most interesting approaches is laser machining of diamond cutting edges. The technology combines the wear resistance of thick layer diamonds with a geometrical flexibility so far known only for carbide tools. In the presented study, the wear resistance of different Polycrystalline Diamond (PCD) and Chemical Vapor Deposition (CVD)-Diamond grades machined with two different laser systems has been tested for machining CFRP. In comparison state-of-the-art grinded PCD cutting inserts are being tested. The comparison of machining characteristics is done by machining CFRP in a continuous turning process with a single fiber orientation. Machining forces are measured to evaluate tool wear. The resulting work piece quality is analyzed by measuring the surface roughness. The machined CFRP is a M21 resin system with an IMA-12K fiber from Hexcel©. Laser machined cutting inserts show equal or superior wear resistance compared to the grinded cutting inserts. In result today lasered cutting inserts are the machining tools available with the highest tool life time. In combination with the freely adaptable tool geometry, lasered cutting inserts are the superior tool system for upcoming machining tasks.
Operator Related Causes for Low Correlation Between CAT Simulations and Physical Results
Authors: Rosenqvist M. , Falck A-C. , Söderberg R. , Wärmefjord K.
Published: April 2014

The objective of this study was to explore correlation between CAT (Computer Aided Tolerancing) simulation and physically measured results in running production with focus on operator dependant factors. Therefore, the manual assembly of 25 different system solutions (locating scheme, tolerances, fasteners etc for a part) was analyzed. The study has been performed in the automotive industry and the system solutions are from 3 different cars in 2 different factories, all manual assembly in a paced line.

The analysis shows several interesting results; in running production 33% of the measurements are not ok although 28% had their tolerance zone adjusted according to the measured results to make them ok. The conclusion is that the CAT simulations do not predict all the variation and therefore additional factors need to be included to enable accuracy improvement.

Further relationships between additional factors such as operator influence and bad geometrical quality can be proven.

A short term solution is suggested as well as a long term solution involving the need for development of additional functions in CAT tools, the overall goal being to decrease the difference between simulation results and actual physical results.
Experimentally Validated Thermo-Mechanically Coupled FE Simulations of Al/Mg Friction Stir Welded Joints
Authors: Kheireddine A. H. , Ammouri A. H. , Kridli G. T. , Hamade R. F.
Published: April 2014

Numerical simulations of the friction stir welding of dissimilar metal joints is a daunting task given the complex issues involved such as the flow mixing action and the phase transformations. In this work, a 3D thermo-mechanical FE model is developed to simulate the dissimilar friction stir welding (DFSW) of aluminum-magnesium bi-metallic joints. The model is built using a manufacturing-processing-specific FEM software package (DEFORM 3D). Suitable constitutive laws are implemented to describe flow stress for both welded constituents: Al and Mg. The flow patterns of the stirring action from the simulations were verified against flow patterns of steel shots reported from experiments published in the literature. Also, the simulated interface patterns were found to be in agreement with microscopic images of welded sections taken from reported experiments. Furthermore, simulated temperature profiles favorably compare with temperature measurements previously published in the literature. The numerical model output includes relevant results such as material flow and volume fractions throughout the joint but most importantly in the recrystallized stir zone.
Experimental Research on Dynamic Characteristics of a Rolling Agricultural Tire (Influence of Running Condition)
Authors: Fujita Katsuhide , Saito Takashi , Kaneko Mitsugu
Published: April 2014

When agricultural machines are operated on pavements, the vibration and noise caused by the interaction between the tire lugs and the road surface are inevitable. In conventional studies, it is considered that the dynamic behavior of a rolling agricultural tire is influenced by the vibration characteristics of the tire. Resonance occurs when the lug excitation frequency of the tire, which is defined as the lug number multiplied by the number of revolutions of the tire, becomes equal to the natural frequency of the tire. In other words, the rolling tire shows large vibrations in the direction of the natural mode corresponding to the natural frequency of the tire. However, in the conventional equipment, the diameter of the drum is smaller than that of the tire. Therefore, the real running condition on the road was not realized by the rolling test using the conventional equipment. In this study, a new equipment is produced to realize the running condition in the rolling test. The dynamic and vibratory characteristics of operating agricultural machine are investigated by using this new equipment. The obtained results are compared to the conventional ones and the influence of the running condition on dynamic characteristics of rolling tire is investigated.
Gas Separation Using a Membrane
Authors: Alkhamis Nawaf , Anqi Ali , Oztekin Dennis E. , Alsaiari Abdulmohsen , Oztekin Alparslan
Published: April 2014

Computational fluid dynamics simulation will be conducted for multicomponent fluid flows in a channel containing spacers. The Navier-Stokes equation and the species transport equations are solved for various values of Reynolds numbers. The membrane will be modeled as a functional surface, where the membrane fluxes of each component will be determined based on the local partial pressures of each species, the permeability and the selectivity of the membrane. Laminar flow modeling is employed for the flow inside the channel without the spacers; while k-ω turbulent modeling is used to simulate the flow inside the channel with the spacer, for Re = 100, 150 and 200. The spacers are placed in an inline arrangement. The presence of spacers in the channel improves the membrane performance at Re = 200. The effects of the spacer on the separation process at low flow speeds (Re = 100 and 150) are negligible. The performance of the system will be measured by the maximum mass separation with minimal friction losses.
Effects of Environmental Factors on the Growth of Algae for Biofuel Production in a Household-Based Alternative Energy System
Authors: Allameh Seyed M. , Schutzman Clara , Beckman Ella , Allameh Hadi , Steinitz-Kannan Miriam
Published: April 2014

The efficiency and cost effectiveness of using algae to create biofuel has been much debated in recent years. A household-based biofuel system that uses sewage as a medium in which to grow mixed algae cultures is a possible solution to decreasing the production and transportation costs of biofuel. Aside from the manufacturing issues involved, it is important to determine what variables most affect the growth of algae and the production of biofuel. This study presents the results of an ANOVA-based set of experiments that evaluate the effect of several variables on algae growth in wastewater. While much work remains to be done, these results will help determine the optimal environmental conditions for a household-based biofuel system that utilizes mixed algae cultures.
Modelling of Misaligned Rotor System in Aero-Engines and Interval Method Investigation
Authors: Wang Guihua , Ma Yanhong , Li Tianrang , Li Jun , Hong Jie
Published: April 2014

Based on the structural and dynamic characteristics of aero-engine rotor system, we used Lagrange method to develop a two-bearing and a multi-bearing rotor model with misalignment. An equation of motion was derived with features of response examined. Due to the uncertainty of mechanical parameters, interval method was adopted to investigate the dynamic response of rotor system with misalignment. Dynamic response and influence of the key mechanical parameters will be obtained in further research.

The two times harmonic was found as a distinctive feature of misalignment and the magnitude of it in spectrum is closely related to some key mechanical factors. We also found interval method outstandingly performed in investigating dynamic response when some key parameters are uncertain.
Control of Drilling and Coring Device Based on Online Identification
Authors: Quan Qiquan , Li S. , Jiang S. , Hou X. , Deng Z.
Published: April 2014

This paper presents a drilling and coring device for the lunar exploration, which is possibly utilized to acquire the lunar regolith with a certain depth. The drilling device is composed of three components: rotary unit, percussive unit and penetrating unit. The rotary-percussion drill can work in two different operating modes: rotary mode and rotary-percussive mode, depending on the properties of cut object. In the relatively loose regolith, rotation and penetration can make the drill work in a well state. However, once rock is encountered in the drilling process, besides rotation and penetration, percussion must be launched to reduce the drilling power and the required penetrating force. Due to the indetermination of the lunar environment, it is not easy to control the coring drill to adapt to the encountered conditions. To obtain a high coring ratio with relatively low power, an intelligent drilling strategy is inevitably proposed to accomplish the drilling process control. Considering the lunar soil simulant should cover the possible composition of real lunar soil, simulant are classified into several levels based on the generalized drillability. For each level of drillability of lunar soil simulant, experiments are conducted to get the characteristics in frequency-domain of rotary torque output. The sampled characteristics of rotary torque output are utilized to train the object-recognition system based on Support Vector Machine (SVM). Information in all the levels of drillability of lunar soil simulant is stored in the object-recognition system as an expert system. To understand the properties of the drilling object, rotary torque is selected to identify the level of drillability of simulant in drilling process. Subsequently, once the level is obtained, drilling strategy is adjusted to adapt to the current level correspondingly in real time. Experiments are conducted to verify the intelligent drilling strategy successfully.
Vibration and Dynamic Analysis of Oil Well Drillstring Considering Coupled Axial and Torsional Effects Using Cylindrical Superelement
Authors: Ahmadian M. T. , Ghorbani Sh. , Firoozbakhsh K. , Barari A.
Published: April 2014

In this paper axial and torsional vibrations of a drillstring are studied using cylindrical superelement. Drillstring vibration equation is derived by calculating kinetic and potential energy and work done by external forces on drillstring, and utilizing Hamilton’s principle. The model is analyzed by implementing finite element technique with consideration drillstring weight, centrifugal force due to rotation of drillstring, axial force resulting from bit with the formation contact and torsional torque caused by the stick-slip phenomenon. To calculate the vibrational response of drillstring, a computational finite element scheme was developed. For a typical case of oil well drillstring, the time response of axial and torsional vibrations of bit are presented. Also, time history of rotational speed of bit and frictional torque caused by the stick-slip phenomenon on bit, are calculated. Very good agreement is found between findings with implementing superelement and those were reported in the literature. The time consumption by conventional finite element method is very larger than implementing cylindrical superelement for the same problem. This indicates by implementing a few cylindrical superelements, the same results in much smaller computer time than the conventional finite element method, can be extracted.
Optimizing Machining of Machine Tool Casting Bodies by Means of Optical Scanning
Authors: Gessner Andrzej , Staniek Roman
Published: April 2014

The hereby presented study reports on the results of research funded by the NCBiR improvement grant. The goal of the undertaken experimental effort was to eliminate the laborious process of marking out from the technological procedure of cast machining. Marking out, even in highly automatized machining enterprises, is performed manually. It assesses casting accuracy, as well as denotes surpluses on machining surfaces. The precision of marking out is, therefore, dependent on individual performance of a given worker. Moreover, gauging casts of cylindrical (non-perpendicular) shape is highly problematic. Incorrect marking out generates quantifiable material (cast iron) and machining losses, as well as production interruptions.

Herein, we present an innovative cast machining technology based on cast model scanning. Prior to machining, each body is scanned according to the technology guidelines. The subsequent comparison of the cast model and the model of the machined body affords geometrical accuracy assessment of the cast and the determination of optimal machining surpluses. The surplus verifying criteria include: machining volume minimization, tool working motions minimization, and idle tool motion minimization. Moreover, in special cases, high productive cutting (HPC) or high speed machining (HSM) optimization of cast technology, as well as elimination of superfluous procedures (e.g. milling of machining datum surfaces), are possible. The proposed comparative analysis of the aforementioned 3D models additionally affords acquisition of data for positioning (horizontal alignment) of the machined cast, e.g. the required length of technological supports.

The hereby presented experimental results (obtained in an industrial setting) confirm the proposed elimination of the marking out process, thereby affording time reduction of preparatory procedures, initial assessment, and positioning of the cast for machining, as well as a decrease of machining volume by approx. 10 % (for the investigated casts). Experimental simulation results allowed us to estimate the machining volume minimization reaching up to 25 % (depending on the cast shape and the machining process specifications). Moreover, our investigation indicated a possibility of detection of casting flaws caused by insufficient surface brushing down. As the casts are painted post-brushing, the interfering sand mold remains are easily overlooked and often cause cutting-tool damage leading to costly production interruptions.
Efficient Simulation of Acoustic Emission With Reflections Removal Based on Infinite Element and Rayleigh Damping
Authors: Xiao D. H. , He T. , Liu X. D. , Shan Y. C. , Yu H. S.
Published: April 2014

Acoustic Emission (AE) is defined as the transient elastic wave generation due to a rapid release of strain energy within or on the surface of a structure, which is well known as a sensitive technique to detect various types of damage, such as crack propagation in structure. This paper presents a new simulation method for AE by investigating the removal of unwanted reflections in the waveguides including plate and thin-walled cylinder structures which is based on the theory of the infinite element and Rayleigh damping. The finite element (FE) models are established with reflections removal condition proposed in this paper. The properties of AE source mechanism, propagation and reflection are investigated through finite element (FEM). To validate accuracy of the FE technique, the AE simulation of an isotropic plate and the pencil lead broken test on a steel plate are carried out, and the data is processed by the Choi-Williams transformation. It manifests that the simulation results are in good coincide with the experiment results. Then the removal effect is investigated by AE simulations in a thin-walled cylinder and an anisotropic plate. All of the results demonstrate that the Rayleigh damping has significant influence on the removal effect of infinite elements. Moreover, illustrate that high accuracy removal of unwanted reflection can be realized by the infinite elements with appropriate Rayleigh damping.
A Multibody Motorcycle Model for the Analysis and Prediction of Chatter Vibrations
Authors: Catania Giuseppe , Leonelli Luca , Mancinelli Nicolò
Published: April 2014

The chatter phenomenon, appearing during high speed cornering maneuvers performed by racing motorcycles, consists of a self-excited vertical oscillation of both the front and rear unsprung masses in the range of frequency between 17 and 22 Hz. The suspensions are not generally able to dampen the above vibrations which start from the rear wheel and suddenly propagate to the front wheel during the corner entry phase, making the vehicle’s handling unpredictable and, ultimately, weakening the overall performance, that is the lap time. It is not clear which is the determining factor causing this phenomenon. Therefore, numerical simulation on a three dimensional, multibody motorcycle model is proposed, taking into account the effects of the major parameters involved, in order to highlight which of them takes part in the vibration. Accurate models for tire and drivetrain have been developed, making it possible to consider tire carcass deformability, chain transmission in both traction and braking states, full drivetrain inertia and anti-hop clutch effect. A critical maneuver experimentally measured on the race track is analyzed. The modal response of the linearized system is evaluated for several configurations extracted from the maneuver. The above maneuver is then simulated with the model, showing the actual vibration uprising. A critical discussion of the possible physical interpretations of the phenomenon is given.
Predicting the Treatment Response of Oral Appliances for Obstructive Sleep Apnea Using Computational Fluid Dynamics and Fluid-Structure Interaction Simulations
Authors: Zhao Moyin , Barber Tracie , Cistulli Peter , Sutherland Kate , Rosengarten Gary
Published: April 2014

In this study we used computational fluid dynamics (CFD) to analyze the therapeutic effect of an oral device (mandibular advancement splint – MAS, that protrudes the lower jaw during sleep) as a treatment for Obstructive Sleep Apnea (OSA). Anatomically-accurate upper airway (UA) computational models were reconstructed from magnetic resonance images (MRI) of 7 patients with and without a MAS device fitted. CFD simulations of UA airflow were performed at the maximum flow rate during inspiration. The CFD results indicated the lowest pressure often occurs close to the soft palate and the base of the tongue. The airway pressure gradient was estimated as the best indicator for treatment response since the change in the pressure drop forms a linear correlation with the change in patients’ Apnea-Hypopnea Index (AHI). This correlation has the potential to be developed into a model for predicting the outcome of the MAS treatment. However the rigid wall assumption of CFD models is the major uncertainty. To overcome this uncertainty we set up a full fluid-structure interaction model for a typical responder case with a compliant UA wall. The results demonstrated the different UA flow field associated with using MAS alleviated the airway collapse, which was successfully predicted for the untreated patient. We thus show for the first time that FSI is more accurate than CFD with rigid walls for the study of OSA, and can predict treatment response. Comparison of the FSI and CFD results for the UA flow and pressure profiles showed variation between the models. The structural deflection in oropharynx effectively reformed the flow pattern, however, the maximum pressure drops of both results were close. This supports the competence of the CFD method in clinical applications, where maximum pressure drop data can be used to develop a treatment-predicting model.
Computer Simulation and Modelling of Standing Wave Piezoelectric Ultrasonic Motor Using a Single Flexural Vibration Ring Transducer
Authors: Shafik M. , Makombe L. , Mills B.
Published: April 2014

A rotary standing wave ultrasonic motor using single flexural ring transducer is developed and presented in this paper. The motor consists of three main components, the stator, rotor and housing unit. The stator is a piezoelectric transducer ring. The rotor is designed of a compact driving wheel and the shaft. The housing unit is made of a transparent thermoplastic Perspex material and is part of the motor working mechanism. The motor design, structure, working principles and modelling using finite element analysis is discussed and presented in this paper. The simulation and modelling using finite element analysis for the motor is used in the motor design development process. Finite element has been used to examine the motor structure by performing an algebraic solution of a set of equations, describing an ideal model structure, with a finite number of variables. The established simulation and modelling for ultrasonic motor using finite element analysis enabled to select the material of the flexural transducer ring, investigate the material deformation, defining the operating parameters for the motor and establish the principles of motion. The motor working principles is based on creating travelling waves vibration modes, of oscillating structures that are superimposed in the stator, generating elliptical micro motions at the stator tips. Pressing the rotor against the stator tips, using an elastic spring, the micro motions are converted into a rotary motion via the friction between the tips of the stator and the rotor. A prototype of the motor was fabricated and its characteristics measured. Experimental tests showed that the electrical working parameters are: Current: 100 m-amp’s, Voltage: 100 volts, Frequency: 41.7kHz, typical speed of movement: 32 revolutions per minute, a resolution of less than 50μm and maximum load of 1.5 Newton.
Process Capability Analysis With GD&T Specifications
Authors: Liu Jinya , Huang Wenzhen , Kong Zhenyu , Zhou Yingqing
Published: April 2014

Geometric dimensioning & tolerancing (GD&T) and process capability indices (PCIs) play critical roles in quality assurance. Conventional PCIs, when used together with GD&T, strongly rely on certain assumptions (e.g. normality and regularity of specification region). GD&T requirements often involve interrelated tolerances, creating irregular tolerance regions. Violation of these assumptions misleads the results (18) and interpretation in applications. A non-conformity (NC) index is developed based on nonparametric distribution model and numerical assessment techniques. Kernel is used for probability density (pdf) estimation and Monte Carlo integration algorithm is adopted for NC analysis, i.e. integration of a pdf over a specification region. The method is validated by case study.
Integrated Approach for System Oriented Analyses and Optimization of Complex Hybrid Powertrain Applications by Means of Vehicle-in-the-Loop Roller Test Bench
Authors: Albers Albert , Schwarz Alexander , Behrendt Matthias
Published: April 2014

Central activity in the development process of automotive drive systems is the validation to meet the customers’ demands. Thereby the transmission topology as well as the operation and drive strategy and their independencies have a great influence on the comfort and the energy efficiency of the vehicle. Especially in modern drivelines, like in hybrid electric vehicles there are great independencies between those factors, which have to be considered and integrated in order to achieve a global optimum.

In this contribution an integrated validation and development environment with the focus on hybrid transmission applications is presented. This approach is capable to integrate and consider aspects of complex powertrain systems, as hybrid powertrains, and to cover the competing aspects of NVH, drivability as well as energy efficiency. The approach is an integral combination of new or already published as well as established individual methods that have been extended with challenging aspects of hybrid powertrain development. One integrated method is the time-efficient arrangement of measuring points in order to shorten the global needed conditioning phases. For gearshift evaluation of a dual clutch transmission, this reduces operation time on the roller test bench about 80% compared to an experienced test driver [1]. The integrated approach uses system identification to create time and cost efficient test runs for the test based optimization [2]. Thereby advanced methods for rating the drivability and for automatic identification of NVH-Phenomena [3] are used to optimize multi criteria objective functions. The measurement is done in the IPEK-X-in-the-Loop Framework (XiL) [4], which enables a transmission assessment on the complete vehicle level.
A Hybrid Energy Model for Predicting High Frequency Vibrational Response of Thin Plates Under Heavy Fluid Loading
Authors: Kong Xiangjie , Chen Hualing , Zhu Danhui , Zhang Wenbo
Published: April 2014

Energy Finite Element Analysis (EFEA) is a method developed for high-frequency structural response prediction in recent years. In this paper, a hybrid model is developed to improve the prediction levels of the current EFEA energy governing equation for the thin plate in contact with heavy fluid. The neglect of the contribution of direct field is the primary prediction source of error in EFEA especially when the damping is significant. In order to fix this issue, both the reverberant field and the contribution of direct field are considered in the derivation. The fluid loading effect is incorporated in the derivation of the governing equation of direct field component in terms of effective mass and total damping factor in polar coordinates. As for the reverberant plane wave component, instead of the driving point, the injected power is modified as the scattered energy arising from direct field located at the boundaries, which is in consistent with the formation mechanism. The overall vibrational energy is the linear superposition of both fields. Numerical simulations on a rectangular plate validate the hybrid model through the comparison with the analytical modal solutions and show that the proposed hybrid model has a more accurate prediction comparing with the classical EFEA results.
Study of a Concrete Mixer Hybrid Truck
Authors: Mapelli Ferdinando Luigi , Tarsitano Davide , Annese Davide , Pirri Nicola , Zorzi Emanuele
Published: April 2014

Decrease of availability of fossil fuels and environment issues, push research towards the development of high efficiency power trains for vehicles that transport people, goods and mobile operating machines, like the concrete mixer trucks considered in this paper. Conventional concrete mixer trucks use diesel engine to move the truck and a hydraulic system which keep spinning the concrete drum. A hybrid powertrain based on battery-powered electrical drives can replace the conventional hydraulic system assuring an efficiency improvement. Furthermore, thanks to the reversibility of the electrical drives, it is possible to recover kinetic energy during the braking phases of the truck. Aim of this paper is to study and develop a hybrid powertrain for the concrete mixer drum. The study is based on a full energetic model of the vehicle developed for sizing the components and designing the control strategies. A model of the conventional hydraulic mixer truck has also been proposed in order to evaluate the benefit introduced by the proposed hybrid system. Simulation models have been validated comparing experimental data collected on a conventional mixer truck in different operating conditions.