bluuebunny/crossref_metadata_2025 huggingface dataset:
Experimental Heat Transfer Distributions Over an Aft Loaded Vane With a Large Leading Edge at Very High Turbulence Levels
Authors: Varty Justin W. , Ames Forrest E.
Published: February 2017

Vane heat transfer distributions have been acquired on an aft loaded vane with a large leading edge over a range of turbulence conditions and across a range of Reynolds numbers. The large leading edge was designed to reduce heat transfer levels around the vane stagnation region and provide an opportunity to internally cool the region using a double wall cooling method. Heat transfer measurements were acquired in a linear cascade using a constant heat flux technique. The cascade was designed in a four vane, three full passage configuration with inlet bleeds flows and exit tailboards shaped along streamlines. Heat transfer measurements were acquired at exit chord Reynolds numbers of 500,000, 1,000,000, and 2,000,000 over seven turbulence conditions. The turbulence conditions included a low turbulence condition (Tu ≈ 0.7%), a small grid (M = 3.175 cm) at far and near locations (Tu ≈ 3.5% & 7.9%), a larger grid (Tu ≈ 8.0%), an aero-combustor closely coupled to the cascade and with a decay spool in between (Tu ≈ 13.5% and 9.3%) as well as with a new very high turbulence generator (Tu ≈ 17.4%). Heat transfer levels in the stagnation region are correlated in terms of approach flow Reynolds number and turbulence conditions and compared with recent large cylindrical leading edge test surface data using the TRL parameter. The surface heat transfer measurements are presented at different Reynolds numbers in terms of Stanton number based on exit conditions. These comparisons provide useful information on the level of turbulence augmentation in laminar regions of the flow as well as the onset location and length of transition. Midspan surface static pressure distributions were acquired at all the conditions and were used as a basis to determine experimental isentropic Mach number distributions. These data are reported in part but were also used to help generate the free-stream boundary condition for a boundary layer calculation. Predictive comparisons generated from boundary layer calculations (STAN7) using an algebraic turbulence model (ATM) and a well-known transition model (Mayle) are provided. At low turbulence levels the close comparisons provide confidence in the experimental technique. At higher turbulence levels the comparisons may provide a better indication of the physics of response of vane heat transfer to the external turbulence. These data are expected to help clarify the physics of vane heat transfer at very high turbulence levels.
Metamaterial Application in Stress Wave Mitigation Generated by Impulsive Force
Authors: Rodrigues Gustavo Simão , Weber Hans Ingo
Published: February 2017

The idea to use metamaterials to mitigate mechanical waves is recent and constitutes a technology under development. These materials have a special design, presenting characteristics not found in nature. The interesting feature is a negative effective mass density. This property is achieved by creating in the structure masses linked by springs which act as internal resonators and, as a result, it is observed that metamaterials act as mechanical filters, preventing or reducing the intensity of propagation of mechanical waves that travel in the structure, when the frequency of propagation is close to the resonance frequencies of the internal resonators.

An internal combustion generates a blast wave which acts on a structure as an impulsive effort. This is a basic phenomenon in the shooting of an armament leading to this research that target to investigate the possible application of metamaterials to improve recoil mechanism technology. A recoil mechanism moderates the firing loads on the supporting structure by prolonging the time of resistance to the propellant gas forces. Depending on application of the armament, recoil can be very undesirable. Firstly, carriage mount where the armament is fixed will suffer premature wear. Secondly and more critical, if the armament is mounted onto a vehicle, its dynamics during shooting is completely affected and an accident can be caused when shooting occurs during a critical situation, like a curvilinear path for example.

It is intended to use numerical simulations and experimental validation to verify the behavior of the designed metamaterial under a controlled impulse input. Finite Element Method (FEM) is used to simulate wave propagation through a common material and then through a special designed metamaterial to evaluate how this kind of pulse will be affected by internal resonators. After the simulations, a prototype adequate to validate numerical results will be investigated on a test bench. In a further development the impulse input will be adapted to real measured blast efforts.
Functional Models With Inherent Behavior: Towards a Framework for Safety Analysis Early in the Design of Complex Systems
Authors: McIntire Matthew G. , Keshavarzi Elham , Tumer Irem Y. , Hoyle Christopher
Published: February 2017

This paper represents a step toward a more complete frame-work of safety analysis early in the design process, specifically during functional modeling. This would be especially useful when designing in a new domain, where many functions have yet to be solved, or for a problem where the functional architecture space is large. In order to effectively analyze the inherent safety of a design only described by its functions and flows, we require some way to simulate it.

As an already-available function failure reasoning tool, Function Failure Identification and Propagation (FFIP) utilizes two distinct system models: a behavioral model, and a functional model. The behavioral model simulates system component behavior, and FFIP maps specific component behaviors to functions in the functional model. We have created a new function-failure reasoning method which generalizes failure behavior directly to functions, by which the engineer can create functional models to simulate the functional failure propagations a system may experience early in the design process without a separate behavioral model.

We give each basis-defined function-flow element a pre-defined behavior consisting of nominal and failure operational modes, and the resultant effect each mode has on its functions connected flows. Flows are represented by a two-variable object reminiscent of a bond from bond graphs: the state of each flow is represented by an effort variable and a flow-rate variable. The functional model may be thought of as a bond graph where each functional element is a state machine. Users can quickly describe functional models with consistent behavior by constructing their models as Python NetworkX graph objects, so that they may quickly model multiple functional architectures of their proposed system. We are implementing the method in Python to be used in conjunction with other function-failure analysis tools.

We also introduce a new method for the inclusion of time in a state machine model, so that dynamic systems may be modeled as fast-evaluating state machines. State machines have no inherent representation of time, while physics-based models simulate along repetitive time steps. We use a more middle-ground pseudo time approach. State transitions may impose a time delay once all of their connected flow conditions are met. Once the entire system model has reached steady state in a timeless sense, the clock is advanced all at once to the first time at which a reported delay is ended. Simulation then resumes in the timeless sense.

We seek to demonstrate this modeling method on an electrical power system functional model used in previous FFIP studies, in order to compare the failure scenario results of an exhaustive fault combination experiment with similar results using the FFIP method.
High Performance Balanced Flow Modulating Hydraulic Control Valves
Authors: Elgamil Mohamed , El-Husseiny Marwan , Kassem Saad
Published: February 2017

Inertia, strength, actuator capabilities and flow gain represent major concerns in valve design. In this paper, balanced rotary plate valves are introduced, aiming at maximizing flow gain and strength, and minimizing inertia for high valve dynamic performance. A newly developed electromagnetic actuator capable of driving the valve is presented. A valve of this type incorporates a limited angle rotating plate (rotor) inserted between two stators, such that control orifices of considerable large areas result from small input angular displacements, and thus a high flow gain is realized. The rotor is designed to be highly balanced regarding the axial pressure and flow forces. A rotor of thin sections and low inertia would consequently have enough strength to withstand the loads. The geometrical features of the rotor and the stator plates are determined such that the walls separating the various chambers undergo similar deformations with small relative location changes to keep control orifices unchanged as they are subjected to similar pressure differences. Control orifice pairs exist at both sides of the rotor plate and thus the control areas are duplicated. A proposed mechanical design for a valve size NG 6 is presented and the stresses and deformations in its main parts are determined and verified to be safe using ANSYS Mechanical software package. Computational fluid dynamics analysis of the flow pattern is performed using ANSYS/FLUENT. The analysis results show that the proposed valve design well suits building single stage valves of high flow capacity and high dynamic performance.
Rotordynamic Analysis Using 3D Elements in Fixed and Rotating Reference Frame
Authors: Kumar Devesh
Published: February 2017

To achieve greater efficiency with lightweighting, new configurations are being explored in aero engine design. Typically, these configurations include large flexible structures such as fan blades which require adequate modeling techniques to capture their dynamic effects accurately. For the analyses of these components, the traditional one-dimensional Rotordynamics modeling approach is not sufficient and even two-dimensional axisymmetric harmonic elements cannot capture discrete rotor blades and their complex non-uniform geometries. These limitations motivate the use of three-dimensional (3D) solid/shell elements. They allow for a geometrically complete representation of the rotor as well as analysis in both the fixed and the rotating reference frames. The advantages of 3D elements for rotordynamic analyses are demonstrated using a turbofan engine model. The results reveal the effect of dynamic coupling between the fan blades and the rotor shaft on rotor deformation due to unbalance loads.
Combustion Performance, Noise, and Vibrations of an IDI Engine Fueled With Carinata Biofuel
Authors: Soloiu Valentin , Moncada Jose , Knowles Aliyah , Naes Tyler , Simons Emerald , Muiños Martin , Harp Spencer
Published: February 2017

The performance of an indirect injection engine fueled with a biodiesel blend was investigated at 2400 rpm and 6 bar IMEP. The single cylinder experimental engine was run using C50 and compared to a ULSD#2 baseline. Brassica carinata oilseed was studied as it can potentially provide improvements for existing fuel infrastructures. Cylinder pressure data for C50 showcased a lower heat release and slightly higher injection pressure due to higher SMD. Brake specific fuel consumption was 6% higher for C50 given the characteristic LHV of biodiesel. Vibrations and sound measurements were analyzed in the frequency and crank angle domain through the Brüel & Kjær PULSE software platform. Sound pressure correlations were determined according to the piston normal force on the cylinder liner, intake and exhaust valve timing, and operating speed. For both fuels, vibrations parallel to the cylinder axis reached 1.6–2.6 m/s2 in the 40–120 Hz frequency range; noise reached 80–87 dB at frequencies of 1–4 kHz. C50 produced 0.4 g/kWh fewer NOx emissions which correlate to a lower maximum bulk gas temperature and richer air-fuel ratio. The average ringing intensity was 0.05 MW/m2 for both fuels due to a comparable pressure rise rate. When the engine was run with C50, the reference mechanical efficiency of 53% was effectively maintained. This offers validation for further implementation of blended biodiesel fuel in IDI engines.
Performance Evaluation of Thrust Washer Bearings Using a Customized Bench Scale Test Rig
Authors: Myers Kyle , Jenson Sean , Brooksbank Mike , Ali Muhammad , Alam Khairul , Choi Junghun , Wilhelm Jay , Gillespie Joseph , Walker Richard
Published: February 2017

The work presented here outlines details of tests performed on thrust washer bearings using a customized test rig, which was designed, fabricated, and instrumented to conduct tests on thrust washer bearings of varying sizes and thicknesses. The test rig was able to vary speed, axial load, oil input pressure, and oil input temperature. The system was composed of 6 main parts; the structure, drive system, runner, instrumentation pad, loading system, and instrumentation. The main support structure was fabricated using 1 inch square hollow bar stock steel (1018 steel). A 1 hp DC motor with a max speed of 3050 rpm and varying speed controller was used as a direct drive system to spin the runner against the bearing. The tests were conducted on three aluminum bearings of same design under almost constant operating conditions. The data obtained from tests performed on bearings included oil temperature, bearing temperature, oil film thickness, and pressure on bearing pads. It was found that the temperature at the surface of bearing and oil film pressure was directly related to the applied load. This information will be used to advance our understanding of smaller diameter thrust washer bearings and will assist in extrapolating these results to improve upon larger scale bearings.
Evaluation of Stress Wave Attenuation in a Polymer Matrix Composite Using Finite Element Analysis Technique
Authors: Nargund Shrikant
Published: February 2017

The dynamic behavior of polymer composites is significantly affected by the properties of their micro constituents including shape and size of inclusions and inclusions/matrix adhesion properties. Wave propagation through such a composite is a complex phenomenon as it includes random scattering, absorption and transmittance of the incident wave and is dependent upon factors such as the properties, size and placement of the inclusions inside the matrix. Finite element modeling provides a viable approach for investigating the effects of micro constituent structure on the dynamic behavior of polymer composites. In this paper, we investigate the stress wave attenuation characteristics of a particulate polymer matrix composite using Finite Element (FE) analysis approach. The wave attenuation of ultrasonic sinusoidal waves of frequency ranging from 1 MHz to 4 MHz is evaluated for different FE models. The spherical inclusions are randomly distributed inside the polymer matrix with a certain minimum distance apart from each other. Inclusion-Matrix adhesion properties are studied by modeling a small region at the interface of inclusions and matrix known as interphase region. The interphase region is modeled explicitly using the cohesive zone modeling approach to study how the properties of this region will affect the wave attenuation characteristics of the polymer composite. Cohesive zone models are governed by traction separation law which helps in the measurement of the inclusion-matrix bonding strength and also allow the study of de-bonding at the interface in the critically stressed region produced due application of load. Thus the FE models consist of three phases; polymer matrix, particulate inclusions and the interphase region. Various three dimensional FE models are created using 3D tetrahedral/hexahedral elements by varying the radius of the spherical inclusions and by varying volume fraction of the inclusions. The analyses are performed using a general purpose finite element software LS-Dyna. A rate dependent viscoelastic material model with four terms in prony series expansion is used for modeling the polymer matrix. A linear elastic isotropic material model is used for modeling the inclusions. The wave attenuation is measured as reduction in the amplitude of the wave as it passes through the composite. A comparison of results for various models is done to check for general trend of attenuation coefficient as a function of size of inclusions, volume fraction of inclusions, frequency of loading and interphase region properties. Results show that volume fraction and load frequency have a maximum effect on the wave attenuation coefficient. Interphase region stiffness and interface de-bonding also plays an important role in attenuation characteristics of the polymer composite.
Fatigue Analysis of an Innovative Extensible Wind Turbine Blade
Authors: Li Jiale , Yu Xiong (Bill)
Published: February 2017

This paper describes the feasibility analyses of an innovative, extensible ‘smart’ blade technology aims to significantly improve the wind turbine energy production. This innovative ‘smart’ blade will be extended at low wind speed to harvest more wind energy. It will be retracted to its original shape above rated wind speed, to protect the blade from possible damages under high wind speed. The extended blade, however, will inevitably increase the fatigue damage of the wind turbine blade of which fatigue demand, which often controls the design requirement of wind turbine blade. A rain-flow counting method is used for calculating stress range cycles during turbine blade operation. The analyzes model in the research is built based on a 100 kW utility-scale wind turbine installed on the campus of Case Western Reserve University with a data acquisition system installed on the wind turbine tower to monitor the operation data continuously over the years. In this analyses, the data set consists of four years’ wind speed data at 10-minutes time interval and blade rotational speed from March 2014 to February 2015 have been used. The results show that the fatigue damage of this extensible blade increased is acceptable considering its increased power output.
Real-Time Simulation of Flexible Multibody Models
Authors: Prescott William
Published: February 2017

This paper will look at how to include flexible modes into a real-time multibody simulation. The approach proposed in this paper is to divide the equations into two separate systems: rigid and flexible, which are then co-simulated by two separate integrators. After the flexible equations are integrated at each time step the modal coordinates are used to update the joint and force attachment locations in the rigid model then the joint forces from the rigid model are fed to the flexible model. This approach essentially means a new rigid model is solved at each time step. The use of a co-simulation approach will also allow separate processors to be used for the flexible and rigid equations.
Analysis and Optimization of Robotized Grinding of Titanium High Pressure Compressor Blades
Authors: Meshreki M. , Shi Z. , Arrien F. , Attia M. H.
Published: February 2017

An analysis for a robotized grinding process of aerospace Titanium high pressure compressor blades was performed. In this process, the blade was grabbed on the robotic arm. A Scotch-Brite grinding wheel, on a pneumatic actuator, was used to grind the edges of the blades. The objective of this research work was to identify the major factors that influence the accuracy of the process and the final part quality. This objective was achieved by analyzing the dynamic characteristics of the wheel grabbed on the motor as well as analyzing the dynamic characteristics of the blade grabbed on the robotic arm. The frequency response functions (FRF) were identified at different robot configurations and positions. In addition, the vibrations of the various system components during the grinding process were monitored and analyzed to determine the effect of the speed on the relative vibrations between the workpiece and the wheel. Considering the dynamics of the wheel and the motor, rotational speed ranges were recommended. It was found that the vibrations of the grinding process were higher at two ranges: The first corresponds to the first natural frequency of the robot and the second corresponds to the first natural frequency of the wheel and the second natural frequency of the robot. By avoiding these ranges, part quality within the specified tolerances was obtained.
The Numerical Technique for Turbine Blades and Underplatform Dampers Interaction Modeling Based on Substructure Method
Authors: Semenova Irina , Sazhenkov Nikolai , Nikhamkin Mikhail , Semenov Sergey
Published: February 2017

Friction dampers are commonly used in jet and turboprop engines to decrease vibration stresses of turbine blades by irreversible conversion of mechanical energy into heat. Effectiveness of the energy transfer depends on dampers design, material and operational conditions. Optimization of dampers design is a complex task usually associated with nonlinear contact problems analysis and complicated experimental verification. It also coupled with high time costs causing the engineering task to be modified into compound research problem. The paper presents time effective numerical technique for gas turbine blades underplatform dry-friction dampers efficiency study. The presented technique is based on finite-element method with a numerical model reduction by Craig-Bampton and Guyan algorithms. The model consisted of dummy blades pair with wedge damper between the platforms. Technique allows considering three dimensional shapes of parts, nonlinear contact forces, friction, various operational loads and conditions. The model was verified by experiment completed on special test rig based on vibration shaker and 3D laser vibrometer. Relationship between the blades oscillation amplitude and the centrifugal load on the damper was obtained. Optimal operational range with maximum damper efficiency was defined. Impact of so called anti-phase and in-phase modes of adjacent blades on damper efficiency was investigated.
Computational Design and Development of Alumina-Nickel Droplet Composites
Authors: Akhtar S. Sohail , Arif A. F. M. , Siddiqui M. U. , Raza Kabeer , Kareem L. Taiwo , Hakeem Abbas S.
Published: February 2017

Computational design for property management of composite materials offers a cost sensitive alternate approach in order to understand the mechanisms involved in the thermal and structural behavior of material under various combinations of inclusions and matrix material. The present study is concerned with analyzing the elasto-plastic and thermal behavior of Al2O3-Ni droplet composites using a mean field homogenization and effective medium approximation (EMA) using an in-house code. Our material design approach relies on a method for predicting potential optimum thermal and structural properties for Al2O3-Ni composites by considering the effect of inclusion orientation, volume, size, thermal interface resistance, percolation and porosity. The primary goal for designing such alumina-based composites is to have enhanced thermal conductivity for effective heat dissipation and spreading capabilities. At the same time, other functional properties like thermal expansion coefficient, elastic modulus, and electrical resistivity have to be maintained or enhanced. The optimum volume fraction was found to occur between 15 and 20 vol. %Ni while the average nickel particle size of 5 μm was found a minimum size that will enhance the thermal conductivity. The Young’s modulus was found decreasing as the volume fraction of nickel increases, which would result in enhanced fracture toughness. Electrical conductivity was found to be greatly affected by the percolation phenomenon in the designed range of volume fraction minimum particle size. As a validation, Al2O3 composites with 10% and 15% volume fraction Ni and droplet size of 18 μm are developed using spark Plasma Sintering process. Thermal conductivity and thermal expansion coefficient of the samples are measured to complement the computational design. Microstructural analysis of the sintered samples was also studied using optical microscope to study the morphology of the developed samples. It was found that the present computational design tool was accurate enough in predicting the desired properties of Al2O3-Ni composites.
Location Sensor Fusion and Error Correction in Intelligent Vehicles
Authors: Beyerl Thomas , Ibru Bernard , Williams Johnnie , Augusma Imani , Soloiu Valentin
Published: February 2017

Autonomous vehicles provide an opportunity to reduce highway congestion and emissions, while increasing highway safety. Intelligently routed vehicles will also be better integrated with existing traffic patterns, minimizing travel times. By reducing the time wasted in traffic; harmful emissions will consummately be reduced. Well-designed autonomous control systems provide for increased highway safety by reducing the frequency and severity of traffic accidents caused by driver error. In order to achieve this, a robust multi-layered control system must be designed, which minimizes the likelihood of computer error, while enabling seamless transition to and from human control.

Autonomous vehicle navigation systems rely on accurate and timely sensor inputs to determine a vehicle’s location, attitude, speed, and acceleration. This paper describes a telemetry sensor fusion approach, which enables an autonomous vehicle to navigate, complex intersections, based on previously planned paths and near field sensors. This reduces computational overhead on the vehicle’s computer, and provides real time redundancy for system errors or delays. In conjunction with a full complement of environmental sensors, this path planning - path following approach enhances the robustness of autonomous vehicle operating models.

This research supports the rapidly expanding field of autonomous automobiles by examining novel concepts for robust telemetry sensor fusion between inertial, GPS, and wheel speed sensors, which allows for error correction and enhanced positional accuracy, when compared to conventional navigation algorithms.
Feasibility Analysis of a Hybrid Photovoltaic/Thermal Cogeneration System for Domestic Applications
Authors: Ruiz-Casanova Eduardo , Rubio-Maya Carlos , Soto-Sánchez Ana Laura , Mendoza-Covarrubias Crisanto , Martínez-Patiño Jesús
Published: February 2017

A PV/T hybrid system is able to simultaneously produce electricity and heat from solar radiation. The feasibility of implementing PV/T systems depends primarily on climatic and economic characteristics of locations where are planned to be placed. Particularly in Mexico, there are only a few studies in the scientific literature which report the feasibility of using such innovative systems. Therefore, in this work the development of a techno-economic study is presented aiming to predict the performance and feasibility of implementation of this type of hybrid systems. Firstly, a PV/T system was designed to partially cover the needs of electricity and hot sanitary water in the domestic sector (considering a house of four inhabitants). Then, PV/T hybrid system operation was simulated using TRNSYS software over a full year using data from a typical meteorological year (TMY) of Morelia city (Michoacan State). Finally, an economic analysis was conducted, estimating the inherent cash flows and computing some economic indicators to determine the feasibility of implementation of PV/T system adapted to Mexican economic conditions. The simulation results show that the proposed system consisting of 1.55 m2 of collection area, will annually produce 1480.95 kWh and 393.57 kWh of thermal and electrical energy, respectively. The system is able to meet up to 51.2% of thermal energy and 29.2% of the electricity needed. The system reaches a total efficiency of 57.48%. The results of economic analysis indicate that in optimistic case, the proposed system has a simple payback period of 6.62 years, a net present value of $2129.0 Mexican pesos, and an internal rate of return of 14%, showing economic feasibility. The results show the great potential of the use of the hybrid PV/T systems for domestic water heating and electric production at particular locations in Mexico.
Fluidized Bed Particle Heat Exchanger for Supercritical Carbon Dioxide Power Cycles
Authors: Steiner Peter , Schwaiger Karl , Walter Heimo , Haider Markus , Hämmerle Martin
Published: February 2017

Numerous studies in the field of power generation deal with efficiency and flexibility enhancement of power plants. Supercritical carbon dioxide (sCO2) power cycles promise significantly higher efficiencies and very compact constructions compared to conventional Rankine cycles. An opportunity to increase the flexibility of such power cycles, is the integration of Thermal Energy Storage (TES) systems into the process. In this work the sandTES technology, a particle based TES system is introduced, which can be used to improve the load change characteristics of power plants even at highest temperatures. After introducing the main concept and the key technologies of the sandTES technology, a utility scale heat exchanger for implementation in a high temperature sCO2 power cycle is presented and discussed. Finally crucial design parameters of the presented heat exchanger (HEX) are outlined as well as their influences on the HEX dimensions are discussed.
On Nonlinear Dynamics and Flight Control at High Angles of Attack With Uncertain Aerodynamics
Authors: de Freitas Virgílio Pereira Mateus , Prado Igor Afonso Acampora , de Castro Davi Ferreira , Balthazar José Manoel , da Silva Roberto Gil Annes , Nabarrete Airton
Published: February 2017

In this paper we consider the flight dynamics of fighter aircraft at high angles of attack with uncertain aerodynamic coefficients. Stochastic parametric uncertainty is dealt with by employing spectral decomposition of the random variables by means of the generalized polynomial chaos expansion. We propose an optimal linear feedback strategy for the automatic pilot system to recover the aircraft from stall and provide acceptable dynamic response. Optimality of the proposed control law is proved by solving the Hamilton-Jacobi-Bellman equation and asymptotically stability of the controlled nonlinear aircraft model is guaranteed in the Lyapunov sense. Numerical results are verified with Monte-Carlo simulations.
A New High Strain-Rate Biaxial Experiment to Validate Constitutive Models for Polymers
Authors: Teller Sean S. , Schmitt Eric C. , Bergström Jörgen S.
Published: February 2017

We have developed a new high strain rate experiment in biaxial tension that allows for constitutive model validation at engineering strain rates from 50/s to over 1000/s. In the experiment, a flat disk of the material is clamped at a fixed radial distance. A rail-guided impact sled with a hemispherical impact head is released from the desired height and impacts the disk at the center, potentially deforming the sample to failure. Drop height and impact mass can be varied to modify peak strain rate and impact energy, and the wide range of test conditions allow for testing to be performed on many classes of materials, including thermoplastics and elastomers. The stress and strain fields are calculated using finite element simulations with the proposed constitutive model, and the constitutive model is validated by matching the force versus displacement data of the impact head recorded during experiment to the simulation. In this paper, we discuss results from the experiment and finite element simulations of the experiment on PA (polyamide, nylon) and PEEK (polyether ether ketone). The new experiment allows for validation and refinement of constitutive models, including failure, at high strain rates and in a multiaxial stress state.
Stochastic Optimization of Nonlinear Energy Sinks Using Resonance-Based Clustering
Authors: Boroson Ethan , Missoum Samy
Published: February 2017

Nonlinear energy sinks (NESs) are promising devices for achieving passive vibration mitigation. Unlike traditional tuned mass dampers (TMDs), NESs, characterized by nonlinear stiffness properties, are not tuned to specific frequencies and absorb energy over a wider range of frequencies. NES efficiency is achieved through time-limited resonances, leading to the capture and dissipation of energy. However, the efficiency with which a NES dissipates energy is highly dependent on design parameters and loading conditions. In fact, it has been shown that a NES can exhibit a near-discontinuous efficiency. Thus, NES optimal design must account for uncertainty. The premise of the stochastic optimization method proposed is the segregation of efficiency regions separated by discontinuities in potentially high dimensional space. Clustering, support vector machine classification, and dedicated adaptive sampling constitute the basic techniques for maximizing the expected value of NES efficiency. Previous works depended solely on the ratio of energy dissipated by the NES for clustering. This work also includes information about the type of m:p resonances present. Three examples of optimization for the maximization of the expected value of efficiency for NESs subjected to transient loading are presented. The optimization accounts for both design variables with uncertainty and aleatory variables to characterize loading.
Design of a 4-Cylinder Gasoline Turbo Engine Intake Manifold
Authors: Tang Guangwu , Wang Di , Wu Bin , Chen Yuchao , Liu Xiang , Silaen Armin K. , Zhou Chenn Q.
Published: February 2017

A redesign of the intake manifold on a turbo engine transformed from naturally-aspirated engine was conducted. A new intake manifold geometry was proposed to meet both the flow uniformity and structural strength requirements. Additionally, the new intake manifold design has to meet power and torque performance requirements. In order to perform this study, a systematic design methodology was proposed. One-dimensional characteristic analysis was firstly conducted using the commercial software GT-Power, by which the intake manifold length and the pressure stabilizing cavity volume were determined. The results indicate that the intake manifold length and the pressure stabilizing cavity volume have limited effect on the engine performance. Next, the commercial computational fluid dynamics (CFD) software ANSYS Fluent was utilized to simulate the flow characteristics inside the intake manifold to investigate the flow uniformity and the pressure drop. With the newly designed geometry for the intake manifold, the maximum flow uniformity coefficient is 1.83%. This is lower than the standard requirement of 3%. Due to the fact that the intake manifold for the turbo engine will experience larger pressure than the original naturally-aspirated engine, the strength and the mode frequency of the new intake manifold design were verified by using the commercial finite element analysis (FEA) software Abaqus. The maximum stresses at internal and external of intake manifold structure were 110 MPa and 93 MPa respectively, which are lower than the yield strength. Additionally, the frequencies of the first mode and second mode are 159.87 Hz and 237.10 Hz respectively, which indicates that a physical support may be needed. This comprehensive design methodology will ensure the performance of an intake manifold design for a turbo engine transformed from a naturally-aspirated engine is met.
Feasibility Study of Multi-User Collaboration Awareness Concepts in Computer-Aided Design Applications
Authors: Hill J. Logan , Salmon John L.
Published: February 2017

New, experimental, synchronous, multi-user CAD systems, such as BYU’s NXConnect, allow users to work together simultaneously in the same CAD model. Although multi-user CAD comes close to approximating the old collaborative drafting table experience, NXConnect still falls short in a few key areas, most notably of which is in collaboration awareness. This results in redundant work and lost time. Investigation was done with other multi-user software to see what features help each user to be aware of what is being worked on. This resulted in a proposed plugin for NXConnect consisting of two elements: a preview-based real-time feature update and a temporary plane indicating where a user is creating a sketch. Teams using NXConnect with and without the plugin were studied. Teams using the plugin found a small improvement in working collaboratively.
A Systems Design Approach to Appropriate, Smart Technology in a Youth Agriculture Initiative
Authors: Janse van Rensburg Nickey , Hurter Warren , Malan Naude
Published: February 2017

A transformative research paradigm is imbedded in knowledge mobilization processes involving close collaboration between researchers and the community. The research presents the development of an integrated, connected food ecosystem that, because of its fundamental design and use of appropriate, smart technology, which tends to naturally create inclusion and prosperity opportunities for many and not simply for the few. The research relies on multi-stakeholder participation to develop appropriate technologies to enhance economic activity amongst unemployed youths in Johannesburg, South Africa. A human-centered, systems engineering approach to develop a pilot project that promotes integrated, online, technologically supported food system is presented. The research is also concerned with how to measure the impact of the intervention the on food resilience as a result of urban farming. This paper presents the systems analysis of the current local food network and the proposed integrated solutions for a pilot project to establish a minimal viable project that can be tested. The research describes the planning and implementation of a pilot project as a minimal viable product to test in the market.
Experimental Study of the Transmission Spectrum of a Sonic/Ultrasonic Acoustic Metamaterial
Authors: He Yanbo , Vipperman Jeffrey S.
Published: February 2017

Acoustic metamaterials have received much attention recently. In the past decades, countless structures have been studied for their novel physical phenomenon or potential applications. The goals of many of the works were to explore ways to enlarge the band gap, lower the band gap frequency, and/or generate greater attenuation of vibration. However, most of the work was limited to simulation, with experimental studies rarer. In this work, we would like to experimentally present the transmission spectrum of an acoustic metamaterial with a proposed structure called the coated double hybrid lattice (CDHL) [1]. The CDHL has both crystalline structure and local resonators, which provide high-frequency and low-frequency band gaps, respectively. A structure was fabricated and tested to experimentally determine the transmission spectrum. Both, a higher frequency band gap and a lower frequency band gap, were obtained. Vibration is clearly attenuated in the frequency range of 70–90 kHz. This is due to the Bragg scattering effect. At the same time, around the frequency of 4.8kHz, another band gap is observed which is attributed to local resonance. It turns out that our experimental results coincide with our previous simulation quite well.
Limitations on the Reliability of In Vitro Predictive Toxicity Models to Predict Pulmonary Toxicity in Rodents
Authors: Gernand Jeremy M.
Published: February 2017

Given the rapidly proliferating varieties of nanomaterials and ongoing concerns that these novel materials may pose emerging occupational and environmental risks, combined with the possibility that each variety might pose a different unique risk due to the unique combination of material properties, researchers and regulators have been searching for methods to identify hazards and prioritize materials for further testing. While several screening tests and toxic risk models have been proposed, most have relied on cellular-level in vitro data. This foundation enables answers to be developed quickly for any material, but it is yet unclear how this information may translate to more realistic exposure scenarios in people or other more complex animals. A quantitative evaluation of these models or at least the inputs variables to these models in the context of rodent or human health outcomes is necessary before their classifications may be believed for the purposes of risk prioritization. This paper presents the results of a machine learning enabled meta-analysis of animal studies attempting to use significant descriptors from in vitro nanomaterial risk models to predict the relative toxicity of nanomaterials following pulmonary exposures in rodents. A series of highly non-linear random forest models (each made up of an ensemble of 1,000 regression tree models) were created to assess the maximum possible information value of the in vitro risk models and related methods of describing nanomaterial variants and their toxicity in rat and mouse experiments. The variety of chemical descriptors or quantitative chemical property measurements such as bond strength, surface charge, and dissolution potential, while important in describing observed differences with in vitro experiments, proved to provide little indication of the relative magnitude of inflammation in rodents (explained variance amounted to less than 32%). Important factors in predicting rodent pulmonary inflammation such as primary particle size and chemical type demonstrate that there are critical differences between these two toxicity assays that cannot be captured by a series of in vitro tests alone. Predictive models relying primarily on these descriptors alone explained more than 62% of the variance of the short term in vivo toxicity results. This means that existing proposed nanomaterial toxicity screening methods are inadequate as they currently stand, and either the community must be content with the slower and more expensive animal testing to evaluate nanomaterial risks, or further conceptual development of improved alternative in vitro screening methodologies is necessary before manufacturers and regulators can rely on them to promote safer use of nanotechnology.
CFD Analysis Comparing Steady Flow and Pulsatile Flow Through the Aorta and its Main Branches
Authors: Martin John D.
Published: February 2017

A computational fluid dynamics (CFD) study has been done comparing pulsatile and non-pulsatile blood flow through the aortic arch and its main branches. The pulsatile flow was to mimic the blood flow due to a beating heart and the non-pulsatile or steady flow was to mimic cardiopulmonary bypass (CPB). The purpose of the study was too narrow in on possible reasons CPB may contribute to the development of atherosclerosis. The main focus of the study was to look at the wall shear stress (WSS) values due to their close association with the development of atherosclerosis. In addition velocity and pressure data were also analyzed. The results of this study showed a stark contrast between the WSS values between the CPB model and the beating heart model. The CPB model did not have any points of oscillating WSS combined with the fact that there were regions of very high and very low constant WSS values in comparison with the beating heart analysis suggests that there may be potential for atherosclerotic development or plaque buildup within the artery. The beating heart model showed a range of WSS values within the aorta that were much lower overall compared with the CPB model.
Deterministic Hazard Evaluation for Natural Gas Pipes Failure
Authors: Pourgol Mohammad Mohammad , Mehrzad Arash , Soleimani Morteza
Published: February 2017

Gas stations and distribution facilities in a city districts may result in accidents resulting injuries to people living in these districts. The exposure to released toxic materials is another hazard in gas pipes accidents. Therefore, the gas pipe lines demand special attention for the risk assessment.

In this study, the gas pipe rupture is evaluated on accident scenarios. Fire concentration range has been analyzed for different scenarios for cold and hot weather conditions. Furthermore, the length of flame has been simulated based on releasing flammable materials with governed equations. For modeling, PHAST software is utilized for simulation of released material in environment by considering the atmosphere conditions. Sensitivity analysis is done by 10% increasing in important parameter of problem. As a case study, a gas station is used for assessment. Furthermore, the results are verified with some published studies.
Thermal Performance of Sierpinski Carpet Fractal Fins in a Forced Convection Environment
Authors: Calamas David , Dannelley Daniel , Keten Gyunay
Published: February 2017

When certain fractal geometries are used in the design of fins or heat sinks the surface area available for heat transfer can be increased while system mass can be simultaneously decreased. The Sierpinski carpet fractal pattern, when utilized in the design of an extended surface, can provide more effective heat dissipation while simultaneously reducing mass. In order to assess the thermal performance of fractal fins for application in the thermal management of electronic devices an experimental investigation was performed. The first four fractal iterations of the Sierpinski carpet pattern, used in the design of extended surfaces, were examined in a forced convection environment. The thermal performance of the Sierpinski carpet fractal fins was quantified by the following performance metrics: efficiency, effectiveness, and effectiveness per unit mass. The fractal fins were experimentally examined in a thermal testing tunnel for a range of Reynolds numbers. As the Reynolds number increased, the fin efficiency, effectiveness and effectiveness per unit mass were found to decrease. However, as the Reynolds number increased the Nusselt number was found to similarly increase due to higher average heat transfer coefficients. The fourth iteration of the fractal pattern resulted in a 6.73% and 70.97% increase in fin effectiveness and fin effectiveness per unit mass when compared with the zeroth iteration for a Reynolds number of 6.5E3. However, the fourth iteration of the fractal pattern resulted in a 1.93% decrease in fin effectiveness and 57.09% increase in fin effectiveness per unit mass when compared with the zeroth iteration for a Reynolds number of 1.3E4. The contribution of thermal radiation to the rate of heat transfer was as high as 62.90% and 33.69% for Reynolds numbers of 6.5E3 and 1.3E4 respectively.