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Mechanical and Aerospace Engineering Faculty Research & Creative Works

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Articles 301 - 330 of 808

Full-Text Articles in Aerospace Engineering

Experimental Measurement Of Residual Stress And Distortion In Additively Manufactured Stainless Steel Components With Various Dimensions, M. Ghasri-Khouzani, H. Peng, R. Rogge, R. Attardo, P. Ostiguy, J. Neidig, R. Billo, D. Hoelzle, M. R. Shankar Nov 2017

Experimental Measurement Of Residual Stress And Distortion In Additively Manufactured Stainless Steel Components With Various Dimensions, M. Ghasri-Khouzani, H. Peng, R. Rogge, R. Attardo, P. Ostiguy, J. Neidig, R. Billo, D. Hoelzle, M. R. Shankar

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Disk-shaped 316L stainless steel parts with various diameters and heights were additively manufactured using a direct metal laser sintering (DMLS) technique. Neutron diffraction was used to profile the residual stresses in the samples before and after removal of the build plate and support structures. Moreover, distortion level of the parts before and after the removal was quantified using a coordinate measuring machine (CMM). Large tensile in-plane stresses (up to ≈ 400 MPa) were measured near the as-built disk top surfaces, where the stress magnitude decreased from the disk center to the edges. The stress gradient was steeper for the disks …

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Structural Vs.. Compositional Disorder In Thermal Conductivity Reduction Of Sige Alloys, Jihui Nie, Raghavan Ranganathan, Zhi Liang, Pawel Keblinski Jul 2017

Structural Vs.. Compositional Disorder In Thermal Conductivity Reduction Of Sige Alloys, Jihui Nie, Raghavan Ranganathan, Zhi Liang, Pawel Keblinski

Mechanical and Aerospace Engineering Faculty Research & Creative Works

We Use Equilibrium Molecular Dynamics Simulations to Determine the Relative Role of Compositional and Structural Disorder in a Phononic Thermal Conductivity Reduction by Studying Three 50-50 SiGe Alloy Structures: Ordered Alloys, Disordered Alloys, and Amorphous Alloys, as Well as Pure Amorphous Si and Ge Structures for Reference. While Both Types of Disorders Significantly Reduce Thermal Conductivity, Structural Disorder is Much More Effective to This Aim. the Examination of Phonon Lifetimes in Disordered Alloys Shows High Values in a Low Frequency Regime Governed by Umklapp Scattering that Are Reduced Rapidly with Increasing Frequency Following Rayleigh Scattering Behavior. the Local Properties Analysis …

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Singularity Formation In The Geometry Of Perturbed Shocks Of General Mach Number, Wouter Mostert, Dale I. Pullin, Ravi Samtaney, Vincent Wheatley Jul 2017

Singularity Formation In The Geometry Of Perturbed Shocks Of General Mach Number, Wouter Mostert, Dale I. Pullin, Ravi Samtaney, Vincent Wheatley

Mechanical and Aerospace Engineering Faculty Research & Creative Works

While planar shock waves are known to be stable to small perturbations in the sense that the perturbation amplitude decays over time, it has also been suggested that plane propagating shocks can develop singularities in some derivative of their geometry (Whitham (1974) Linear and nonlinear waves. Wiley, New York) in a nonlinear, wave reinforcement process. We present a spectral-based analysis of the equations of geometrical shock dynamics that predicts the time to singularity formation in the profile of an initially perturbed planar shock for general shock Mach number. We find that following an initially sinusoidal perturbation, the shock shape remains …

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Novel Layered Double Hydroxides-Hydroxyapatite/Gelatin Bone Tissue Engineering Scaffolds: Fabrication, Characterization, And In Vivo Study, Fateme Fayyazbakhsh, Mehran Solati-Hashjin, Abbas Keshtkar, Mohammad Ali Shokrgozar, Mohammad Mehdi Dehghan, Bagher Larijani Jul 2017

Novel Layered Double Hydroxides-Hydroxyapatite/Gelatin Bone Tissue Engineering Scaffolds: Fabrication, Characterization, And In Vivo Study, Fateme Fayyazbakhsh, Mehran Solati-Hashjin, Abbas Keshtkar, Mohammad Ali Shokrgozar, Mohammad Mehdi Dehghan, Bagher Larijani

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Developing Porous Biodegradable Scaffolds through Simple Methods is One of the Main Approaches of Bone Tissue Engineering (BTE). in This Work, a Novel BTE Composite Containing Layered Double Hydroxides (LDH), Hydroxyapatite (HA) and Gelatin (GEL) Was Fabricated using Co-Precipitation and Solvent-Casting Methods. Physiochemical Characterizations Showed that the Chemical Composition and Microstructure of the Scaffolds Were Similar to the Natural Spongy Bone. Interconnected Macropores Ranging over 100 to 600 Μm Were Observed for Both Scaffolds While the Porosity of 90 ± 0.12% and 92.11 ± 0.15%, as Well As, Young's Modulus of 19.8 ± 0.41 and 12.5 ± 0.35 GPa Were …

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Design And Analysis Of Adaptive Control Systems Over Wireless Networks, Ali Albattat, Benjamin Gruenwald, Tansel Yucelen Jul 2017

Design And Analysis Of Adaptive Control Systems Over Wireless Networks, Ali Albattat, Benjamin Gruenwald, Tansel Yucelen

Mechanical and Aerospace Engineering Faculty Research & Creative Works

In this paper, we study the design and analysis of adaptive control systems over wireless networks using event-triggering control theory. The proposed event-triggered adaptive control methodology schedules the data exchange dependent upon errors exceeding user-defined thresholds to reduce wireless network utilization and guarantees system stability and command following performance in the presence of system uncertainties. Specifically, we analyze stability and boundedness of the overall closed-loop dynamical system, characterize the effect of user-defined thresholds and adaptive controller design parameters to the system performance, and discuss conditions to make the resulting command following performance error sufficiently small. An illustrative numerical example is …

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A Decentralized Adaptive Control Architecture For Large-Scale Active-Passive Modular Systems, Benjamin C. Gruenwald, Ehsan Arabi, Tansel Yucelen, Animesh Chakravarthy, Drew Mcneely Jun 2017

A Decentralized Adaptive Control Architecture For Large-Scale Active-Passive Modular Systems, Benjamin C. Gruenwald, Ehsan Arabi, Tansel Yucelen, Animesh Chakravarthy, Drew Mcneely

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Decentralized control of large-scale active-passive modular systems is considered. These systems consist of physically interconnected and generally heterogeneous modules, where local control signals can be only applied to a subset of these modules (i.e., active modules) and the rest are not subject to any control signals (i.e., passive modules). Using a set-theoretic adaptive control approach predicated on restricted potential functions, we design decentralized command following control architectures for each active module such that they can effectively perform their tasks with strict performance guarantees in the presence of unknown physical interconnections between modules and module-level system uncertainties. The efficacy of the …

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An Algorithm For Enlarging The Region Of Attraction Using Trajectory Reversing, Nilay Kant, Dhrubajit Chowdhury, Ranjan Mukherjee, Hassan K. Khalil Jun 2017

An Algorithm For Enlarging The Region Of Attraction Using Trajectory Reversing, Nilay Kant, Dhrubajit Chowdhury, Ranjan Mukherjee, Hassan K. Khalil

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Trajectory reversing is a method commonly used for estimating the region of attraction of stabilized equilibria. Using a discrete set of points obtained by trajectory reversing, this paper presents an algorithm for estimation and mathematical representation of the region of attraction using convex hulls. Several two-dimensional examples are presented to illustrate the usefulness of the algorithm. The method provides larger estimates compared to that obtained by existing algorithms, but its main advantage lies in its applicability to higher-order systems. The mathematical representation of the region of attraction is useful in applying the Impulse Manifold Method, which was developed for stabilization …

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Enlarging The Region Of Attraction Of Equilibria Of Underactuated Systems Using Sum Of Squares And Impulse Manifold Method, Dhrubajit Chowdhury, Nilay Kant, Ranjan Mukherjee, Hassan K. Khalil Jun 2017

Enlarging The Region Of Attraction Of Equilibria Of Underactuated Systems Using Sum Of Squares And Impulse Manifold Method, Dhrubajit Chowdhury, Nilay Kant, Ranjan Mukherjee, Hassan K. Khalil

Mechanical and Aerospace Engineering Faculty Research & Creative Works

This paper presents an algorithm to enlarge the estimate of the Region of Attraction of stable equilibria of underactuated systems. To achieve this, we use a combination of the Sum of Squares (SOS) method and the Impulse Manifold Method (IMM). Initially, the SOS method is used to optimize the control input u(x) in order to obtain an enlarged Region of Attraction. The IMM is then applied on enlarged Region of Attraction obtained using SOS to further enlarge it. The IMM is implemented using high gain feedback and to demonstrate the efficacy of our algorithm, we present simulation results where an …

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Validation Of Adaptive Control Laws Using Optimization And Trajectory Sensitivity, Mario Luca Fravolini, Antonio Ficola, Fabio Radicioni, Tansel Yucelen, Ehsan Arabi Jun 2017

Validation Of Adaptive Control Laws Using Optimization And Trajectory Sensitivity, Mario Luca Fravolini, Antonio Ficola, Fabio Radicioni, Tansel Yucelen, Ehsan Arabi

Mechanical and Aerospace Engineering Faculty Research & Creative Works

In this paper it is proposed an easy-to-use verification and validation method for adaptive control laws that relies on time domain simulations. The problem is set as a trajectory falsification problem that is the search of closed loop trajectories that, starting from a set of admissible initial conditions, reach a set of unsafe states. The falsification is placed as a nonlinear optimization problem whose decision variables are the initial condition of the states and the uncertain parameters of the system. The falsification is performed iteratively using the local gradient of the sensitivity function derived from a linearized model of the …

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Swing-Up Of The Inertia Wheel Pendulum Using Impulsive Torques, Nilay Kant, Ranjan Mukherjee, Hassan K. Khalil Jun 2017

Swing-Up Of The Inertia Wheel Pendulum Using Impulsive Torques, Nilay Kant, Ranjan Mukherjee, Hassan K. Khalil

Mechanical and Aerospace Engineering Faculty Research & Creative Works

The swing-up control problem of the inertia wheel pendulum is revisited in this paper. As different from existing methods, purely impulsive control inputs are used for swing-up. A mathematical formulation of the problem indicates that swing-up can be achieved using impulsive inputs applied at two discrete time instants. Two different swing-up schemes are presented and validated using numerical simulations where the impulsive inputs are approximated by high-gain feedback. The results of numerical simulations establish a direct link between high wheel velocities during swing-up and control strategies that take the pendulum directly to the upright configuration. They also indicate that the …

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Identifying Design Parameters Controlling Damage Behaviors Of Continuous Fiber-Reinforced Thermoplastic Composites Using Micromechanics As A Virtual Testing Tool, Ditho Pulungan, Gilles Lubineau, Arief Yudhanto, Recep Yaldiz, Warden Schijve Jun 2017

Identifying Design Parameters Controlling Damage Behaviors Of Continuous Fiber-Reinforced Thermoplastic Composites Using Micromechanics As A Virtual Testing Tool, Ditho Pulungan, Gilles Lubineau, Arief Yudhanto, Recep Yaldiz, Warden Schijve

Mechanical and Aerospace Engineering Faculty Research & Creative Works

In this paper, we propose a micromechanical approach to predict damage mechanisms and their interactions in glass fibers/polypropylene thermoplastic composites. First, a representative volume element (RVE) of such materials was rigorously determined using a geometrical two-point probability function and the eigenvalue stabilization of homogenized elastic tensor obtained by Hill–Mandel kinematic homogenization. Next, the 3D finite element models of the RVE were developed accordingly. The fibers were modeled with an isotropic linear elastic material. The matrix was modeled with an isotropic linear elastic, rate-independent hyperbolic Drucker–Prager plasticity coupled with a ductile damage model that is able to show pressure dependency of …

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Intensity Control Of Individual Dbd Plasma Filament. I. Experiment With A Needle Electrode, M. C. Paliwoda, J. L. Rovey May 2017

Intensity Control Of Individual Dbd Plasma Filament. I. Experiment With A Needle Electrode, M. C. Paliwoda, J. L. Rovey

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Filamentary volume dielectric barrier discharge (DBD) produces patterned plasma structures that are currently being explored for reconfigurable metamaterial applications. In this work, the presence and intensity of a single filament (within an array of filaments) are controlled by biasing a low voltage needle electrode by less than 7% of the driving voltage. The current, voltage, and time-averaged normalized light intensity were measured while varying the needle voltage through self-biasing resistors. For a 7.5 kV, 3.2 kHz DBD in air, the needle-controlled filament intensity varies from 80% to 0% of the light intensity of surrounding filaments. When the biased voltage prevents …

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Intensity Control Of Individual Dbd Plasma Filament. Ii. Fundamental Physical Mechanism, M. C. Paliwoda, J. L. Rovey May 2017

Intensity Control Of Individual Dbd Plasma Filament. Ii. Fundamental Physical Mechanism, M. C. Paliwoda, J. L. Rovey

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Filamentary volume dielectric barrier discharge (DBD) produces patterned plasma structures that are currently being explored for reconfigurable metamaterial applications. Previous work has demonstrated control of the presence and intensity of a single DBD plasma filament (within an array of filaments) by biasing a low voltage needle electrode. The results were attributed to redistributed charge inside the DBD due to the modified electric field created by the needle electrode. In the present work, results from a 3D electrodynamic field simulation bolster this argument. Results show that increasing needle bias voltage causes changes in the transverse electric field structure, resulting in redistribution …

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Investigating The Potential Of Using Off-Axis 3d Woven Composites In Composite Joints’ Applications, Mohamed Nasr Saleh, Ying Wang, Arief Yudhanto, Adam Joesbury, Prasad Potluri, Gilles Lubineau, Constantinos Soutis Apr 2017

Investigating The Potential Of Using Off-Axis 3d Woven Composites In Composite Joints’ Applications, Mohamed Nasr Saleh, Ying Wang, Arief Yudhanto, Adam Joesbury, Prasad Potluri, Gilles Lubineau, Constantinos Soutis

Mechanical and Aerospace Engineering Faculty Research & Creative Works

The effect of circular notch has been evaluated for three different architectures of three-dimensional (3D) carbon fiber woven composites (orthogonal, ORT; layer-to-layer, LTL; angle interlock, AI) through open-hole quasi-static tension and double-lap bearing strength tests in the off-axis (45°) direction. Damage characterization is monitored using Digital Image correlation (DIC) for open-hole testing and X-ray Computed Tomography (CT) for double-lap bearing strength test. The off-axis notched 3D woven composites exhibit minor reduction (less than 10 %) of the notched strength compared to the un-notched strength. DIC strain contour clearly show stress/strain localization regions around the hole periphery and stress/strain redistribution away …

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Phonon Interference In Crystalline And Amorphous Confined Nanoscopic Films, Zhi Liang, Thomas E. Wilson, Pawel Keblinski Feb 2017

Phonon Interference In Crystalline And Amorphous Confined Nanoscopic Films, Zhi Liang, Thomas E. Wilson, Pawel Keblinski

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Using Molecular Dynamics Phonon Wave Packet Simulations, We Study Phonon Transmission Across Hexagonal (H)-BN and Amorphous Silica (A-SiO2) Nanoscopic Thin Films Sandwiched by Two Crystalline Leads. Due to the Phonon Interference Effect, the Frequency-Dependent Phonon Transmission Coefficient in the Case of the Crystalline Film (Si|h-BN|Al Heterostructure) Exhibits a Strongly Oscillatory Behavior. in the Case of the Amorphous Film (Si|a-SiO2|Al and Si|a-SiO2|Si Heterostructures), in Spite of Structural Disorder, the Phonon Transmission Coefficient Also Exhibits Oscillatory Behavior at Low Frequencies (Up to ∼1.2 THz), with a Period of Oscillation Consistent with the Prediction from the Two-Beam …

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Surrogate Modeling Of Ultrasonic Simulations Using Data-Driven Methods, Xiaosong Du, Robert Grandin, Leifur Leifsson Feb 2017

Surrogate Modeling Of Ultrasonic Simulations Using Data-Driven Methods, Xiaosong Du, Robert Grandin, Leifur Leifsson

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Ultrasonic testing (UT) is used to detect internal flaws in materials and to characterize material properties. In many applications, computational simulations are an important part of the inspection-design and analysis processes. Having fast surrogate models for UT simulations is key for enabling efficient inverse analysis and model-assisted probability of detection (MAPOD). In many cases, it is impractical to perform the aforementioned tasks in a timely manner using current simulation models directly. Fast surrogate models can make these processes computationally tractable. This paper presents investigations of using surrogate modeling techniques to create fast approximate models of UT simulator responses. In particular, …

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Aerodynamic Design Of A Rectangular Wing In Subsonic Inviscid Flow By Surrogate-Based Optimization, Xiaosong Du, Anand Amrit, Andrew Thelen, Leifur Leifsson, Yu Zhang, Zhong Hua Han, Slawomir Koziel Jan 2017

Aerodynamic Design Of A Rectangular Wing In Subsonic Inviscid Flow By Surrogate-Based Optimization, Xiaosong Du, Anand Amrit, Andrew Thelen, Leifur Leifsson, Yu Zhang, Zhong Hua Han, Slawomir Koziel

Mechanical and Aerospace Engineering Faculty Research & Creative Works

The paper presents results of aerodynamic design of a rectangular wing in subsonic inviscid flow using surrogate-based local and global search algorithms. The aerodynamic design problem is formulated in Benchmark Cases 3 and 6 developed by the AIAA Applied Aerodynamics Discussion Group. Both involve lift-constrained drag minimization at a Mach number of 0.5 with relatively low lift coefficients (0.2625 and 0.375) with several nonlinear constraints and a small number design variables (up to 15). In this work, the local search is performed using variable-fidelity modelling and output space mapping, whereas the global search is performed using approximation-based surrogates. The paper …

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Aerodynamic Design Of The Rae 2822 In Transonic Viscous Flow: Single- And Multi-Objective Optimization Studies, Anand Amrit, Xiaosong Du, Andrew Thelen, Leifur Leifsson, Slawomir Koziel Jan 2017

Aerodynamic Design Of The Rae 2822 In Transonic Viscous Flow: Single- And Multi-Objective Optimization Studies, Anand Amrit, Xiaosong Du, Andrew Thelen, Leifur Leifsson, Slawomir Koziel

Mechanical and Aerospace Engineering Faculty Research & Creative Works

This paper addresses a benchmark aerodynamic design problem proposed by the AIAA Aerodynamic Design Optimization Discussion Group: Drag minimization of the RAE 2822 in transonic viscous flow at a fixed lift coefficient with constraints on the pitching moment coefficient and the cross-sectional area. The single-objective optimization (SOO) problem is solved using surrogate-based optimization (SBO) with the surrogates constructed through output space mapping and variable-resolution Reynolds-Averaged Navier-Stokes computational fluid dynamics models. Improving the implementation of our search algorithms enabled us to obtain the SOO optimal design four times faster than in our prior work in terms of CPU time. To explore …

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Airfoil Design Under Uncertainty Using Non-Intrusive Polynomial Chaos Theory And Utility Functions, Xiaosong Du, Leifur Leifsson, Slawomir Koziel, Adrian Bekasiewicz Jan 2017

Airfoil Design Under Uncertainty Using Non-Intrusive Polynomial Chaos Theory And Utility Functions, Xiaosong Du, Leifur Leifsson, Slawomir Koziel, Adrian Bekasiewicz

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Fast and accurate airfoil design under uncertainty using non-intrusive polynomial chaos (NIPC) expansions and utility functions is proposed. The NIPC expansions provide a means to efficiently and accurately compute statistical information for a given set of input variables with associated probability distribution. Utility functions provide a way to rigorously formulate the design problem. In this work, these two methods are integrated for the design of airfoil shapes under uncertainty. The proposed approach is illustrated on a numerical example of lift-constrained airfoil drag minimization in transonic viscous flow using the Mach number as an uncertain variable. The results show that compared …

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Expedite Design Of Variable-Topology Broadband Hybrid Couplers For Size Reduction Using Surrogate-Based Optimization And Co-Simulation Coarse Models, Piotr Kurgan, Slawomir Koziel, Leifur Leifsson, Xiaosong Du Jan 2017

Expedite Design Of Variable-Topology Broadband Hybrid Couplers For Size Reduction Using Surrogate-Based Optimization And Co-Simulation Coarse Models, Piotr Kurgan, Slawomir Koziel, Leifur Leifsson, Xiaosong Du

Mechanical and Aerospace Engineering Faculty Research & Creative Works

In this paper, we discuss a computationally efficient approach to expedite design optimization of broadband hybrid couplers occupying a minimized substrate area. Structure size reduction is achieved here by decomposing an original coupler circuit into low- and high-impedance components and replacing them with electrically equivalent slow-wave lines with reduced physical dimensions. The main challenge is reliable design of computationally demanding low-impedance slow-wave structures that feature a quasi-periodic circuit topology for wideband operation. Our goal is to determine an adequate number of recurrent unit elements as well as to adjust their designable parameters so that the coupler footprint area is minimal. …

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Molecular Simulation Of Steady-State Evaporation And Condensation: Validity Of The Schrage Relationships, Zhi Liang, Thierry Biben, Pawel Keblinski Jan 2017

Molecular Simulation Of Steady-State Evaporation And Condensation: Validity Of The Schrage Relationships, Zhi Liang, Thierry Biben, Pawel Keblinski

Mechanical and Aerospace Engineering Faculty Research & Creative Works

The Accuracy, or Even the Validity, of the Schrage Relationships Expressing the Rate of Evaporation and Condensation in Terms of Local Interfacial Thermodynamics Properties and the Mass Accommodation Coefficient is a Subject of Significant Discussion. in This Work, We Carry Out Molecular Dynamics (MD) Simulations of Evaporation and Condensation of Fluid Ar in a Nanochannel. by Adjusting the Temperature Difference, ΔT, between the Evaporating and Condensing Surfaces, We Control the Steady-State Evaporation and Condensation Fluxes (JMD). We Find that Across a Wide ΔT Range Studied, JMD is Always in Excellent Agreement with the Prediction from the Exact Schrage Relationships. Furthermore, …

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Robust Airfoil Design Optimization Using Stochastic Expansions And Utility Theory, Xiaosong Du, Leifur Leifsson, Slawomir Koziel Jan 2017

Robust Airfoil Design Optimization Using Stochastic Expansions And Utility Theory, Xiaosong Du, Leifur Leifsson, Slawomir Koziel

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Efficient and effective robust airfoil design optimization is proposed by integrating stochastic expansions and utility theory. In this work, the stochastic expansions are generated efficiently using non-intrusive polynomial chaos (NIPC) expansions. The robust design problem is formulated using utility functions which transfer a targeted response using a prescribed mathematical function to represent the designers' risk preferences. The proposed approach is demonstrated using examples of lift-constrained airfoil drag minimization in transonic viscous flow using the Mach number as an uncertain variable in the range of 0.70 to 0.75. The results are compared with the common problem formulation for robust design of …

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Pareto Ranking Bisection Algorithm For Em-Driven Multi-Objective Design Of Antennas In Highly-Dimensional Parameter Spaces, Adrian Bekasiewicz, Slawomir Koziel, Leifur Leifsson, Xiaosong Du Jan 2017

Pareto Ranking Bisection Algorithm For Em-Driven Multi-Objective Design Of Antennas In Highly-Dimensional Parameter Spaces, Adrian Bekasiewicz, Slawomir Koziel, Leifur Leifsson, Xiaosong Du

Mechanical and Aerospace Engineering Faculty Research & Creative Works

A deterministic technique for fast surrogate-assisted multi-objective design optimization of antennas in highly-dimensional parameters spaces has been discussed. In this two-stage approach, the initial approximation of the Pareto set representing the best compromise between conflicting objectives is obtained using a bisection algorithm which finds new Pareto-optimal designs by dividing the line segments interconnecting previously found optimal points, and executing poll-type search that involves Pareto ranking. The initial Pareto front is generated at the level of the coarsely-discretized EM model of the antenna. In the second stage of the algorithm, the high-fidelity Pareto designs are obtained through optimization of corrected local-approximation …

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Assessment Of Multimode Spacecraft Micropropulsion Systems, Steven P. Berg, Joshua L. Rovey Jan 2017

Assessment Of Multimode Spacecraft Micropropulsion Systems, Steven P. Berg, Joshua L. Rovey

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Multimode spacecraft micro propulsion systems that include a high-Thrust chemical mode and high-specific impulse electric mode are assessed with specific reference to CubeSat-sized satellite applications. Both cold-gas butane propellant and ionic liquid chemical monopropellant modes are investigated alongside pulsed plasma, electrospray, and ion electric thruster modes. These systems are studied by varying electric propulsion usage percent and calculating the payload mass fraction and thruster burn time for missions requiring 250, 500, and 1000 m/s delta-V. Systems involving chemical monopropellants have the highest payload mass fractions for a reference mission of 500 m/s delta-V and 6U-sized CubeSat, where 1U is a …

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Probabilistic Analysis And Verification Framework For Adaptive Flight Control, Mario Luca Fravolini, Tansel Yucelen, Marcello Napolitano Jan 2017

Probabilistic Analysis And Verification Framework For Adaptive Flight Control, Mario Luca Fravolini, Tansel Yucelen, Marcello Napolitano

Mechanical and Aerospace Engineering Faculty Research & Creative Works

A crucial aspect that could facilitate the applications of adaptive control systems in aerospace applications is the development of effective validation and verification procedures. Most of the existing analysis and design frameworks for adaptive controllers are based on the Lyapunov direct method. One well-known drawback of this approach is the conservatism in the estimation of the uniform ultimate boundedness region with little practical utility. To overcome this limitation, a probabilistic framework for the design of uniform ultimate boundedness regions is proposed where uncertain parameters and adaptive controls are considered as random variables. In this framework, the design is translated into …

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Resilient Control Of Active-Passive Networked Multiagent Systems In The Presence Of Persistent Disturbances, Dzung Tran, Tansel Yucelen, John Daniel Peterson Jan 2017

Resilient Control Of Active-Passive Networked Multiagent Systems In The Presence Of Persistent Disturbances, Dzung Tran, Tansel Yucelen, John Daniel Peterson

Mechanical and Aerospace Engineering Faculty Research & Creative Works

An active-passive networked multiagent system consists of agents subject to inputs (active agents) and agents without any inputs (passive agents). Specifically, this class of networked multiagent systems utilizes a novel form of dynamic consensus filters, where the states of all agents converge to the average of the exogenous inputs applied only to the active agents, and it has broad practical applications including, for example, real-time situational awareness and data gathering using sensor networks and distributed control of multirobot systems. In this paper, we focus on active-passive networked multiagent systems that are subject to constant and/or harmonic exogenous disturbances. In particular, …

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Plume Characterization Of Electric Solid Propellant Pulsed Microthrusters, Matthew S. Glascock, Joshua L. Rovey, Shae Williams, Jason Thrasher Jan 2017

Plume Characterization Of Electric Solid Propellant Pulsed Microthrusters, Matthew S. Glascock, Joshua L. Rovey, Shae Williams, Jason Thrasher

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Electric solid propellants are an attractive option for propulsion because they are ignited only by an applied electric current. This leads to capabilities such as on-demand throttling and reignition in chemical combustion operation, and it lends itself to application in electric propulsion. In this work, the plasma plume created by electric solid propellant pulsed micro thrusters is investigated using a nude Faraday probe, a triple Langmuir probe, and residual gas analysis. The thrusters are tested at a vacuum level of 2 x 10-5torr. Results indicate an average plume electron temperature of 1.7 eV and a density of 1011 to 1014cm-3. …

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Local Field Effects On Magnetic Suppression Of The Converging Richtmyer-Meshkov Instability, Vincent Wheatley, Wouter Mostert, D. M. Bond, Ravi Samtaney Dec 2016

Local Field Effects On Magnetic Suppression Of The Converging Richtmyer-Meshkov Instability, Vincent Wheatley, Wouter Mostert, D. M. Bond, Ravi Samtaney

Mechanical and Aerospace Engineering Faculty Research & Creative Works

We examine how the suppression of the converging shockdriven Richtmyer-Meshkov instability by an applied magnetic field is dependent on the local magnetic field strength and orientation. In particular, we examine whether the extent of suppression can be reasonably predicted by a linear model for the planar case. This is done for cylindrically converging cases with a high perturbation wavenumber and two different initial magnetic field configurations.

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Effects Of The Cooling Rate On The Shear Behavior Of Continuous Glass Fiber/Impact Polypropylene Composites (Gf-Ipp), H. Wafai, G. Lubineau, A. Yudhanto, M. Mulle, W. Schijve, N. Verghese Dec 2016

Effects Of The Cooling Rate On The Shear Behavior Of Continuous Glass Fiber/Impact Polypropylene Composites (Gf-Ipp), H. Wafai, G. Lubineau, A. Yudhanto, M. Mulle, W. Schijve, N. Verghese

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Fiber-reinforced composites with improved dissipation of energy during impact loading have recently been developed based on a polypropylene copolymer commonly called impact polypropylene (IPP). Composites made of IPP reinforced with glass fibers (GF) are particularly attractive to the automotive industry due to their low cost and good impact resistance. In such composites, the cooling rate varies depending on processing techniques and manufacturing choices. Here, we study the effects of the cooling rate of GF-IPP composites on shear behavior, which is critical in impact applications, using [±45]s monotonic and cyclic (load/unload) tensile specimens. The specimens were manufactured under a wide range …

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Effect Of Amino-Functionalization On Insulin Delivery And Cell Viability For Two Types Of Silica Mesoporous Structures, Abdollah Zakeri Siavashani, Masoumeh Haghbin Nazarpak, Fateme Fayyazbakhsh, Tayebeh Toliyat, Steven James Peter Mcinnes, Mehran Solati-Hashjin Dec 2016

Effect Of Amino-Functionalization On Insulin Delivery And Cell Viability For Two Types Of Silica Mesoporous Structures, Abdollah Zakeri Siavashani, Masoumeh Haghbin Nazarpak, Fateme Fayyazbakhsh, Tayebeh Toliyat, Steven James Peter Mcinnes, Mehran Solati-Hashjin

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Inorganic Mesoporous Structures Are a Class of Novel Biomaterials that Have Shown Practical Applications in Delivery of a Variety of Therapeutic Agents. in the Present Study, Two Mesoporous Structures Were Prepared, and the Effect of Surface Modification on their Insulin Delivery and in Vitro Cytotoxicity Was Evaluated. Morphological and Structural Characterizations of Silica Particles Were Accomplished by Different Analytical Techniques, Including Scanning Electron Microscopy, X-Ray Diffraction, Fourier Transform Infrared Spectroscopy (FTIR), and Brunauer–Emmett–Teller (BET) Surface Area Analyses. the Drug Loading Capacity and in Vitro Drug Release Behavior of Silica Structures Were Investigated under Simulated Gastrointestinal Conditions and Phosphate-Buffered Saline Solution …

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