In this chapter we describe the dynamic response of nonlinear phononic structures, focusing on granular crystals as the most prominent example. The chapter begins with a brief history of nonlinear lattices and with an introduction to granular crystals. It describes past and recent work on one-dimensional (1D) and two-dimensional (2D) granular crystals, categorized according to the crystals' periodicity and dynamical regime. It concludes with an overview of other nonlinear phononic systems and...
Topics: DTIC Archive, CALIFORNIA INST OF TECH PASADENA DIV OF ENGINEERING AND APPLIED SCIENCE, *DYNAMIC...
Fundamental understanding of dynamic behavior of polycrystalline ceramics is advanced through constitutive theory development and computational modeling. At the mesoscale, microstructures of silicon carbide grains (hexagonal crystal structure) or aluminum oxynitride grains (cubic crystal structure) are subjected to compression or shear at high rates with varying confining pressure. Each grain is resolved by numerous three-dimensional finite elements, and behavior of each grain is modeled using...
Topics: DTIC Archive, ARMY RESEARCH LAB ABERDEEN PROVING GROUND MD WEAPONS AND MATERIALS RESEARCH...
This report consists of two parts. The objective of the first part of the research was to use a sol-gel in-situ produced silica nanoparticle-modified epoxy to manufacture fiber composites in order to enhance the mechanical properties of fiber composites. Vacuum assisted resin transfer molding (VARTM) process was used to fabricate unidirectional E-glass fiber reinforced silica/epoxy nanocomposites. Off-axis composite specimens with and without silica nanoparticles were tested to compare the...
Topics: DTIC Archive, PURDUE UNIV LAFAYETTE IN SCHOOL OF AERONAUTICS AND ASTRONAUTICS, *FIBER REINFORCED...
We have significant accomplishments on uncertainty quantification in inverse problems for dynamical systems, generalized sensitivity and optimal design of experiments, elasticity and viscoelasticity modeling for buried target detection, and general inverse problem methodology for proliferating populations. Our efforts have continued on development of efficient accurate integration of Fokker Planck equations. Our objective is to analyze and optimize the dynamic behavior of nonlinear stochastic...
Topics: DTIC Archive, NORTH CAROLINA STATE UNIV AT RALEIGH CENTER FOR RESEARCH IN SCIENTIFIC COMPUTATION,...
Weapon release at supersonic speeds from an internal bay is highly advantageous. For this reason, both experimental and numerical methods were used to investigate store separation from a cavity (L=D=4.5) into Mach 2.94 ow. The experiment used a piezoresistive pressure transducer, Schlieren and high-speed photography for data acquisition. The computational solution used the OVERFLOW solver. A sphere and a Mk-82, scaled to 1:20, were formed using frozen tap water. The sphere model was freedrop...
Topics: DTIC Archive, AIR FORCE INST OF TECH WRIGHT-PATTERSON AFB OH GRADUATE SCHOOL OF ENGINEERING AND...
Topics: DTIC Archive, MICHIGAN UNIV ANN ARBOR, *ELECTRIC BATTERIES, DYNAMIC RESPONSE, FATIGUE LIFE, GAIN,...
Marine structures are designed to operate in hostile environments consisting of corrosive sea-water, hot and cold temperature extremes, transient dynamic loads like hull-slamming and complex three-dimensional hydrostatic loads. Additionally, naval structures are required to withstand weapons impacts and blast loads resulting from surface and underwater explosions. Recent assessments of marine structures have demonstrated that sandwich structures and composite materials can provide high...
Topics: DTIC Archive, GEORGIA INST OF TECH ATLANTA, *MARINE ENGINEERING, *STRUCTURAL PROPERTIES,...
The dynamics of magnetic hysteresis, including the training effect and the field sweep rate dependence of the exchange bias, is experimentally investigated in exchange-coupled potassium split graphene nanoribbons (GNRs). We find that, at low field sweep rate, the pronounced absolute training effect is present over a large number of cycles. This is reflected in a gradual decrease of the exchange bias with the sequential field cycling. However, at high field sweep rate above 0.5 T/min, the...
Topics: DTIC Archive, ARMY RESEARCH LAB RESEARCH TRIANGLE PARK NC ARMY RESEARCH OFFICE, *MAGNETIC...
A comprehensive study was conducted to evaluate the performance of spatially tailored aero-thermal structures under thermo-mechanical loadings. Starting from the first principles, analytical analyses were conducted to develop thermo-mechanical stress fields for mixed mode dynamic curving cracks in functionally graded materials (FGMs) under steady-state and transient loading conditions. Asymptotic analysis was used in conjunction with displacement potentials to develop the stress fields around...
Topics: DTIC Archive, RHODE ISLAND UNIV KINGSTON, *THERMOMECHANICS, AERODYNAMIC HEATING, ALUMINUM,...
The goal of this work is to develop an efficient numerical modeling method for the vibration of hybrid electric vehicle (HEV) battery packs to support probabilistic forced response simulations and fatigue life predictions. There are two important sources of variations in HEV battery packs that affect their structural dynamic response. One source is the uncertain level of pre-stress due to bolts or welds used for joining cells within a pack. The other source is small structural variations among...
Topics: DTIC Archive, MICHIGAN UNIV ANN ARBOR, *ELECTRIC BATTERIES, DYNAMIC RESPONSE, ELECTROLYTIC CELLS,...
The dynamic multiaxial response of hot-pressed AlN is characterized through quasi-static uniaxial compression, dynamic uniaxial compression and dynamic confined compression experiments within the strain rate range of 10(expn -3) -10(expn 3) s(expn -1). Real-time visualization shows the failure patterns change from axial splitting under uniaxial dynamic compression to shear faulting under confinement. The compressive strength is moderately sensitive to both the confining stress and the loading...
Topics: DTIC Archive, ARMY RESEARCH LAB ABERDEEN PROVING GROUND MD WEAPONS AND MATERIALS RESEARCH...
A joint National Aeronautics and Space Administration (NASA) and Department of Energy (DOE) team is developing concepts and technologies for affordable nuclear Fission Power Systems (FPSs) to support future exploration missions. A key deliverable is the Technology Demonstration Unit (TDU). The TDU will assemble the major elements of a notional FPS with a non-nuclear reactor simulator (Rx Sim) and demonstrate system-level performance in thermal vacuum. The Rx Sim includes an electrical...
Topics: NASA Technical Reports Server (NTRS), NUCLEAR REACTORS, ELECTRICAL RESISTANCE, HEAT SOURCES,...
Flutter may sound like a benign word when associated with a flag in a breeze, a butterfly, or seaweed in an ocean current. When used in the context of aerodynamics, however, it describes a highly dangerous, potentially deadly condition. Consider the case of the Lockheed L-188 Electra Turboprop, an airliner that first took to the skies in 1957. Two years later, an Electra plummeted to the ground en route from Houston to Dallas. Within another year, a second Electra crashed. In both cases, all...
Topics: NASA Technical Reports Server (NTRS), AERODYNAMIC FORCES, AEROELASTICITY, DYNAMIC STRUCTURAL...
The launch environment is a challenging regime to work due to changing system dynamics, changing environmental loading, joint compression loads that cannot be easily applied on the ground, and control effects. Operational testing is one of the few feasible approaches to capture system level dynamics since ground testing cannot reproduce all of these conditions easily. However, the most successful applications of Operational Modal Testing involve systems with good stationarity and long data...
Topics: NASA Technical Reports Server (NTRS), FLIGHT CHARACTERISTICS, DYNAMIC RESPONSE, SOFTWARE...
Abstract Handling qualities embody those qualities or characteristics of an aircraft that govern the ease and precision with which a pilot is able to perform the tasks required in support of an aircraft role. These same qualities are as critical, if not more so, in the operation of spacecraft. A research, development, test, and evaluation process was put into effect to identify, understand, and interpret the engineering and human factors principles which govern the pilot-vehicle dynamic system...
Topics: NASA Technical Reports Server (NTRS), SPACECREWS, CONTROLLABILITY, SPACECRAFT CONTROL, MANNED SPACE...
An enhanced design methodology for minimizing the error in on-line Kalman filter-based aircraft engine performance estimation applications is presented in this paper. It specific-ally addresses the under-determined estimation problem, in which there are more unknown parameters than available sensor measurements. This work builds upon an existing technique for systematically selecting a model tuning parameter vector of appropriate dimension to enable estimation by a Kalman filter, while...
Topics: NASA Technical Reports Server (NTRS), ENGINE CONTROL, PERFORMANCE PREDICTION, ENGINE DESIGN,...
A procedure is developed for using nonlinear experimental response data to guide the modal basis selection in a nonlinear reduced-order simulation. The procedure entails using nonlinear acceleration response data to first identify proper orthogonal modes. Special consideration is given to cases in which some of the desired response data is unavailable. Bases consisting of linear normal modes are then selected to best represent the experimentally determined transverse proper orthogonal modes and...
Topics: NASA Technical Reports Server (NTRS), NONLINEARITY, SIMULATION, ORTHOGONALITY, MATHEMATICAL MODELS,...
Observations have shown that the concentration of nitrogen dioxide decreased in both hemispheres in the years following the eruption of Mt. Pinatubo. In contrast, the observed ozone response was largely asymmetrical with respect to the equator, with a decrease in the northern hemisphere and little or no change in the southern hemisphere. Simulations including enhanced heterogeneous chemistry due to the presence of the volcanic aerosol reproduce a decrease of ozone in the northern hemisphere,...
Topics: NASA Technical Reports Server (NTRS), NITROGEN DIOXIDE, OZONE DEPLETION, VOLCANIC ERUPTIONS,...
The fortnightly Mf ocean tide is the largest of the long-period tides (periods between 1 week and 18.6 years), but Mf is still very small, generally 2 cm or less. All long-period tides are thought to be near equilibrium with the astronomical tidal potential, with an almost pure zonal structure. However, several lines of evidence point to Mf having a significant dynamic response to forcing. We use a combination of numerical modeling, satellite altimetry, and observations of polar motion to...
Topics: NASA Technical Reports Server (NTRS), ANELASTICITY, TIDES, EARTH ROTATION, DYNAMIC RESPONSE,...
Presenting an overview of the research DFRC is planning within the Subsonic Fixed Wing (SFW) Light Weight Airframes and Propulsion. Describ ing our TRL maturation and new research going forward using the X-56A as a validation testbed.
Topics: NASA Technical Reports Server (NTRS), FIXED WINGS, FLEXIBLE WINGS, WING PROFILES, SLENDER WINGS,...
This paper summarizes data and findings from the first Aeroelastic Prediction Workshop (AePW) held in April, 2012. The workshop has been designed as a series of technical interchange meetings to assess the state of the art of computational methods for predicting unsteady flowfields and static and dynamic aeroelastic response. The goals are to provide an impartial forum to evaluate the effectiveness of existing computer codes and modeling techniques to simulate aeroelastic problems, and to...
Topics: NASA Technical Reports Server (NTRS), UNSTEADY AERODYNAMICS, AEROELASTICITY, SEPARATED FLOW,...
Bird strikes are a common problem for the aerospace industry and can cause serious damage to an aircraft. Ballistic gelatin is frequently used as a surrogate for actual bird carcasses in bird strike tests. Numerical simulations of these tests are used to supplement experimental data, therefore it is necessary to use numerical modeling techniques that can accurately capture the dynamic response of ballistic gelatin. An experimental technique is introduced to validate these modeling techniques. A...
Topics: NASA Technical Reports Server (NTRS), BIRD-AIRCRAFT COLLISIONS, TERMINAL BALLISTICS, DYNAMIC...
The semi-empirical force-limiting vibration method was developed and implemented for payload testing to limit the structural impedance mismatch (high force) that occurs during shaker vibration testing. The method has since been extended for use in analytical models. The Space Communications and Navigation Testbed (SCAN Testbed), known at NASA as, the Communications, Navigation, and Networking re-Configurable Testbed (CoNNeCT), project utilized force-limiting testing and analysis following the...
Topics: NASA Technical Reports Server (NTRS), IMPEDANCE, VIBRATION TESTS, DYNAMIC STRUCTURAL ANALYSIS,...
This paper examines Probabilistic Sensitivity Analysis (PSA) methods and tools in an effort to understand their utility in vehicle loads and dynamic analysis. Specifically, this study addresses how these methods may be used to establish limits on payload mass and cg location and requirements on adaptor stiffnesses while maintaining vehicle loads and frequencies within established bounds. To this end, PSA methods and tools are applied to a realistic, but manageable, integrated launch vehicle...
Topics: NASA Technical Reports Server (NTRS), ADAPTERS, LAUNCH VEHICLES, PAYLOADS, SENSITIVITY ANALYSIS,...
This paper presents the implementation of gust modeling capability in the CFD code FUN3D. The gust capability is verified by computing the response of an airfoil to a sharp edged gust. This result is compared with the theoretical result. The present simulations will be compared with other CFD gust simulations. This paper also serves as a users manual for FUN3D gust analyses using a variety of gust profiles. Finally, the development of an Auto-Regressive Moving-Average (ARMA) reduced order gust...
Topics: NASA Technical Reports Server (NTRS), AEROELASTICITY, AUTOREGRESSIVE MOVING AVERAGE, COMPUTATIONAL...
No abstract available
Topics: NASA Technical Reports Server (NTRS), TRANSFER FUNCTIONS, DYNAMIC LOADS, AEROSPACE SYSTEMS,...
A model for the dynamic response of heterogeneous media is presented. A given medium is discretized into a number of subvolumes, each of which may contain an elastic anisotropic material, void, or fluid, and time-dependent boundary conditions are applied to simulate impact or incident pressure waves. The full time-dependent displacement and stress response throughout the medium is then determined via an explicit solution procedure. The model is applied to simulate the coupled...
Topics: NASA Technical Reports Server (NTRS), ACOUSTIC ATTENUATION, DYNAMIC RESPONSE, ELASTIC WAVES, IMPACT...
An experiment was performed to determine the degradation in the bit-error-rate (BER) in the high-data-rate cables chosen for the Orion Service Module due to extreme launch conditions of vibrations with a magnitude of 60g. The cable type chosen for the Orion Service Module was no. 8 quadrax cable. The increase in electrical noise induced on these no. 8 quadrax cables was measured at the NASA Glenn vibration facility in the Structural Dynamics Laboratory. The intensity of the vibrations was set...
Topics: NASA Technical Reports Server (NTRS), BIT ERROR RATE, ELECTROMAGNETIC NOISE, VIBRATION, COAXIAL...
This paper summarizes the on-orbit modal test and the related modal analysis, model validation and correlation performed for the ISS Stage ULF4, DTF S4-1A, October 11,2010, GMT 284/06:13:00.00. The objective of this analysis is to validate and correlate analytical models with the intent to verify the ISS critical interface dynamic loads and improve fatigue life prediction. For the ISS configurations under consideration, on-orbit dynamic responses were collected with Russian vehicles attached...
Topics: NASA Technical Reports Server (NTRS), INTERNATIONAL SPACE STATION, FATIGUE LIFE, CORRELATION,...
The U.S. Department of Energy (DOE), Lockheed Martin Corporation (LM), and NASA Glenn Research Center (GRC) have been developing the Advanced Stirling Radioisotope Generator (ASRG) for use as a power system for space science missions. In support of this program, GRC has been involved in testing Stirling convertors, including the Advanced Stirling Convertor (ASC), for use in the ASRG. This testing includes electromagnetic interference/compatibility (EMI/EMC), structural dynamics, advanced...
Topics: NASA Technical Reports Server (NTRS), STIRLING CYCLE, DYNAMIC RESPONSE, ELECTROMAGNETIC...
The U.S. Department of Energy (DOE), Lockheed Martin Corporation (LM), and NASA Glenn Research Center (GRC) have been developing the Advanced Stirling Radioisotope Generator (ASRG) for use as a power system for space science missions. In support of this program, NASA?s Glenn Research Center (GRC) has been involved in testing Stirling convertors, including the Advanced Stirling Convertor (ASC), for use in the ASRG. This testing includes electromagnetic interference/compatibility (EMI/EMC),...
Topics: NASA Technical Reports Server (NTRS), STIRLING CYCLE, ELECTROMAGNETIC COMPATIBILITY, DYNAMIC...
The anticipated NASA Mars Sample Return Mission (MSR) requires a simple and reliable method in which to return collected Martian samples back to earth for scientific analysis. The Multi-Mission Earth Entry Vehicle (MMEEV) is NASA's proposed solution to this MSR requirement. Key aspects of the MMEEV are its reliable and passive operation, energy absorbing foam-composite structure, and modular impact sphere (IS) design. To aid in the development of an EEV design that can be modified for various...
Topics: NASA Technical Reports Server (NTRS), MARS SAMPLE RETURN MISSIONS, COMPOSITE STRUCTURES, DYNAMIC...
Spatially explicit and temporally continuous estimates of photosynthesis will be of great importance for increasing our understanding of and ultimately closing the terrestrial carbon cycle. Current capabilities to model photosynthesis, however, are limited by accurate enough representations of the complexity of the underlying biochemical processes and the numerous environmental constraints imposed upon plant primary production. A potentially powerful alternative to model photosynthesis through...
Topics: NASA Technical Reports Server (NTRS), PHOTOSYNTHESIS, CARBON CYCLE, BIOCHEMISTRY, ECOSYSTEMS,...