Results for “Hybrid Structures”

NASA NTRS1979

Strength of adhesive-bonded hybrid structures

Structures prepared from materials with different thermal and mechanical properties by means of fiber-strengthened binders can fail in a number of ways. The present lecture is focused on failures through debonding at the metal or at the fiber-reinforced plastic. A method for calculating the stress distribution in adhesive layers as a function of the load is outlined, and its usefulness in providing insight into the behavior of bonds in hybrid structures is noted. Means of eliminating the unfavorable effects of temperature, humidity, creep and relaxation on the bonds in the manufacture of hybrid structures are examined, along with test methods developed for such structures.

Kirschke, L.↗

NASA NTRS2016

Double Sided Si(Ge)/Sapphire/III-Nitride Hybrid Structure

One aspect of the present invention is a double sided hybrid crystal structure including a trigonal Sapphire wafer containing a (0001) C-plane and having front and rear sides. The Sapphire wafer is substantially transparent to light in the visible and infrared spectra, and also provides insulation with respect to electromagnetic radio frequency noise. A layer of crystalline Si material having a cubic diamond structure aligned with the cubic <111> direction on the (0001) C-plane and strained as rhombohedron to thereby enable continuous integration of a selected (SiGe) device onto the rear side of the Sapphire wafer. The double sided hybrid crystal structure further includes an integrated III-Nitride crystalline layer on the front side of the Sapphire wafer that enables continuous integration of a selected III-Nitride device on the front side of the Sapphire wafer.

Park, Yeonjoon↗

NASA NTRS2017

Method of Fabricating Double Sided Si(Ge)/Sapphire/III-Nitride Hybrid Structure

One aspect of the present invention is a double sided hybrid crystal structure including a trigonal Sapphire wafer containing a (0001) C-plane and having front and rear sides. The Sapphire wafer is substantially transparent to light in the visible and infrared spectra, and also provides insulation with respect to electromagnetic radio frequency noise. A layer of crystalline Si material having a cubic diamond structure aligned with the cubic <111> direction on the (0001) C-plane and strained as rhombohedron to thereby enable continuous integration of a selected (SiGe) device onto the rear side of the Sapphire wafer. The double sided hybrid crystal structure further includes an integrated III-Nitride crystalline layer on the front side of the Sapphire wafer that enables continuous integration of a selected III-Nitride device on the front side of the Sapphire wafer.

Park, Yeonjoon↗

NASA NTRS2003

Impact Resistance of Lightweight Hybrid Structures for Gas Turbine Engine Fan Containment Applications

The ballistic impact resistance of hybrid composite sandwich structures was evaluated with the ultimate goal of developing new materials or structures for potential gas turbine engine fan containment applications. The sandwich structures investigated consisted of GLARE-5 laminates as face sheets with lightweight cellular metallic materials such as honeycomb, foam, and lattice block as a core material. The impact resistance of these hybrid sandwich structures was compared to GLARE-5 laminates and 2024-T3 Al sheet, which were tested as a function of areal weight (material thickness). The GLARE-5 laminates exhibited comparable impact properties to that of 2024-T3 Al at low areal weights, even though there were significant differences in the static tensile properties of these materials. The GLARE-5, however, did have a greater ballistic limit than straight aluminum sheet at higher areal weights. Furthermore, there is up to a 25% advantage in ballistic limit for the GLARE-5/foam sandwich structures compared to straight 2024-T3 Al. But no advantage in ballistic limit was observed between any of the hybrid sandwich structures and thicker versions of GLARE-5. Recommendations for future work are provided, based on these preliminary data.

Hebsur, Mohan G.↗

NASA NTRS2014

Detailed Post-Soft Impact Progressive Damage Assessment for Hybrid Structure Jet Engines

Currently, certification of engine designs for resistance to bird strike is reliant on physical tests. Predictive modeling of engine structural damage has mostly been limited to evaluation of individual forward section components, such as fan blades within a fixed frame of reference, to direct impact with a bird. Such models must be extended to include interactions among engine components under operating conditions to evaluate the full extent of engine damage. This paper presents the results of a study aim to develop a methodology for evaluating bird strike damage in advanced propulsion systems incorporating hybrid composite/metal structures. The initial degradation and failure of individual fan blades struck by a bird were investigated. Subsequent damage to other fan blades and engine components due to resultant violent fan assembly vibrations and fragmentation was further evaluated. Various modeling parameters for the bird and engine components were investigated to determine guidelines for accurately capturing initial damage and progressive failure of engine components. Then, a novel hybrid structure modeling approach was investigated and incorporated into the crashworthiness methodology. Such a tool is invaluable to the process of design, development, and certification of future advanced propulsion systems.

bird strike↗

NASA NTRS2004

Advanced Ceramic Matrix Composites with Multifunctional and Hybrid Structures

Ceramic matrix composites are leading candidate materials for a number of applications in aeronautics, space, energy, and nuclear industries. Potential composite applications differ in their requirements for thickness. For example, many space applications such as "nozzle ramps" or "heat exchangers" require very thin (< 1 mm) structures whereas turbine blades would require very thick parts (> or = 1 cm). Little is known about the effect of thickness on stress-strain behavior or the elevated temperature tensile properties controlled by oxidation diffusion. In this study, composites consisting of woven Hi-Nicalon (trademark) fibers a carbon interphase and CVI SiC matrix were fabricated with different numbers of plies and thicknesses. The effect of thickness on matrix crack formation, matrix crack growth and diffusion kinetics will be discussed. In another approach, hybrid fiber-lay up concepts have been utilized to "alloy" desirable properties of different fiber types for mechanical properties, thermal stress management, and oxidation resistance. Such an approach has potential for the C(sub I)-SiC and SiC(sub f)-SiC composite systems. CVI SiC matrix composites with different stacking sequences of woven C fiber (T300) layers and woven SiC fiber (Hi-Nicalon (trademark)) layers were fabricated. The results will be compared to standard C fiber reinforced CVI SiC matrix and Hi-Nicalon reinforced CVI SiC matrix composites. In addition, shear properties of these composites at different temperatures will also be presented. Other design and implementation issues will be discussed along with advantages and benefits of using these materials for various components in high temperature applications.

Singh, Mrityunjay↗

NASA NTRS2011

Lower Hybrid Solitary Structures

Lower hybrid solitary structures (LHSS) have been observed by sounding rockets in the auroral ionosphere for over a decade and a half. LHSS are spatial structures embedded in space plasmas containing ambient whistler mode hiss. They are characterized by a density depletion of a few percent to several tens of percent in which electric fields near, both above and below, the lower hybrid resonance are more intense than the background fields by a factor of three to five. LHSS have dimensions across the magnetic field of a few to many thermal ion gyroradii, usually 10-100 meters and a density profile that is Gaussian and consistent with cylindrical symmetry. Along the magnetic field the dimensions are estimated to be several kilometers to several hundred kilometers. Electric field interferometry reveals that the phase fronts of LHSS electric fields rotate azimuthally within the density depletions; right-hand above the lower hybrid resonance and left-hand below the lower hybrid resonance [Pincon et al., 1997; Schuck et al., 1998; Bonnell et al., 1998; Tjulin et al., 2003; Schuck et al., 2003]. The description of this phenomena was driven by the observations the Cornell University sounding rocket program headed by the late Paul Kintner.

Schuck, Peter W.↗

NASA NTRS2017

RTAPS (Research and Technology for Aerospace Propulsion Systems): Simulation of Structural Loads within a Hybrid Gear Resulting From Loading at the Gear Teeth

This report investigates the practical usage of hybrid structures for rotorcraft gearing. The primary driver for utilizing hybrid structures for rotorcraft gearing is to reduce the drive system weight. The hybrid structure concept featured in this study for rotorcraft gearing consists of a metallic gear tooth-rim, a web section manufactured from composite materials, and a metallic hub. The metallic gear tooth-rim is manufactured from conventional gear steel alloys, such as AISI 9310. The gear tooth-rim attaches to the outer diameter of the web section made from composite materials. The inner diameter of the composite web can then attach to a metallic hub, completing the assembly. It is assumed that areas of the shafting or hub where rolling element bearings may ride must remain as gear steel alloys for this study.

Hybrid Structures↗

NASA NTRS2017

RTAPS (Research and Technology for Aerospace Propulsion Systems): Simulation of Structural Loads within a Hybrid Gear Resulting From Loading at the Gear Teeth

This report investigates the practical usage of hybrid structures for rotorcraft gearing. The primary driver for utilizing hybrid structures for rotorcraft gearing is to reduce the drive system weight. The hybrid structure concept featured in this study for rotorcraft gearing consists of a metallic gear tooth-rim, a web section manufactured from composite materials, and a metallic hub. The metallic gear tooth-rim is manufactured from conventional gear steel alloys, such as AISI 9310. The gear tooth-rim attaches to the outer diameter of the web section made from composite materials. The inner diameter of the composite web can then attach to a metallic hub, completing the assembly. It is assumed that areas of the shafting or hub where rolling element bearings may ride must remain as gear steel alloys for this study.

Naffin, Richard K.↗

NASA NTRS2016

Integrated Multi-Color Light Emitting Device Made with Hybrid Crystal Structure

An integrated hybrid crystal Light Emitting Diode ("LED") display device that may emit red, green, and blue colors on a single wafer. The various embodiments may provide double-sided hetero crystal growth with hexagonal wurtzite III-Nitride compound semiconductor on one side of (0001) c-plane sapphire media and cubic zinc-blended III-V or II-VI compound semiconductor on the opposite side of c-plane sapphire media. The c-plane sapphire media may be a bulk single crystalline c-plane sapphire wafer, a thin free standing c-plane sapphire layer, or crack-and-bonded c-plane sapphire layer on any substrate. The bandgap energies and lattice constants of the compound semiconductor alloys may be changed by mixing different amounts of ingredients of the same group into the compound semiconductor. The bandgap energy and lattice constant may be engineered by changing the alloy composition within the cubic group IV, group III-V, and group II-VI semiconductors and within the hexagonal III-Nitrides.

Park, Yeonjoon↗

NASA NTRS2017

Integrated Multi-Color Light Emitting Device Made with Hybrid Crystal Structure

An integrated hybrid crystal Light Emitting Diode ("LED") display device that may emit red, green, and blue colors on a single wafer. The various embodiments may provide double-sided hetero crystal growth with hexagonal wurtzite III-Nitride compound semiconductor on one side of (0001) c-plane sapphire media and cubic zinc-blended III-V or II-VI compound semiconductor on the opposite side of c-plane sapphire media. The c-plane sapphire media may be a bulk single crystalline c-plane sapphire wafer, a thin free standing c-plane sapphire layer, or crack-and-bonded c-plane sapphire layer on any substrate. The bandgap energies and lattice constants of the compound semiconductor alloys may be changed by mixing different amounts of ingredients of the same group into the compound semiconductor. The bandgap energy and lattice constant may be engineered by changing the alloy composition within the cubic group IV, group III-V, and group II-VI semiconductors and within the hexagonal III-Nitrides.

Park, Yeonjoon↗

NASA NTRS2011

Hybrid Composite Cryogenic Tank Structure

A hybrid lightweight composite tank has been created using specially designed materials and manufacturing processes. The tank is produced by using a hybrid structure consisting of at least two reinforced composite material systems. The inner composite layer comprises a distinct fiber and resin matrix suitable for cryogenic use that is a braided-sleeve (and/or a filamentwound layer) aramid fiber preform that is placed on a removable mandrel (outfitted with metallic end fittings) and is infused (vacuum-assisted resin transfer molded) with a polyurethane resin matrix with a high ductility at low temperatures. This inner layer is allowed to cure and is encapsulated with a filamentwound outer composite layer of a distinct fiber resin system. Both inner and outer layer are in intimate contact, and can also be cured at the same time. The outer layer is a material that performs well for low temperature pressure vessels, and it can rely on the inner layer to act as a liner to contain the fluids. The outer layer can be a variety of materials, but the best embodiment may be the use of a continuous tow of carbon fiber (T-1000 carbon, or others), or other high-strength fibers combined with a high ductility epoxy resin matrix, or a polyurethane matrix, which performs well at low temperatures. After curing, the mandrel can be removed from the outer layer. While the hybrid structure is not limited to two particular materials, a preferred version of the tank has been demonstrated on an actual test tank article cycled at high pressures with liquid nitrogen and liquid hydrogen, and the best version is an inner layer of PBO (poly-pphenylenebenzobisoxazole) fibers with a polyurethane matrix and an outer layer of T-1000 carbon with a high elongation epoxy matrix suitable for cryogenic temperatures. A polyurethane matrix has also been used for the outer layer. The construction method is ideal because the fiber and resin of the inner layer has a high strain to failure at cryogenic temperatures, and will not crack or produce leaks. The outer layer serves as more of a high-performance structural unit for the inner layer, and can handle external environments.

DeLay, Thomas↗

NASA NTRS1989

Hybrid interconnection structures for real-time parallel processing

The use of hybrid interconnection structures that combine link connections and bus connections for real-time parallel processing is discussed. Idealistic parallel computation models for two real-time computing applications are described with attention given to a tightly coupled network model for object tracking and a network model for image processing. Consideration is given to the following different interconnection structures: the crossbar, the hypercube, the circular linked array, and the bus array.

Kim, K. H.↗

NASA NTRS2005

Film Delivery Module For Fiber Placement Fabrication of Hybridized Composite Structures

A new fabrication technology has been developed at the NASA Marshall Space Flight Center that will allow for the fabrication of hybridized composite structures using fiber placement processing. This technology was originally developed in response to a need to address the issue of hydrogen permeation and microcracking in cryogenic propellant tanks. Numerous thin polymeric and metallized films were investigated under low temperatures conditions for use as barrier films in a composite tank. Manufacturing studies conducted at that time did not address the processing issues related to fabrication of a hybridized tank wall. A film processing head was developed that will allow for the processing of thin polymeric and metallized films, metallic foils, and adhesives using fiber placement processing machinery. The film head is designed to enable the simultaneous processing of film materials and composite tape/tow during the composite part layup process and is also capable of processing the film during an independent operation. Several initial demonstrations were conducted to assess the performance of the film module device. Such assessments included film strip lay-up accuracy, capability to fabricate panels having internal film liners, and fabrication of laminates with embedded film layers.

Hulcher, Anthony Bruce↗

NASA NTRS2004

Analysis of SMA Hybrid Composite Structures using Commercial Codes

A thermomechanical model for shape memory alloy (SMA) actuators and SMA hybrid composite (SMAHC) structures has been recently implemented in the commercial finite element codes MSC.Nastran and ABAQUS. The model may be easily implemented in any code that has the capability for analysis of laminated composite structures with temperature dependent material properties. The model is also relatively easy to use and requires input of only fundamental engineering properties. A brief description of the model is presented, followed by discussion of implementation and usage in the commercial codes. Results are presented from static and dynamic analysis of SMAHC beams of two types; a beam clamped at each end and a cantilevered beam. Nonlinear static (post-buckling) and random response analyses are demonstrated for the first specimen. Static deflection (shape) control is demonstrated for the cantilevered beam. Approaches for modeling SMAHC material systems with embedded SMA in ribbon and small round wire product forms are demonstrated and compared. The results from the commercial codes are compared to those from a research code as validation of the commercial implementations; excellent correlation is achieved in all cases.

Turner, Travis L.↗

NASA NTRS2005

Analysis of SMA Hybrid Composite Structures in MSC.Nastran and ABAQUS

A thermoelastic constitutive model for shape memory alloy (SMA) actuators and SMA hybrid composite (SMAHC) structures was recently implemented in the commercial finite element codes MSC.Nastran and ABAQUS. The model may be easily implemented in any code that has the capability for analysis of laminated composite structures with temperature dependent material properties. The model is also relatively easy to use and requires input of only fundamental engineering properties. A brief description of the model is presented, followed by discussion of implementation and usage in the commercial codes. Results are presented from static and dynamic analysis of SMAHC beams of two types; a beam clamped at each end and a cantilever beam. Nonlinear static (post-buckling) and random response analyses are demonstrated for the first specimen. Static deflection (shape) control is demonstrated for the cantilever beam. Approaches for modeling SMAHC material systems with embedded SMA in ribbon and small round wire product forms are demonstrated and compared. The results from the commercial codes are compared to those from a research code as validation of the commercial implementations; excellent correlation is achieved in all cases.

Turner, Travis L.↗

NASA NTRS1993

A hybrid structured-unstructured grid method for unsteady turbomachinery flow computations

A hybrid grid technique for the solution of 2D, unsteady flows is developed. This technique is capable of handling complex, multiple component geometries in relative motion, such as those encountered in turbomachinery. The numerical approach utilizes a mixed structured-unstructured zonal grid topology along with modeling equations and solution methods that are most appropriate in the individual domains, therefore combining the advantages of both structured and unstructured grid techniques.

Mathur, Sanjay R.↗

NASA NTRS2017

Jet Noise Prediction Using Hybrid RANS/LES with Structured Overset Grids

Hybrid RANS/LES simulations using the structured overset grid approach and a low dissipation finite-difference method within the Launch Ascent and Vehicle Aerodynamics (LAVA) solver framework are presented for jet noise prediction. The simulations are part of a validation effort to demonstrate jet noise prediction capability, to assess noise characteristics of next generation quiet supersonic commercial jets. Results are compared with experimental data acquired in the Small Hot Jet Acoustic Rig in the Aeroacoustic Propulsion Laboratory at NASA Glenn Research Center. Details of the structured overset grids, numerical discretization, and turbulence model are provided. Near-field comparisons to PIV data and far-field comparisons to microphone data are discussed. Excellent agreement of time-averaged mean quantities along the jet center-line and lip-line are obtained. Good agreement with root-mean-squared (RMS) quantities along the jet center-line are also obtained. An over prediction of lip-line RMS at the nozzle exit is observed leading to a small over-prediction of side-line far-field noise (less than 2 dB). Good agreement with far-field noise in the Mach wave radiation directions is achieved.

Housman, Jeffrey A.↗