Engineering Papers⌕ Search

SEARCH · Engineering Papers

Results for “NiPS”

Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 19 records
All sourcesNASA NTRSDOE OSTI
NASA NTRS2018

Numerical Simulation of AFP Nip Point Temperature Prediction for Complex Geometries

Material placement at the ideal nip point temperature over complex surfaces with uniformity across the width of the compaction rollers results in optimized part properties for Automated Fiber Placement (AFP) processes. However, current AFP systems utilize heat control models and methodologies, based on multiple process parameters such as feed-rate and orientation, that are mostly open-loop. Here, infrared (IR) heater input is calibrated as a function of process parameters during machine qualification. This work presents a numerical simulation to predict arrayed-infrared (AIR) emitter radiation onto a substrate that includes view factor implementation, IR radiative heat flow calculation, energy rate balance, and a transient heat transfer model. The purpose of this numerical model is to predict nip point temperature on complex surfaces, serving as a baseline for a new arrayed-infrared (AIR) thermoset heater to improve AFP process control. It is anticipated that this simulation will accurately control the temperature for high-speed AFP layup of complex geometries. An anticipated result of an AIR heater system is that material calibration and testing will be reduced as temperature is instantaneously monitored and controlled. Therefore, temperature across the roller width will be uniform during placement of complex parts, independent of their geometry.

Xia, Kaishu↗
NASA NTRS1980

Radiation damage in silicon NIP solar cells

The performance parameters of n(+) p p(+) silicon solar cells of varying thicknesses with boron doped p base resistivities of 1250 and 84 ohm centimeters were determined. High injection theory was used to analyze the experimental data. Results from an analysis of open circuit voltages show a much greater contribution to V(oc) from the back junction than is the case for the lower resistivity in common use. The base minority carrier distribution is seen to be significant in determining the contribution of V(B), the base contribution to V(oc). Although V(B) is small, its value increases with increasing radiation fluence. In this connection it is noted that, with illumination from the p(+) side, the sign of V(B) becomes positive, and V(B) itself becomes an additive term to V(oc). Diffusion lengths determined under high injection conditions are significantly greater than those obtained under low injection, while damage coefficients under low injection are higher than those obtained under high injection conditions.

Weinberg, I.↗
NASA NTRS1985

Railroad safety program, volume 1

Since 1981, the Federal Railroad Administration (FRA) has annually prepared a National Inspection Plan (NIP) whose purpose is to summarize regional efforts to improve railroad transportation safety. The research concluded on the following tasks including the problems, conclusions and recommendations associated with these tasks is summarized: (1) the preparation of the 1983 NIP, with recommended procedures for improving future NIPs; (2) the development of an outline for the 1984 NIP, including a methodology for the allocation of inspection resources and other specialized regional activities; (3) the management and development of the 1984 NIP; and (4) the development of an instruction manual to be used in the preparation of future NIPs.

Source record↗
NASA NTRS1998

Hybrid IR-Gas Heater for Automated Tow Placement

A hybrid infrared-hot gas heat source has been developed and tested for the NASA Langley Tow Placement Facility. The IR heat source provides supplemental heat to the nip region. The additional heat is intended to reduce the need for conduction heating by the compaction roller, which causes (he roller to stick to the panel surface. Initial bench scale testing was performed to identify the most effective means of focusing IR energy into the nip region. A compact lamp and reflector that placed the lamp as close to the nip point as possible was found to deliver the highest heat flux in the nip region. A prototype heater was installed on the NASA Langley tow placement robot. Panels placed with a 400 C (sticking) compaction roller gave DCB initiation toughness numbers comparable to those reported for autoclave processed panels but were found to have unexpectedly high void contents. Placement with compaction roller temperatures that prevented roller sticking resulted in mode I fracture toughness approximately 70% that reported for autoclave processed panels. The variability in strength among specimens placed with reduced roller temperature was found to be greatly reduced, which implies that use of supplemental nip point heat may improve the robustness of the tow placement process. Use of the IR heat source permitted placement with a compaction roller temperature that would have resulted in negligible interfacial strength with the hot gas torch alone. The roller temperature reductions eliminated the need for the robot operator to attend placement operations.

Grenoble, Ray W.↗
NASA NTRS1983

Railroad safety program, task 2

Aspects of railroad safety and the preparation of a National Inspection Plan (NIP) for rail safety improvement are examined. Methodology for the allocation of inspection resources, preparation of a NIP instruction manual, and recommendations for future NIP, are described. A statistical analysis of regional rail accidents is presented with causes and suggested preventive measures included.

Source record↗
NASA NTRS1994

Replicate Wolter-I x-ray mirrors

Cylindrical (hyperbolic - parabolic Wolter I) mirrors have been electroformed from nickel over an electroless nickel-phosphorous (NiP) plated aluminum mandrel in support of the NASA AXAF-S x-ray spectrometer program. The electroless nickel was diamond turned and polished to achieve a surface finish of 10 angstroms rms or better. Gold was then plated on the nickel alloy after an electrochemical passivation step. Next a heavy layer of pure nickel was plated one millimeter thick with controlled stress at zero using a commercial PID program to form the actual mirror. This shell was removed from the NiP alloy coated mandrel by cryogenic cooling and contraction of the aluminum to release the mirror. It is required that the gold not adhere well to the NiP but all other plated coatings must exhibit good adherence. Four mirrors were fabricated from two mandrels prepared by this method. The area of each part is 0.7 square meters (7.5 square feet).

Engelhaupt, D. E.↗
NASA NTRS1995

Apparatus for consolidating a pre-impregnated, filament-reinforced polymeric prepreg material

An apparatus and method were developed for providing a uniform, consolidated, unidirectional, continuous, fiber-reinforced polymeric material. The apparatus comprises a supply means, a forming means, a shaping means, and a take-up means. The forming means further comprises a pre-melting chamber and a stationary bar assembly. The shaping means is a loaded cooled nip-roller apparatus. Forming takes place by heating a polymeric prepreg material to a temperature where the polymer becomes viscous and applying pressure gradients at separate locations along the prepreg material. Upon exiting the forming means, the polymeric prepreg material is malleable, consolidated, and flattened. Shaping takes place by passing the malleable, consolidated, flattened prepreg material through a shaped, matched groove in a loaded, cooled nip-roller apparatus to provide the final solid product.

Sandusky, Donald A.↗
NASA NTRS1978

Laser wire stripping

Bench-mounted and hand-held laser units cut insulation from wires without nipping or scraping conductor. Process eliminates quality control problems and is fast, clean, precise, and repeatable.

Heisman, R. M.↗
NASA NTRS1983

Interactive Planning System

NASA Interactive Planning System (NIPS) assists program-planning groups at NASA Headquarters in developing long-range plans for total space effort. Functions involve meeting goals and objectives within time, budget, and resource-management and allocation problem.

Nippert, D. A.↗
NASA NTRS1984

Special Pyrheliometer Shroud Development

To insure that the insolation values accurately represent the input power to a power conversion unit the field of view (FOV) of the concentrator aperture and the insolation radiometer must be the same. The calculations, implementation, and results of this approach are covered. Three instruments were used to measure the insolation: an Eppley Normal Incidence Radiometer (NIP) and two versions of the kendall cavity radiometer. The shrouds used to limit the FOV of the radiometers were designed to simulate the FOV of the PDC-1 concentrater with the cold water cavity calorimeter. This technique of matching the FOV of an insolation radiometer to the FOV of a specific concentrater and receiver aperture appears to be both practical and effective. The efficiency of a power conversion unit will be too low if the insolation is measured with a radiometer which has a FOV which is larger than the FOV of the concentrator.

Dennison, E. W.↗
NASA NTRS1993

Continuous fiber thermoplastic prepreg

A pultrusion machine employing a corrugated impregnator vessel to immerse multiple, continuous strand, fiber tow in an impregnating material, and an adjustable metered exit orifice for the impregnator vessel to control the quantity of impregnating material retained by the impregnated fibers, is provided. An adjustable height insert retains transverse rod elements within each depression of the corrugated vessel to maintain the individual fiber tows spread and in contact with the vessel bottom. A series of elongated heating dies, transversely disposed on the pultrusion machine and having flat heating surfaces with radiused edges, ensure adequate temperature exposed dwell time and exert adequate pressure on the impregnated fiber tows, to provide the desired thickness and fiber/resin ratio in the prepreg formed. The prepreg passing through the pulling mechanism is wound on a suitable take-up spool for subsequent use. A formula is derived for determining the cross sectional area opening of the metering device. A modification in the heating die system employs a heated nip roller in lieu of one of the pressure applying flat dies.

Wilson, Maywood L.↗
NASA NTRS1993

Extrusion process optimization for toughness in balloon films

An experimental optimization process for blown film extrusion is described and examined in terms of the effects of the technique on the toughness of balloon films. The optimization technique by Cantor (1990) is employed which involves the identification of key process variables including screw speed, nip speed, bubble diameter, and frost-line height for analysis to optimize the merit function. The procedure is employed in the extrusion of a low-density polyethylene polymer, and the resulting optimized materials are toughness- and puncture-tested. Balloon toughness is optimized in the analytical relationship, and the process parameters are modified to attain optimal toughness. The film produced is shown to have an average toughness of 24.5 MPa which is a good value for this key property of balloon materials for high-altitude flights.

Cantor, K. M.↗
NASA NTRS1993

A new NASA LaRC Multi-Purpose Prepregging Unit

A multi-purpose prepregging machine has been designed and built for NASA Langley Research Center. The machine has numerous advantages over existing units due to its various modular components. Each of these can be used individually or simultaneously depending on the required prepregging method. A reverse roll coater provides the ability to prepare thin films from typical hot-melt thermoset formulations. Also, if necessary, the design allows direct fiber impregnation within the reverse roll coater gap. Included in the impregnation module is a solution dip tank allowing the fabrication of thermoplastic prepregs from solution. The proceeding modules within the unit consist of four nip stations, two hot-plates, a hot-sled option and a high temperature oven. This paper describes the advantages of such a modular construction and discusses the various processing combinations available to the prepregger. A variety of high performance prepreg material systems were produced on IM7 (Hercules) carbon fiber. These included LaRC RP46, a PMR-type resin processed from methanol and two polyamide acids, LaRC IA and LaRC ITPI, prpregged from N-methyl pyrrolidinone (NMP). Parameters involved in the production of these prepreg materials are presented as are the mechanical properties of the resulting good quality laminates. A brief introduction into the existing prepregging science is presented. Topics relating to solution prepregging are identified with a focus on the current research effort and its future development.

Wilkinson, S. P.↗
NASA NTRS1997

Method to Produce Flexible Ceramic Thermal Protection System Resistant to High Aeroacoustic Noise

A method of producing a three dimensional angle interlock ceramic fiber which is stable to high aeroacoustic noise of about 170 decibels and to high temperatures of about 2500 F is disclosed. The method uses multiple separate strands of a ceramic fiber or ceramic tow suitable for weaving having multiple warp fibers and multiple fill fibers woven with a modified fly-shuttle loom or rapier shuttleless loom which has nip rolls, a modified fabric advancement mechanism and at least eight harnesses in connection with a Dobby pattern chain utilizing sufficient heddles for each warp fiber and a reed which accommodates at least 168 ends per inch. The method produces a multilayered top fabric, rib fabric and single-layered bottom fabric.

Sawko, Paul M.↗
NASA NTRS2003

Dry Process for Manufacturing Hybridized Boron Fiber/Carbon Fiber Thermoplastic Composite Materials from a Solution Coated Precursor

An apparatus for producing a hybrid boron reinforced polymer matrix composite from precursor tape and a linear array of boron fibers. The boron fibers are applied onto the precursor tapes and the precursor tape processed within a processing component having an impregnation bar assembly. After passing through variable-dimension forming nip-rollers, the precursor tape with the boron fibers becomes a hybrid boron reinforced polymer matrix composite. A driving mechanism is used to pulled the precursor tape through the method and a take-up spool is used to collect the formed hybrid boron reinforced polymer matrix composite.

Harry L Belvin↗
NASA NTRS2002

Process of Making Boron-Fiber Reinforced Composite Tape

The invention is an apparatus and method for producing a hybrid boron reinforced polymer matrix composition from powder pre-impregnated fiber tow bundles and a linear array of boron fibers. The boron fibers are applied onto the powder pre-impregnated fiber tow bundles and then are processed within a processing component having an impregnation bar assembly. After passing through variable-dimension forming nip-rollers, the powder pre-impregnated fiber tow bundles with the boron fibers become a hybrid boron reinforced polymer matrix composite tape. A driving mechanism pulls the powder pre-impregnated fiber tow bundles with boron fibers through the processing line of the apparatus and a take-up spool collects the formed hybrid boron-fiber reinforced polymer matrix composite tape.

Patent↗
NASA NTRS1998

Tape-Drop Transient Model for In-Situ Automated Tape Placement of Thermoplastic Composites

Composite parts of nonuniform thickness can be fabricated by in-situ automated tape placement (ATP) if the tape can be started and stopped at interior points of the part instead of always at its edges. This technique is termed start/stop-on-the-part, or, alternatively, tape-add/tape-drop. The resulting thermal transients need to be managed in order to achieve net shape and maintain uniform interlaminar weld strength and crystallinity. Starting-on-the-part has been treated previously. This paper continues the study with a thermal analysis of stopping-on-the-part. The thermal source is switched off when the trailing end of the tape enters the nip region of the laydown/consolidation head. The thermal transient is determined by a Fourier-Laplace transform solution of the two-dimensional, time-dependent thermal transport equation. This solution requires that the Peclet number Pe (the dimensionless ratio of inertial to diffusive heat transport) be independent of time and much greater than 1. Plotted isotherms show that the trailing tape-end cools more rapidly than the downstream portions of tape. This cooling can weaken the bond near the tape end; however the length of the affected region is found to be less than 2 mm. To achieve net shape, the consolidation head must continue to move after cut-off until the temperature on the weld interface decreases to the glass transition temperature. The time and elapsed distance for this condition to occur are computed for the Langley ATP robot applying PEEK/carbon fiber composite tape and for two upgrades in robot performance. The elapsed distance after cut-off ranges from about 1 mm for the present robot to about 1 cm for the second upgrade.

Costen, Robert C.↗
NASA NTRS2005

Valiant 'Zero-Valent' Effort Restores Contaminated Grounds

Dense non-aqueous phase liquids (DNAPLs) are chemical compounds that can contaminate soil and groundwater to the point of irreparability. These substances are only slightly soluble in water, and are much denser than water. Because of their solubility, DNAPLs form separate liquid phases in groundwater, and because of their density, DNAPLs sink in aquifers instead of floating at the water table, making it extremely difficult to detect their presence. If left untreated in the ground, they can taint fresh water sources. Common DNAPLs include chlorinated hydrocarbon compounds such as carbon tetrachloride, chloroform, tetrachloroethylene, and trichloroethylene. Trichloroethylene was used during the early days of the Space Program, as a solvent for flushing rocket engines, and for metal cleaning and degreasing of equipment, electronics, and heavy machinery. As a result, areas of Cape Canaveral s Launch Complex 34, the site of several historic Saturn rocket launches occurring from 1959 to 1968, were polluted with chlorinated DNAPLs. Through the direction and guidance of Dr. Jacqueline Quinn, an environmental engineer in the Spaceport Engineering and Technology Directorate at NASA s Kennedy Space Center, a biodegradable environmental cleanup technology was developed to reductively dechlorinate DNAPL sources in polluted water at Launch Complex 34. It was important for Kennedy to nip this problem in the bud, in light of the fact that the Space Center is also a National Wildlife Refuge, home to thousands of shorebirds, endangered sea turtles and eagles, manatees, alligators, and diverse habitats that include brackish marshes and salt water estuaries. The success in remediating this historic launch site has led to numerous commercial applications that are restoring the health of our environmental surroundings.

Source record↗