Engineering Papers⌕ Search

SEARCH · Engineering Papers

Results for “materials evaluation”

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 1,369 records · Page 76
All sourcesNASA NTRSDOE OSTI
NASA NTRS1995

Evaluation of Thermal Control Coatings and Polymeric Materials Exposed to Ground Simulated Atomic Oxygen and Vacuum Ultraviolet Radiation

Numerous thermal control and polymeric samples with potential International Space Station applications were evaluated for atomic oxygen and vacuum ultraviolet radiation effects in the Princeton Plasma Physics Laboratory 5 eV Neutral Atomic Oxygen Facility and in the MSFC Atomic Oxygen Drift Tube System. Included in this study were samples of various anodized aluminum samples, ceramic paints, polymeric materials, and beta cloth, a Teflon-impregnated fiberglass cloth. Aluminum anodizations tested were black duranodic, chromic acid anodize, and sulfuric acid anodize. Paint samples consisted of an inorganic glassy black paint and Z-93 white paint made with the original PS7 binder and the new K2130 binder. Polymeric samples evaluated included bulk Halar, bulk PEEK, and silverized FEP Teflon. Aluminized and nonaluminized Chemfab 250 beta cloth were also exposed. Samples were evaluated for changes in mass, thickness, solar absorptance, and infrared emittance. In addition to material effects, an investigation was made comparing diffuse reflectance/solar absorptance measurements made using a Beckman DK2 spectroreflectometer and like measurements made using an AZ Technology-developed laboratory portable spectroreflectometer.

Kamenetzky, R. R.↗
DOE OSTI2019

Active, tailorable adhesives for dissimilar material bonding, repair and reassembly

Joining of materials and components is inevitable as it allows versatility in assembly and repair along with reduction in time and cost of manufacturing. However, joints are mostly considered the ‘weak-links’ of the structure due to the complex phenomena and interactions of several elements of either similar or dissimilar materials. These complexities combined with the need for lightweight structures and increased safety require better understanding and development of robust dissimilar material joints. The proposed technique uses ‘active adhesives’ and inherits all the advantages of bonded joints, such as lightweight, elimination of holes and associated stress-concentrations, and overcomes its shortcomings of disassembly and repair. Thermoplastic adhesives modified by the incorporation of electrically conductive graphene nanoplatelets at a concentration above the percolation point provide a unique synergy of mechanical, thermal and electrical properties. While the choice of the thermoplastic is governed by the desired application, the addition of the graphene nanoplatelets allows energy to be deposited primarily in the adhesive. The percolated network of graphene particles in the adhesive can quickly couple to microwave (MW) radiation via non-contact methods and increase the adhesive temperature to above the required processing temperatures. The adhesive melts and flows over the adherends and upon cooling forms a structural adhesive bond. Furthermore, the process can be used to disassemble the adhesive joint if repair or reworking is required. The dissimilar material joints in this study include fiber reinforced polymer composites (FRP) made of glass and carbon fibers being joined with metals such as advanced high strength steel (AHSS) and aluminum (Al). The global objectives of the proposed work were achieved through: a) processing, material development and optimization of the active adhesive, b) lab-scale evaluation and detailed material characterization and, c) design, testing and applications. An integrated experimental and numerical approach that used novel non-destructive evaluation techniques to validate the simulations were used. Such experimentally validated simulations could be used to predict designs beyond the experimental matrix. Overall, this project showed the feasibility and robustness of ‘active’, ‘reversible’ thermoplastic adhesives and their use in large-scale multi-material joints.

36 MATERIALS SCIENCE↗
NASA NTRS1998

Flammability, Odor, Offgassing, and Compatibility Requirements and Test Procedures for Materials in Environments that Support Combustion

This handbook establishes NASA program requirements for evaluation, testing, and selection of materials to preclude unsafe conditions related to flammability, odor, offgassing, and fluid compatibility. Materials intended for use in space vehicles, specified test facilities, and specified ground support equipment (GSE) must meet the requirements of this document. Additional materials performance requirements may be specified in other program or NASA center specific documentation. Responsible NASA centers materials organizations must include applicable requirements of this document in their materials control programs. Materials used in habitable areas of spacecraft, including the materials of the spacecraft, stowed equipment, and experiments, must be evaluated for flammability, odor, and offgassing characteristics. All materials used in other areas must be evaluated for flammability characteristics. In addition, materials that are exposed to liquid oxygen (LOX), gaseous oxygen (GOX), and other reactive fluids' must be evaluated for compatibility with the fluid in their use application. Materials exposed to pressurized breathing gases also must be evaluated for odor and offgassing characteristics. The worst-case anticipated use environment (most hazardous pressure, temperature, material thickness, and fluid exposure conditions) must be used in the evaluation process. Materials that have been shown to meet the criteria of the required tests are acceptable for further consideration in design. Whenever possible, materials should be selected that have already been shown to meet the test criteria in the use environment. Existing test data are compiled in the NASA Marshall Space Flight Center (MSFC) Materials and Processes Technical Information System (MAPTIS) and published periodically as the latest revision of a joint document with Johnson Space Center (JSC), MSFC-HDBK-527/JSC 09604. MAPTIS can be accessed by computer datalink. Systems containing materials that have not been tested or do not meet the criteria of the required tests must be verified to be acceptable in the use configuration by analysis or testing. This verification rationale must be documented and submitted to the responsible NASA center materials organization for approval.

Source record↗
DOE OSTI2015

Comparison of German and American fabrication standards for transportation and storage containments of high level radioactive material type B packages - 15055

As the competent authority for the evaluation of German radioactive material (RAM) transport and storage packages, BAM (the German Federal Institute for Materials Research and Testing) has evaluated various international cask manufacturers regarding compliance with the German Type B(U) licensing requirements. The US NRC has recommended paragraphs in the ASME Boiler and Pressure Vessel (B and PV) Code, Section III, Division 3, as the measure to quantify the safety requirements of the US regulations regarding fabrication of RAM transportation and storage containments. The objective of this study is to compare the fabrication criteria of the German Dangerous Goods Procedural Rules (BAM-GGR) and the German Institute for Standardization (DIN) with the US quantitative measures for fabrication of RAM package containment vessels. This comparison will cover major similarities and differences between the requirements of the German standards and the ASME Code requirements for Type B package containment fabrication QC (quality control). While the material most often used for German RAM containment applications is ductile cast iron (DCI), in the US forged austenitic stainless steel is typically used. This study focuses on fabrication QC measures required to ensure reproducible and acceptable properties for DCI containments. (authors)

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
NASA NTRS1978

Development, fabrication and test of a high purity silica heat shield

A highly reflective hyperpure ( 25 ppm ion impurities) slip cast fused silica heat shield material developed for planetary entry probes was successfully scaled up. Process development activities for slip casting large parts included green strength improvements, casting slip preparation, aggregate casting, strength, reflectance, and subscale fabrication. Successful fabrication of a one-half scale Saturn probe (shape and size) heat shield was accomplished while maintaining the silica high purity and reflectance through the scale-up process. However, stress analysis of this original aggregate slip cast material indicated a small margin of safety (MS. = +4%) using a factor of safety of 1.25. An alternate hyperpure material formulation to increase the strength and toughness for a greater safety margin was evaluated. The alternate material incorporates short hyperpure silica fibers into the casting slip. The best formulation evaluated has a 50% by weight fiber addition resulting in an 80% increase in flexural strength and a 170% increase in toughness over the original aggregate slip cast materials with comparable reflectance.

Rusert, E. L.↗
NASA NTRS2010

Evaluation of Ultrasonic and Thermal Nondestructive Evaluation for the Characterization of Aging Degradation in Braided Composite Materials

This paper examines the ability of traditional nondestructive evaluation (NDE) techniques to measure the degradation of braided polymer composite materials subjected to thermal-humidity cycling to simulate aging. A series of braided composite coupons were examined using immersion ultrasonic and pulsed thermography techniques in the as received condition. These same specimens were then examined following extended thermal-humidity cycling. Results of this examination did not show a significant change in the resulting (NDE) signals.

Martin, Richard E.↗
NASA NTRS1997

Unique Tuft Test Facility Dramatically Reduces Brush Seal Development Costs

Brush seals have been incorporated in the latest turbine engines to reduce leakage and improve efficiency. However, the life of these seals is limited by wear. Studies have shown that optimal sealing characteristics for a brush seal occur before the interference fit between the brush and shaft is excessively worn. Research to develop improved tribopairs (brush and coating) with reduced wear and lower friction has been hindered by the lack of an accurate, low-cost, efficient test methodology. Estimated costs for evaluating a new material combination in an engine company seal test program are on the order of $100,000. To address this need, the NASA Lewis Research Center designed, built, and validated a unique, innovative brush seal tuft tester that slides a single tuft of brush seal wire against a rotating shaft under controlled loads, speeds, and temperatures comparable to those in turbine engines. As an initial screening tool, the brush seal tuft tester can tribologicaly evaluate candidate seal materials for 1/10th the cost of full-scale seal tests. Previous to the development of the brush seal tuft tester facility, most relevant tribological data had been obtained from full-scale seal tests conducted primarily to determine seal leakage characteristics. However, from a tribological point of view, these tests included the confounding effects of varying contact pressures, bristle flaring, high-temperature oxidation, and varying bristle contact angles. These confounding effects are overcome in tuft testing. The interface contact pressures can be either constant or varying depending on the tuft mounting device, and bristle wear can be measured optically with inscribed witness marks. In a recent cooperative program with a U.S. turbine engine manufacturer, five metallic wire candidates were tested against a plasma-sprayed Nichrome-bonded chrome carbide. The wire materials used during this collaboration were either nickel-chrome- or cobaltchrome-based superalloys. These tests corroborated full-scale seal test results and provided insight into previously untested combinations. As the cycle temperature for improved efficiency turbine engines increases, new brush seal materials combinations must be considered. Future brush seal tuft testing will include both metallic and ceramic bristles versus commercial and NASA-developed shaft coatings. The ultimate goal of this work is to expand the current data base so that seal designers can tailor brush seal materials to specific applications.

Fellenstein, James A.↗
NASA NTRSDate not supplied

Enabling Evaluation of In-Situ Regolith-Based Construction Materials with Modified Methods for Testing Compressive Strength of Non-Cement Mortar Specimens Using Simulants & Analog Site Soils

Objectives for Phase II of NASA’s Artemis Program include establishment of lunar surface infrastructure to support a sustainable, long-term human presence on the Moon. Terrestrially, awareness of climate impacts from cement and concrete production has led to renewed interest in traditional building materials using earthen and pozzolanic binders with locally sourced aggregates [1, 2, 3]. In remote, austere,and resource-constrained environments, use of site-sourced materials is often an economic necessity in addition to being valuable for local autonomy and self-sufficiency. This study evaluates modifications to ASTM cement mortar testing methods, incorporating details from European standards for earthen plasters and lime-based mortars. Development of consistent, simplified methods for evaluating in-situ materials will be essential not only for meeting future climate goals and sustainable construction needs, but also for conducting autonomous robotic manipulation and evaluation of regolith construction materials.

ISRU↗
DOE OSTI2022

An Open-Source Framework for PV in the Circular Economy Evaluation

This open-source tool follows the dynamic Material and flows for each component and material in a PV system, from mining to end of life to evaluate the material and energy impacts of different paths. Following circularity principles, virgin material inputs can be offset by recovered materials to reduce impacts due to mining and extraction. Unlike consumer products, renewable energy technologies generate power over their useful life to quickly offset energy required for manufacturing. The model provides unique baselines of PV evolution, and allows us to evaluate the material and soon energy return on investment of decisions such as field repair, off-site refurbishment, reuse, or recycling. Energy layer and cost, as well as visual dashboard under development.

circular economy modeling↗
NASA NTRS1986

Future directions in materials and structures for space applications

A comprehensive evaluation is made of materials and structural technology requirements for future space transportation systems, large spacecraft, and space structures. Exceptional promise is noted in carbon-carbon composites for large area thermal protection systems. High temperature test facilities, techniques, and instrumentation systems have unfortunately been neglected, and a materials systems data base suitable for high confidence design of long life space structures has yet to be compiled with a view to material environments in low earth and geosynchronous orbits. A coordinated analysis, ground test, and in-orbit experimentation program for candidate structure designs is called for.

Venneri, S. L.↗
DOE OSTI2024

Effect of micro-fin tube geometry parameters on evaporator material savings

A Performance Evaluation Criteria (PEC) analysis is presented that explores the influence of the micro-fin tube geometry on the required material volume. The analysis was done using a local flow boiling model, which can quantify the effect of fin parameters and the tube diameter. The PEC was done while requiring that the compared surfaces satisfy the same heat duty and pressure drop. The following tube parameters and ranges were explored: tube diameter (3 mm ≤ D o ≤ 6 mm), fin base thickness (0.12 mm ≤ t bf ≤ 0.29 mm), helix angle (6° ≤ α ≤ 30°), fin apex angle (11° ≤ β ≤ 22°), total number of fins (43 ≤ n f ≤ 70), and the fin height (0.11 mm ≤ e ≤ 0.3 mm). The tube that provided the smallest material requirements within the examined parameter ranges had: D o = 3 mm, t bf = 0.12 mm, α = 6°, β = 11°, n f = 43, and e = 0.3 mm. In general, small D o and t bf and large n f and e provided the best performance and work to minimize the required material volume to provide a given heat duty and pressure drop. The helix and the fin-tip apex angles were found to have very little influence on the performance for the examined range of parameters and angles associated with the lowest production cost should be chosen.

Evaporation↗
NASA NTRS2006

An Analysis of Nondestructive Evaluation Techniques for Polymer Matrix Composite Sandwich Materials

Structural sandwich materials composed of triaxially braided polymer matrix composite material face sheets sandwiching a foam core are being utilized for applications including aerospace components and recreational equipment. Since full scale components are being made from these sandwich materials, it is necessary to develop proper inspection practices for their manufacture and in-field use. Specifically, nondestructive evaluation (NDE) techniques need to be investigated for analysis of components made from these materials. Hockey blades made from sandwich materials and a flat sandwich sample were examined with multiple NDE techniques including thermographic, radiographic, and shearographic methods to investigate damage induced in the blades and flat panel components. Hockey blades used during actual play and a flat polymer matrix composite sandwich sample with damage inserted into the foam core were investigated with each technique. NDE images from the samples were presented and discussed. Structural elements within each blade were observed with radiographic imaging. Damaged regions and some structural elements of the hockey blades were identified with thermographic imaging. Structural elements, damaged regions, and other material variations were detected in the hockey blades with shearography. Each technique s advantages and disadvantages were considered in making recommendations for inspection of components made from these types of materials.

Cosgriff, Laura M.↗
NASA NTRS2011

Preliminary Evaluation of Commercial Off the Shelf (COTS) Packing Materials for Flight Medication Dispenser (FMD) Technology Development

This slide presentation reviews preliminary results of the program to evaluate Commercial Off the Shelf (COTS) packaging materials for pharmaceutical stability. The need for improved packaging is due to possible changes in chemical and/or physical properties of the drugs, which cause reported reduced potency and/or altered bioavailability and decreased efficacy.

Du, B.↗
NASA NTRS1983

Fuel containment and damage tolerance in large composite primary aircraft structures

Technical problems related to fuel containment and damage tolerance of composite material wings for transport aircraft was investigated. The major tasks are the following: (1) the preliminary design of damage tolerant wing surface using composite materials; (2) the evaluation of fuel sealing and lightning protection methods for a composite material wing; and (3) an experimental investigation of the damage tolerant characteristics of toughened resin graphite/epoxy materials. The design concepts investigated for the upper and lower surfaces of a composite wing for a transport aircraft are presented and the relationship between weight savings and the design allowable strain used within the analysis is discussed. Experiments which compare the fuel sealing characteristics of bolt-bonded joints and bolted joints sealed with a polysulphide sealant are reviewed. Data from lightning strike tests on stiffened and unstiffened graphite/epoxy panels are presented. A wide variety of coupon tests were conducted to evaluate the relative damage tolerance of toughened resin graphite/epoxies. Data from these tests are presented and their relevance to the wing surface design concepts are discussed.

Griffin, C. F.↗
DOE OSTI2017

Determining interface properties limiting open-circuit voltage in heterojunction solar cells

The development of new thin-film photovoltaic (PV) absorbers is often hindered by the search for an optimal heterojunction contact; an unoptimized contact may be mistaken for poor quality of the underlying absorber, making it difficult to assess the reasons for poor performance. Therefore, quantifying the loss in device efficiency and open-circuit voltage (V OC ) as a result of the interface is a critical step in evaluating a new material. In this work, we fabricate thin-film PV devices using cuprous oxide (Cu 2 O), with several different n-type heterojunction contacts. Their current-voltage characteristics are measured over a range of temperatures and illumination intensties ( JVTi ). We quantify the loss in V OC due to the interface and determine the effective energy gap at the interface. The effective interface gap measured by JVTi matches the gap measured by X-ray photoelectron spectroscopy, albeit with higher energy resolution and an order of magnitude faster. We discuss potential artifacts in JVTi measurements and areas where analytical models are insufficient. Applying JVTi to complete devices, rather than incomplete material stacks, suggests that it can be a quick, accurate method to assess the loss due to unoptimized interface band offsets in thin-film PV devices.

14 SOLAR ENERGY↗
DOE OSTI2022

Evaluating cascaded and tunable phase change materials for enhanced thermal energy storage utilization and effectiveness in building envelopes

The incorporation of phase change materials (PCMs) in envelope is considered an effective thermal energy storage (TES) method for energy savings and load flexibility in buildings. However, an important limitation of PCMs is their fixed and narrow transition temperature range. Because the interior temperature setpoints are typically different in summer versus winter, and the exterior temperature varies substantially above and below the setpoints during the year, PCMs with a fixed transition temperature are utilized only during part of the year. In this paper, we provide an extensive numerical analysis of the performance of a lightweight building envelope containing three different types of PCMs: traditional single-layer PCM with a fixed transition temperature, novel cascaded two-layer PCM with different transition temperatures, and a "futuristic" tunable PCM whose transition temperature can be varied in-situ using external excitation. We compare their performances by evaluating the relationship between the PCM utilization and parameters such as latent heat, transition temperature range, PCM thickness, and PCM location. While traditional PCMs are mostly active during one season, properly designed cascaded and tunable PCMs can be active much longer, thereby allowing load shift and energy savings in both heating and cooling seasons. Under the operating conditions considered in this study, tunable PCMs performed best, providing the highest utilization (about 2 times the traditional PCMs) and enhanced effectiveness (up to 99% peak load reduction in cooling season and 34% peak load reduction in heating season) with the same amount of material as the traditional PCMs; however, cascaded PCMs can be a good alternative while tunable PCMs are unavailable.

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATI↗