Materials Literature
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A multi-scale micromechanics approach is devised and applied to characterize the fracture toughness and impact resistance of glass composites enriched with nano particles. The technical approach integrates multi-scale mechanics with finite element based progressive failure analysis (PFA) for damage tracking and fractu…
The low-temperature performance characteristics of a commercial lean NOX trap catalyst were evaluated using infra-red thermography (IRT) before and after a high-temperature aging step. Reaction tests included propylene oxidation, oxygen storage capacity measurements, and simulated cycling conditions for NOX reduction,…
Magnetic material is mixed with plaster cement to form a composite magnetic building material for electromagnetic wave (EMW) attenuation in indoor wireless communication systems. Samples were prepared as tiles and placed in the propagation path of the EMW between two broadband horn antennas. The attenuation capability…
Nanoparticle chains of two types are studied. The first type involves chains coupled with a dielectric slab. Such chains can operate as optical waveguides or antennas radiating surface wave beams. The second chain type involves twisted chains, where asymmetric chain elements are twisted in the transverse of the chain'…
We have carried out the research of the influence of neutron radiation on the characteristics of heterostructures (AI x Ga 1-x ) 0.5 In 0.5 P. We have calculated light strength diminution constants (τ 0 K τ ) and the degradation of carrier lifetime.
The modelling of ortho-positronium annihilation processes in nanoporous humidity-sensitive ceramics were performed using the Tao-Eldrup model. It is shown that this model is adequate for modelling “pick-off” annihilation processes in ceramic materials for sensors applications and calculation of the size of their nanop…
This paper presents the successful application of bio-inspired optimization algorithms to electromagnetics problems. The problem considered is the design of antireflective surfaces using sub-wavelength gratings periodically created inside the substrate. We apply the rigorous coupled wave analysis to model the reflecti…
The various seat problems are happening in the field. Customers are getting more sensitive to the quality of a vehicle than ever these days. The long-term accumulated staining of iInterior trim contamination, as a result, is one of the most important factors in regarding that of the vehicle and newly reflected in IQS…
A prototype X-band scale model for a quasi optical 3-port circulator utilizing a double-layer circularly polarizing frequency selective surface is proposed. The operating principles and measured characteristics of the device are discussed. A prototype device operating at 9.9 GHz is built and validated experimentally.…
In this paper, results of finite element crash simulation are presented for a TRIP steel side rail with and without considering the phase transformation during forming operations. A homogeneous phase transformation model is adapted to model the mechanical behavior of the austenite-to-martensite phase. The forming proc…
Transmission terahertz time-domain spectroscopy (THz-TDS) measurements of carbon nanotube arrays are presented. A relatively thin film with vertically aligned multi-walled carbon nanotubes has been prepared and measured using THz-TDS. Experimental results were obtained from 80GHz to 2.5THz, and the sample has been cha…
Computational micromechanics techniques are applied towards determining the effective thermal and electrical conductivity of carbon nanotube-polymer nanocomposites containing fully aligned SWCNTs. Various representative volume element configurations at a wide range of CNT volume fractions are used in order to quantify…
Smart or adaptive materials include a broad range of materials that change shape from external electric or magnetic fields, light, chemistry, or heat induced phase transformations. Conversely, many of these materials change their internal electronic structure from external loads which can provide sensing capabilities.…
This paper investigates the influence of through -thickness stitching on damage tolerance of NCF sandwich composites. Stitch-bonded non-crimp fabrics (NCF) are a popular choice for both monolithic and sandwich composite structur es. It appears that the fine binding thread used in the production of NCF fabrics offers i…
Vehicle door closure systems often include self-balancing double pendulum mechanisms. For example, the counterweight in the outside handle assembly is used to reduce handle motion under inertia loadings occurring during crash events. The system is configured in such a way that the inertia forces developed during a cra…
Magnesium alloys are not corrosion resistant in many applications and they require coating protection. In this study, we developed an electroless E-coating technique for magnesium alloys and discussed a cathodic E-coating deposition mechanism for the electroless E-coating process. This coating can be formed within a f…
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Casting, machining and structural simulations were completed on a V8 engine block made in Compacted Graphite Iron (CGI) for use in a racing application. The casting and machining simulations generated maps of predicted tensile strength and residual stress in the block. These strength and stress maps were exported to a…
Silicon carbide diesel particulate filter (DPF) is now recognized as the most effective and robust way to reduce not only the mass but also the number of emitted particles on diesel passenger cars. Widespread use of expensive catalytic platinum-containing coatings has contributed to increased harmful NO₂ emissions. A…
Engineering fracture mechanics has played a vital role in the development and certification of virtually every aerospace vehicle that has been developed since the mid-20th century. NASA Langley Research Center s Durability, Damage Tolerance and Reliability Branch has contributed to the development and implementation o…