Materials

Solar and Thermal Energy Harvesting Textile Composites for Aerospace Applications

The proposed research focuses on developing novel energy harvesting devices that can be integrated with loadbearing structures in an air vehicle (e.g. a UAV). Several ambient energy sources are available on a UAV: light, heat, and vibration. The amount of energy available from light and heat exceeds that in vibration, so this work focuses on the first two modes of harvesting.

Posted in: Briefs, Materials, Aircraft structures, Solar energy, Heat exchangers, Composite materials, Textiles
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Thermo-Elastic Nondestructive Evaluation of Fatigue Damage in PMR-15 Resin

New aircraft are expected to use more composite materials. This drives the need for nondestructive evaluation (NDE) of composite materials. Current aircraft are flown beyond their design lives, and have to be inspected for fatigue and other types of damage. This necessitates a need to understand the NDE signal-material relationship to evaluate the component state.

Posted in: Briefs, Materials, Aircraft structures, Composite materials, Fatigue, Resins, Non-destructive tests
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Characterization of Ceramic Composite Materials Using Terahertz Nondestructive Evaluation Techniques

This work describes the use of nondestructive evaluation (NDE) techniques to characterize defects such as rust, voids, etc. in materials, and to analyze and predict strain and stress-induced breakdown. The use of terahertz (THz) imaging as an evaluation tool for novel materials and systems has found much success in recent years. While suggested as a potential NDE tool for use in the field of ceramic and ceramic matrix composite materials, the use of THz spectroscopy and imaging in the examination of the effects of mechanical and thermally induced strain on ceramic composite materials is not well established. In order to assess the effectiveness of THz imaging for use in the analysis of ceramic composite material health, it is necessary to determine if THz spectroscopic imaging can clearly highlight areas of the samples that have been affected by mechanical and thermal stress.

Posted in: Briefs, Materials, Ceramics, Composite materials, Materials properties, Non-destructive tests
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High Strain Rate Mechanical Properties of Glassy Polymers

Arange of experimental data has been generated describing the response of glassy polymers to high strain rate loading in compression. Recently, research programs that study the combined effects of temperature and strain rate have made significant steps in providing better understanding of the physics behind the observed response, and also in modeling this response. However, limited data are available in tension, and even more limited are data describing both the compressive and tensile response of the same polymer. In those studies that do examine tensile response, often there are large gaps in the strain rate dependence. These gaps are due to the relative difficulty of performing characterization experiments in tension, especially on polymers and especially at high rates.

Posted in: Briefs, Materials, Materials properties, Polymers, Tensile Strength
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Investigation of Basalt Woven Fabrics for Military Applications

Basalt rock is a black or gray fine-grained rock in the family of igneous rocks, formed by cooling of molten lava. It is commonly found in the Earth’s crust, is abundant throughout the world, and can be easily mined. Basalt rock possesses certain qualities similar to thermoplastics and metals, i.e., it melts when heated to specific temperatures (1100 to 1300 °C), and can be drawn into flexible fibers, a process similar to the manufacture of S-2 and E-glass fibers.

Posted in: Briefs, Materials, Defense industry, Fabrics, Fibers, Materials properties
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Size Scale and Defect Engineered Nanostructures for Optimal Strength and Toughness

Realistic combinations of ceramics and/or semiconductors have been developed that simultaneously achieve high hardness (>40 GPa) and toughness (>400 MPa*m1/2). To achieve this goal, there were three primary objectives: (1) the development of physically based dislocation models to understand the deformation of brittle materials, (2) the synthesis of model ceramic nanocomposites that demonstrate high hardness and toughness, and (3) the detailed understanding of the arrangements and types of dislocation structures in small volumes. This involved the uniaxial compression of Si nanovolumes (spheres and towers) using a combination of TEM in situ indentation and molecular dynamics simulations for objective (1), the deposition of Si-SiC core-shell nanotowers for objective (2), and the HR TEM analysis of deformed Si nanovolumes for objective (3).

Posted in: Briefs, Materials, Ceramics, Composite materials, Nanotechnology, Semiconductors, Durability
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High-Temperature Silicon Carbide Power Module for Military Hybrid Electric Vehicles

The ever-increasing electrical power, power density, and cooling requirements of present and future military platforms are pushing silicon-based power electronics systems to their operational limits. To address future needs, wide bandgap semiconductor materials such as silicon carbide (SiC) and gallium nitride (GaN) were developed for electronic applications. Using these semiconductor materials, a new generation of wide bandgap power devices is being developed.

Posted in: Briefs, Materials, Power electronics, Materials properties, Semiconductors, Hybrid electric vehicles, Military vehicles and equipment
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Tunable Infrared Material System

The objective of this work was to lay the groundwork for the development of a new tunable II-VI infrared (IR) material system using mature III-V semiconductors as lattice-matched substrates. Mercury cadmium selenide (HgCdSe) was studied as an alternative to mercury cadmium telluride (HgCdTe) as an IRdetecting material.

Posted in: Briefs, Materials, Optics, Nanomaterials, Semiconductors
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Nonlinear Acoustic Metamaterials for Sound Attenuation Applications

An acoustic crystal composed of tightly packed spherical particles can exhibit a wide spectrum of acoustic properties with responses varying from linear to highly nonlinear regimes. The physical attractiveness of these crystals resides in the controllability of such acoustic responses by simple manipulation of static pre-compression applied to the material.

Posted in: Briefs, Materials, Materials properties, Acoustics, Noise
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Transparent Ceramics for High-Energy Laser Systems

When a high-energy laser (HEL) beam transmits through a window material, a part of the laser energy is absorbed by the material and causes optical aberrations. This absorbed energy results in material heating in the local exposed region, changing its refractive index based on the material’s thermo-optic coefficient, thermal expansion coefficient, and stress optic coefficient. These changes result in beam distortion and loss of output power, measured as optical path distortion (OPD), which has a severe impact on system performance.

Posted in: Briefs, Materials, Windows and windshields, Lasers, Ceramics, Heat resistant materials
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