This work presents a structural design optimization of composite rotor blades for a typical unmanned helicopter. Multiple parameters that influence the stiffness and weight of the rotor blade are considered as design variables. These include the number of composite plies, the thickness of composite plies, and the web location as a fraction of the rotor blade airfoil chord. To further improve the stiffness, carbon nano-tubes are doped into the composite material and the percentage of doped carbon nano-tubes are considered as an additional design variable. The structural analysis of the rotor blade is carried out using principle of the Variational Asymptotic Method (VAM). Using VAM, the 3D elastic rotor blade problem is decoupled into two reduced-dimension sequential problems of 2D cross-sectional analysis and 1D beam analysis. Variational Asymptotic Beam Sectional Analysis (VABS) tool is used for the 2D cross-section analysis to obtain the blade stiffness. Orthogonal array based design of experiments approach is followed to efficiently explore the design space. A novel orthogonal array, named MGB-4P OA which has 18 sample design points, is used to construct the design of experiments. VABS is used for cross-sectional analysis at the 18 sample design points of the MGB-4P orthogonal array. Second order polynomial nonlinear response surface models are generated for the blade stiffness and blade weight using their respective values from the orthogonal array. The response surface models predict the output of the structural analysis from VABS and the estimated blade weights accurately, and are therefore, considered as surrogate models for the objective functions during optimization. A recently developed nature inspired meta-heuristic Multi-Objective Bat-Algorithm (MOBA) optimization routine is employed in conjunction with Pareto analysis for optimizing the design variables for the mutually conflicting objectives of maximizing the rotor blade stiffness and minimizing the blade weight.

Dandinasivara, Abhiram, Ganguli, Ranjan, Harursampath, Dineshkumar

Q&A: Dr. Mahmooda Sultana, Multifunctional Sensor Researcher/Engineer at NASA Goddard

TBMG-344055/1/2019

Dr. Sultana won funding to advance a nanomaterial-based detector platform that can sense environmental parameters from minute concentrations of target gases and vapors, to atmospheric pressure and temperature, and then transmit that data via a wireless antenna — all from the same 3 × 5’’ self-contained platform.

Individual Quantum Dots Imaged in 3-D for the First Time

TBMG-338963/1/2019

Researchers have developed an imaging technique that uses a tiny, super sharp needle to nudge a single nanoparticle into different orientations and capture 2-D images to help reconstruct a 3-D picture. The method demonstrates imaging of individual nanoparticles at different orientations while in a laser-induced excited state.

Film Blocks Electromagnetic Interference

TBMG-337002/1/2019

Electromagnetic interference (EMI) can harm smartphones, tablets, chips, drones, wearables, aircraft, and human health. EMI is increasing with the explosive proliferation of devices that generate it. A technique was developed to produce relatively low-cost EMI-blocking composite films.

Control of the Diameter and Chiral Angle Distributions During Production of Single-Wall Carbon Nanotubes

TBMG-336011/1/2019

Pulsed laser vaporization (PLV) production of single-wall carbon nanotubes (SWNTs) on traditional Co/Ni catalyst was explored with respect to variations in the production temperature. The Rh/Pd results were also reproduced for comparison. The nanotube-type populations were measured via photoluminescence (PL), UV-Vis-NIR (ultraviolet-visible-near-infrared) absorption, and Raman spectroscopy. A small reduction in the average nanotube diameter at lowered production temperature has long been known to occur; however, temperature effect on nanotube population (and not just for diameters) has never been explored.

Thermochromic Windows Convert Sunlight into Electricity

TBMG-3341512/1/2018

Relying on advanced materials such as perovskites and single-walled carbon nano-tubes, a window technology was developed that responds to heat by transforming from transparent to tinted. As the window darkens, it generates electricity. The color change is driven by molecules (methylamine) that are reversibly absorbed into the device. When solar energy heats up the device, the molecules are driven out, and the device is darkened. When the Sun is not shining, the device is cooled back down, and the molecules re-absorb into the window device, which then appears transparent.

One-Dimensional Material with High Current Density

TBMG-3323511/1/2018

Current density is the amount of electrical current per cross-sectional area at a given point. As transistors in integrated circuits become smaller and smaller, they need higher and higher current densities to perform at the desired level. Most conventional electrical conductors, such as copper, tend to break due to overheating or other factors at high current densities, presenting a barrier to creating increasingly small components.

Technique Creates Adaptive Materials

TBMG-3309710/1/2018

A technique that enables on-demand control of composite behavior could enable a variety of new capabilities for future rotorcraft design, performance, and maintenance. The focus of the research was on controlling how molecules interact with each other; specifically, having them interact in such a way that changes at a small size, or nanoscale, could lead to observed changes at a larger size, or macroscale.

Electric double layer capacitors prepared with polyvinyl alcohol and multi-walled carbon nanotubes

2018-36-03139/3/2018

Portable electronics, wearables, electric vehicles and solar cells are sectors in increasingly development which include innovation and miniaturization of the devices. In this scenario, the development of smaller and lightweight energy storage devices, which store more energy, is required. Besides, it is desirable for these devices to be environmentally friendly to minimize pollution. In an attempt to meet these requirements, this work purposes the development and the characterization of nanofibers-based electrode composed of Polyvinyl alcohol (PVA) and multi-walled carbon nanotubes (MWCNT) for electric double layer capacitors (ELCDs) devices with aqueous electrolyte. This composite has been prepared by electrospinning technique and consolidate an electrical conductive and high-surface material electrode. After that, the PVA/MWCNT electrode was assembled in coin cell device with Sodium Sulfate (Na2SO4) electrolyte for electrochemical characterization. The characterization results showed that EDLCs devices present specific capacitance of ∼4.8 Fg-1, energy density of ∼0.1 Wh kg-1, power density of ∼600W kg-, fast charge transfer at electrode/electrolyte interface and high lifetime All these results encourage further development on PVA/MWCNT materials as electrode for EDLCs and Li-Air batteries devices. This new generation of devices are opening niches of applications on multi billionaire markets from communication to transport.

Real, Carla Giselle Martins, Vicentini, Rafael, Nunes, Willian Gonçalves, Boas, Otávio Vilas, Costa, Lenon Henrique, Soares, Davi Marcelo, Zanin, Hudson

Faster, More Efficient Information Processing

TBMG-328609/1/2018

For decades, computer chips have been shrinking thanks to a steady stream of technological improvements in processing density. Experts have, however, been warning that we'll soon reach the end of the trend known as Moore's Law, in which the number of transistors per square inch on integrated circuits doubles every year. In order to continue improving chip performance, either the material the transistors are made of — from silicon, to carbon nanotubes or graphene — or how current materials store and process information would need to change.

Nano-Fiber Filters for Automotive Applications

2018-28-00417/9/2018

Engines have well lubricated metallic moving parts protected by oil films. Microscopic airborne particles can easily break down the oil film and change the tight working tolerances of operating components of an engine. In addition to the above requirement, a modern diesel engine requires a highly precise injection system to meet stringent emission norms and it requires an average of 15,000 L of air per unit fuel consumed. Meticulous filtration is key to ensure purity of air and fuel available to engine. A Polyacrylonitrile based nanofiber synthesized using electro-spinning process is an alternative to conventional cellulose media filters. A Scanning Electron Microscope image is analyzed to obtain the fiber diameter and a 2-D modeling is done using this image data. The trend of developing miniaturized model in filtration application and analysis using computational fluid dynamics has limited research till now. The objectives of the paper are to analyze variation of pressure drop and quality factor for automotive filtration applications. Pressure drops across the single layer of nano-fiber filter, conventional fuel filter and double layer nano-fiber filter are calculated by Ansys fluent analysis. Electro-spun nanofiber filter can separate large number of particles which is beneficial for the longer lifecycle and higher performance of an engine. A single layer polyacrylonitrile nanofiber filter is found to have minimum pressure drop resulting in higher quality factor for filtration applications. As the number of layers of nanofiber increases the pressure drop observed is higher compared to conventional filter.

Malviya, Rajat Malviya

An Analytical Study of Buckling Behavior of Nanocomposite Beams

2018-28-00507/9/2018

The structural members like beams are often subjected a mode of sudden failure due to high compressive load which is characterised as buckling. The buckling behaviour is one of the most important parameters needs to be considered while designing the structural members like beams. The polymer composites are the one of the most emerging materials used in air craft structural applications. This paper studies the buckling behaviour of Carbon Nanotube (CNT) reinforced polymer composite beams by using Classical Laminate Plate Theory (CLPT) approach. The elastic constants obtained for the CNT reinforced polymer composite by applying Mori-Tanaka method are further used to analyse the effect of stacking sequence, CNT Volume fraction in the composite, and CNT radii on the critical buckling loads of an eight layered nanocomposite beam. The Numerical results are also presented and compared for various boundary conditions of beams like clamped-clamped and hinged-hinged. The main intention behind this study is to find the suitability of the nanocomposites as structural components like air-craft wings and ducts.

Peyyala, Pramod Kumar, Baddepudi, Malathi, Subba Rao, V. Venkata

Theoretical Analysis of High Thermal Conductivity Polymer Composite Fin Based Automotive Radiator under Forced Convection

2018-28-00997/9/2018

Though high thermal conductivity polymer composites are prepared based on the thermal requirements, the effectiveness and overall heat transfer performance of the radiators have to be addressed comprehensively to validate the concerned efforts taken to prepare the high thermal conductivity polymer composites. In this article, theoretical analysis on the thermal performance of the cross flow type heat exchanger under convection is performed only by concentrating on the term thermal conductivity of the material. Micro channel based geometry is extracted from the given heat exchanger problem to reduce the complexities of simulation. The term cooling system performance index (CSPI) is used to achieve the expected targets in the present investigation. For shorter fins, the effect of thermal conductivity on the cooling system performance index under lower Reynolds number is insignificant. Further discussions on effect of thermal conductivity on various cases are presented with brief explanations.

Vadivelu, M A, Ramesh Kumar, C, Naiju, C D

Carbon Fiber/Epoxy Mold with Embedded Carbon Fiber Resistor Heater - Case Study

05-11-02-00114/7/2018

The article presents a complete description of the design and manufacturing of a Carbon Fiber/epoxy mold with an embedded Carbon Fiber resistor heater, and the mold performances in terms of its surface temperature distribution and thermal deformations resulting from the heating. The mold was designed for manufacturing aileron skins from Vacuum Bag Only prepreg cured at 135°C. The glass transition temperature of the used resin-hardener system was about 175°C. To ensure homogenous temperature of the mold working surface in the course of curing, the Carbon Fiber heater was embedded in a layer of a highly heat-conductive cristobalite/epoxy composite, forming the core of the mold shell. Because the cristobalite/epoxy composite displayed much higher thermal expansion than CF/epoxy did, thermal stresses could arise due to this discrepancy in the course of heating. Therefore, to lower these stresses, the Carbon Fiber/epoxy faces were separated from the cristobalite/epoxy core containing the heating element by the buffer layer of carbon nanotubes/epoxy displaying intermediate thermal expansion. The determined mold surface thermal deformation was in the range of 1 mm in 20°C-135°C temperature range and, at 135°C, the mold surface temperature unevenness was in the range of 10°C. Despite such temperature unevenness, the Tg values determined with the help of the specimens cut out from the different parts of the cured skin were of satisfactory values.

Czarnocki, Piotr, Boczkowska, Anna, Frączek, Wojciech, Chabera, Paulina, Kubis, Michał, Marjanowski, Jędrzej

Biosensor Could Monitor Glucose Levels in Tears and Sweat

TBMG-285223/1/2018

Constantly tracking a person's glucose levels through their tears or sweat could be one step closer to providing people with diabetes an improved monitoring tool. Researchers report in the journal ACS Nano the development of an ultra-thin, flexible sensor that could be incorporated into contact lenses or on the backs of watches for real-time glucose tracking.

Advanced Carbon Aerogels for Energy Applications

TBMG-283022/1/2018

Carbon aerogels (CAs) are nano-porous carbons comprising a particularly significant class of carbon nano-materials for a variety of sustainable energy applications. Carbon aerogels are specifically promising in that they possess a tunable, three-dimensional, hierarchical morphology with ultrafine cell size and an electrically conductive framework. They are available as macroscopic, centimeter-sized monolithic materials. Carbon aerogels hold great technological promise for a variety of sustainable energy applications including hydrogen and electrical energy storage, desalination, and electrocatalysis.

Optical Ultrasound Needle for Heart Surgery

TBMG-281611/1/2018

Doctors currently rely on external ultrasound probes, combined with pre-operative imaging scans, to visualize soft tissue and organs during minimally invasive procedures, as the miniature surgical instruments used do not support internal ultrasound imaging.

Products of Tomorrow: January 2018

TBMG-281821/1/2018

This column presents technologies that have applications in commercial areas, possibly creating the products of tomorrow. To learn more about each technology, see the contact information provided for that innovation.

Bulk Preparation of Holey Graphene via Controlled Catalytic Oxidation

TBMG-281731/1/2018

Researchers at NASA have developed new methods to manufacture carbon materials (e.g., nanotubes, graphene) with holes through the graphitic surface of the particles. The methods generate materials with increased accessible surface area, increased functional groups at damage sites, and improved through-surface molecular transport properties. The materials generated using these techniques are anticipated to be applicable to a variety of industries, especially energy storage (e.g. supercapacitors and batteries) and separation membranes (e.g. for gas, ions, organics, proteins, etc.).

High Temperature Graphene-Peek Adhesive

17AERP12_0912/1/2017

Compounding graphene into polymers has the potential to improve various material properties, even at very low concentrations. Armament Research, Development and Engineering Center, Watervliet, New York Joining of composites can be a challenging issue. If adhesives are used, the joints are permanent and cannot be undone. If they need to be undone, inserts are often used and these inserts increase cost and weight. Additionally, fibers can be cut in the process leading to a part with weakened mechanical properties. Even with these drawbacks, most components that need to be joined are threaded together, allowing for removal of the parts at a later time. However, threaded connections are costly to design and manufacture, and are often the location of fatigue failures due to their inherent stress concentrations. From an environmental and cost standpoint, there is a large waste associated with the removal of material to form the threads, even more so in sectored threads, where up to half of the machined thread is then cut away. Additionally, threaded joints often require grease to seal out environmental contamination and ensure that they can later be disassembled. This effort is aimed at replacing seldom-used threaded connections with a reusable thermoplastic adhesive.

Soft Robotic Gripper Manipulates Objects Without Training

TBMG-2794412/1/2017

An engineering team at the University of California San Diego has designed and built a gripper that can pick up and manipulate objects without needing to see them and without being trained. The gripper is unique because it brings together three different capabilities; it can twist objects, it can sense objects, and it can build models of the objects it’s manipulating. This allows the gripper to operate in low light and low-visibility conditions, for example.

High Temperature Graphene-Peek Adhesive

TBMG-2795312/1/2017

Joining of composites can be a challenging issue. If adhesives are used, the joints are permanent and cannot be undone. If they need to be undone, inserts are often used and these inserts increase cost and weight. Additionally, fibers can be cut in the process leading to a part with weakened mechanical properties.

Stronger Silk Offers Biomedical Applications

TBMG-2790711/15/2017

Engineers have found they can make a material that is more than twice as stiff as its natural counterpart and can be shaped into complex structures such as meshes and lattices.

Effects of Reflux Temperature and Molarity of Acidic Solution on Chemical Functionalization of Helical Carbon Nanotubes

05-11-01-00049/19/2017

The use of nanomaterials and nanostructures have been revolutionizing the advancements of science and technology in various engineering and medical fields. As an example, Carbon Nanotubes (CNTs) have been extensively used for the improvement of mechanical, thermal, electrical, magnetic, and deteriorative properties of traditional composite materials for applications in high-performance structures. The exceptional materials properties of CNTs (i.e., mechanical, magnetic, thermal, and electrical) have introduced them as promising candidates for reinforcement of traditional composites. Most structural configurations of CNTs provide superior material properties; however, their geometrical shapes can deliver different features and characteristics. As one of the unique geometrical configurations, helical CNTs have a great potential for improvement of mechanical, thermal, and electrical properties of polymeric resin composites. The coil spring shape of these CNTs give them the capability to withstand high loads and considerable deformations that can be recovered, upon unloading. In addition, due to their helical shape, the entanglement of these CNTs with each other and the polymeric crosslinked molecular chains is much higher compared to the straight CNTs. Therefore, they can potentially absorb more impact loads and deliver higher resilience and flexibility in composites. One of the main issues for using these nanomaterials in composites is the uniform dispersion of these nanoparticles in the matrix system, besides their poor interface properties. This research reports a method for functionalization of helical CNTs (HCNTs) and investigates the effects of processing parameters, which can influence the effectiveness of the proposed chemical functionalization methods. The proposed method uses a refluxing process with a strong acidic solution; here, the effects of molarity and temperature, as two influential parameters, were investigated. For characterization of the functionalized helical CNTs, X-ray diffraction spectroscopy (XRD), Raman spectroscopy, Fourier transform infrared spectroscopy (FTIR), visual dispersion inspection, and Scanning Electron Microscopy (SEM) methods were used. According to the results, all functionalization processes were successful in increasing the attachment of functional groups to the surface of helical CNTs that resulted in better dispersion of helical CNTs in DI water. The increase in molarity (M) of the acidic solution beyond 3M resulted a higher dispersion rate and a lower crystallinity. In the case of using a high-reflux temperature, helical CNTs which were processed with a 3M or 16M acids displayed a substantial increase in the solubility compared to the ones which were refluxed at a low temperature.

Taklimi, Sean, Ghazinezami, Ali, Cluff PhD, Kim, Askari, Davood

Clean Water with Sandia Sensor Solution

TBMG-275089/1/2017

Water utilities have a Goldilocks problem: If they don't add enough chlorine, nasty bacteria that cause typhoid and cholera survive the purification process. Too much chlorine produces disinfection byproducts such as chloroform, which increase cancer risks. The amount of chlorine needs to be “just right” for safe drinking water.

Printed Sensors Monitor Tire Wear in Real Time

TBMG-27512

9/1/2017

Electrical engineers at Duke University have invented an inexpensive printed sensor that can monitor the tread of car tires in real time, warning drivers when the rubber meeting the road has grown dangerously thin. If adopted, the device will increase safety, improve vehicle performance, and reduce fuel consumption.