Browse Topic: Conductivity
ABSTRACT Thermal management systems (TMS) of armored ground vehicle designs are often incapable of sustained heat rejection during high tractive effort conditions and ambient conditions. The use of a latent heat energy storage system that utilizes Phase Change Materials (PCMs) is an effective way of storing thermal energy and offers key advantages such as high-energy storage density, high heat of fusion values, and greater stability in temperature control. Military vehicles frequently undergo high-transient thermal loads and often do not provide adequate cooling for powertrain subsystems. This work outlines an approach to temporarily store excess heat generated by the transmission during high tractive effort situations through use of a passive PCM retrofit thereby extending the operating time, reducing temperature transients, and limiting overheating. A numerical heat transfer model has been developed based around a conceptual vehicle transmission TMS. The model predicts the
To advance soft robotics, skin-integrated electronics, and biomedical devices, researchers have developed a 3D printed material that is soft and stretchable — traits needed for matching the properties of tissues and organs — and that self-assembles. Their approach employs a process that eliminates many drawbacks of previous fabrication methods, such as less conductivity or device failure
Lithium-ion (Li-ion) batteries employ binders that encounter challenges such as poor conductivity and expansion during charging. In a recent study, scientists have developed a high-performing binder using poly(vinylphosphonic acid) for silicon oxide-based anodes in Li-ion batteries. This binder offers enhanced performance as demonstrated by the superior durability, and discharging capacity of the anodes compared to conventional options. With patents filed internationally, this technology holds promise for broader applications in electric vehicles and beyond
Advanced two-dimensional (2D) materials discovered in the last two decades are now being produced at scale and contribute to a wide range of performance enhancements in engineering applications. The most well known of these novel materials is graphene, a nearly transparent nanomaterial comprised of a single layer of bonded carbon atoms. In relative terms, it has the highest level of heat and electrical conductivity, protects against ultraviolet rays, and is the strongest material ever measured. These properties have made graphene an attractive potential material for a variety of applications, particularly for transportation-related uses, and especially for automotive engineering. The goal of drastically reducing greenhouse gas emissions has prioritized the electrification of transportation, the decarbonization of industry, and the development of products that require less energy to make, last longer, and are fully recyclable. While this chapter reviews the current state of graphene
Advanced two-dimensional materials discovered in the last two decades are now being produced at scale and are contributing to a wide range of performance enhancements in engineering applications. The most well known of these novel materials is graphene, a nearly transparent nanomaterial comprising a single layer of bonded carbon atoms. In relative terms, it has the highest level of heat and electrical conductivity, protects against ultraviolet rays, and is the strongest material ever measured. These properties have made graphene an attractive potential material for a variety of applications, particularly for transportation-related uses, and especially for aerospace engineering. The goals of reducing greenhouse gas emissions and creating a world that achieves net-zero emissions have prioritized the electrification of transportation, the decarbonization of industry, and the development of products that require less energy to make, last longer, and are fully recyclable. These aspects have
A team of inventors from NASA Langley and NASA Ames have created a new type of carbon fiber polymer composite that has a high thermal conductivity. This was achieved by incorporating Pyrolytic Graphite Sheets (PGSs) and Carbon Nanotubes (CNTs), which enhance the material’s ability to transfer heat when compared to typical carbon fiber composites
Corrosion control is always of concern to the designer of electronic enclosures. The use of EMI gaskets to provide shielding often creates requirements that are in conflict with ideal corrosion control. This SAE Aerospace Recommended Practice (ARP) presents a compatibility table (see Figure 1) which has as its objective a listing of metallic couples that are compatible from a corrosion aspect and which still maintain a low contact impedance
The microstructure of the alloy and the manner in which it responds to heat treatment has been investigated. The alloy was aged at 550OC when it was initially spray-formed, or when its thickness was decreased by 38%. Before further aging of some specimens, a four-hour solution treatment at 1015OC was performed. The subsequent phase was a cold deformation that was barely 60% of the sample's initial thickness. The alloys' electrical conductivity and hardness may be evaluated based on how long they had been created. Following solution treatment and cold rolling, the alloy's peak hardness was around 380 kgf/mm2. In samples aged immediately under spray-produced conditions, the maximum peak hardness of 255 kgf/mm2 was attained. Conductivities in freshly cold-rolled samples could reach up to 75% of the standard for annealed copper internationally. It looks at the microstructural features of this alloy in this context, paying close attention to how various processing conditions affect them
A single strand of fiber has the flexibility of cotton and the electric conductivity of a polymer, called polyaniline. The newly developed material showed good potential for wearable e-textiles. Researchers tested the fibers with a system that powered an LED light and another that sensed ammonia gas
Innovators at the NASA Kennedy Space Center have developed a new optical sensor for measuring concentration in a liquid solution. The sensor was designed for measuring the pretreat solution concentration within the Universal Waste Management System (UWMS), a specialized toilet designed for the International Space Station (ISS) and other future missions. The sensor was developed to replace the current pretreat concentration sensor within the UWMS that uses electrical conductivity instead of light-based methods
This SAE Aerospace Standard (AS) defines the requirements for a threadless, flexible, high conductive, self-bonding coupling assembly which, when installed on defined ferrules, provides a flexible connection for joining ducting and components in pressurized fluid systems. The assembled coupling is designed to provide interchangeability of parts and components between qualified manufacturers for use from -65 to +265 °F at 130 psi nominal operating pressures and for the service life of the aircraft system. FAR 23.954, FAR 25.603, FAR 25.605, FAR 25.609, FAR 25.613, FAR 25.901, FAR 25.954, and FAR 25.981 certification requirements have identified the need for high-current capable flexible fluid assembled couplings. The coupling assembly does not require inspection or maintenance to remain current capable for the life of the aircraft. This specification provides two test philosophies necessary for low-pressure couplings: 1 Electromagnetic effects/lightning testing of assembled couplings to
In the 1st generation Toyota "MIRAI" fuel cell stack, carbon protective surface coating is deposited after individual Ti bipolar plate being press-formed into the desired shape. Such a process has relatively low production speed, not ideal for large scale manufacturing. A new coating concept, consisting of a nanostructured composite layer of titanium oxide and carbon particles, was devised to enable the incorporation of both the surface treatment and the press processes into the roll-to-roll production line. The initial coating showed higher than expected contact resistance, of which the root cause was identified as nitrogen contamination during the annealing step that inhibited the formation of the composite film structure. Upon the implementation of a vacuum furnace chamber as the countermeasure, the issue was resolved, and the improved coating could meet all the requirements of productivity, conductivity, and durability for use in the newer generation of fuel cell stacks
Researchers at the National Institute of Standards and Technology (NIST) have fabricated a novel device that could dramatically boost the conversion of heat into electricity. If perfected, the technology could help recoup some of the recoverable heat energy that is wasted in the U.S. at a rate of about $100 billion each year
Drawing inspiration from how spiders spin silk to make webs, a team of researchers from the National University of Singapore, together with international collaborators, has developed an innovative method of producing soft fibers that possess three key properties (strong, stretchable, and electrically conductive), and at the same time can be easily reused to produce new fibers
This specification covers an aluminum-beryllium alloy in the form of bars, rods, tubing, and shapes consolidated from powder by extrusion
This specification covers inert, fluorochemical, liquid heat transfer agents
This specification covers a titanium alloy in the forms of investment castings having four grades of permissible discontinuities
This specification covers an aluminum alloy in the form of die forgings or hand forgings up to 5 inches (125 mm) in thickness, and forging stock of any size (see 8.7
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