Mechanical Components

Natural DNA-Based Nonvolatile Resistive Switching Memory

Motivated by the demand for an even larger storage capacity in the information era, research efforts have been devoted to the development of more efficient and cost-effective memory elements.

Posted in: Briefs, Aeronautics, Aerospace, Aviation, Data Acquisition, Manufacturing & Prototyping, Composites, Materials, Mechanical Components, Data Acquisition
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Content Addressable Memory (CAM) Technologies for Big Data and Intelligent Electronics Enabled By Magneto-Electric Ternary CAM

Content addressable memory (CAM) is one of the most promising hardware solutions for high-speed data searching and has many practical applications such as anti-virus scanners, internet protocol (IP) filters, and network switches. Since CAM stores the data in its internal memory elements and compares them with the search data in parallel, it can achieve much faster speed compared to the software lookup.

Posted in: Briefs, Aerospace, Communications, Data Acquisition, Defense, Electronic Components, Electronics & Computers, Energy Efficiency, Internet of Things, Materials, Metals, Mechanical Components, MEMs, Semiconductors & ICs, Data Acquisition, Sensors
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Measuring Propellant Stress Relaxation Modulus Using Dynamic Mechanical Analyzer

Structural analysis of solid rocket motors is challenging for several reasons, but the most important of these is the complex behavior of the propellant. The mechanical response of a solid propellant is time and temperature dependent. The complexity of the mathematical analysis of the propellant depends on the loading conditions, but for some loading situations, the linear viscoelasticity assumption is reasonable. In particular, linear viscoelasticity is perhaps the most appropriate material behavior description for use in the simulations of stresses related to storage conditions. Typically, simulations use a viscoelastic model in the form of a Prony series and a Williams–Landel–Ferry (WLF) equation. The parameters in these models are derived from stress relaxation experiments, making the stress relaxation experiment a key viscoelastic test, analogous to the tensile test for linear elastic materials.

Posted in: Briefs, Aerospace, Defense, Fluid Handling, Propulsion, Solid propellants, Spacecraft fuel, Performance tests
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Non-Destructive Damping Measurement for MEMS Acceleration Switches

Microelectromechanical systems (MEMS) three-axis acceleration threshold sensors have been developed to measure acceleration threshold levels using voltage switching when the threshold is reached. Switches with different damping coefficients result in different mechanical impedances and response times. Analytical and numerical methods to model damping coefficient values based on empirical data are needed to characterize three-axis acceleration sensors; traditional methods use the displacement of an underdamped system to calculate the damping ratio.

Posted in: Briefs, Aerospace, Defense, Mechanical Components, Simulation and modeling, Sensors and actuators, Switches
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Damping Measurement for Wafer-Level Packaged MEMS Acceleration Sensors

Microelectromechanical system (MEMS) three-axis acceleration threshold sensors have been developed to measure acceleration threshold levels using voltage switching when the threshold is reached. Determining damping coefficients is important for categorizing how each threshold sensor or switch operates. Switches with different damping coefficients result in different mechanical impedances and response times. Analytical and numerical methods to model damping coefficient values based on empirical data are needed to characterize three-axis acceleration sensors; traditional methods use the displacement of an underdamped system to calculate the damping ratio.

Posted in: Briefs, Defense, MEMs, Sensors, Measuring Instruments, Sensors and actuators, Switches
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Rotating Detonation-Wave Engines

All Navy aircraft and missiles use gasturbine engines for propulsion. Many ships are also dependent on gasturbine engines to generate both propulsive power and electricity. These engines are fundamentally similar to engines used to power commercial airplanes. Future ships moving to an “all electric” paradigm for the propulsion system will still require these gas-turbine engines to generate electricity for the propulsion system and also for other critical onboard systems. Because of the amount of power required by modern warfighting ships, and the prospect that this power requirement will only increase, there is a strong interest in improving the specific fuel consumption of these engines.

Posted in: Briefs, Mechanical Components, Electric power, Fuel economy, Gas turbines, Marine vehicles and equipment, Military aircraft, Missiles
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Thermal Analysis and Microhardness Mapping in Hybrid Laser Welds in a Structural Steel

The concept of combining a laser welding system with a conventional arc welding system (GTAW) was first proposed in order to improve the stability of the laser welding system and to allow greater flexibility in part fit-up. Prior research stated that using a YAG laser at a power of 3 kW, one was able to hybrid laser weld a 4-mm-thick aluminum alloy at a speed of 4 n/min. For a mild steel plate, butt welding at 1 m/min with 5 kW of 6-mm-thick plate was realized. Just as significantly as the weld speed was the ability to hybrid laser weld with gaps up to 1.5 mm in a plate 6 mm thick. The glass metal arc welding (GMAW) laser hybrid process can increase the gap bridging ability, i.e., it appreciably broadens the range of tolerances with regard to edge preparation quality. The arc’s energy input in the hybrid welding process also permits control of the cooling conditions. Via the keyhole, the laser beam brings about easier ignition of the arc, stabilization of the arc welding process, and penetration of the energy deep into the material. The improvement of the energy input leads to a greater welding depth and speed being achieved with the hybrid process compared with individual processes on their own.

Posted in: Briefs, Mechanical Components, Lasers, Welding, Steel, Thermal testing
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Encapsulated Ball Bearings for Rotary Micro Machines

Microelectromechanical systems (MEMS)-fabricated silicon rotary elements for micro-motors, micro-generators, and micro-turbomachinery have received growing attention with applications in power conversion and actuation. Within these technologies, the bearing mechanism is the primary determinant of device performance and reliability. Active bearings, such as magnetic or electrostatic, have the advantage of being controlled during the operation, but at the cost of the accompanying circuitry. Passive bearings span a large range of velocities that include center-pin bushings with low revolution rates possible, and hydrostatic or hydrodynamic bearings with high revolution rates possible.

Posted in: Briefs, Mechanical Components, Microelectricmechanical device, Bearings
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Reverse Pressure Capable Finger Seal

Each finger seal consists of a number of multiple thin metal laminates, each with a multitude of flexible projections that are referred to as “fingers.” To form a functional seal, multiple laminates are formed into a stack, with each laminate oriented so that the slots between its fingers cover the slots of the neighboring laminates. For protection and support of the laminates, forward and aft cover plates are placed on each side of the finger seal stack. A high pressure exists on one side of the seal, providing a driving force to push the air from one side of the seal to the other.

Posted in: Briefs, Mechanical Components, Coatings Colorants and Finishes, Seals and gaskets
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Reactive Structure and Smart Armor for Future Ground Vehicles

AReactive Structure Technology (RST) is a new class of smart structure that can react to external excitations (such as blast or ballistic impacts) in a carefully designed way using the energy pre-stored internally or from the external excitations to counteract the hazardous loading or perform other desired tasks. A reactive structure deflects an incoming projectile in order to protect a vehicle body. When a projectile hits the face plate (armor), the embedded sensors feed the impact signal to a control unit, and actuators are triggered to move the faceplate. The movement of the faceplate deflects the projectile and significantly reduces the possibility of penetration in the back plate.

Posted in: Briefs, Mechanical Components, Sensors and actuators, Active safety systems, Protective structures, Military vehicles and equipment
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