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Strain Gauges Indicate Differential-CTE-Induced Failures

Failures are indicated by changes in slopes of strain versus temperature. A method of detecting mechanical failure induced by variation in temperature at an adhesive bond between two materials that have different coefficients of thermal expansion (CTEs) involves monitoring of strain-gauge readings. This method can be regarded as an exploitation of the prior observation that the readings of strain gauges commonly used in tensile and compressive testing of material specimens include features indicative of incremental failures in the specimens. In this method, one or more strain gauges are bonded to either or both of the two materials near the bond between the materials. (The adhesive used to bond the strain gauges would not ordinarily be the same as the one used to bond the two materials). Then strain-gauge readings are recorded as the temperature of the materials is varied through a range of interest. Any significant discontinuity in the slope of the resulting strain-versus- temperature curve(s) is taken to be a qualitative indication of a failure of the bond between the two materials and/or a failure within one of the materials in the vicinity of the bond.

Posted in: Briefs, TSP

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Counterrotating-Shoulder Mechanism for Friction Stir Welding

The weights and costs of fixtures for holding workpieces could be reduced. A counterrotating- shoulder mechanism has been proposed as an alternative to the mechanism and fixtures used in conventional friction stir welding. The mechanism would internally react most or all of the forces and torques exerted on the workpiece, making it unnecessary to react the forces and torques through massive external fixtures.

Posted in: Manufacturing & Prototyping, Briefs

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Motorcycle Design Optimized With Finite-Element Software

Sierra Design Engineering, Mount Aukum, California; BUB Enterprises, Grass Valley, California; and ALGOR, Inc., Pittsburgh, Pennsylvania FEA software was used to analyze key components of a racing streamliner. A streamliner motorcycle designed and built by Sierra Design Engineering and BUB Enterprises achieved a new world-record speed of 350.884 miles per hour last year at the Bonneville Salt Flats in Utah. In 1989, the original engine and transmission were designed by Joe Harralson of Sierra Design Engineering, with the rest of the streamliner being designed and built by BUB Enterprises.

Posted in: Briefs

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Desktop 3D Scanner

NextEngine, Santa Monica, CA, offers the Desktop 3D Scanner, a full-color multi-laser scanner that scans complex shapes for CAD and 3D design applications on the desktop. About the size of a cereal box, the scanner connects directly to a PC via USB 2.0. It operates with proprietary MultiStripe Laser Triangulation (MLT) technology that features twin arrays of four Class 1M 10-mW solid-state lasers with custom optics at a 650-nm wavelength. The scanner also features twin 3-megapixel CMOS RGB image sensors, optically synchronous RGB color texture capture, and built-in spatially diverse white-light texture illuminators. Full-color photo data is captured for each surface point, and there is no preset limit for the size of objects to be scanned. Objects larger than 5.1 x 3.8" in macro mode and 13.5 x 10.1" in wide mode can be composite-captured with supplied ScanStudio(tm) software. The unit has throughput of 50,000 processed points per second, and comes with an AutoPositioner(tm) to capture multiple surfaces of objects, and a PartGripper(tm) to secure objects during scanning. For Free Info Visit http://info.hotims.com/10966-120

Posted in: Products

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Dr. Karen Jackson, Aerospace Engineer, Landing and Impact Research (LandIR) Facility

NASA Langley Research Center, Hampton, VA Dr. Karen JacksonIn a crash, keeping the occupants alive and uninjured is paramount. In order to study the dynamics of an impact, military and general aviation aircraft, like cars, must be tested for their ability to keep their riders safe. A part of Structural Dynamics Branch in the Research and Technology Directorate at NASA Langley, the Landing and Impact Research Facility (LandIR) tests aircraft by crashing them. Dr. Karen Jackson is part of the research team.

Posted in: Who's Who

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MoO3 Cathodes for High-Temperature Lithium Thin-Film Cells

Cycle lives of these cathodes exceed those of LiCoO2 and LiMn2O4 cathodes. MoO3 has shown promise as a cathode material that can extend the upper limit of operating temperature of rechargeable lithium thin-film electrochemical cells. Cells of this type are undergoing development for use as energy sources in cellular telephones, wireless medical sensors, and other, similarly sized portable electronic products. The LiCoO2 and LiMn2O4 cathodes heretofore used in these cells exhibit outstanding cycle lives (of the order of hundreds of thousands of cycles) at room temperature, but operation at higher temperatures reduces their cycle lives substantially: for example, at a temperature of 150 °C, cells containing LiCoO2 cathodes lose half their capacities in 100 charge/discharge cycles.

Posted in: Briefs, TSP

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Ion-Conducting Organic/Inorganic Polymers

Properties can be tailored through a choice of starting alkoxysilane and diamine ingredients. Ion-conducting polymers that are hybrids of organic and inorganic moieties and that are suitable for forming into solidelectrolyte membranes have been invented in an effort to improve upon the polymeric materials that have been used previously for such membranes. Examples of the prior materials include perfluorosulfonic acid-based formulations, polybenzimidazoles, sulfonated polyetherketone, sulfonated naphthalenic polyimides, and polyethylene oxide (PEO)-based formulations. Relative to the prior materials, the polymers of the present invention offer greater dimensional stability, greater ease of formation into mechanically resilient films, and acceptably high ionic conductivities over wider temperature ranges. Devices in which films made of these ion-conducting organic/ inorganic polymers could be used include fuel cells, lithium batteries, chemical sensors, electrochemical capacitors, electrochromic windows and display devices, and analog memory devices.

Posted in: Briefs, TSP

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