Test & Measurement

Simulating the Structural Behavior of Laminated Glass

This report investigates the strength of archi- tectural laminated glass and the viability of its use for window glass in commercial buildings. Some researchers recommend that the structural behavior of laminated glass (typically consisting of two glass layers and a plasticized PVB [polyvinyl butyral] interlayer) is equivalent to the structural behavior of monolithic glass (one solid piece of glass) for most common applications. However, if this monolithic equivalency assumption is not valid, its implementation would result in the unconservative design and use of laminated glass, which could lead to failure of the glass at the design load. Using ALGOR Mechanical Event Simulation (MES) software, laminated and monolithic glass plates were modeled and analyzed to compare their response to a wind load. Stress results for the two plates were very different due to shear deformations experienced by the interlayer of the laminated plate. This research may help to ensure the safe use of laminated window glass.

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Pressure-Application Device for Testing Pressure Sensors

This device generates a pulse of known pressure. A portable pressure-application device has been designed and built for use in testing and calibrating piezoelectric pressure transducers in the field. The device generates pressure pulses of known amplitude. A pressure pulse (in contra- distinction to a steady pressure) is needed because in the presence of a steady pressure, the electrical output of a piezoelectric pressure transducer decays rapidly with time.

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Small Low-Temperature Thermometer With Nanokelvin Resolution

The magnetic field is generated by permanent magnets instead of a solenoid. An improved high-resolution thermometer (HRT) for use in scientific experiments at temperatures

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Optical Measurement of Temperatures in Muscles and Tendons

Small, electrically and chemically neutral sensors would be implanted surgically. Miniature fiber-optic-coupled sensors based on optically excited, self-resonant microbeams have been proposed for measuring temperatures within muscle fascicles and tendons. The proposed sensors could be used in medical and biological research on humans and other animals. The proposed sensors would be variants of those described in several previous articles in NASA Tech Briefs: "Proximity Measurement of Pressure and Temperature" (NPO-20223), Vol. 22, No. 1 (January 1998), page 48; and "Measurement of Stresses and Strains in Muscles and Tendons" elsewhere in this issue.

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Measurement of Stresses and Strains in Muscles and Tendons

Small, electrically and chemically neutral sensors would be implanted surgically. Miniature fiber-optic-coupled sensors based on optically excited, self-resonant microbeams are being developed for measuring stresses and strains within muscle fascicles and tendons. These sensors could be used in medical and biological research on humans and other animals, or to obtain data for the design of lifelike robots.

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Broad-Band, Noninvasive Radio-Frequency Current Probe

This circuit responds in approximately constant proportion to current over a wide frequency range. An instrument that noninvasively measures alternating current over a broad frequency band (typically from about 0.3 to about 110 MHz) has been invented. This instrument could be especially useful for assessing radio-frequency hazards by measuring currents in various parts of humans or personnel exposed to radio-frequency electromagnetic fields.

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Web-Based Technology Distributes Lean Models

Users can share models while protecting intellectual property. Everybody creates models. These models are used to understand how products will hold up to the stresses, use, and abuse of real-world deployment; analyze the impact of design decisions on cost; simulate interactions; or evaluate numerous other metrics. Unfortunately, because of the variety of software tools available and the cost of acquiring them, models may not be compatible with the software used by customers and suppliers. Sharing models creates the fear of exposing intellectual property, especially if those sharing the models can understand the source code.

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