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MATERIALS AND PROCESSES Two dielectric isolation methods have been explored for implementation of circuits for this program. These are: (1) thermally grown silicon dioxide with a polycrystalline silicon matrix, and (2) glass isola...
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MATERIALS AND PROCESSES Two dielectric isolation methods have been explored for implementation of circuits for this program. These are: (1) thermally grown silicon dioxide with a polycrystalline silicon matrix, and (2) glass isolation with a dummy silicon support slice. The latter technique appears most applicable to the present program because of still lower capacitances to the substrate. In addition, the glass isolation lends itself to the simpler implementa¬tion of beam-lead technology if desired.
CIRCUITS Emitter current-steered (ECL) and saturating high speed (TTL) circuit configurations have been explored, both with the view toward obtaining the contract's required speed/power product. In addition, the circuits were considered from the point of view of radiation hardening possibilities. The present activities are direct¬ed toward the use of the TTL logic function. Linear high frequency amplifier studies have been performed and evaluations made as to implementation utilizing dielectric isolation techniques.
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Experimental model testing was then done by investigating various means of achieving damping in the configuration to determine its effect on the isolation and to determine the best possible pivot arrangements. Prom these results, ...
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Experimental model testing was then done by investigating various means of achieving damping in the configuration to determine its effect on the isolation and to determine the best possible pivot arrangements. Prom these results, an optimum experimental DAVI design was obtained.
An experimental platform was constructed utilizing four optimum DAVI models for isolation. This configuration utilizing the DAVI was capable of testing up to 200 pounds, and the frequency was varied from S c.p.s. to 100 c.p.s. to obtain the transmissibllity curves. Drop tests of the DAVI platform were done and compared to drop tests of conventional spring-mass systems with the same spring rate.
Results of the analysis and model testing show the DAVI to be capable of over 98-percent isolation at very low frequencies with low static deflections. The isolation provided by the DAVI d- configuration, at a tuned frequency, is independent of the mass of the isolated item. Analysis and drop tests show that the DAVI L gives better shock transmissibllity for its fundamental mode than a conven¬tional isolation system with the same spring rate.
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This report describes the development of a novel uplift-prevention Friction Pendulum isolator called the XY-FP. It presents the principles of operation and mathematical model of the XP-FP isolator, describes its mechanical behavio...
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This report describes the development of a novel uplift-prevention Friction Pendulum isolator called the XY-FP. It presents the principles of operation and mathematical model of the XP-FP isolator, describes its mechanical behavior through testing of a single isolator, and demonstrates its effectiveness through testing of a quarter-scale steel-frame model structure. The computer program 3D-BASIS-ME was modified to include an element representative of the mechanical behavior of the new XY-FP isolator, and the validity and accuracy of analytical methods to predict its behavior is assessed. The study shows that the XY-FP isolator provides effective uplift prevention regardless of the state of displacement in the bearing, allows for decoupling of the bi-directional horizontal motion along two orthogonal directions, and has the capability to provide distinct stiffness and energy dissipation along the principal directions of the bearing. In addition, by encompassing much less structural material, the isolator offers a lighter and more economical alternative to the standard Friction Pendulum bearing. Moreover, it provides an architecturally flexible solution in terms of integration into a structural system when space considerations are important.
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A set of Neoprene isolation bearings remaining from a 1981 shake table test series conducted at the Earthquake Simulator Laboratory at the Earthquake Engineering Research Center (now the Pacific Earthquake Engineering Research Cen...
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A set of Neoprene isolation bearings remaining from a 1981 shake table test series conducted at the Earthquake Simulator Laboratory at the Earthquake Engineering Research Center (now the Pacific Earthquake Engineering Research Center) were retested in 2012. The new test series was conducted at the NEES site at the Richmond Field Station, University of California, Berkeley. The retest program had the dual purpose of determining the changes in the isolation properties, namely, the horizontal stiffness and equivalent viscous damping, and to study the behavior of the isolators at dynamic inputs that constitute beyond design-basis earthquake levels.
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The requirements for a preliminary design study and verification procedure for a total main rotor isolation system at n/rev are established. The system is developed and analyzed, and predesign drawings are created for an isolation...
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The requirements for a preliminary design study and verification procedure for a total main rotor isolation system at n/rev are established. The system is developed and analyzed, and predesign drawings are created for an isolation system that achieves over 95 percent isolation of all six degrees of freedom.
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In view of the utility of space vehicles as orbiting science laboratories, the need for vibration isolation systems for acceleration-sensitive experiments has gained increasing visibility. To date, three active microgravity vibrat...
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In view of the utility of space vehicles as orbiting science laboratories, the need for vibration isolation systems for acceleration-sensitive experiments has gained increasing visibility. To date, three active microgravity vibration isolation systems have successfully been demonstrated in flight. A tutorial discussion of the microgravity vibration isolation problem, including a description of the acceleration environment of the International Space Station and attenuation requirements, as well as a comparison or the dynamics of passive isolation, active rack-level isolation, and active payload-level isolation is provided. The flight test results of the three demonstrated systems: suppression of transient accelerations by levitation, the microgravity vibration isolation mount, and the active rack isolation system are surveyed.
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