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2169 Steel Waveform Experiments

Furnish, Michael D.; Alexander, Charles S.; Reinhart, William D.; Brown, Justin L.

In support of LLNL efforts to develop multiscale models of a variety of materials, we have performed a set of eight gas gun impact experiments on 2169 steel (21% Cr, 6% Ni, 9% Mn, balance predominantly Fe). These experiments provided carefully controlled shock, reshock and release velocimetry data, with initial shock stresses ranging from 10 to 50 GPa (particle velocities from 0.25 to 1.05 km/s). Both windowed and free-surface measurements were included in this experiment set to increase the utility of the data set, as were samples ranging in thickness from 1 to 5 mm. Target physical phenomena included the elastic/plastic transition (Hugoniot elastic limit), the Hugoniot, any phase transition phenomena, and the release path (windowed and free-surface). The Hugoniot was found to be nearly linear, with no indications of the Fe α – ε phase transition. Releases were non-hysteretic, and relatively consistent between 3- and 5-mm–thick samples (the 3 mm samples giving slightly lower wavespeeds on release). Reshock tests with explosively welded impactors produced clean results; those with glue bonds showed transient releases prior to the arrival of the reshock, reducing their usefulness for deriving strength information. The free-surface samples, which were steps on a single piece of steel, showed lower wavespeeds for thin (1 mm) samples than for thicker (2 or 4 mm) samples. A configuration used for the last three shots allows release information to be determined from these free surface samples. The sample strength appears to increase with stress from ~1 GPa to ~ 3 GPa over this range, consistent with other recent work but about 40% above the Steinberg model.

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TYPE SAND Report YEAR 2012
DOIOSTI

Simulation of Photovoltaic Power Output for the Salt River Project Integration Study

Hansen, Clifford; Luketa-Hanlin, Amanda

One year of power output was simulated at one-minute intervals for each of fourteen hypothetical utility-scale photovoltaic power plants and for the aggregate power output from a large number of distribution-connected photovoltaic systems. For utility-scale plants, the simulation first constructs one-year time series of global horizontal irradiance at one-minute intervals at each plant location, and a performance model translates irradiance and weather information to AC output power. Distribution-connected photovoltaic systems comprise a variety of system configurations: residential-scale rooftop systems at various tilts; commercial-scale flat-roof mounted systems; and commercial-scale ground-mounted tracked systems. For distribution-connected PV systems, the simulation estimates the time series of spatially-averaged irradiance for the region containing the systems, and the performance model is employed to estimate power aggregate power from all systems. The simulation results are validated by comparing statistics for the time series of irradiance with statistics for measured irradiance within the region.

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TYPE SAND Report YEAR 2012
DOIOSTI
Results 61001–61100 of 99,299
Results 61001–61100 of 99,299