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Void nucleation, growth, and coalescence in A356 aluminum notch specimens was determined from a combination of experiments, finite element analysis, nondestructive analysis, and image analysis. Notch Bridgman tension experiments were performed on specimens to failure and then other specimens were tested to 90%, 95%, and 98% of the failure load. The specimens were evaluated with nondestructive X-ray tomography and optical image analysis. Finite element simulations of the notch tests were performed with an elastic–plastic internal state variable material model that incorporated the pertinent microstructures (silicon particle volume fraction and size distribution and porosity volume fraction and size distribution). Parametric finite element simulations were performed to give insight into various initial conditions and responses of the notch tensile bars. The various methods all corroborated the same damage progression.

As a result of an arms reduction treaty between the United States and the Russian Federation, both countries will each be storing over 40,000 containers of plutonium. To help detect any deterioration of the containers and prevent leakage, we are designing a digital radiography and computed tomography system capable of handling this volume reliably, efficiently, and at a lower cost.

We apply dual-band infrared (DBIR) imaging as a dynamic thermal tomography tool for wide area inspection of a Boeing 737 aircraft (owned by the FAA/AANC at the Sandia hangar in Albuquerque, NM) and several Boeing KC-135 aircraft panels (used for the round robin experiment conducted at Tinker AFB, OK). Our analyses are discussed in this report. After flash-heating the aircraft skin, we record synchronized DBIR images every 40 ms, from onset to 8 seconds after the heat flash. We analyze selective DBIR image ratios which enhance surface temperature contrast and remove surface-emissivity clutter (from dirt, dents, tape, markings, ink, sealants, uneven paint, paint stripper, exposed metal and roughness variations). The Boeing 737 and KC-135 aircraft fuselage panels have varying percent thickness losses from corrosion. We established the correlation of percent thickness loss with surface temperature rise (above ambient) for a partially corroded F-18 wing box structure (with a 2.9 mm uncorroded thickness) and several aluminum plates (with 1.0, 1.1, 2.3, and 3.9 mm thicknesses) which had 6 to 60% thickness losses at milled flat-bottom hole sites.© (1993) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

The beta-backscatter method of measuring thin laminates on thick substrates was evaluated for possible production inspection applications of aluminum ion plating on U-0.75 Ti parts. The choice of radiation source, the effects of surface curvature, and background radiation from uranium isotopes were examined. Measurements of aluminum coatings on U-0.75 Ti test coupons and cylindrical parts were made with the ..beta..-backscatter technique and compared to ..cap alpha..-transmission measurements.

The efficiency of a silicon surface-barrier detector with a proton radiator for detecting 14 MeV neutrons was measured as 0.29% using a polyethylene radiator, and 0.34% using a paraffin radiator. Absolute fluence and timing information can be obtained by counting the number and time distribution of pulses from the radiator/surface-barrier detector. Fluence values with an accuracy better than +- 10% could be obtained with a single 1 cm/sup 2/ detector at fluence levels greater than 3.5 x 10/sup 4/ n/cm/sup 2/, and +- 20% at fluence levels greater than 8.6 x 10/sup 3/ n/cm/sup 2/. The volume occupied by a single 1 cm/sup 2/ area surface-barrier detector could be as small as 0.1 cm/sup 3/, satisfying the requirement of miniaturization for many JTA applications.