National and international comparisons in Rockwell hardness tests show significant differences. Uncertainties in the geometry of the Rockwell diamond indenters are largely responsible for these differences. By using a stylus instrument, with a series of calibration and check standards, and calibration and uncertainty calculation procedures, we have calibrated the microform geometric parameters of Rockwell diamond indenters. These calibrations are traceable to fundamental standards. The expanded uncertainties (95 % level of confidence) are ±0.3 μm for the least-squares radius; ±0.01° for the cone angle; and ±0.025° for the holder axis alignment calibrations. Under ISO and NIST guidelines for expressing measurement uncertainties, the calibration and uncertainty calculation procedure, error sources, and uncertainty components are described, and the expanded uncertainties are calculated. The instrumentation and calibration procedure also allows the measurement of profile deviation from the least-squares radius and cone flank straightness. The surface roughness and the shape of the spherical tip of the diamond indenter can also be explored and quantified. Our calibration approach makes it possible to quantify the uncertainty, uniformity, and reproducibility of Rockwell diamond indenter microform geometry, as well as to unify the Rockwell hardness standards, through fundamental measurements rather than by performance comparisons.

Summary Table of ContentsThis report summarizes the available data on the airborne sound transmission loss properties of wood-frame construction and evaluates the methods for predicting the airborne sound transmission loss. The first part of the report comprises a summary of sound transmission loss data for wood-frame interior walls and floor-ceiling construction. Data bases describing the sound transmission loss characteristics of other building components, such as windows and doors, are discussed.The second part of the report presents the prediction of the sound transmission loss of wood-frame construction. Appropriate calculation methods are described both for single-panel and for double-panel construction with sound absorption material in the cavity. With available methods, single-panel construction and double-panel construction with the panels connected by studs may be adequately characterized. For double-panel construction with the panels unconnected (double-row-of-stud construction), however, the available prediction methods significantly overestimate the measured sound transmission loss performance. A new prediction method has been developed that appears to yield better results than previously available theoretical methods. This new prediction method is described and illustrated using several examples.Technical appendices are included that summarize laboratory measurements, compare measurement with theory, describe details of the prediction methods, and present sound transmission loss data for common building materials.

Floor vibrations induced in a Bureau of Engraving and Printing building by a recently-installed perforator were investigated by measuring relative acceleration amplitudes and phase relationships between a reference position and points on a grid laid out on the affected floor. From these measurements, it was possible to determine mode shapes, resonant frequencies and displacement amplitudes. On the basis of the displacement amplitudes, anticipated cyclic stresses in the structural system were estimated. The results of the measurements and analysis were compared with existing data on vibration-induced structural damage and fatigue strength of steel and reinforced concrete. Damping ratios were also determined in a separate test, in order to ascertain at later dates whether any structural deterioration is taking place.

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