Abstract: The invention determines density of a sample while the sample is immersed in a gaseous medium having variable density. The apparatus includes a chamber for containing the gaseous medium and the sample, means for selectively varying the density of the gaseous medium over a range of densities, and means for producing electrical signals related to the density of the gaseous medium. In the chamber is a balance beam having a sample pan at a first end and a coil assembly at an opposing second end. Also at the second end of the beam is a first counter-weight having a volume and mass which is substantially equivalent to the volume and mass of sample pan, and which creates a moment that is substantially equivalent to the moment created by the sample pan. At the first end of the beam is a second counter-weight having a volume and mass which is substantially equivalent to the volume and mass of the coil assembly, and which creates a moment which is substantially equivalent to the moment created by the coil assembly.

Abstract: The invention provides a method and apparatus for determining a relationship between hydrostatic stress and volumetric strain in a sample of compressible material, where the sample is immersed in a fluid medium having a density. The method includes steps of varying the hydrostatic stress on the sample by changing the density of the fluid medium over a range of densities, determining a change in apparent weight of the sample as the density of the fluid medium is changed, and determining the volumetric strain in the sample based on the change in apparent weight of the sample and the change in density of the fluid medium.

Abstract: A multidimensional surface mechanics measurement system applies forces to a surface while minimizing coupling between the forces so applied. The system includes first, second, and third elongate members, a coupler for coupling the elongate members together, and a probe connected to the coupler having a contact point for contacting the surface. The first elongate member extends in a first axial direction that is substantially normal to the surface, the second elongate member extends in a second axial direction that is substantially orthogonal to the first axial direction, and the third elongate member extends in a third axial direction that is substantially orthogonal to the first and second axial directions. Desired relationships between the free length and diameter, and between the axial stiffness and transverse stiffness, and the orthogonal relative positioning of the elongate members, minimizes cross-talk between the measurement axes while maintaining the necessary structural rigidity.

Abstract: The invention determines density of a sample while the sample is immersed in a gaseous medium having variable density. The apparatus includes a chamber for containing the gaseous medium and the sample, means for selectively varying the density of the gaseous medium over a range of densities, and means for producing electrical signals related to the density of the gaseous medium. In the chamber is a balance beam having a sample pan at a first end and a coil assembly at an opposing second end. Also at the second end of the beam is a first counter-weight having a volume and mass which is substantially equivalent to the volume and mass of sample pan, and which creates a moment that is substantially equivalent to the moment created by the sample pan. At the first end of the beam is a second counter-weight having a volume and mass which is substantially equivalent to the volume and mass of the coil assembly, and which creates a moment which is substantially equivalent to the moment created by the coil assembly.