Neutron apparatus for measuring strain in composites
AssigneeThe United States of America as represented by the United States Department of Energy
InventorsDavid S. Kupperman, Saurindranath Majumdar, John F. Faber, Jr., J. P. Singh
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Abstract
A method and apparatus for orienting a pulsed neutron source and a multi-angle diffractometer toward a sample of a ceramic-matrix or metal-matrix composite so that the measurement of internal strain (from which stress is calculated) is reduced to uncomplicated time-of-flight measurements.
Claims12
A method for real-time simultaneous measurement of strain in the constituents of a composite comprising:
- directing a polychromatic beam of neutrons from a pulsed source toward a sample,
- orienting a multi-angle diffractometer so that two opposite detectors are on a line perpendicular to said neutron beam,
- measuring, using Bragg's law, the strain on a vector bisecting the angle between said neutron beam and said line perpendicular to said neutron beam.
A method of determining the strain at the fiber-matrix interface in a ceramic-matrix or metal-matrix composite comprising:
- determining the lattice spacing d over a volume of a strain-free powdered sample of a ceramic-matrix or metal-matrix composite,
- determining the lattice spacing d.sub.0 associated with a particular lattice plane in a stressed sample of said composite,
- calculating the strain associated with said lattice plane using the formula e=(d-d.sub.0)/d.sub.0.
An apparatus for the real-time measurement of strain comprising:
- a pulsed neutron source emitting a neutron beam,
- a multi-angle diffractometer oriented so that two opposite detectors are on a line perpendicular to said neutron beam,
- means for determining the time of flight of said diffracted neutrons from a sample to said detectors.
Dependencies are inferred from the claim text.