US Government As Represented by the Secretary of the Army

Edward J Troiano

Mark A Johnson

Moayyed A Hussain

Anthony P Parker

Mark Fleszar

John H Underwood

Craig Stanton

A simple, inexpensive, and fast method of establishing if a defect does or does not exist within a thick-walled solid geometry, which is especially useful to detect if such a defect, a crack, exists within a gun barrel. With further analysis, the method allows not only the identification of the defect's presence; but, a means of establishing the size thereof&#x2014;which, for example, is critical to understanding if a gun tube has a defect that would warrant its being taken out of service for the safety of its crew or removed from manufacturing. The method involves creating an acoustic vibration in the particular thick-walled, solid geometry, esp. a gun barrel, and observing the vibration pattern which results. The size of the particular defect can be ascertained by a) manually using a correlation between the magnitude of the defect and the relative changes in the decay coefficient or shifts in frequency data or (b) automatically using a Bayes maximum likelihood, statistical pattern classification algorithm and a library comprised of either the decay coefficients or the means and covariances of defect-free and cracked objects.

Crack detection in thick-walled cylinders

A manufacturing method includes a first step of performing swage autofrettage on an object; a second step of heat soaking the object; and a third step of performing hydraulic autofrettage on the object. The second and third steps may be repeated one or more times. A final step may be heat soaking the object. The object may be, for example, a pressure vessel or gun barrel.

Multiple autofrettage

A segmented pilot ball is assembled within a spherical bearing for procesg a self lubricating liner. The two-part pilot ball includes a major annularly shaped hollow segment with a smaller cutout portion. A minor segment has the shape of the cutout portion so that when the major and minor segments are assembled, the minor segment complements the major segment to define the spherical outer shape of the pilot ball. An inner plug is shaped to fit within the assembled major and minor segments to provide a compressive force and interior support to the pilot ball within the outer race of the bearing. The bearing is formed by applying uncured liner material to the inner surface of the outer race either before or while rotating the outer race, to evenly distribute the liner and to increase the rate of drying. The outer race is then rotated while heating, in order to reduce liner flow and to form a uniform coating. The major segment is inserted inside the outer race, and is then rotated so that it mates with the outer race. The minor segment is inserted into position for assembly with the major segment, and the plug is then inserted co-axially with the assembled major and minor segments to form the pilot ball. Once the bearing is formed and the outer race is cured, the pilot ball is disassembled and removed.

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Schenectady, NY, United States of America

Edward J Troiano