Comparison of Autofrettage Calculation Methods
Abstract
The use of residual bore compression to strengthen cannon barrels can be traced back to an 1856 test conducted by Captain Thomas Jefferson Rodman using ten-inch columbiads (ref 1). His residual stress was produced by a hollow casting method, and it is clear that Rodman did not understand the true reason for the nine-factor improvement in fatigue life over a solid cast gun. This problem had been corrected by l880, when the Army was using the Rodman plan casting method and was measuring the residual stress by a slitting method performed on test rings (ref 2). By 1890, the use of steel for cannons was producing an active discussion of the relative merits between compound guns made by shrinking several hoops together and wire wound (square wire) guns. Both produced high residual hoop compression at the bore. Thus, the compound construction became the favored method for cannons, but wire-wound pressure vessels are still used for other applications. However, the autofrettage method was just around the corner and this was well established by 1930 (ref 3). The design and manufacture of medium-size monoblock cannons after 1960 was greatly aided by the development of the swage process for producing the residual bore compression. This is still the primary method used at Watervliet Arsenal, but the hydraulic method remains popular for most high-pressure applications.
Document Details
- Document Type
- Technical Report
- Publication Date
- Jan 01, 2001
- Accession Number
- ADA387191
Entities
People
- Edward Troiano
- G. P. O'hara
Organizations
- United States Army Armament Research, Development and Engineering Center