Crack Initiation and Propagation on the M140 Gun Mount Recoil Spring

摘要

The study was a research program to determine and correct the premature failure of the M140 gun mount recoil spring. Laboratory tests were conducted in an attempt to produce crack initiation and propagation on the outside spring diameter. The compressed spring assembly was bolted to the table of a planer, and the outside coil diameter was rubbed with a specially designed fixture. Three tests of at least 1000 cycles each were performed. The spring was examined periodically throughout the tests for crack formations, however, no evidence of cracks was discovered. An analytical study was made by Foster-Miller Associates, Incorporated of Waltham, Massachusetts in which the major theories available in literature for describing fatigue crack initiation and propagation were reviewed. (Author)