Metallurgical and Mechanical Analyses of a Failed Fuse Holder from the XM264 Rocket
Abstract
This rocket is used to provide a concealing smoke screen. The rocket warhead consists of an aluminum case, an M439 electronic time fuse, an expulsion charge assembly, 72 smoke pellets made from a red phosphorus composition, 18 felt separators, a base nose cone assembly, and an outer nose cone assembly. The fuse, enclosed by a fuse holder, is located in the warhead base. The fuse is detonated at a predetermined time to ignite the expulsion charge. One aluminum fuse holder from the XM264 red phosphorus smoke rocket that failed during testing was analyzed to determine the cause of failure. Cracks were observed on both sides of the die cast fuse holder. Radiographic analysis was conducted to confirm the damage observed. All dimensions of this failed fuse holder were found to be within requirements specified in the part drawing, except the central cup. This region was 30% thinner than specified. Metallographic analysis indicated a mixed fine-grained and eutectic structure in the thin center-disc area and a large dendritic structure in the thick circumferential area. Fractographic examination of the fracture surface showed fracture initiating at large brittle impurity-rich particles. A stress analysis concluded that failure occurred as a result of insufficient material thickness in the central cup region and from stress concentration around the wall edge. Suggestions for a new design with thicker central sections were confirmed by U.S. Army Chemical Research Development and Engineering Center at APG, MD.
Document Details
- Document Type
- Technical Report
- Publication Date
- Aug 01, 1991
- Accession Number
- ADA241530
Entities
People
- John C. Beck
- Martin G. Wells
- Wego Wang