Accession Number : ADA321163

Title :   Failure Analysis and Mechanical Tests of Failed Aluminum Alloy 7277 Rivets on Armored Vehicle Launched Bridges.

Descriptive Note : Final rept. Apr 94-Sep 95,

Corporate Author : ARMY RESEARCH LAB FORT BELVOIR VA

Personal Author(s) : Homer, Howard E.

PDF Url : ADA321163

Report Date : SEP 1996

Pagination or Media Count : 84

Abstract : A number of the manufactured buttonheads of the 0.75-in-diameter hot-driven aluminum rivets (made of alloy 7277) were found to have fallen off Class 60 Armored Vehicle Launched Bridges (AVLB) that had been employed in Saudi Arabia during Operation Desert Storm. The presence of white corrosion deposits observed on the fractured surfaces of the failed heads indicated corrosion. The objectives of the work were to determine the cause of rivet head failures and conduct a number of mechanical tests to evaluate the integrity of the corroded rivets without their heads or with cracked heads. Corroded aluminum rivet samples were obtained, examined, and tested. The rivet head failures were caused by stress corrosion cracking initiated in the sharp head-to-shank fillets that acted as stress raisers. Depending on the amounts of the white corrosion products formed, they bound the headless rivet shanks in the rivet holes. No failures similar to those in the rivet heads were found in the rivet shanks. With corroded shanks remaining in the rivet holes of the bridge parts and with major stresses acting in shear on the shanks, the corroded rivet shanks or the crack rivet buttonheads can still allow the bridge to function satisfactorily until the corroded aluminum rivets are replaced.

Descriptors :   *MECHANICAL PROPERTIES, *ALUMINUM ALLOYS, *FAILURE, *RIVETS, *ARMORED VEHICLES, *BRIDGES, TEST AND EVALUATION, STRESSES, MILITARY OPERATIONS, FUNCTIONS, CORROSION, CRACKS, FRACTURE(MECHANICS), SURFACES, HOLES(OPENINGS), SAMPLING, LAUNCHING, PARTS, SAUDI ARABIA.

Subject Categories : Inorganic Chemistry
      Properties of Metals and Alloys
      Couplers, Fasteners, and Joints
      Military Operations, Strategy and Tactics

Distribution Statement : APPROVED FOR PUBLIC RELEASE